AGINGSCIENCES™ – Anti-Aging Firewalls™

It has long been suspected that polymorphisms in the cholesterol ester transfer protein (CETP) gene confer important longevity benefits.  This post is prompted by recent news about the gene.  The post reviews what is known about the actions of the gene and its variants, and speculates about how this knowledge could lead to a new anti-aging intervention.

CEPT inhibition and coronary heart disease

The interest in the CEPT gene goes back a long time.  A 2000 publication states “Cholesteryl ester transfer protein (CETP) is a plasma glycoprotein that mediates the transfer of cholesteryl ester from high density lipoproteins (HDL) to triglyceride-rich lipoproteins in exchange for triglycerides. — Several genetic variants at CETP locus have been identified and they have been generally associated with increased HDL-cholesterol concentrations.”  Thus, it was originally thought that these gene variations could be life-extending because the higher HDL would be cardioprotective.   Interest developed in drugs that limit the expression of CEPT, the hope being that they would have a profound effect on raising HDL cholesterol.  “In our view, CETP inhibitors in combination with statins will be profoundly beneficial in reducing human atherosclerosis, primarily because they normalize HDL particles and prevent the transfer of cholesteryl ester from HDL to atherogenic lipoproteins(ref).” “A relative new strategy for raising HDL cholesterol, inhibition of cholesteryl ester transfer protein (CETP), is markedly effective. CETP inhibitors prevent the transfer of cholesteryl ester from HDL to triglyceride-rich lipoproteins in exchange for triglyceride. One inhibitor, torcetrapib, binds to CETP on HDL, markedly increases HDL cholesteryl ester, — (ref) .“   

Unfortunately torcetrapib had serious problems.  “A large clinical trial in patients with CAD who were taking atorvastatin was recently stopped prematurely because of excess mortality in those receiving torcetrapib versus placebo, and 2 other trials reported no benefit of torcetrapib on coronary atherosclerosis or carotid intima-media thickness as compared with subjects on atorvastatin alone. The adverse effects of torcetrapib may be compound specific, and because the crystal structure of CETP is now known, it should be possible to develop more optimal CETP inhibitors that do not form a nonproductive complex with CETP on the HDL particle, as has been reported for torcetrapib(ref).”  A 2009 report indicates ”Recently, Phase III clinical studies of torcetrapib, one of the CETP inhibitors developed by researchers at Pfizer, were unexpectedly terminated because of an increase in cardiovascular events and mortality. Torcetrapib has some compound-specific and off-target effects, such as raising blood pressure and aldosterone, which could affect an increase in cardiovascular events and mortality.”

The abandonment  of torcetrapib due to side effects dealt a mighty blow to the area of pharmacologic CETP inhibition, although not necessarily a fatal one.  See JTT-705: is there still future for a CETP inhibitor after torcetrapib? Also, “Dalcetrapib (JTT-705) and anacetrapib, which have not been reported to have the off-target effects of torcetrapib, are currently in Phase III. They are expected to reveal whether CETP inhibition is beneficial for atherosclerosis-related diseases(ref).”  Results of the safety and tolerability study of Dalcetrapib were promising(ref).  A clinical trial of the Tolerability and Efficacy of Anacetrapib for patients with coronary heart disease is ongoing(ref).

CEPT gene variations and cardiovascular diseases

Most of the studies of CEPT have looked at the CEPT gene and its variants in the context of HDL and impact on cardiovascular disease processes.  The 2009 report Polymorphism in the CETP gene region, HDL cholesterol, and risk of future myocardial infarction: Genomewide analysis among 18 245 initially healthy women from the Women’s Genome Health Study looks at whether CEPT and HDL-C have causal roles in atherothrombosis. “One method to evaluate this issue is to examine whether polymorphisms in the CETP gene that impact on HDL-C levels also impact on the future development of myocardial infarction. METHODS AND RESULTS: In a prospective cohort of 18 245 initially healthy American women, we examined over 350 000 singe-nucleotide polymorphisms (SNPs) first to identify loci associated with HDL-C and then to evaluate whether significant SNPs within these loci also impact on rates of incident myocardial infarction during an average 10-year follow-up period. Nine loci on 9 chromosomes had 1 or more SNPs associated with HDL-C at genome-wide statistical significance (P<5×10(-8)). However, only SNPs near or in the CETP gene at 16q13 were associated with both HDL-C and risk of incident myocardial infarction (198 events). For example, SNP rs708272 in the CETP gene was associated with a per-allele increase in HDL-C levels of 3.1 mg/dL and a concordant 24% lower risk of future myocardial infarction (age-adjusted hazard ratio, 0.76; 95% CI, 0.62 to 0.94), consistent with recent meta-analysis. Independent and again concordant effects on HDL-C and incident myocardial infarction were also observed at the CETP locus for rs4329913 and rs7202364. Adjustment for HDL-C attenuated but did not eliminate these effects. CONCLUSIONS: In this prospective cohort of initially healthy women, SNPs at the CETP locus impact on future risk of myocardial infarction, supporting a causal role for CETP in atherothrombosis, possibly through an HDL-C mediated pathway.”

A 2006 study I405V polymorphism of the cholesteryl ester transfer protein (CETP) gene in young and very old people reports “We recruited 100 healthy young people (median age 31 years) and 100 very old people (median age 89 years) and analysed their DNA for the presence of I405V polymorphism. — The frequency of the VV genotype in very old people was more than double that in the young population. Subjects with this genotype had lower serum concentrations of CETP. Young people with the V/V genotype had a less atherogenic lipoprotein profile (lower total cholesterol, LDL cholesterol, Apo B, and Apo B/Apo A-I ratio) than those with the I/V or I/I genotypes. The older subjects, particularly the older women with the V/V genotype, had larger LDL than the young people. The prevalence of clinical endpoints was much lower among the very old people with the V/V genotype. In conclusion, the V/V genotype of the I405V CETP polymorphism is more frequent among very old people than young ones, and is associated with a lower incidence of vascular damage.”

A number of other studies have supported a possible life-extending role for CEPT polymorphisms, but always in the contexts of lipids, raising HDL, and preventing cardiovascular diseases.  See, for example, this list of citations.  

Latest news: CEPT and dementia

A break in the pattern was reported two days ago.   Going back a couple of years, researchers at the Albert Einstein College of Medicine of Yeshiva University conducted a study where they searched for the presence of “longevity genes” in a cohort of aged Ashkenazi Jews.  As reported in a 2008 Science Daily article “Participating in the study were 305 Ashkenazi Jews more than 95 years old and a control group of 408 unrelated Ashkenazi Jews. — All participants were grouped into cohorts representing each decade of lifespan from the 50’s on up. Using DNA samples, the researchers determined the prevalence in each cohort of 66 genetic markers present in 36 genes associated with aging. — The Einstein researchers were able to construct a network of gene interactions that contributes to the understanding of longevity. In particular, they found that the favorable variant of the gene CETP acts to buffer the harmful effects of the disease-causing gene Lp(a).” 

A January 13 2010 report ‘Longevity Gene’ Helps Prevent Memory Decline and Dementia in Science Daily discusses a January report on JAMA describing further investigations by the same researchers relating the CEPT gene in the Ashkenazi Jews to the risks of Alzheimer’s Disease.  The JAMA report is entitled Association of a Functional Polymorphism in the Cholesteryl Ester Transfer Protein (CETP) Gene With Memory Decline and Incidence of Dementia.  “Objective  To test the hypothesis that a single-nucleotide polymorphism (SNP) at CETP codon 405 (isoleucine to valine V405; SNP rs5882) is associated with a lower rate of memory decline and lower risk of incident dementia, including Alzheimer disease (AD).”  “The researchers of the current study hypothesized that the CETP longevity gene might also be associated with less cognitive decline as people grow older. To find out, they examined data from 523 participants from the Einstein Aging Study, an ongoing federally funded project that has followed a racially and ethnically diverse population of elderly Bronx residents for 25 years. — At the beginning of the study, the 523 participants — all of them 70 or over — were cognitively healthy, and their blood samples were analyzed to determine which CETP gene variant they carried. They were then followed for an average of four years and tested annually to assess their rates of cognitive decline, the incidence of Alzheimer’s disease and other changes.  – – “We found that people with two copies of the longevity variant of CETP had slower memory decline and a lower risk for developing dementia and Alzheimer’s disease,” says Amy E. Sanders, M.D., assistant professor in the Saul R. Korey Department of Neurology at Einstein and lead author of the paper. “More specifically, those participants who carried two copies of the favorable CETP variant had a 70 percent reduction in their risk for developing Alzheimer’s disease compared with participants who carried no copies of this gene variant. — The favorable gene variant alters CETP so that the protein functions less well than usual(ref).”

The new news is in fact not completely new.  A  December 2006 news report states “An Israeli study involving 158 people who lived to 95 or beyond has found that those who inherit a particular version of the gene CETP are twice as likely to have a sharp and alert brain when they are elderly. — They are also five times less likely than people with a different version of CETP to develop Alzheimer’s disease and other forms of dementia, according to the study by a team at the Albert Einstein College of Medicine at Yeshiva University. — About 8 per cent of people aged 70 have the CETP variant, but this rises to 25 per cent among centenarians. This is thought to play a key role in explaining why some people live to very old ages.  The research, published in the journal Neurology, found that those with CETP VV were twice as likely as the others to have good brain function. — A separate investigation of 124 Ashkenazi Jews aged between 75 and 85 found that CETP VV appeared to protect against dementia: those with the variant were five times less likely to suffer from it.”

The researchers at the Albert Einstein College of Medicine also have found that telomere maintenance plays a very important role in maintaining the longevity of the centenarian Ashkenazi Jews, as reported in the November 2009 blog entry Timely telomerase tidbits. From a November 2009 Science Daily story: “As we suspected, humans of exceptional longevity are better able to maintain the length of their telomeres,” said Yousin Suh, Ph.D., associate professor of medicine and of genetics at Einstein and senior author of the paper. “And we found that they owe their longevity, at least in part, to advantageous variants of genes involved in telomere maintenance. — More specifically, the researchers found that participants who have lived to a very old age have inherited mutant genes that make their telomerase-making system extra active and able to maintain telomere length more effectively. For the most part, these people were spared age-related diseases such as cardiovascular disease and diabetes, which cause most deaths among elderly people.” 

So, variants in the CEPT gene appear to be protective against cardiovascular diseases and also protective against memory decline and dementia. Further, drugs are in Phase III clinical trials that may mimic the effects of these gene variants.   As usual several questions are still to be answered including: 

·        Do variations in the CEPT gene actually confer overall additional longevity or simply accompany longevity conferred by other genes?  If so, which variations are most effective and how much additional longevity can they provide? 

·        In the centenarians, what is the relationship between having extraordinary telomerase- maintenance genes and CEPT polymorphic genes?  Is it coincidental or in any sense causative that some centenarians have both of these kinds of gene variations?

·        In the event that effective and safe pharmacological means are established to inhibit CEPT expression (Dalcetrapib or Anacetrapib), will these be longevity-enhancing drugs? 

·        If so, how will they work: by maintaining high HDL levels and protecting cardiovascular health, by protecting mental functioning and preventing dementia, and/or by additional means yet to be characterized?

·        Are there nutraceuticals that inhibit CEPT expression and that could provide similar benefits?

A new study reported in the press this week looks at the relationship of exercise to expression of telomerase and telomere lengths in athletes and non-athletes.  Other studies on the same topic have appeared in the last year or so.  My purpose here is to review these studies in the context of some earlier studies. It is not just a simple matter of “the more and the harder the exercise, the better.”

The 12^th theory of aging in my treatise Telomere Shortening and Damage forwards the hypothesis that longer telomere lengths are likely to be correlated with longer lifespans and that keeping one’s telomeres as long as possible through expression of telomerase is vital for health and longevity. I have devoted numerous blog entries to telomeres and telomerase, including most recently Timely telomerase tidbits, Breakthrough telomere research finding, and Telomere and telomerase writings. On the other hand, it is also well established that regular exercise is also strongly supportive of longevity(ref)(ref)(ref).  The mechanisms through which exercise improves health and life expectancy hitherto appeared to be complex and unclear.  The new research suggests that telomere extension may be a key mediator of the health and longevity benefits of regular exercise.

