The change in color of our hair associated with aging results from a depletion of the resources of the cells responsible for pigmentation. Researchers specify the mechanism involving melanin-producing stem cells.
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A new American study sheds light on the gray area surrounding the mechanism of hair “aging”. Published in Nature, it offers a better understanding of how melanocyte stem cells (melanin producers) turn hair gray and then white with age. The phenomenon is directly related to the loss of plasticity of melanocyte stem cells (MSCs), which normally move along the hair follicle and enable hair pigmentation. According to the authors, the loss of chameleon function in MSCs could be the cause of graying and hair color loss.
The natural phenomenon that turns our hair gray over time is called “canitie”. The number of MSCs increases with age, but the cells accumulate in a certain area of the hair follicle and become blocked. They cannot return to the germination chamber where proteins normally activate them into pigment cells responsible for hair color.
An experiment on mice transmissible to humans
Researchers conducted experiments on mice to better understand what happens when hair ages. They pulled out and forced hair regrowth, only to find that the stem cells housed in the bulb of the follicle had increased from 15% before hair removal to about 50% with “forced aging”. Without activating proteins, the melanocyte stem cells stopped producing pigment. In contrast, cells that continued to move continued to mature and produce pigment over the two years of the study.
To reverse or prevent the change in hair pigmentation in humans with aging, one possible way would be to help blocked cells move back between compartments of the developing hair follicle.