2023-04-19 17:02:55
Gray hair is in fashion, but not everyone likes to show it off and many dream of some solution to reverse it that doesn’t mean having to dye it from time to time. A new investigation, published in the journal ‘Nature’, has revealed in detail the process behind the hair bleaching. A discovery in mice that, if confirmed in humans, would open the door to a potential treatment to return hair to its natural color.
According to the study results, certain stem cells have a unique ability to move between growth compartments in hair follicles, but just as easily stop flowing and lose their ability to mature and maintain hair color as they age. people get old.
Led by researchers at New York University Grossman School of Medicine, the new work focused on a type of skin cells in mice, which is also found in human skin, called melanocyte stem cells, or McSC. These are responsible for the melanocyte regenerationcells specialized in producing melanin and essential for coloring our hair.
The new study showed that McSCs are remarkably moldable, meaning that during normal hair growth, These cells continually move back and forth. in the maturity axis as they transit between compartments of the developing hair follicle, where they are exposed to different levels of protein signals.
Specifically, the research team found that McSCs transform between their most primitive stem cell state and the next stage of their maturation, the transit amplification state, depending on their location.
As hair ages, falls out, and then repeatedly grows back, an increasing number of McSCs become ‘stuck’ in the stem cell compartment called the bulge of the hair follicle. There they remain, do not mature to the transit amplified state, and do not travel back to their original location in the germinal compartment, where WNT proteins would have pushed them to regenerate into pigment cells.
“Our study adds to our basic understanding of how melanocyte stem cells work to color hair. The newly discovered mechanisms raise the possibility that this same melanocyte stem cell process may exist in humans. If so, does it present a potential avenue for reverse or prevent aging of human hair by helping stuck cells move back between compartments of the developing hair follicle,” explains the study’s principal investigator, Qi Sun, a postdoctoral fellow at NYU Langone Health.
The researchers say that the plasticity of McSCs is not present in other stem cells self-regenerating, like those formed by the hair follicle itself, which are known to move in only one direction along a set timeline as they mature. In this way, the transit-amplifying hair follicle cells never return to their original stem cell state. This helps explain in part why hair can continue to grow even when its pigmentation fails, adds Sun.
Earlier work by the same NYU research team showed that WNT signaling was needed to stimulate McSCs to mature and produce pigment.
In the latest experiments in mice whose hair was physically aged by epilation and forced regrowth, the number of hair follicles with McSCs stuck in the follicle pons increased from 15% before epilation to almost half after forced aging. These cells remained unable to regenerate or mature into pigment-producing melanocytes. They ceased their regenerative behavior because they were no longer exposed to much WNT signaling, and thus their ability to produce pigment in new hair follicles, which continued to grow, was impaired.
In contrast, the McSCs that continued to move back and forth between the follicle bulge and the hair germ maintained their ability to regenerate, mature into melanocytes, and produce pigment throughout the entire two-year study period.
“It is the loss of chameleon function in melanocyte stem cells that may be responsible for aging and loss of hair color. These findings suggest that melanocyte stem cell motility and reversible differentiation are key to maintaining healthy, colored hair,” said study principal investigator Mayumi Ito, a professor in the Ronald O. Perelman Department of Dermatology and the Department of in Cell Biology at NYU Langone Health.
The team has plans to investigate ways to restore motility of McSCs or to physically move them back to their germ compartment, where they can produce pigment.
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