In my earlier post How am I doing I said “All of this is just a start though. I not only want a full head of hair; I want it to be black instead of gray.” Also, in an earlier post Why does your hair turn gray? I described research that pointed to hydrogen peroxide as the culprit for hair turning gray. Newly-reported research looks in a different direction and deeper, shedding light on the underlying cell-level cause of graying hair. Melanocytes are cells that live in hair follicles of mammals that produce melanin, the pigment responsible for hair color. Normally, the melanocytes gives hair its characteristic color of youth – black in my case. (Melanin is also responsible for skin color and the color in moles, freckles, suntan and the cancer melanoma. Older people may develop light or dark patches on their skin due to too-little or too-much melanin.)
The new research suggests that gray or white hair is due to age-related depletion of melanocytes which is a direct result of depletion of melanocyte stem-cells(MSCs) which in turn is the result of DNA damage. It has been known for some time that “ – hair graying is caused by defective self-maintenance of MSCs(ref).” These stem cells, also living in hair follicles, can normally both reproduce making new stem cells and differentiate into mature color-producing melanocytes. The new research based on experimentation with mice suggests that DNA damage to MSCs causes them to stop reproducing and instead terminally differentiate into melanocytes. As the melanocytes in hair follicles die off, there are no new melanocytes to replace them because there are no more MSCs to make them. The result is loss of hair color, in other words, white or gray hair. The researchers discovered that when mice were exposed to intense radiation, MSCs stopped self-reproducing and terminally differentiated into melanocytes. Consequently, the fur on the mice turned from brown to gray. It is thought that the cessation of self-reproduction of genetically damaged MSCs could be an evolutionary protection against cancers.
Wanting black hair, this poses a challenge for me. If my hair follicle MSCs have died off, how do I get them back? There seems to be no short term answer though there may be one in the longer term.
It appears that there is a larger issue at stake here when it comes to aging. The reader may want to review my discussion of the 14th theory of aging Decline in Adult Stem Cell Differentiation. What the new research says with respect to that theory is 1. that there is not only the issue of decline in differentiation to be concerned with as part of aging but also an issue of stem cell self-renewal, and 2. At least some stem cells stop self-renewal in the presence DNA damage.
Both immediate and long-term anti-aging interventions appear to be suggested. In the immediate outlook the obvious approach is to use antioxidants to minimize DNA damage. Millions of people are already doing this. See the Cell DNA Damage theory of aging in my treatise as well as the associated firewall discussion. For the longer term, it may be possible to induce Pluripotent Stem Cells (iPSC) to selectively differentiate in a controlled manner into adult stem cells, including MSCs. See the earlier post on this Blog Rebooting cells and longevity. If a practical iPSC approach could be found to generating MSCs in hair follicles, I might get my black hair back. Meanwhile I stay tuned for more research in this area. I do not plan to use shoe polish.