Scientists studying hair follicles in mice may have finally discovered the mechanism behind how and why hair turns gray. These findings may one day lead to the development of new methods to stop or reverse the graying process.
Scientists already knew that hair turns gray when there is a lack of certain cells called melanocytes (pigment-producing cells); But we still don’t fully understand why or how this happens, and if there’s a way to prevent it.
According to Science AlertA new study provides more details about the phenomenon of hair graying, while disproving previously held ideas about how melanocytes develop. Melanocytes are derived from melanocyte stem cells (McSCs) in hair follicles. The new study focuses on these stem cells.
As we age, these pigment-producing cell precursors seem to get stuck in an area called the “follicular bulge.” In this condition, not enough of them turn into melanocytes to fill the growing hair shaft with color.
In experiments conducted on mice, after the forced aging process, the number of hair follicles with melanocyte stem cells trapped in the follicle bulge increased from 15% to about half. These cells were no longer regenerated or transformed into mature cells to produce pigment and remained as melanocyte stem cells. what are youa dermatologist and hair specialist from New York University says:
The researchers found that melanocyte stem cells, unlike other types of stem cells, can switch between a pure stem cell state and a transient proliferative (TA) state. The transient proliferative state is an intermediate state between a stem cell and a complete melanocyte cell.
It seems that the state of TA is very important for the health of melanocyte stem cells and the continuation of hair color production; But the researchers found that the ability to transition into the TA state depends on receiving signals from specific locations. When the cells are stuck in the follicular ridge, they don’t receive these signals.
It should be mentioned that the described cases should be observed in human hair follicles; But there may be similar mechanisms in our hair. Ultimately, this research could even provide a way to develop treatments that prevent our hair from losing its color.
The researchers write in the journal Nature: “The results define a new model, according to which the process of reversal of differentiation is an integral part of maintaining the biological balance of stem cells, and the regulation of melanocyte stem cell motility may represent a new approach to prevent hair graying.”
Melanocyte stem cells migrate to change state. Other stem cells do not do this, and this mobility and flexibility seems to be necessary for the continuous production of melanin by melanocytes.
Hair follicle stem cells do not need to be transferred to the state of follicle cells; Therefore, while the production of melanocytes stops, the follicle itself can continue to grow new hair. This partly explains why hair can continue to grow even when it loses its color.
Meanwhile, there are other mechanisms and not everything depends on the stem cells; Because genetics and level Stress is also effective in graying hair with age. Mayumi Itodermatologist and hair specialist from New York University says: “These findings show that the motility of melanocyte stem cells and their reversible differentiation is the key to maintaining the health and color of hair.”
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