Scientists may have figured out why our hair turns gray as we age.
A new study suggests that as our hair ages, stem cells may get stuck and lose their ability to maintain hair color.
Certain stem cells — cells that can develop into many different cell types — have the unique ability to move between the growth chambers of the hair follicle.
It is these cells that lose their ability to move with age, paving the way for gray hair.
The research, led by New York University’s (NYU) Grossman School of Medicine, focused on cells in the skin of mice that are also present in humans, called melanocyte stem cells (McSC).
The scientists say that if their discovery applies to humans, it could open up a potential way to reverse or prevent hair graying.
Hair color is controlled by whether the constantly proliferating pool of McSCs within the follicle allows the signal to become mature cells, allowing the protein pigment to be responsible for the color.
The study, published in the journal Nature, found that during normal hair growth, these cells are constantly moving back and forth between the compartments of the developing hair follicle.
It is within these compartments that McSCs are exposed to signals that affect maturation.
According to the findings, as hair ages, falls out, and then repeatedly grows back, more and more McSCs get stuck in a stem cell compartment called the follicular bulge.
They remain there without maturing and without returning to their original position in the compartment, where they are pushed to regenerate as pigment cells.
Qi Sun, lead researcher on the study and a postdoctoral researcher at NYU Langone Health in New York, said: “Our study adds to our fundamental understanding of how melanocyte stem cells color hair.
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“The newly discovered mechanism raises the possibility that the same fixed localization of melanocyte stem cells may exist in humans.
“If so, it offers a potential way to reverse or prevent hair graying in humans by helping clogged cells move again between developing hair follicle compartments.”
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“Loss of chameleon-like function in melanocyte stem cells may be Causes of hair graying and loss of hair color.”
The researchers plan to investigate ways to restore the movement of McSCs, or physically move them back to their germ chambers, where they can produce pigments.