Scientists may have found the reason why our hair turns grey as we age.
A new study suggests stem cells may get stuck and lose their ability to maintain hair colour as our locks age.
Certain stem cells – cells that can develop into many different cell types – have a unique ability to move between growth compartments in hair follicles.
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It is these cells that lose the ability to move with age, paving the way for grey 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 found in humans called melanocyte stem cells, or McSCs.
The scientists suggested that if their findings hold true for humans, it could open up a potential way to reverse or prevent the greying of hair.
Hair colour is controlled by whether continually multiplying pools of McSCs within hair follicles allow the signal to become mature cells that make the protein pigments responsible for colour.
The study, published in the journal Nature, found that during normal hair growth, such cells continually move back and forth as they travel between compartments of the developing hair follicle.
It is inside these compartments where McSCs are exposed to signals that influence maturity.
According to the findings, as hair ages, sheds, and then repeatedly grows back, increasing numbers of McSCs get stuck in the stem cell compartment called the hair follicle bulge.
They remain there and do not mature, and do not travel back to their original location in the compartment, where they would have been prodded to regenerate into pigment cells.
The lead investigator of the study Qi Sun, a postdoctoral fellow at NYU Langone Health in New York, said: “Our study adds to our basic understanding of how melanocyte stem cells work to colour hair.
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“The newfound mechanisms raise the possibility that the same fixed-positioning of melanocyte stem cells may exist in humans.
“If so, it presents a potential pathway for reversing or preventing the greying of human hair by helping jammed cells to move again between developing hair follicle compartments.”
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The study’s senior investigator Mayumi Ito, a professor at the Ronald O Perelman Department of Dermatology and the Department of Cell Biology at NYU Langone Health, said: “It is the loss of chameleon-like function in melanocyte stem cells that may be responsible for greying and loss of hair colour.”
The researchers plan to investigate means of restoring movement of McSCs or of physically moving them back to their germ compartment, where they can produce pigment.