Sustained exercise can keep leukocytes younger

The latest study, an e-publication dated January 8 2010 from a University of Colarado group, is Leukocyte Telomere Length is Preserved with Aging in Endurance Exercise-Trained Adults and Related to Maximal Aerobic Capacity.  “To determine if age-associated reductions in TL (telomere length) are related to habitual endurance exercise and maximal aerobic exercise capacity (maximal oxygen consumption, VO(2)max), we studied groups of young (18 – 32 years; n = 15, 7m) and older (55 – 72 years; n = 15, 9m) sedentary and young (n = 10, 7m) and older endurance exercise-trained (n = 17, 11m) healthy adults. Leukocyte TL (LTL) was shorter in the older (7059 +/- 141bp) vs. young (8407 +/- 218) sedentary adults (P < 0.01). LTL of the older endurance-trained adults (7992 +/- 169bp) was approximately 900bp greater than their sedentary peers (P < 0.01) and was not significantly different (P=0.12) from young exercise-trained adults (8579 +/- 413). — Our results indicate that LTL is preserved in healthy older adults who perform vigorous aerobic exercise and is positively related to maximal aerobic exercise capacity. This may represent a novel molecular mechanism underlying the “anti-aging” effects of maintaining high aerobic fitness.”

So, older folks who vigorously exercise keep up their leukocyte telomere lengths and folks who sit around watching TV instead do not.  This message seems repeated in several other research reports. A 2009 study, this time from a German group, is: Beneficial Effects of Long-term Endurance Exercise on Leukocyte Telomere Biology.  “This study examines telomere biology and senescence-associated factors in endurance athletes and matched controls without physical activity. –Methods: Leukocytes where isolated from the peripheral blood of professional young track & field athletes (n=32, age 20.4 years, running 73±5 km/week), aged athletes performing regular endurance training (n=25, age 51.1 years, running 80±8 km/week, 35 years training history) and two control groups of age-matched, physically inactive healthy volunteers (26 young and 21 aged subjects).  –Results: Telomere repeat amplification protocols revealed an activation of leukocyte telomerase in young athletes to 256±19% and in elderly athletes to 182±11% compared to controls. Western blots showed an up-regulation of the telomere-capping protein TRF2 in young (179±1%) as well as in aged athletes (176±10%). FlowFISH assays and real-time PCR measurements of leukocyte telomere length showed no difference between young athletes and young controls. Sedentary elder controls exhibited a significant reduction of leukocyte telomere length (FF: 53±3%; PCR: 70±8%; vs. young controls). Importantly, there was a striking conservation of telomere length in aged athletes (FF: 88±4%; PCR: 84±7%; vs. young controls). Further analysis of telomere-associated proteins and cellular senescence regulators demonstrated an increase of TRF2, Ku70 and Ku80 mRNA and a reduced protein expression of Chk2, p16 and p53 in aged athletes compared to untrained elder controls.”

More or less the same story.  Among the younger people exercise seems to have a strong effect on leukocyte telomerase expression but no effect on telomere lengths.  But in the older folks, only those who exercised kept up most of their telomere lengths.  Further, their cells showed markedly lower levels of senescence markers.  As far as leukocytes are concerned, vigorous regular exercise definitely seems to keep them young. 

A 2009 mouse and human study Physical Exercise Prevents Cellular Senescence in Circulating Leukocytes and in the Vessel Wall looks a bit further at the molecular dynamics of exercise and comes to a consistent conclusion.  “Exercise upregulated telomerase activity in the thoracic aorta and in circulating mononuclear cells compared with sedentary controls, increased vascular expression of telomere repeat-binding factor 2 and Ku70, and reduced the expression of vascular apoptosis regulators such as cell-cycle–checkpoint kinase 2, p16, and p53. Mice preconditioned by voluntary running exhibited a marked reduction in lipopolysaccharide-induced aortic endothelial apoptosis. Transgenic mouse studies showed that endothelial nitric oxide synthase and telomerase reverse transcriptase synergize to confer endothelial stress resistance after physical activity. To test the significance of these data in humans, telomere biology in circulating leukocytes of young and middle-aged track and field athletes was analyzed. Peripheral blood leukocytes isolated from endurance athletes showed increased telomerase activity, expression of telomere-stabilizing proteins, and downregulation of cell-cycle inhibitors compared with untrained individuals. Long-term endurance training was associated with reduced leukocyte telomere erosion compared with untrained controls. — Conclusions— Physical activity regulates telomere-stabilizing proteins in mice and in humans and thereby protects from stress-induced vascular apoptosis.”

Watch out for your muscle satellite cells

There is a caution however, for more or harder exercise is not always better.  And leukocytes are not the only relevant cells to consider.  Earlier studies indicate that too strenuous or prolonged exercise can lead to serious depletion of telomerase in muscle satellite cells.  Muscle satellite cells “are small mononuclear progenitor cells with virtually no cytoplasm found in mature muscle. They are found sandwiched between the basement membrane and sarcolemma (cell membrane) of individual muscle fibres, and can be difficult to distinguish from the sub-sarcolemmal nuclei of the fibres. Satellite cells are able to differentiate and fuse to augment existing muscle fibres and to form new fibres. These cells represent the oldest known adult stem cell niche, and are involved in the normal growth of muscle, as well as regeneration following injury or disease.”   

Under conditions of hard exercise satellite cells can be forced into multiple rounds of duplication and differentiation leading to telomere shortening.  The 2003 publication Athletes with exercise-associated fatigue have abnormally short muscle DNA telomeres tells the story. “Although the beneficial health effects of regular moderate exercise are well established, there is substantial evidence that the heavy training and racing carried out by endurance athletes can cause skeletal muscle damage. This damage is repaired by satellite cells that can undergo a finite number of cell divisions. — In this study, we have compared a marker of skeletal muscle regeneration of athletes with exercise-associated chronic fatigue, a condition labeled the “fatigued athlete myopathic syndrome” (FAMS), with healthy asymptomatic age- and mileage-matched control endurance athletes. — Three of the FAMS patients had extremely short telomeres (1.0 +/- 0.3 kb). The minimum TRF lengths of the remaining 10 symptomatic athletes (4.9 +/- 0.5 kb, P < 0.05) were also significantly shorter that those of the control athletes. CONCLUSION: These findings suggest that skeletal muscle from symptomatic athletes with FAMS show extensive regeneration which most probably results from more frequent bouts of satellite cell proliferation in response to recurrent training- and racing-induced muscle injury.”

The 2008 study The effects of regular strength training on telomere length in human skeletal muscle looked at power lifters and showed that long-term exercise is not necessarily associated with satellite cell telomere loss although lifting heavier loads mean more loss.  “These results show for the first time that long-term training is not associated with an abnormal shortening of skeletal muscle telomere length. Although the minimum telomere length in PL (power lifters) remains within normal physiological ranges, a heavier load put on the muscles means a shorter minimum TRF length in skeletal muscle.”

The effect of exercise on telomeres in satellite cells is further reported in the 2009 publication The biology of satellite cells and telomeres in human skeletal muscle: effects of aging and physical activity.  “New insights suggest that telomeres in skeletal muscle are dynamic structures under the influence of their environment. When satellite cells are heavily recruited for regenerative events as in the skeletal muscle of athletes, telomere length has been found to be either dramatically shortened or maintained and even longer than in non-trained individuals. This suggests the existence of mechanisms allowing the control of telomere length in vivo.”  Whether satellite cell telomeres get shorter or longer or stay the same with exercise depend, among other matters, on the expression of telomerase in the satellite cells as a result of the exercise, and this in turn depends on several factors including physical condition of the person and the nature of the exercise.

Finally a late 2008 study report Relationship between physical activity level, telomere length, and telomerase activity looks at the results of exercise on telomeres in peripheral blood mononuclear cells (PBMCs). “A Peripheral Blood Mononuclear Cell (PBMC) is any blood cell having a round nucleus. For example: a lymphocyte, a monocyte or a macrophage. These blood cells are a critical component in the immune system to fight infection and adapt to intruders. The lymphocyte population consists of T cells (CD4 and CD8 positive ~75%), B cells and NK cells (~25% combined)(ref).”  According to the report:  “The purpose of this study was to examine the relationship of exercise energy expenditure (EEE) with both telomere length and telomerase activity in addition to accounting for hTERT C-1327T promoter genotype. — Sixty-nine (n = 34 males; n = 35 females) participants 50-70 yr were assessed for weekly EEE level using the Yale Physical Activity Survey. Lifetime consistency of EEE was also determined. Subjects were recruited across a large range of EEE levels and separated into quartiles: 0-990, 991-2340, 2341-3540, and >3541 kcal x wk(-1). Relative telomere length and telomerase activity were measured in peripheral blood mononuclear cells (PBMC). — CONCLUSION: These results indicate that moderate physical activity levels may provide a protective effect on PBMC telomere length compared with both low and high EEE levels.”

These studies leave me tentatively concluding:

·        Regular mildly cardiovascular exercise is likely to protect telomere lengths with aging across the three cell categories studied.

·        Vigorous aerobic exercise approaching “maximal aerobic exercise activity” may further serve to keep telomere lengths at youthful levels in leukocytes.

·        However, excessively strenuous exercise such as lifting very heavy weights or leading to exercise-associated fatigue may lead to compromised telomere lengths in muscle and/or PBMC cells and be life-shortening.

So, I believe moderation should be the rule.  See the suggestions for regular exercise in my treatise.

In the January 5 post Important new mesenchymal stem cell therapies, I promised this post specifically devoted to research on use of stem cells for cartilage regeneration.  It is a long and fairly thorough post with focus on regeneration of cartilage damage due to osteoarthritis, the toughest kind to deal with.

About cartilage and osteoarthritis

From Wikipedia, “Cartilage is a stiff yet flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs. It is not as hard and rigid as bone but is stiffer and less flexible than muscle. — Cartilage is composed of specialized cells called chondrocytes that produce a large amount of extracellular matrix composed of collagen fibers, abundant ground substance rich in proteoglycan, and elastin fibers. Cartilage is classified in three types, elastic cartilage, hyaline cartilage and fibrocartilage, which differ in the relative amounts of these three main components. — Unlike other connective tissues, cartilage does not contain blood vessels. The chondrocytes are supplied by diffusion, helped by the pumping action generated by compression of the articular cartilage or flexion of the elastic cartilage. Thus, compared to other connective tissues, cartilage grows and repairs more slowly.” Hyaline Cartilage lines the ends of bones in joints in the body where there is movement, such as in the elbow or knee.  A synovial fluid bathes the joint continuously so as to provide a frictionless interface.

Osteoarthritis (OA) is classically thought to be a “wear and tear” disease where the cartilage gradually wears out, like brake shoes do in a car, leaving bones rubbing directly on bones.  It can occur in the knees, hands, hips and the spinal areas of the lower back and neck.  “In osteoarthritis of the spine, the spaces between the vertebrae narrow. Bone spurs often form. When bone surfaces rub together, the vertebral joints (facets) and areas around the cartilage become inflamed and painful. Gradually, your spine stiffens and loses flexibility. Once these changes appear on X-rays, osteoarthritis has already started(ref).”  Osteoarthritis can create stiffness, be very painful, and be seriously debilitating. 

The classical view is that osteoarthritis is an incurable disease of progressing age: “Osteoarthritis gradually worsens with time, and no cure exists. But osteoarthritis treatments can relieve pain and help you remain active. Taking steps to actively manage your osteoarthritis may help you gain control over your symptoms(ref).”  According to this view, if the osteoarthritis situation gets bad enough your best recourse might be surgery such as total knee replacement.    

