STUCK STEM CELLS – REASON FOR THE GREY HAIRS AT EARLY STAGE

Certain stem cells have a unique ability to move between growth compartments in hair follicles, but get stuck as people age and so lose their ability to mature and maintain hair color, a new study shows.

Stem cells – some of them have unique or we can say a different capability to travel between the hair follicles growth compartments and that is what responsible for the color of the hair, that is revealed by new studies from NYU Grossman School of Medicine researchers

The study was performed on the skin of the mice as well humans have those stem cells named melanocyte stem cells, or else they were known as McSCs.

McSCs is responsible to control the color of the hair by nonfuction but the cells are continually multiplying pools of these McSCs within the hair follicles. These hair follicles gets the signals to grow into the mature stem cells which is responsible for the color or pigment of the hair we have.

Somehow with specificity researchers or a team of researcher found that the transformation of McSCs from their most primitive stem cells stage to next maturation stage , the transit amplifying stage and totally depends on their location of movement.

The latest study that was published on 19th April 2023 in Nature (journal) that the stem cells (McSCs) are plastic that is product by our human cells.

This indicates that during normal hair growth, such cells which is designated as plastic continuously moves forward and backward on the level of maturity axis because they were moving between the compartments of developing these hair follicles. Inside the compartment the protein signal influences the exposer of McSCs to different level of maturity or growth phase.

During the ageing process where our hair gets older , they sheds, and then repetitively grown back again, that leads to the accumulation of McSCs in the compartment known as hair follicle bulge. At that stage they stay there and do not get matured  and also not able to travel back to their originating location in the germ compartment, where they regenerate into the pigment cells due to the WNT proteins.

 "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 new discovery of the mechanism increases the possibilities that the same fixed-locating of melanocyte stem cells may be present in humans. If this is true, then it is the responsible pathway for getting back or we can prevent the grey hair by getting those jammed stem cells to move between developing hair follicle compartments.

  McSC plasticity is not found in other self-regenerating stem cells as researcher said, such as those cells who is responsible for creating of the hair follicle itself, which are known to move in only one direction along an designed pathway as they mature.

For example, transit-amplifying hair follicle cells never get back to their original stem cell stage. This leads to tell us that in part why hair can keep growing even while its losses its color, says Sun.

The same research team at NYU earlier said that to stimulate the McSCs WNT signalling is required to mature those cells and also to produce pigmentation or color to the hair. Also, those studies tell us that as compared to WNT signalling McSCs were trillion times less exposed to signalling in the hair follicle bulge than in the hair germ compartment, that is situated diretly below the bulge.

The latest experiment performed on the mice who’s haired was physically aged by plucking and forced to regrowth, the number of hair follicles with McSCs lodged in the follicle bulge increased from 15% before plucking to nearly half after forced aging. These cells remained incapable of regenerating or maturing into pigment-producing melanocytes.

 The researchers found that the stucked McSCs,, Stopped their regenerative ability as they were no longer in exposure to much WNT signaling and hence their ability to generate pigment in new hair follicles, which continued to grow.

By contrast, other McSCs that continued to move back and forth between the follicle bulge and hair germ retained their ability to regenerate as McSCs, mature into melanocytes, and produce pigment over the entire study period of two years.

"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 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," said Ito, who is also a professor in the Department of Cell Biology at NYU Langone.

Ito says the team has plans to investigate means of restoring Moavble ability of McSCs or of physically moving them back to their germ compartment, where they can produce pigmentation or color.

For the study, researchers used recent 3D-intravital-imaging and scRNA-seq techniques to track cells in almost real time as they aged and moved within each hair follicle.

Funding for the study was provided by National Institutes of Health grants P30CA016087, S10OD021747, R01AR059768, R01AR074995, and U54CA263001; and Department of Defense grants W81XWH2110435 and W81XWH2110510.

Besides Sun and Ito, other NYU Langone researchers involved in this study are co-investigators Wendy Lee, Hai Hu, Tatsuya Ogawa, Sophie De Leon, Ioanna Katehis, Chae Ho Lim, Makoto Takeo, Michael Cammer, and Denise Gay. Other study co-investigators are M. Mark Taketo, at Kyoto University in Japan, and Sarah Millar, at Icahn School of Medicine at Mount Sinai in New York City.

 SOURCE: REFERENCE