Science finds a formula to reverse the process of gray hair

2023-04-23 01:12:00

A team of researchers from New York identifies a kind of ‘jam’ of the cells responsible for pigmentation that prevents hair from coloring over time

Beyond the feminine debate of yes to the liberation of the reeds o to dye bondage, the important thing is to be able to choose, science has revealed why they appear, and, with it, perhaps, their reversibility. A team of researchers from New York University has found the cell ‘failure’ whereby cells stop producing color pigments.

Seen under a microscope, scientists have observed how inside each hair, in each hair, there are certain mother cells possessing a unique ability to move between compartments of growth of hair folliclesbut they get ‘stuck’ as the people get old and thus lose their ability to mature and maintain hair color. And the gray hairs appear.

The team of New York University Langone Medical Center He has been working on revealing this process for more than a decade. It was in 2011 that it was found how two groups of stem cells jointly control hair color: one of them is in charge of the hair follicles, where each hair grows; and others are melanocytes, or melanocyte stem cells, or McSCs. In the magazine Cellpublished how the protein called Wnt was the one that coordinated hair color from the melanocytes, as well as gray hair.

This new work, led by researchers at the Grossman School of Medicine, focused on cells in the skin of mice, also present in humans, called cmelanocyte stem cells. Hair color depends on whether McSCs, which do not function but multiply continuously in hair follicles, are signaled to become mature cells that produce the protein pigments responsible for color.

The novelty is that the research that has been published Nature shows that these cells are remarkably plastic. And this means? During normal hair growth, these cells continually move back and forth in the axis of maturation as they transit between compartments of the developing hair follicle. It is within these compartments that McSCs are exposed to different levels of protein signals (WNTs) that influence maturity.

Specifically, the research team found that McSCs transform between their most primitive stem cell state and the next phase of their maturation, the transit-amplify state, depending on their location.

Stem cells that dye hair (on the left, in pink) must be in the germ compartment of the hair to be activated (on the right) and become pigment

All this process, which is complicated at the cellular level, means that as the hair ages, falls out and grows back repeatedlyan increasing number of cells responsible for pigmentation get stuck in the stem cell compartment called the bulge of the hair follicle. There they remain, do not mature and do not return to their original location in the germinal compartment, where proteins would have prompted them to regenerate into pigment cells.

How can you reverse gray hair to normal without dye?

“Our study expands our basic understanding of how melanocyte stem cells work to color hair,” says the study’s principal investigator, Dr. Qi Sun, a postdoctoral fellow at NYU Langone Health. “The newly discovered mechanisms raise the possibility that the same fixed position of melanocyte stem cells could exist in humans. If so, it presents a potential pathway to reverse or prevent graying of human hair by helping stuck cells move back between compartments of the developing hair follicle.”

The researchers say that the plasticity of McSCs is not present in other self-regenerating stem cells, such as those that make up the hair follicle itself, which are known to move in only one direction along a set timeline as they grow. mature. For example, hair follicle cells that are amplified in transit never return to their original stem cell state. This helps to explain in part why hair can continue to grow, even if its pigmentation fails“says Sun.

“The loss of chameleon function of melanocytic stem cells may be the cause of graying and loss of hair color,” said study principal investigator Mayumi Ito, a Ronald O. Perelman Professor in the Department of Dermatology and Department of Cell Biology at NYU Langone Health. “These findings suggest that the motility and reversible differentiation of melanocyte stem cells are key to maintaining healthy and colored hair.”

In this sense, Ito expresses the intention of implementing processes to restore the activity of the McSCs or even physically transfer them back to their germinal compartment, where they can produce pigment.

How do the pigments responsible for gray hair get ‘stuck’?

Previous work by the same research team at NYU Grossman School of Medicine demonstrated that WNT signaling was required to stimulate McSCs to mature and produce pigment. That study had also shown that McSCs were many trillion times less exposed to WNT signaling in the pons of the hair follicle than in the germinal compartment of hair, located directly below the pons.

With all these data, experiments were carried out on mice whose hair was physically aged by epilation and forced regrowth, the number of hair follicles with McSCs lodged 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.

Among the conclusions found, the researchers discovered that the stuck McSCs stopped regenerating when they were no longer exposed to too much WNT signaling and, therefore, their ability to produce pigment in new hair follicles, which continued to grow. That is, the new hair grew in the absence of pigment, the gray hair.

In contrast, other McSCs that did continue to move back and forth between the follicle bulge and the hair germ retained their ability to regenerate as McSCs, mature into melanocytes and produce pigment throughout the two-year study period.

Is there a genetic footprint in the appearance of gray hair?

In 2016, another publication in Nature Communications echoed the identification of a gene responsible for gray hair, IRF4. Its role in hair coloring was already known, but then it was directly associated with graying hair.

This gene is involved in regulating the production and storage of melanin, the pigment that determines the color of hair, skin, and eyes. Graying of hair is caused by the absence of melanin in the hair, so scientists want to discover the role of IRF4 in this process.

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