The classical view of osteoarthritis is evolving in that it is increasingly being seen as a disease that can arise from multiple causes in younger as well as older people and in that there is an increasingly brighter prospect for cartilage regeneration, even of seriously damaged joints, without need for drastic surgery.   Osteoarthritis can arise from mutated genes, traumatic injury or an operation as well as from wear and tear. It is not uncommon for people in their 40s and 50s to have a serious osteoarthritis problem.  Osteoarthritis can frequently arise in young people and even in children, such as when associated with a mutation in the type II procollagen gene (COL2A1)(ref)(ref).

Osteoarthritis can create collateral damage besides loss of cartilage.  In the case of the spine, for example, “Sometimes, the wear-and-tear of osteoarthritis puts pressure on the nerves leaving the spinal column. This can cause weakness and pain in the arms or legs. Osteoarthritis might also cause bone spurs to form in the spinal area. Osteoarthritis of the spine sometimes is called spinal spondylosis if the damage affects the facet joint and the disks in the spine(ref).”

Osteoarthritis involves a number of degenerative processes and any effective regenerative treatment must be able to deal with these. From the 2008 review article Technology Insight: Adult Mesenchymal Stem Cells for Osteoarthritis Therapy:  “Much research into the pathophysiology of OA has focused on the loss of articular cartilage, caused by mechanical and oxidative stresses, aging or apoptotic chondrocytes.  Articular chondrocytes within diseased cartilage synthesize and secrete proteolytic enzymes, such as matrix metalloproteinases and aggrecanases, which degrade the cartilaginous matrix. The proinflammatory cytokine interleukin 1 (IL-1) is the most powerful inducer of these enzymes and of other mediators of OA in articular chondrocytes. The induction of these factors leads to matrix depletion through a combination of accelerated breakdown and reduced synthesis.  Other proinflammatory cytokines, such as tumor necrosis factor, are also involved in cartilage breakdown and, together with biomechanical factors implicated in OA etiopathophysiology, contribute to induction of the disease.” 

First-generation cartilage regeneration using implanted chondrocytes

The objective of cartilage regeneration in the case of a joint where the cartilage is seriously compromised by OA is to induce new cartilage to grow in the joint, modeling  and organizing itself correctly in the process so as to restore the original functionality of the joint.  The area of therapy is sometimes called cartilage tissue engineering.  Hyaline cartilage is formed by chondrocytes, specialized cells that reside in and “produce and maintain the cartilaginous matrix, which consists mainly of collagen and proteoglycans.”    So, first-generation attempts at joint cartilage regeneration have been focused on introduction of new chondrocytes into osteoarthritis-compromised joints. The method has become known as ACT (or ACI), standing for Autologous Chondrocyte Transplantation (or implantation) and its use goes back to 1987.  “In ACT, a cartilage biopsy is taken from the patient and articular chondrocytes are isolated. The cells are then expanded after several passages in vitro and used to fill the cartilage defect. Since its introduction, ACT has become a widely applied surgical method with good to excellent clinical outcomes. More recently, classical ACT has been combined with tissue engineering and implantable scaffolds for improved results. However, there are still major problems associated with the ACT technique which relate mainly to chondrocyte de-differentiation during the expansion phase in monolayer culture and the poor integration of the implants into the surrounding cartilage tissue(ref).”

Results of ACT, when it could be applied, were often not bad.  According to a 2000 publication reported on a number of ACT papers, regarding one study  “The Swedish clinical experience with ACT now extends to more than 800 patients, including 200 patients with a minimum follow-up of 2 years. — Treatment of chondral and osteochondral lesions with ACT appears to produce new tissue similar in histologic and mechanical characteristics to hyaline cartilage, resulting in good clinical outcomes in more than 75% of patients. Results are best in lesions of the distal femur, including multiple defects. Patellar lesions require strict attention to alignment, and trochlear results are size-dependent.”  Regarding another paper “The multicenter results presented in this paper appear to parallel the Swedish experience and demonstrate a durable repair out to 36 months. ACT appears to be an efficacious and safe treatment for full-thickness chondral lesions of the femoral condyles and trochlea.” However regarding a third paper “Osteochondral grafts improve symptoms, but may increase risk of osteoarthritis.”   

“Currently, more than 12,000 ACIs are documented. Different studies showed a permanence of clinical results that were gained in a period of about 10 years [14–16]. Despite good clinical results, some disadvantages hamper the prevalence of ACI: (a) the nonuniform spatial distribution of chondrocytes and the lack of initial mechanical stability, (b) the suture of the periosteal flap into the surrounding healthy cartilage and the necessity of a perifocal solid cartilage shoulder that limits ACI to the treatment of small defects and excludes the treatment of OA diseased cartilage, and (c) the arthrotomic surgery(ref).”

The last decade showed the emergence of Arthroscopic treatment regimens for osteoarthritis of the knee, with some degree of success.  “Arthroscopic treatment included joint insufflation, lysis of adhesions, anterior interval release, contouring of cartilage defects to a stable rim, shaping of meniscus tears to a stable rim, synovectomy, removal of loose bodies, and removal of osteophytes that affected terminal extension. — CONCLUSIONS: This arthroscopic treatment regimen can improve function and activity levels in patients with moderate to severe osteoarthritis. Of 69 patients, 60 (87%) patients had a satisfactory result. However, in this group of 60, 11 patients needed a second procedure, resulting in a 71% satisfactory result after 1 surgery.”  There was also some degree of success reported in implanting scaffolds in osteoarthritis-damaged knees and using a modified form of ACT to regenerate knee cartilage(ref).  “Tissue regeneration was found even when implants were placed in joints that had already progressed to osteoarthrosis. Cartilage injuries can be effectively repaired using tissue engineering, and osteoarthritis does not inhibit the regeneration process.”

However, ACT has several limitations and often can’t be used when severe cartilage loss is due to degenerative arthritis or osteoarthritis.  An excellent summary of the limits of ACT can be found in the write-up of a clinical trial of a second-generation stem cell therapy.  “this treatment requires the extraction of chondrocytes directly from the patient and thus causes trauma in healthy articular cartilage. Also, this type of treatment cannot be applied to large lesions, nor is the efficacy satisfactory in patients over the age of 40 whose cellular activation levels are low. Thus, autologous chondrocyte transplant is rather limited in the number of cells harvested and their activation level and is therefore restricted in terms of treatment site, severity of the condition, and the size of lesion. The current technology allows the application of treatments in local cartilage defects but not in degenerative arthritis or rheumatoid arthritis. The technology needs to be taken up to another level in order to benefit such prevalent arthritic disorders. Treatments using stem cells do not cause damage to healthy articular cartilage as they don’t require the harvesting of healthy cartilage tissues from the patients. Moreover, the number of successfully cultured cells is larger due to the excellent proliferation capability of stem cells and thus, mass supply is possible(ref).”

Second -generation cartilage regeneration using mesenchymal stem cells

Problems and limitations of ACT have led to interest in a better alternative as outlined in the March 2009 publication Mesenchymal stem cells in connective tissue engineering and regenerative medicine: applications in cartilage repair and osteoarthritis therapy. Animal experiments have demonstrated that under appropriate signaling conditions, mesenchymal stem cells (MSCs) differentiate into chondrocytes and can produce hyaline cartilage replacing that lost in injured sites.  I have discussed a number of attractive properties of mesenchymal stem cells in the post Important new mesenchymal stem cell therapies.  These properties are highly relevant to cartilage regeneration, including freedom from an immune or inflammatory response, donor independence, easy duplication in-vitro, homing capability and, particularly, that MSCs seem to be the body’s own natural means for cartilage renewal(ref). 

I mentioned the 2007 publication Chondrogenic potential of human adult mesenchymal stem cells is independent of age or osteoarthritis etiology, indicating that neither the ability to collect sufficient numbers of MSCs nor the capability of those MSCs to differentiate into chondrocytes is affected by age of the person contributing the MSCs or whether or not they have osteoarthritis.  “No correlation of age or OA etiology with the number of mononuclear cells in BM, MSC yield, or cell size was found. Proliferative capacity and cellular spectrum of the harvested cells were independent of age and cause of OA.”  So, a patient’s own MSCs can be used for cartilage regeneration, even if the patient has osteoarthritis which destroyed the original cartilage.  Despite this publication’s conclusions,  some researchers are still concerned as to whether MSCs from an old sick person are as good as ones from a young healthy person.  I personally wonder whether the telomere lengths of MSCs from old people are equal to those from younger people, and whether the epigenetic markers of MSCs from sick people allow those cells to be good candidates for tissue regeneration.

The 2009 publication Tissue engineering in the rheumatic diseases is an excellent treatise covering both the first and second generation tissue engineering approaches for osteoarthritis cartilage damage and I suggest it for anyone wishing to go into further depth than possible in this post.  “Inflammatory conditions in the joint hamper the application of tissue engineering during chronic joint diseases. Here, most likely, cartilage formation is impaired and engineered neocartilage will be degraded. Based on the observations that mesenchymal stem cells (a) develop into joint tissues and (b) in vitro and in vivo show immunosuppressive and anti-inflammatory qualities indicating a transplant-protecting activity, these cells are prominent candidates for future tissue engineering approaches for the treatment of rheumatic diseases.”  The following selective quotes are from the same paper.

“Diseases like rheumatoid arthritis (RA) or degenerative arthritis (osteoarthritis, OA) are accompanied by a progressive reduction of extracellular matrices (ECMs) in joint cartilage and bone and, eventually, loss of joint function and excessive morbidity. Current pharmacological treatment of RA focuses on alleviating symptoms and/or modifying the disease process. Despite recent success in controlling pain and inflammation, marginal cartilage regeneration has been observed.”  The last comment is important: there is a natural process of cartilage regeneration, though usually inadequate.  The passage goes on “Obviously, suppression of inflammation is not sufficient to restore joint structure and function. Probably, cartilage repair may be achieved only by triggering local cartilage tissue responses leading to recovery of chondrocyte remodeling. An imbalance in joint cartilage, subchondral bone, and synovial membrane remodeling is one important characteristic of OA.”

“Besides clinically applied tissue-specific chondrocytes, undifferentiated mesenchymal stem cells (MSCs) are of special interest as cell candidates. In particular, bone marrow MSCs are comprehensively characterized and represent promising candidates [5]. They are easy to isolate and expand, they differentiate into various tissues like cartilage [6] and bone [7], and therefore they are able to regenerate osteochondral defects. Additionally, as they target diseased organs and secrete many bioactive factors, such as immunosuppressives for T cells facilitating their allogeneic use, they serve as vehicles capable of presenting proteins with therapeutic effects.“

“In this regard, secreted bioactive factors provide a regenerative environment, referred to as trophic activity, stimulating, for instance, mitosis and differentiation of tissue-intrinsic repair or stem cells (reviewed in [8]). Because of their anti-inflammatory and immunosuppressive properties, MSCs have been used as agents in autoimmune diseases (ADs) and have been applied in arthritis animal models (reviewed in [9]).”

The 2008 review article Technology Insight: Adult Mesenchymal Stem Cells for Osteoarthritis Therapy also provides a good summary of the reasons for basing therapies for large areas damaged by osteoarthritis on use of MSCs.  “Unlike chondrocytes, the use of MSCs is not hindered by the limited availability of healthy articular cartilage or an intrinsic tendency of the cells to lose their phenotype during expansion. The use of MSCs also obviates the need for a cartilage biopsy and, thereby, avoids morbidity caused by damage to the donor-site articular surface.”

Mesenchymal stem cell delivery modes for tissue regeneration

A number of approaches have been suggested for obtaining and delivering MSCs to a site requiring regeneration(ref). 

1.      Get the MSCs from the patient or some other source (another person or umbilical cord blood), multiply them and inject them directly into the site requiring regeneration, e.g. intra-articular injection, perhaps with hyaluronic acid,

2.     Same but first implanting a biodegradable synthetic or natural scaffold, perhaps employing a collagen hydrogel,

3.     Attraction of autologous MSCs within the body using microfractures, an established technique, and

4.     Attraction of autologous MSCs within the body using scaffolds and stem-cell attracting and differentiating factors.

