No gray hairs? Scientists discover the biological key to preserving hair color

NEW YORK — Scientists may have discovered a method to prevent hair from turning gray, shedding light on a tell-tale sign of aging that both women and men have sought to conceal for generations. Researchers in New York have found that specific stem cells, known as melanocyte stem cells (McSCs), possess the unique ability to move between growth compartments in hair follicles.

However, they also discovered that as hair ages, sheds, and regrows, an increasing number of these stem cells become trapped in a compartment called the hair follicle bulge. Consequently, these hairs remain in the bulge and fail to return to their original location in the compartment, where proteins would have assisted them in regenerating into pigment cells, thereby preserving their color.

The study, conducted by researchers at the NYU Grossman School of Medicine, examined the physically-aged hairs of mice and observed that more stem cells became stuck after forced aging. These cells also remained incapable of regenerating or maturing into pigment-producing hairs that maintain their color.

hair coloring stem cells
Hair-coloring stem cells (at left, in pink) need to be in the hair germ compartment in order to be activated (at right) to develop into pigment. (Courtesy of the journal Nature)

The scientists are hopeful that their research could pave the way for solutions to maintain hair health and color well into old age. The study focused on McSCs, which both mice and humans carry, and are responsible for hair color. The NYU team determined that McSCs are adaptable, meaning that they continually shift back and forth along the maturity axis as they move between compartments of the developing hair follicle, where they encounter varying levels of maturity-influencing protein signals.

How can scientists use this discovery to stop graying hair?

As hair ages, the study found that increasing numbers of McSCs become trapped in the hair follicle bulge, unable to mature into the transit-amplifying state or return to their original location in the germ compartment. Proteins in this compartment help them regenerate into pigment cells.

The researchers note that McSC adaptability is not present in other self-regenerating stem cells, such as those composing the hair follicle itself. These cells move in only one direction along an established timeline as they mature. This helps explain, in part, why hair can continue to grow even as its color fades away.

“Our study adds to our basic understanding of how melanocyte stem cells work to color hair,” says study lead investigator Qi Sun, PhD, a postdoctoral fellow at NYU Langone Health, in a media release. “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.”

The research team plans to explore potential means of restoring the motility of McSCs or physically moving them back to their germ compartment, where they can produce pigment, thus preventing hair from turning gray.

“It is the loss of chameleon-like function in melanocyte stem cells that may be responsible for graying and loss of hair color,” adds study senior investigator Mayumi Ito, PhD, a professor in the Ronald O. Perelman Department of Dermatology and the 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 findings are published in the journal Nature.

South West News Service writer James Gamble contributed to this report.

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