A potential breakthrough has been made in understanding how hair turns grey, with scientists identifying the underlying mechanism.
This discovery could pave the way for the development of treatments that target these cells to either halt or reverse the greying process.
The study, published in the journal Nature online and led by researchers from NYU Grossman School of Medicine, discovered that certain stem cells in hair follicles, called melanocyte stem cells or McSCs, have the ability to move between growth compartments in the follicles during normal hair growth.
However, as people age, increasing numbers of McSCs get stuck in the stem cell compartment called the hair follicle bulge, which results in the loss of their ability to mature and maintain hair color.
The researchers found that McSC plasticity is not present in other self-regenerating stem cells, such as those making up the hair follicle itself, which move in only one direction along an established timeline as they mature.
“Our study adds to our basic understanding of how melanocyte stem cells work to color hair,” said study lead investigator Qi Sun, PhD, a postdoctoral fellow at NYU Langone Health.
“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 graying of human hair by helping jammed cells to move again between developing hair follicle compartments.”
During experiments on mice, researchers found that as hair aged, more stem cells became lodged in a specific part of the hair follicle and were unable to mature into pigment-producing cells.
These cells stopped regenerating because they weren’t exposed to enough signaling, which is needed to produce pigment. However, other stem cells that were still able to move between different parts of the hair follicle were able to continue regenerating and producing pigment over the course of the study.
“It is the loss of chameleon-like function in melanocyte stem cells that may be responsible for graying and loss of hair color,” said study senior investigator Mayumi Ito, PhD, a professor in the Ronald O. Perelman Department of Dermatology and Department of Cell Biology at NYU Langone Health.
“These findings suggest that melanocyte stem cell motility and reversible differentiation are key to keeping hair healthy and colored.”
The team plans to investigate means of restoring the motility of McSCs or of physically moving them back to their germ compartment, where they can produce pigment.