Microfractures and mobilizing the body’s MSCs

Microfracturing was the first MSC cartilage regeneration technique and has been used clinically for years with some success.   “Finally, it should be mentioned that ACI treatment is still controversial. In a prospective randomized controlled trial (level of evidence: therapeutic level I), no significant advantage for the complex ACI compared with standard self-repair-stimulating microfracture could be measured after 2 and 5 years [18].”  Standard self-repair-stimulating microfracture is a technique in which microfractures are deliberately introduced in compromised cartilage to stimulate the body’s own cartilage regeneration capabilities.  As I understand the procedure, a surgeon drills a number of small holes (2mm in diameter) in the cartilage down the point where there is bleeding from the bone marrow.  The theory is that the holes provide access to the cartilage of MSCs from the bone marrow.  See Chondral Resurfacing of Articular Cartilage Defects in the Knee with the Microfracture Technique.  The results of applying this technique are not too shabby. “At the time of the latest follow-up, knee function was rated good to excellent for thirty-two patients (67%), fair for twelve patients (25%), and poor for four (8%). — Microfracture repair of articular cartilage lesions in the knee results in significant functional improvement at a minimum follow-up of two years.” 

Apparently, the microfractures mobilize the body’s own mesenchymal stem cells to regenerate cartilage.  It appears that this process can be enhanced by adding a bit of hyaluronic acid.  “Following microfracture in rabbit knee cartilage defects, application of hyaluronic acid gel resulted in regeneration of a thicker, more hyaline-like cartilage(ref).”  The technique is quite different than removing stem cells from the bone marrow of a patient, growing them in culture and then re-introducing them into the body where the repair is needed.  It depends instead on a) stimulating a part of the body needing cartilage regeneration to send out signals that naturally mobilizes a patient’s own MSCs to multiply, swarm to the cartilage site and do the regeneration job that is needed, and b) providing easy physical access for the stem cells to reach the cartilage area involved. 

The future direction

A distinct possibility is that similar results can be achieved in the future without a need for microfractures, using chemotactic agents, substances that can get MSCs moving to the right place and differentiating into cartilage tissue.  “So, the next generation of tissue engineering focuses on in situ approaches [44]. Here, for joint repair, scaffolds combined with chemotactic molecules and joint tissue formation-stimulating factors are transplanted, resulting in the in situ recruitment of bone marrow MSCs to the defect sites of degenerated cartilage and bone and their subsequent use for factor-guided joint repair. — Although MSC migration factors and their mechanisms are not known yet, molecules such as chemokines [48], bone morphogenetic proteins and platelet-derived growth factor [49], and hyaluronan [50] have been shown to have a dose-dependent chemotactic effect(ref).“ Recent research shows that transforming growth factor TGF-β3 has a capacity to mobilize and initiate the differentiation of the body’s MSCs(ref)(ref). 

Clinical Trials

As to clinical investigations of using MSCs for OA cartilage damage, there is the trial   Autologous Transplantation of Mesenchymal Stem Cells (MSCs) and Scaffold in Full-Thickness Articular Cartilage.  It is a small study started in August 2998 and originally scheduled for completion in May 2010. Another relevant clinical trial just posted and now enlisting participants is Study to Compare the Efficacy and Safety of Cartistem® and Microfracture in Patients With Knee Articular Cartilage Injury or Defect.  “The purpose of the study is to assess and compare the safety and efficacy of the allogeneic-unrelated umbilical cord blood-derived mesenchymal stem cell product (Cartistem®) to that of a microfracture treatment in patients with articular cartilage defect or injury. — This clinical trial for the stem cell therapies is essential because treatment of cartilage defects with umbilical cord blood-derived mesenchymal stem cells, known to have the highest level of activity among all adult stem cells, opens the possibility of articular cartilage regeneration even for aged patients and patients with large lesions unable to benefit from existing treatments.”

Summary

While MSCs offer great promise for tissue regeneration based on both theoretical understandings and experiments with animal models, many questions regarding human use remain incompletely resolved, e.g. use of allogeneic vs. autologous cells, mode of implantation and use of scaffolds, use of chemotactic and messenger molecules, and even nagging issues of whether age and arthritic status of donors are really irrelevant.  In any event, now in 2010 the myth that nothing basic can be done about OA cartilage deterioration has lost credibility.  Clinical trials of MSCs are getting underway and even more can be expected to be launched soon.  My own guess is that in 5-10 years tissue-engineering regeneration of osteoarthritic and other forms of cartilage damage will be in widespread clinical use.  It is the dawn of the age or tissue engineering and regenerative medicine.

One of the great things about following longevity research is that surprises are around every corner.  But I have not imagined a surprise of major importance about vitamin C supplementation.  Yesterday I would have said such a surprise is very unlikely because the stuff has been studied for more than 50 years including the Linus Pauling C-advocacy era.  There is a long history of controversy regarding therapeutic use of vitamin C, especially in megadose amounts(see the citations in ref).  Having been an aficionado of C megadosing back in the 70s, I have long since given up on the substance being other than an important antioxidant supplement.   Well, wrong again!  A 2010 research study just published in the FASEB Journal indicates that vitamin supplementation C cures mice with Werner’s Syndrome and could possibly be very important for the longevity of people with related genetic defects(ref)(ref).  What did we miss and what new is to be learned about vitamin C?

Werner’s Syndrome is a form of adult progeria (premature aging) due to a mutation in the WRN gene, a helicase deficiency.  For background on the disease and its genetic causes see the blog post Werner Syndrome – another model for aging.  

The new study is entitled Vitamin C restores healthy aging in a mouse model for Werner syndrome.  “Werner syndrome (WS) is a premature aging disorder caused by mutations in a RecQ-like DNA helicase. Mice lacking the helicase domain of the WRN homologue exhibit many phenotypic features of WS, including a prooxidant status and a shorter mean life span compared to wild-type animals. Here, we show that Wrn mutant mice also develop premature liver sinusoidal endothelial defenestration along with inflammation and metabolic syndrome. Vitamin C supplementation rescued the shorter mean life span of Wrn mutant mice and reversed several age-related abnormalities in adipose tissues and liver endothelial defenestration, genomic integrity, and inflammatory status. At the molecular level, phosphorylation of age-related stress markers like Akt kinase-specific substrates and the transcription factor NF-kappaB, as well as protein kinase C and Hif-1 transcription factor levels, which are increased in the liver of Wrn mutants, were normalized by vitamin C. Vitamin C also increased the transcriptional regulator of lipid metabolism PPAR . Finally, microarray and gene set enrichment analyses on liver tissues revealed that vitamin C decreased genes normally up-regulated in human WS fibroblasts and cancers, and it increased genes involved in tissue injury response and adipocyte dedifferentiation in obese mice. Vitamin C did not have such effect on wild-type mice. These results indicate that vitamin C supplementation could be beneficial for patients with WS.”  In other words, vitamin C supplementation delivers on restoring a Wrn mutant mice to normal healthy mouse status and the researchers think it might do the same for human patients with WS.

The important implication of the study is that vitamin C could be extremely important for prolonging the lives of people with WS or related genetic defects who normally show accelerated aging around 20 and die by 50.  A discussion of the new result in EurekAlert quotes an author of the study:”Our study clearly indicates that a healthy organism or individuals with no health problems do not require a large amount of vitamin C in order to increase their lifespan, especially if they have a balanced diet and they exercise,” said Michel Lebel, Ph.D., co-author of the study from the Centre de Recherche en Cancerologie in Quebec, Canada. “An organism or individual with a mutation in the WRN gene or any gene affected by the WRN protein, and thus predisposes them to several age-related diseases, may benefit from a diet with the appropriate amount of vitamin C.”

The reports I have read of this study do not make it clear how exactly vitamin C works to overcome the multiple effects of accelerated aging  due to mutation in the WRN gene, and I suspect this is unknown.  I would like to learn more about that  since I doubt only a simple antioxidant effect is involved.  And, if we knew how vitamin C can halt extraordinary aging due to WS, that just possibly might give us a clue as to how something else could halt normal aging.

There is apparently a lot more to learn about the workings of that wonderful, familiar and cheap ascorbic acid stuff.   “Vitamin C has become one of the most misunderstood substances in our medicine cabinets and food,” said Gerald Weissmann, M.D., Editor-in-Chief of the FASEB Journal. “This study and others like it help explain how and why this chemical can help to defend some, but certainly not all, people from premature senescence(ref).”  

Rapidly curing a roaring case of hepatitis back in 1970 using megadoses of vitamin C is what started my interest in anti-aging science.  I will continue popping at least 3 grams a day of C as I have been doing for decades now.

On January 21, this blog will celebrate its first birthday.  The purpose of this post is to review how the blog has evolved from its original intent, to review the ways it has been heading recently, and to discuss whether those ways make sense for the future.  Specifically, I am asking for your feedback on the kinds of content that you would find most useful in the coming months and year and how to make this blog most interesting and useful for you.

How the blog has evolved so far

The original introduction to this blog stated “The purpose of this Blog is to provide a frequently-updated plain-language companion to my Anti-Aging Firewalls treatise site ANTI-AGING FIREWALLS THE SCIENCE AND TECHNOLOGY OF LONGEVITY.   This blog is for people interested in living  longer and better lives by taking advantage of developments on the frontiers of longevity science.  I plan to post comments on recent aging-related developments  from time to time, and welcome any and all discussion by others.”  So, now after 224 posts and 236 comments, what has actually happened?

Where the blog has been going

·        It is frequently updated, several times a week, and still positioned as a companion to the treatise although it frequently goes into far greater scientific depth in topics discussed in the treatise and includes content related to aging that is not in the treatise.  The blog has assumed a life and importance of its own, in many ways exceeding that of the relatively static treatise.

·        The blog is still positioned to address the audience mentioned but is not for the general public.  It is targeted to informed science-minded people, professionals in the medical arts, researchers in the many areas of science covered in the blog, and laypeople with serious interests in anti-aging developments.  It often goes into fairly great technical depth.  I have given up on sticking to “plain language” for that would be incompatible with responsibly covering “developments on the frontiers of longevity science.”  Instead, I have been introducing more and more advanced technical concepts from the disciplines involved.

·        The purpose of the blog is to fill in the pieces of the large puzzle that constitutes aging, and to address fundamental issues related to aging based on hard current scientific research : What are the mechanisms of aging?  How do they relate to each other?  Which ones are primary?  What anti-aging interventions are possible now?  Which ones are coming along, and how far off are they likely to be?.  This requires following and digging ever-deeper into a number of streams of research involving molecular biology, genetics, genomics, proteomics and other “omics.”  And it requires keeping current with research related to a number of aging theories (19 as of now) and ongoing research developments relating to a number of aging-related genes and pathways with names like mTOR, NF-kappaB, Akt, P53, P21, hTERT, and Notch and MAPK signal transduction pathways.

·        Scientific and intellectual integrity are essential characteristics of the blog.  I research the science items in depth before writing them and it sometimes requires several days to do this.  I provide numerous links to research citations and often quote direct passages from research publications.  When I have a personal opinion, I identify it as such. I avoid fringe or cult science.  If an ancient Chinese or Indian herb is reputed to have incredible curative powers I am interested in it only if the claims are supported by a body of reputable Western scientific research.

·        Freedom from commercialism is another important aspect of the blog.  I do not accept advertising though I could probably earn some cash by doing that given blog’s  growing popularity.  Further, I don’t cover commercial products such as supplement combinations except in very rare cases when such a product has a unique scientific character.  I am beholden to no commercial interest and own no stake in nor am I employed by any company selling anti-aging products or services.

·        In the interest of providing depth, new blog items are usually highly hyperlinked with related past blog items and relevant items in my treatise.

·        Current “unique visits” to the blog and treatise typically range from 700 to 1,000 per day.  My ISP defines these visits as unique user URLs that visit at least two pages in a session, e.g. two blog posts or a blog post and my treatise.  These numbers correspond to 1,400+ page views per day.  There has been a slow and irregular upwards trend in usage, perhaps amounting to 5% to 10% per month.  Based on these statistics I estimate that there are probably a few thousand people who occasionally visit the blog, and perhaps a few hundred regular avid readers.  Increasing numbers of international users are being attracted, probably via personal networks.  I would like to see these numbers increased by an order of magnitude during 2010.  This will require ways of making the existence of the blog known to wider audiences.

Blog items seem to fall in the following categories:

–         Coverage of news items and new research discoveries and “breakthroughs.”  Unlike the popular press and many other blogs, I like to provide citations to the original publication whenever possible, citations to previous relevant publications and some discussion of how the discovery fits into the bigger picture and what it means.  An example is the recent post Ginkgo Biloba supplementation has no effect on cognitive decline (but it does have other impacts).

–         Mini-treatises on topics relevant to longevity.  The purpose is usually to provide a review picture of the state of research and research knowledge in a particular area.  These are the postings that usually require the most background research work.  An example is the three-part post Autoimmune diseases and lymphoma: Part I: focus on Lupus, Part II: focus on inflammation and Part III: focus on lymphomas. Another example is DNA demethylation – a new way of coming at cancers. A few of these mini-treatises have been motivated by a personal medical concern, Spinal cord injury pain – a personal story and a new paradigm being a case in point.

–         Original research and intellectual contributions. These are my own ideas not found in the existing literature but representing a synthesis of knowledge and trends that are definitely “out there.”  I have made two major contributions and some minor ones in this regard.  One of the major contributions is the Stem Cell Supply Chain theory of aging, originally written up in this blog and now part of my treatise. Many later posts refer back to this one.  The other major contribution is Giuliano’s Law, related to the exponential acceleration in anti-aging science and the implication of this for personal longevity.  Again, this was a three-part series starting with Giuliano’s Law: Prospects for breaking through the 122 year human age limit and going on to More on Giuliano’s Law; calculating my longevity prospects and Factors that drive Giuliano’s Law. Occasionally I will develop an original insight  while writing a blog post  and mention it in that post.  An example from yesterday’s post Important new mesenchymal stem cell therapies was that acupuncture might work because it mobilizes  mesenchymal stem cells to migrate to a problematic location where they do their job of tissue regeneration.   I plan to research that particular speculation further, incidentally, and report on it in a future blog entry.

–         Humorous pieces.  An example is P38, P39 and P40 channel receptor functions inhibit activities of BF-110, HE111 and HE177 leading to reduced expression of (SC)1000 in BOB which seems to be a typical jargon-filled paper title from a molecular biology journal but in fact describes World War II fighter plane action.  Another example is the Avoidance Magazine stories.

–         Review and housekeeping posts, like this one and the recent post Genes discussed or mentioned in this blog.

–         Only selective reviews of supplements: While many supplements are suggested in my treatise and are of great personal interest to me and to many of my readers, I do not usually review them because they are mostly already well-reviewed in other on-line resources.  I make a few exceptions to this rule when the science is unusual, however, such as in The curious case of l-carnosine.

–         More and more-sophisticated comments: During the first 9 months of the blog’s existence, the number of posts exceeded the number of comments.  Currently more comments are coming in than posts and the comment-to-post ratio is continuing to grow. And the comments are tending to be more sophisticated contributions.

Why these directions?

I believe the above profile gives the blog a unique character and market positioning, different than the many aging and anti-aging sites out there.  The blog strives for both technical depth and true multi-disciplinary breadth and provides viewpoints not normally found in focused research studies.   As I add entries, I believe I am constructing an important database of longevity-related articles, again a key adjunct to my treatise.  As time goes on the blog gains value because of its retrospective as well as current content.  Even  now, if a doctor or scientist wants to learn about aging, the blog is an excellent way to start.

Further there is another, personal, agenda involved.  Researching these articles, writing this blog and updating my treatise is a full-time job for me, and it is a full-time self-educational process.  Eighteen months ago I looked at two options: 1.  entering a full time graduate level program in the life sciences at MIT or Harvard, with the four-year objective of obtaining a second Ph.D. focusing on longevity sciences and writing a Ph.D. in that area, and 2. Pursuing the course I am now pursuing of self-education and communication, using the discipline of blog writing and treatise updating to keep me focused, on track, and constantly digging deeper and learning more.  And, in the process, building an equivalent of the Ph.D. thesis as I move along, constantly improving it – (that is my treatise and the collective writings in this blog).  

I did not like the first track for it would have been a massive digression requiring me to take too many courses and learn too much material only marginally relevant to longevity.  And I would miss keeping up with key longevity developments that were unfolding day-to-day.  While I would have earned a new Ph.D. and a certain amount of institutional credibility, I would have missed much of the party and most likely would have prepared myself for a relatively narrow career.  I compared myself to being a guy with an electrical engineering degree who found himself in a fairly exciting job in a computer industry lab in 1955, already making important contributions, say in the area of storage technology and knowing a lot about computers and where they were heading.  Should that guy drop out for four years to get an academic degree in computer sciences?  Probably not since most of his professors would know less about what was really important about computers and storage than he did, and he too would have missed the most exciting part of the party.

An advantage of this approach is sharing my education with my readers, making my learning far from a lonely process.

My choice of the current educational track often requires me to stop and backfill knowledge, however.  I find it easier and more satisfying to work backwards from current research than to take courses or read entire books which would give me a broader base of mostly-irrelevant knowledge.  For example, suppose I encounter research relating to protein folding and how this effects P53 gene activation in the presence of co-activators under certain conditions of histone acetylation.  I want to understand what the new research means.  This requires digging into these areas to the degree necessary to understand what is going on.  And because these areas are new research frontiers, I am not going to find what I want to know all neatly packaged in a course anywhere or even in one book.  If the area is complex and important, I may decide to generate a blog post about it as a way of forcing my own learning.  I can’t write clearly about something unless I understand it.  So several blog posts are about such “backfill” areas of knowledge, an example being MicroRNAs, diseases and yet-another view of aging.

All of this is to say that as I am learning more and the state of knowledge advances my blog entries have been tending to become more complex, technical and sophisticated, and this tendency is likely to continue.  I am also spending more and more time addressing comments.

Future of the blog

My current plan is to continue the blog along the paths identified above, but I have some questions for my readers:

·        What do you think about the current mix of posts?  Which kinds would you like to see more or less of?

·        What area of content are you most interested in?

·        Do you know how to find all the past items, to use the search features to find past blog entries?  I could write a short post on this.

·        Do you make much use of the hyperlinks?

·        Are you satisfied with how I respond to comments?

·        Do you find this site too personal, not personal enough or are you OK with the current mix?

·        Right now there is backwards hyper linking of blog entries to previous relevant ones, but no forward hyper linking, say linking an early article on telomerase to the many subsequent ones.  Do you think it would be worth the time and effort required for me to generate such forward links?

·        What forms of networking or joint activities would you suggest for me with aging research institutions?  Any specific links you can suggest? People you know who I should contact?

·        Any ideas of how radically to expand the readership of the site?  I already have pretty good search engine placement on Google.

·        Any other suggestions?

While embryonic stem cell therapies are still barely getting off the ground (see the post It’s a long  way to stem cell treatment), several important therapeutic applications of Mesenchymal stem cells (MSCs) are now getting to be well along in the development pipeline and could soon become part of mainline medicine.  

In this post I first enumerate some recently-discovered and exciting properties of MSCs that make these applications possible.  Then, to illustrate that mesenchymal stem cell therapies are going prime-time, I provide a current listing of clinical trials involving MSCs with hyperlinks to further information about each trial.     

Mesenchymal stem cells are multipotent cells that can differentiate into a variety of cell types including chondrocytes, osteoblasts,  myocytes, adipocytes and beta-pancreatic islets cells.  “Mesenchymal stem cells (MSC) represent a population of the bone marrow microenvironment, which participates in the regulation of haematopoietic stem cells (HSC) self-renewal and differentiation. MSC are multipotent non-haematopoietic progenitors, which have been explored as a promising treatment in tissue regeneration(ref).” Some of the properties of these cells are amazing, making them a good platform for a variety of new emerging disease therapies. 

Properties of Mesenchymal stem cells 

·        “MSCs are rare in bone marrow, representing approximately 1 in 10,000 nucleated cells. Although not immortal, they have the ability to expand manyfold in culture while retaining their growth and multilineage potential(ref).”

·        MSCs inhibit immune response.  “Both in vitro and in vivo, the MSC inhibit the T, B, NK and dendritic cell functions(ref).” MSCs suppress lymphocyte proliferation(ref).   Implications are that MSCs might be useful in treating autoimmune diseases,  and that MSCs could work in treating Graft vs Host Disease (GvHD), a major problem encountered in organ transplantation.

·        Because of their freedom from immune responses, MSCs work fine no matter where you get them.  “ Most interestingly, there was no difference in the response rates or side effects between patients receiving mesenchymal stem cells from third-party mismatched donors compared with those patients receiving cells from HLA-identical siblings or from haploidentical family members(ref).

·        MSCs tend to inhibit the inflammatory response. “Based on the observations that mesenchymal stem cells (a) develop into joint tissues and (b) in vitro and in vivo show immunosuppressive and anti-inflammatory qualities indicating a transplant-protecting activity, these cells are prominent candidates for future tissue engineering approaches for the treatment of rheumatic diseases(ref).”

·        MSCs prolong the survival of haemopoietic stem cells(ref).

·        MSCs automatically home in on diseased or damaged tissues requiring regeneration.  “It has been shown that MSCs, when transplanted systemically, are able to migrate to sites of injury in animals, suggesting that MSCs possess migratory capacity. However, the mechanisms underlying the migration of these cells remain unclear(ref).”

·        Arriving at a site having tissue damage and requiring regeneration, MSCs can and “know how to” differentiate into a variety of different types of cell tissues as needed, ranging from heart muscle cells to cartilage osteoclasts, and integrate themselves into a functioning organ so as to renew it.  

·        A 2010 study suggests that one of the communications strategies utilized by MSCs is that they they secrete therapeutic paracrine factors (signaling molecules that affect nearby cells) and also secrete RNA-containing microparticles(ref).

·        There is strong evidence that a number of known medical conditions can be treated with MSCs, and new ones are still being discovered.  “Experimental and clinical data gave encouraging results, showing that MSC injection allowed controlling refractory GVHD, restoring bone development in children with osteogenesis imperfecta or improving heart function after myocardial infarction(ref).”

·        Amazingly, Chondrogenic potential of human adult mesenchymal stem cells is independent of age or osteoarthritis etiology.  This means that the MSCs from an old person with osteoarthritis whose knee or hip cartilage is severely eroded by that osteoarthritis can be used to regenerate new cartilage.  “We conclude that, irrespective of age and OA etiology, sufficient numbers of MSCs can be isolated and that these cells possess an adequate chondrogenic differentiation potential. Therefore, a therapeutic application of MSCs for cartilage regeneration of OA lesions seems feasible.”  This will be the subject of another blog post to follow within a few days.

·        Several non-surgical ways are being experimented with for working with MSCs including site injection, topical application possibly with a structure matrix, and injection with substances that accelerate the natural migration of MSCs to a site requiring restoration. “Harnessing the migratory potential of MSCs by modulating their chemokine-chemokine receptor interactions may be a powerful way to increase their ability to correct inherited disorders of mesenchymal tissues or facilitate tissue repair in vivo(ref).” 

·        I even speculate that one of the main ways acupuncture could work is by creating minor damage that generates chemical messages that attract MSCs to an injury site requiring attention.

Previous blog posts have highlighted various aspects and other potential applications of MSCs.  See the blog posts Terminator stem cells in the early pipeline, Stem cell differentiation and nanotubes, Trojan-horse stem cells might offer an important new cancer therapy.  The blog post State of autologous stem cell therapies is relevant.  However it is already partially obsolete though only 8 months old.  Also, MSCs can be found in other body locations besides bone marrow, like in teeth.  See the post Dental Pulp Stem Cells – the big needle vs the tooth fairy.

Clinical trials involving Mesenchymal stem cells 

A good sign that  a drug or technology is probably headed for big-time medical use is when it is in several clinical trials.  The following  listing is mostly based in information from www.clinicaltrials.gov, “a registry of federally and privately supported clinical trials conducted in the United States and around the world.”  Clicking on any trial heading will lead you to further information about the objectives, methodology and status of the trial involved.   

1.     Safety Study of Adult Mesenchymal Stem Cells (MSC) to Treat Acute Myocardial Infarction  Also see ref.

2.     A Phase I Clinical Trial of the Treatment of Crohn’s Fistula by Adipose Mesenchymal Stem Cell Transplantation

3.     Mesenchymal Stem Cell Transplantation in Decompensated Cirrhosis

4.     Allogeneic Mesenchymal Stem Cell for Graft-Versus-Host Disease Treatment (MSCGVHD

5.     Mesenchymal Stem Cell Infusion as Treatment for Steroid-Resistant Acute GVHD or Poor Graft Function

6.       Prochymal™ Adult Human Mesenchymal Stem Cells for Treatment of Moderate-to-Severe Crohn’s Disease

7.     Safety and Efficacy Study of Umbilical Cord Blood-Drived Mesenchymal Stem Cells to Promote Engraftment of Unrelated Hematopoietic Stem Cell Transplantation (for treating acute leukemia).     

8.  Mesenchymal Stem Cell Infusion as Prevention for Graft Rejection and Graft-Versus-Host Disease (for treating Hematological Malignancies)

9.     Mesenchymal Stem Cells and Subclinical Rejection (related to Organ Transplantation)

10.            Autologous Transplantation of Bone Marrow Mesenchymal Stem Cells on Diabetic Foot

11.   Allogeneic Mesenchymal Stem Cells Transplantation for Primary Sjögren’s Syndrome (pSS)

12.            Mesenchymal Stem Cells in Multiple Sclerosis (MSCIMS)

13.            Mesenchymal Stem Cells in Critical Limb Ischemia

14.            The Use of Autologous Bone Marrow Mesenchymal Stem Cells in the Treatment of Articular Cartilage Defects (for treating Degenerative Arthritis; Chondral Defects;  Osteochondral Defects)

15.  Safety and Efficacy Study of Allogenic Mesenchymal Stem Cells to Treat Extensive Chronic Graft Versus Host Disease ((for combined treatment with prednisone and cyclosporine as primary treatment) 

16.            Mesenchymal Stem Cell Transplantation in the Treatment of Chronic Allograft Nephropathy  (for Kidney Transplant; prevention of Chronic Allograft Nephropathy)

17.            Extended Evaluation of PROCHYMAL[tm] Adult Human Stem Cells for Treatment-Resistant Moderate-to-Severe Crohn’s Disease

18.  Autologous Transplantation of Mesenchymal Stem Cells (MSCs) and Scaffold in Full-Thickness Articular Cartilage (for treating Knee Cartilage Defects;   Osteoarthritis)

19.            Evaluation of the Role of Mesenchymal Stem Cells in the Treatment of Graft Versus Host Disease

20.            Mesenchymal Stem Cell for Osteonecrosis of the Femoral Head

21.            Mesenchymal Stem Cells Under Basiliximab/Low Dose RATG to Induce Renal Transplant Tolerance

22.            Intravenous Stem Cells After Ischemic Stroke

23.            Effect of Mesenchymal Stem Cell Transplantation for Lupus Nephritis

24.            Safety and Efficacy Study of Adult Human Mesenchymal Stem Cells to Treat Acute GHVD

This listing may not be complete but should make the point that MSC therapies are probably heading for big-time.  Yet, I need point out that most of these trials are either just getting off the ground or are Phase I studies focused on safety and dosage rather than on efficacy.  And some of the trials could produce negative results and be aborted.  So it may be a while before most of these therapeutic applications are actually integrated in as part of mainline medicine. 

A few of the studies are in or already beyond Phase II, however, and moving along nicely through the pipeline.  The following is from a report in Medical News Today on a Phase II study:  “A phase II multicenter study performed within the European Group for Blood and Marrow Transplantation (EBMT) Mesenchymal Stem Cell Expansion Consortium, shows that mesenchymal stem cells provide a therapeutic potential for the treatment of acute steroid-refractory GvHD (graft-versus-host disease). — Allogeneic stem-cell transplantation is the treatment of choice for many malignant and non-malignant disorders. Severe graft-versus-host disease (GvHD) is a life-threatening complication which could arise following this treatment. Especially if patients with GvHD do not respond to steroids, therapeutic options are limited and the success uncertain. This publication in one of the leading scientific journals opens new exciting possibilities for patients with GvHD. — The study was launched to assess whether mesenchymal stem cells could reduce the risk of GvHD after stem cell transplantation. Between October 2001 and January 2007, 55 patients were treated. From this, 30 patients had a complete response and nine showed improvement. No patients had side effects during or immediately after infusions of mesenchymal stem cells. This response was not related to donor HLA-match. Three patients had recurrent malignant disease and one developed de-novo acute myeloid leukaemia of recipient origin. — This phase II study shows that the infusion of mesenchymal stem cells expanded in vitro, irrespective of donor, might be an effective therapy for patients with steroid-resistant, acute GvHD. Most interestingly, there was no difference in the response rates or side effects between patients receiving mesenchymal stem cells from third-party mismatched donors compared with those patients receiving cells from HLA-identical siblings or from haploidentical family members. This finding makes the logistical requirements for this approach more convenient, because the establishment of local banks of mesenchymal stem cells would enable unproblematic and rapid availability of mesenchymal stem cells without the need of HLA typing.”

I am optimistic.  In a follow-up blog post, I will focus on research relating to one specific possible therapeutic role of MSCs – cartilage regeneration, an application for those who are suffering from lost cartilage in their knees, hips or elsewhere, a cure that can be done without need for surgery.  It works even if the patient has ongoing osteoarthritis which caused the problem in the first place.  I believe we are finally entering the new era of regenerative medicine. What incredible good news for longevity!

In the Part I post  I described several recent studies relating to calorie restriction (CR), mainly ones exploring the pathways through which CR limits the development of cancers.  I cite a background study on the somatotropic axis and a few additional recent studies here, with focus this time on the gene activation pathways that seem to be involved.  And I touch lightly on how taking resveratrol supplements appears to mimic many of the effects of CR.  

The somatotropic axis and IGF-1 

As background, I begin by commenting on the somatotropic axis, a subject covered well in the 2005 paper Minireview: Role of the Growth Hormone/Insulin-Like Growth Factor System in Mammalian Aging.  “THE SOMATOTROPIC AXIS, consisting of pituitary derived GH (growth hormone) and IGF-I, the main mediator of GH actions, is the key determinant of somatic growth and adult body size. Moreover, the GH/IGF-I system is involved in the regulation of puberty and gonadal function and influences body composition as well as structural and functional maintenance of adult tissues.” This pathway and its associated genes seem to be evolutionary conserved across a multiplicity of species including unicellular yeast, through insects, worms, rodents, and other mammals including humans.   

The pathway seems also very relevant to aging.  The key thing to note is that across many species including fruit flies, roundworms, mice and rats, inhibition of IGF-1 signaling is generally associated with smaller-sized animals and longer lifespans.  Some people take human growth-hormone promoting supplements  because they think it may extend their lives, but the evidence seems to point in the opposite direction.  “– administration of GH is often advocated as an “anti-aging” therapy. In sharp contrast to these findings, GH deficiency, GH resistance, and reduced IGF-I signaling in mice are associated with symptoms of delayed aging and markedly extended longevity.  Although most normal mice die at approximately 2 yr of age, hypopituitary and GH-resistant mutants often survive beyond the age of 3 yr and occasionally past the age of 4 yr, i.e. outside the range encountered in various laboratory strains of this species.  — Association of reduced somatotropic signaling with extended longevity in laboratory stocks of house mice (Mus musculus) is robust, reproducible, and consistent across several mutants, genetic backgrounds, and diets (ref).”  The same can be said for other more primitive species and “it seems entirely reasonable to expect that the involvement of these signaling pathways in the control of aging is universal and includes humans.” 

From the viewpoint of the current discussion, there is strong evidence that the somatotropic axis, i.e., limiting of IGF-1 signaling  is involved in the life-extending actions of calorie restriction. This is pointed out in several publications cited in the Part I post(ref).  “The group’s analysis points to a connection between calorie intake and a protein called Insulin-like Growth Factor (IGF) -1, with obesity increasing and calorie restriction decreasing levels of IGF-1(ref).” 

DAF-16, SMK-1 and PHA-4  It appears, however, that IGF-1 signaling is not necessarily the only or even the most important longevity-related pathway involved in calorie restriction.  .   According to a 2007 Science Daily posting:  “–  Initially, researchers thought that the effect of calorie restriction on aging was mediated through insulin-like signaling pathways in the roundworm Caenorhabditis elegans (C. elegans), but experiments by graduate student Siler Panowski in Dillin’s lab suggested otherwise. — In the worm, signals passed down the insulin/IGF-1 pathway regulate a DNA-binding protein called DAF-16 that belongs to what is called the forkhead family. It was believed that DAF-16 then regulated expression of genes associated with longevity. Dillin had also identified a co-regulator in the pathway called SMK-1 that apparently worked with DAF-16 to regulate longevity. — “When we asked whether DAF-16 and SMK-1 proteins were both necessary for CR-mediated longevity, DAF-16 turned out to be unnecessary but, somewhat surprisingly, SMK-1 was,” says first author Panowski. — Since 15 other forkhead-like factors are expressed in C. elegans, graduate student Suzanne Wolff and former post-doctoral fellow Hugo Aguilaniu, Ph.D., now an assistant professor at the École Normale Supérieure de Lyon, France, set out to determine if any of them teamed up with SMK-1 to delay aging in the CR-response. They did this by knocking out each gene separately and observing whether the genetically altered worms still showed enhanced longevity when calorie-restricted. — Loss of only one of the genes, a gene encoding the protein PHA-4, negated the lifespan-enhancing effect of calorie-restriction in worms.  And, when researchers undertook the opposite experiment–by overexpressing pha-4 in worms–the longevity effect was enhanced. “PHA-4 acts completely independent of insulin/IGF-1 signaling and turns out to be essential for CR-mediated longevity,” says Panowski.”  CREB, CBP, SATB-1 and histone acetylation Again alas , these are not the only pathways involved.  The 2009 publication Role of CBP and SATB-1 in Aging, Dietary Restriction, and Insulin-Like Signaling points out “Here we report that hypothalamic expression of CREB-binding protein (CBP) and CBP-binding partner Special AT-rich sequence binding protein 1 (SATB-1) is highly correlated with lifespan across five strains of mice, and expression of these genes decreases with age and diabetes in mice.”  The same publication states “drugs that enhance histone acetylation increase lifespan and reduce Aβ42-related pathology, protective effects completely blocked by cbp-1 RNAi. Other factors implicated in lifespan extension are also CBP-binding partners, suggesting that CBP constitutes a common factor in the modulation of lifespan and disease burden by DR and the insulin/IGF1 signaling pathway.”  This landmark publication is well worth perusing and I quote a few other passages from it.

“Elucidation of mechanisms mediating lifespan extension and reduction of disease burden, including cancer and neurodegenerative diseases, by DR is a major goal of aging research [1]. Recent studies have implicated sirtuins [2], SKN-1 [3], SMK-1 and PHA-4/Foxa [4], AMPK [5], RHEB-1 [6], daf-16/Fox1a [5], and HSF-1 [7] in mediating lifespan extension by some, but not all [8],[9], protocols of DR in Caenorhabditis elegans. However, a role for expression of these genes in mammalian lifespan has not been addressed, nor, with rare exceptions [7], has a role for expression of these genes in reduction of age-related pathologies by DR. The purpose of the present studies was to discover genes whose expression predicts lifespan and whose expression decreases with age and disease in mammals, whose expression is induced by DR, and whose inhibition attenuates life extension by several distinct protocols of DR. We report that among genes implicated in lifespan extension by DR or the insulin-like signaling pathway, only CBP meets these criteria.”

“In the present study we have discovered that DR induces a transcription factor, CBP, and additional factors that work with CBP to control the expression of other genes involved in determination of lifespan. When we blocked the DR-mediated increase in CBP and associated factors, we blocked all the protective effects of DR on lifespan extension, on the slowed rate of aging, and on protection against pathology in a model of Alzheimer’s disease. Further, in mice expression of CBP and a CBP-interacting factor positively predicted lifespan, and expression of both factors decreased with age and in diabetes. Finally, pharmacological manipulations that mimicked enhanced CBP activity increased lifespan and reduced pathology in a model of Alzheimer’s disease.”

“Mechanisms linking cbp-1 expression to increased lifespan and reduced age-related pathology are therefore of great interest. It is suggestive that all genes implicated in the present screens are either CBP or CBP-binding co-activators [29]–[31]. Similarly, genes recently implicated in mediating lifespan extension by DR, skn-1 and pha-4, also code for transcriptional factors that interact with CBP [37],[38]. Furthermore, transgenic overexpression of cbp-1 did not significantly increase lifespan (Figure S6), suggesting that effects of CBP on lifespan requires increased expression of other factors. Uniquely among factors implicated in mediating lifespan extension by DR, RHEB-1 is not known to interact with CBP [6]. However, RHEB-1 mediates lifespan extension by intermittent fasting-induced longevity [6], which, in contrast to other protocols of DR (including those examined in the present studies), increases lifespan by reducing initial mortality rate, not by reducing age-related acceleration of mortality rate.”

Glucose metabolism

A study cited in the Part I post implicates glucose metabolism in DR, in that healthy cells in-vitro lived longer and had better health indicators when deprived of a glucose nutrient, while the opposite was true of cancer cells(ref).

Epigenetic effects, Akt, mTOR, P16 and hTERT

The Part I post  touched on how these too are involved in CR.

Resveratrol and calorie restriction

Resveratrol supplementation appears to partially mimic some of the longevity-promoting effects of CR, possibly via the IGF-1 channel, possibly via other mechanisms.  This is the probably-good news for us longevity aficionados.  In a mouse study: “We report a striking transcriptional overlap of CR and resveratrol in heart, skeletal muscle and brain. Both dietary interventions inhibit gene expression profiles associated with cardiac and skeletal muscle aging, and prevent age-related cardiac dysfunction. Dietary resveratrol also mimics the effects of CR in insulin mediated glucose uptake in muscle. Gene expression profiling suggests that both CR and resveratrol may retard some aspects of aging through alterations in chromatin structure and transcription. Resveratrol, at doses that can be readily achieved in humans, fulfills the definition of a dietary compound that mimics some aspects of CR(ref).” There is a lot more that can be said about this subject, however, and that will be the subject of a future post.

Wrapping it all up

Researchers are developing ever-better understanding of the underlying molecular/epigenetic mechanisms of CR.  Further – and that is what is most exciting – it appears that with resveratrol and new resveratrol homologs, we may already have a practical anti-aging intervention that takes advantage of the CR pathways nature have given us.  And, stay off of the glucose!

If you are a supplement follower, you may have already read a newspaper article today on the major study on Ginkgo and cognition just reported in JAMA.  Here is a firsthand copy of the abstract of the original article Ginkgo biloba for Preventing Cognitive Decline in Older Adults – A Randomized Trial:

“Context  The herbal product Ginkgo biloba is taken frequently with the intention of improving cognitive health in aging. However, evidence from adequately powered clinical trials is lacking regarding its effect on long-term cognitive functioning.  

Objective  To determine whether G biloba slows the rates of global or domain-specific cognitive decline in older adults.

Design, Setting, and Participants  The Ginkgo Evaluation of Memory (GEM) study, a randomized, double-blind, placebo-controlled clinical trial of 3069 community-dwelling participants aged 72 to 96 years, conducted in 6 academic medical centers in the United States between 2000 and 2008, with a median follow-up of 6.1 years.

Intervention  Twice-daily dose of 120-mg extract of G biloba (n = 1545) or identical-appearing placebo (n = 1524).

Main Outcome Measures  Rates of change over time in the Modified Mini-Mental State Examination (3MSE), in the cognitive subscale of the Alzheimer Disease Assessment Scale (ADAS-Cog), and in neuropsychological domains of memory, attention, visual-spatial construction, language, and executive functions, based on sums of z scores of individual tests.

Results  Annual rates of decline in z scores did not differ between G biloba and placebo groups in any domains, including memory (0.043; 95% confidence interval [CI], 0.034-0.051 vs 0.041; 95% CI, 0.032-0.050), attention (0.043; 95% CI, 0.037-0.050 vs 0.048; 95% CI, 0.041-0.054), visuospatial abilities (0.107; 95% CI, 0.097-0.117 vs 0.118; 95% CI, 0.108-0.128), language (0.045; 95% CI, 0.037-0.054 vs 0.041; 95% CI, 0.033-0.048), and executive functions (0.092; 95% CI, 0.086-0.099 vs 0.089; 95% CI, 0.082-0.096). For the 3MSE and ADAS-Cog, rates of change varied by baseline cognitive status (mild cognitive impairment), but there were no differences in rates of change between treatment groups (for 3MSE, P = .71; for ADAS-Cog, P = .97). There was no significant effect modification of treatment on rate of decline by age, sex, race, education, APOE*E4 allele, or baseline mild cognitive impairment (P > .05).

Conclusion  Compared with placebo, the use of G biloba, 120 mg twice daily, did not result in less cognitive decline in older adults with normal cognition or with mild cognitive impairment.”

Because of the size and controlled nature of the study, I can find no reason to challenge its conclusions.  In fact the conclusions are compatible with those of a January 2007 review study Ginkgo biloba for cognitive impairment and dementia. “AUTHORS’ CONCLUSIONS: Ginkgo biloba appears to be safe in use with no excess side effects compared with placebo. Many of the early trials used unsatisfactory methods, were small, and we cannot exclude publication bias. The evidence that Ginkgo has predictable and clinically significant benefit for people with dementia or cognitive impairment is inconsistent and unconvincing.”

The completely negative results are somewhat puzzling to me however, given a number of earlier research studies indicating that ginkgo biloba extract EGb 761, the same one used in the latest study,  has a capacity to promote neurogenesis in the hippocampus and improves cognitive functioning in small-animal models of Alzheimer’s disease.  For example:

·          The 2008 article Ginkgo Extract Has Multiple Actions on Alzheimer Symptoms, for example, states:  “In ongoing studies, a research team led by Luo found that giving mice with the human Alzheimer’s gene the ginkgo extract called EGb 761 improved the process of making new nerve cells in part of the brain much affected by the disease. The team found evidence that the protective effect of the extract also could be due to decreasing senile plaques or the clumping of beta-amyloid in the brain tissues.”  

·         Another relevant research report is the 2007 publication EGb 761 enhances adult hippocampal neurogenesis and phosphorylation of CREB in transgenic mouse model of Alzheimer’s disease. “The present findings suggest that 1) enhanced neurogenesis by EGb 761 may be mediated by activation of CREB, 2) stimulation of neurogenesis by EGb 761 may contribute to its beneficial effects in AD patients and improved cognitive functions in the mouse model of AD, and 3) EGb 761 has therapeutic potential for the prevention and improved treatment of AD.” 

·         The 2003 report Prenatal exposure of rats to Ginkgo biloba extract (EGb 761) increases neuronal survival/growth and alters gene expression in the developing fetal hippocampus states “These findings, which have provided the first genetic profile of the effects of EGb 761 on the developing rat hippocampus, increase our understanding of the molecular and genetic programs that are activated by the extract. These effects of EGb 761 may underlie its neuroprotective properties.” 

·         Studies of the neuroprotective effects of EGb 761 relating to Alzheimer’s Disease go back some time.  For example the 2000 publication The Ginkgo biloba extract (EGb 761) protects hippocampal neurons against cell death induced by beta-amyloid reported test-tube findings.  “We have investigated here the potential effectiveness of EGb 761 against toxicity induced by (Abeta)-derived peptides (Abeta25-35, Abeta1-40 and Abeta1-42) on hippocampal primary cultured cells, this area being severely affected in AD. A co-treatment with EGb 761 concentration-dependently (10-100 microg/mL) protected hippocampal neurons against toxicity induced by Abeta fragments, with a maximal and complete protection at the highest concentration tested.” 

·          The 2009 report Stimulation of Neurogenesis and Synaptogenesis by Bilobalide and Quercetin via Common Final Pathway in Hippocampal Neurons “Among the constituents tested, bilobalide and quercetin significantly increased cell proliferation in the hippocampal neurons in a dose-dependent manner. Bilobalide and quercetin also enhanced phosphorylation of cyclic-AMP Response Element Binding Protein (CREB) in these cells, and elevated the levels of pCREB and, brain-derived neurotrophic factor in mice brain. Immunofluorescence staining of synaptic markers shows remarkable dendritic processes in hippocampal neurons treated with either quercetin or bilobalide. Furthermore, both constituents restored amyloid-β oligomers (also known as ADDL)-induced synaptic loss and phosphorylation of CREB. The present findings suggest that enhanced neurogenesis and synaptogenesis by bilobalide and quercetin may share a common final signaling pathway mediated by phosphorylation of CREB. Despite a recent report showing that EGb 761 was insufficient in prevent dementia, its constituents still warrant future investigation.”

This all leaves me is thinking:

·        Despite the negative clinical studies related to cognition and dementia, there is much more to ginkgo biloba extract EGb 761 than vitamin-marketing smoke-and-mirrors.

·        I find the results of the large-scale human clinical study hard to understand given the results of the earlier animal studies but, hey, we are not rats and science is science.

·        For the present, I want to avoid any further claim that ginkgo biloba extract supplementation can prevent dementia or enhance cognition.

·        Until I can review the issue in more detail, I am leaving ginkgo biloba extract  as part of my Anti-aging firewalls supplement regimen because of possible health-giving actions the substance may have above and beyond cognition enhancement or dementia prevention.  For example, see Studies on the effect of Ginkgo biloba extracts on NF-kappaB pathway,  Ginkgo biloba Extract Inhibits Tumor Necrosis Factor- –Induced Reactive Oxygen Species Generation, Transcription Factor Activation, and Cell Adhesion Molecule Expression in Human Aortic Endothelial Cells and Ginkgo biloba extract reduces endothelial progenitor-cell senescence through augmentation of telomerase activity.

A number of interesting studies related to calorie restriction (CR) have shown up recently.   I will discuss a few of these studies here, particularly ones relating CR to cancers.   I will discuss additional studies relating CR to gene activation in a Part II post and speculate there on what I think these studies mean. 

Calorie restriction  involves systematic dietary restriction of calorie intake.  It has long been known to work as an effective longevity-enhancing intervention.  “CR when not associated with malnutrition,^[1] improves age related health and slows the aging process in some animals and fungi. CR is one of the few dietary interventions that has been documented to increase both the median and maximum lifespan in a variety of species, among them yeast, fish, rodents and dogs. There are currently ongoing studies on primates to show if CR works on primates, and even though they are showing positive indications^[2][3] it is still not certain that CR has a positive effect on longevity for primates and humans, due to the very lengthy time required for the completion of such lifespan studies(ref).^[2][3] “ 

The news this week in interesting since it describes effects of limiting glucose on the cellular level on both normal and precancerous cells.  The online pre-publication is entitled Glucose restriction can extend normal cell lifespan and impair precancerous cell growth through epigenetic control of hTERT and p16 expression.  “We analyzed normal WI-38 and immortalized (precancerous) WI-38/S fetal lung fibroblasts and found that glucose restriction resulted in growth inhibition and apoptosis in WI-38/S cells, whereas it induced lifespan extension in WI-38 cells.” (Both sets of cells were exposed to either normal or reduced levels of glucose (sugar) while being grown in the laboratory.)  “Moreover, in WI-38/S (precancerous) cells glucose restriction decreased expression of hTERT (human telomerase reverse transcriptase) and increased expression of p16INK4a. Opposite effects were found in the gene expression of hTERT and p16 in WI-38 cells in response to glucose restriction.”   

Said differently, reducing glucose decreased telomerase expression and increased apoptosis in precancerous cells leading them to die off, and produced the opposite effect in normal cells. 

The observed effects were epigenetic.  “The altered gene expression was partly due to glucose restriction-induced DNA methylation changes and chromatin remodeling of the hTERT and p16 promoters in normal and immortalized WI-38 cells. Furthermore, glucose restriction resulted in altered hTERT and p16 expression in response to epigenetic regulators in WI-38 rather than WI-38/S cells, suggesting that energy stress-induced differential epigenetic regulation may lead to different cellular fates in normal and precancerous cells. Collectively, these results provide new insights into the epigenetic mechanisms of a nutrient control strategy that may contribute to cancer therapy as well as anti-aging approaches(ref).”  

A 2008 report in Science Daily Calorie Restriction Limits — And Obesity Fuels — Development Of Epithelial Cancers  further examines the CR-cancer connection.  “A restricted-calorie diet inhibited the development of precancerous growths in a two-step model of skin cancer, reducing the activation of two signaling pathways known to contribute to cancer growth and development,–“ –“ This study employed four diets, two representing calorie reductions of 30 percent and 15 percent, a control diet including 10 percent kilocalories from fat, and an obesity-inducing diet consisting of 60 percent kilocalories from fat.  Agents were then given to the mice to induce premalignant lesions called papillomas, which are precursors to cancer. — Those on the calorie restricted diets had statistically significant inhibition of papilloma formation compared with the other two diets. — In a separate experiment the development of carcinomas and the effect of dietary energy balance on conversion of papillomas to carcinomas was evaluated. This study demonstrated that dietary energy balance determines the number of carcinomas found through its effects on the number of premalignant lesions but does not affect the rate of malignant conversion.” 

The molecular signaling pathways involved in the CR-cancer link appear to be ones discussed several times previously in this blog, namely IGF-1, Akt and mTOR(ref)(ref)(ref).  “Epithelial cancers arise in the epithelium – the tissue that lines the surfaces and cavities of the body’s organs. They comprise 80 percent of all cancers.  “Calorie restriction and obesity directly affect activation of the cell surface receptors epidermal growth factor (EGFR) and insulin-like growth factor (IGF-1R),” Moore said. “These receptors then affect signaling in downstream molecular pathways such as Akt and mTOR.” – “increased Akt and mTOR signaling are linked to the growth, proliferation and survival of many human cancers.”  These findings provide the basis for future translational studies targeting Akt/mTOR pathways through combinations of lifestyle and pharmacologic approaches to prevent and control obesity-related epithelial cancers in humans,” DiGiovanni said(ref).” 

It is interesting that CR inhibiting the Akt-mTOR pathways as mentioned in this study and glucose limitation inhibiting expression of hTERT and promoting P16 in cancer cells as mentioned in the other study seem on the surface to be independent effects.  No doubt, on a deeper level these effects are linked.   

Several other research reports highlight the association between CR and lower levels of cancer.  One research study  reported in 2008 “sheds light on the connection between obesity, calorie intake and pancreatic cancer by comparing a calorie restricted diet, an overweight diet and an obesity-inducing diet in a strain of mice that spontaneously develops pancreatic lesions that lead to cancer. – “Our findings indicate that calorie restriction hinders development of pancreatic cancer, which could have implications for prevention and treatment of pancreatic tumors caused by chronic inflammation and obesity.”–  The group’s analysis points to a connection between calorie intake and a protein called Insulin-like Growth Factor (IGF) -1, with obesity increasing and calorie restriction decreasing levels of IGF-1. IGF-1 is an important growth factor known to stimulate the growth of many types of cancer cells. Inflammatory signaling proteins also were found to be reduced in the blood of the calorie-restricted mice.”

“Mice on the heavier diets had significantly more lesions and larger lesions than those on the restricted calorie diet, — These lesions develop into pancreatic cancer and virtually all of these mice die within six to eight months.   The researchers fed the calorie restricted group a diet that was 30 percent lower in calories than that consumed by the overweight group and 50 percent lower than the obese group. Only 7.5 percent of mice on the calorie-restricted diet developed pancreatic lesions at the end of the experiment, and these lesions were so small that none exhibited symptoms of illness. For mice on the overweight diet, 45 percent developed lesions, as did 57.5 percent of those on the obesity-inducing diet. Lesions were also much larger in the overweight and obese mice than the calorie restricted mice. –. Pancreatic cancer is the fourth leading cause of cancer death and remains mostly intractable to existing treatments(ref). 

Sex differences and hormonal factors may also impact on the results of CR.  Regarding a 2008 study (ref) done by Spanish and Italian researchers, “Using lab rats as stand-ins for humans, the researchers found that the livers of both female rats and calorie-restricted rats produced different levels of 27 proteins than male rats or those on a normal diet. — The findings suggest that a previously unrecognized set of cellular pathways may be involved in the longevity boost from being female and eating a sparse diet, the study says, suggesting that these insights could lead to new ways of boosting human longevity(ref).” 

I will continue this discussion in the follow-up post, Calorie restriction research roundup – Part II.

A news item appeared this week citing mortality and morbidity statistics for patients who undergo abdominal surgery.  This led me to probe a bit into how surgery risks increase with age and even to speculate on why. 

First of all, to be clear on terminology, morbidity relates to ongoing disease, sickness or poor health and mortality describes the probability of death, usually measured in numbers of death per thousand individuals.  Both are cause-independent, that is, if mortality connected with  cancer surgery is counted in terms of deaths in the year following the operation, deaths due to pneumonia, stroke or other causes would be counted along with deaths due to cancer.  Comorbidity refers to the presence of one or more additional diseases or disorders, such as pneumonia and hypertension going along with lung cancer. 

In the latest study Impact of advancing age on abdominal surgical outcomes “Nader N. Massarweh, M.D., and colleagues at University of Washington School of Medicine, Seattle, examined complication and death rates of 101,318 adults age 65 or older who underwent common abdominal procedures such as cholecystectomy (gall bladder removal), hysterectomy and colectomy from 1987 to 2004. Complications were recorded within 90 days of discharge and deaths were recorded within 90 days of hospital admission(ref).” 

A review of the publication states:  “Older adults have a higher risk of complications and early death after common abdominal surgeries than doctors thought, a new study found.”

“Among patients 65 and older, the 90-day complication rate after abdominal surgery was 17.3% and the 90-day death rate was 5.4%, according to an online report in the Dec. 21 Archives of Surgery.”

“The likelihood of complications increased as patients aged beyond 65 years, with the researchers finding the following associations between age and complication frequency (trend test, P<0.001):

• 65 to 69 years, 14.6%
• 70 to 74 years, 16.1%
• 75 to 79 years, 18.8%
• 80 to 84 years, 19.9%
• 85 to 89 years, 22.6%
• 90 and older, 22.7%

Similarly, older patients were at higher risk of mortality. Death rates by age group were (trend test, P<0.001):

• 65 to 69 years, 2.5%
• 70 to 74 years, 3.8%
• 75 to 79 years, 6.0%
• 80 to 84 years, 8.1%
• 85 to 89 years, 12.6%
• 90 and older, 16.7%”

“Among older adults, the risk of complications and early death after commonly performed abdominal procedures is greater than previously reported,” Nader N. Massarweh, MD, of University of Washington School of Medicine, Seattle, and colleagues concluded(ref).”  What I find interesting is the rapid acceleration of death rates with age.  Comparing the 65-69 range with the 85-89 range, over a 20 year age interval the death rate associated with a surgery has gone up by a factor of five.

Reading this report led me to wonder if the reported  magnitudes of increase in risks with advancing age are typical or whether they are unique to the kinds of surgery studied.  So, I set out to look for other large scale studies of age-related morbidity and mortality associated with different surgical procedures.  One such study is reported in the 2005 paper Early mortality among Medicare beneficiaries undergoing bariatric surgical procedures.  “Results:  A total of 16,155 patients underwent bariatric procedures (mean age, 47.7 years [SD, 11.3 years]; 75.8% women). The rates of 30-day, 90-day, and 1-year mortality were 2.0%, 2.8%, and 4.6%, respectively. Men had higher rates of early death than women (3.7% vs 1.5%, 4.8% vs 2.1%, and 7.5% vs 3.7% at 30 days, 90 days, and 1 year, respectively; P<.001). Mortality rates were greater for those aged 65 years or older compared with younger patients (4.8% vs 1.7% at 30 days, 6.9% vs 2.3% at 90 days, and 11.1% vs 3.9% at 1 year; P<.001).   After adjustment for sex and comorbidity index, the odds of death within 90 days were 5-fold greater for older Medicare beneficiaries (aged 75 years; n = 136) than for those aged 65 to 74 years (n = 1381; odds ratio, 5.0; 95% confidence interval, 3.1-8.0).”  Normally, the risk of death associated with bariatric surgery is low (0.5%), but apparently the risk rises very steeply with advanced age, much as observed in the first-mentioned study.

Both of the above studies were concerned with surgeries of the GI track.  Turning to a different kind of operative procedure the report Coronary arteriography and coronary artery bypass surgery: morbidity and mortality in patients ages 65 years or older. A report from the Coronary Artery Surgery Study, ‘Of 2144 patients age 65 years or older entered into the registry of the Coronary Artery Surgery Study (CASS) who had coronary arteriography, 1086 underwent isolated coronary artery bypass grafting. Complications of angiography included death in four patients and nonfatal myocardial infarction in 17. Eight patients suffered neurologic complications, which were transient in five. The perioperative mortality was 5.2% (57 of 1086), which is significantly greater than the perioperative mortality of 1.9% (151 of 7827) in patients younger than 65 years entered in CASS (p less than 0.001). There was a trend toward an increased mortality rate with age; it was 4.6% (37 of 803) in patients age 65-69 years, 6.6% (16 of 241) in those 70-74 years and 9.5% (four of 42) in those 75 years or older. The duration of hospital stay after operation was significantly longer for the patients 65 years or older than for the patients younger than 65 (13.3 vs 11.4 days; p less than 0.001).”  Again, the observed increase of mortality with age was drastic and consistent with that reported in the other studies.

I checked out one more study Effect of patient age on increasing morbidity and mortality following urogynecologic surgery.  “There were 264,340 women in our study population. Increasing age was associated with higher mortality risks per 1000 women (<60 years, 0.1; 60-69 years, 0.5; 70-79 years, 0.9; ≥80 years, 2.8; P < .01) and higher complication risks per 1000 women (<60 years, 140; 60-69 years, 130; 70-79 years, 160; ≥80 years, 200; P < .01). Using multivariable logistic regression, increasing age was associated with an increased risk of death (60-69 years, odds ratio [OR] 3.4 [95% CI 1.7-6.9]; 70-79 years, OR 4.9 [95% CI 2.2-10.9]; ≥80 years, OR 13.6 [95% CI 5.9-31.4]), compared with women <60 years. The risk of peri-operative complications was also higher in elderly women 80 years of age and older (OR 1.4 [95% CI 1.3-1.5]) compared with younger women.”  Again, a similar pattern was observed, 5.6 times he mortality risk in the oldest group compared to that that in the younger group.  Amazing how similar these rates are to those observed in the first-mentioned study above, and amazing the difference that 20 years makes at the end of life! 

These results are not surprising given what we know about aging.  Vulnerability to multiple causes of illness and death starts to accelerate around 50, picks up in the 60s, accelerates further in the 70s and goes into warp overdrive in the 80s – resulting in everybody in known history being dead by age 123.  There are many ways to explain this effect, the 14 theories of aging and seven candidate theories in my treatise being the main ones from a scientific viewpoint.  The darkest view is that given in my blog entry Homicide by DNA methylation.   According to that view, lifelong progression of DNA methylation causes accumulation of irreversible DNA mutational damage.  Even if you could reverse the methylation at old age you could not undo the mutations so its soon curtains for us old folk, no matter what.  End of discussion.  The other theories of aging to some extent allow more hope for the prospect of extending life.  Discovering where the best realistic hope lies is an ultimate objective I have in following and understanding the research described in this blog.