Studies of balding male mice have uncovered a possible cause of hair loss in men and women as well. The findings, published in Nature Aging, provide new insight into how hair and tissues age.
The study shows as hair stem cells age, they lose the adhesion that keeps them lodged inside the hair follicle. As their adhesiveness wanes, the stem cells escape from their location, called the bulge, into the dermis. Once outside their delicate microenvironment, they generally can’t survive.
“The result is fewer and fewer stem cells in the hair follicle to produce hair,” said lead author Rui Yi, the Paul E. Steiner Research Professor of Pathology at Northwestern University Feinberg School of Medicine. “This results in thinning hair and ultimately baldness during ageing.”
This finding could be applicable to older men and women with thinning hair as mice and humans share hair and stem cell similarities, Prof Yi said.
By labelling individual stem cells with a fluorescent marker, the researchers were able, for the first time, to track hair follicle ageing in real time in live animals. Scientists also discovered two key genes responsible for enhancing adhesiveness of the stem cells. They are now trying to reinstate these genes to see if that will reverse hair loss.
During follicles’ normal cycles of life and death, a large number of stem cells remain permanently lodged in the stem cell compartment of hair follicles to keep producing hair follicle cells.
“We believe this stem cell escape mechanism has never been reported before, because nobody could track the aging process in live animals,” Yi said.
Though scientists knew hair follicles become miniaturised during aging, how it happened was unclear. Many thought it was due to cell death or the inability of cells to divide as they age.
“We discovered, at least in part, it is due to hair follicle stem cells migrating away from their niche,” Prof Yi said. “Cell death also occurs during our observation. So, our discovery doesn’t dispute existing theories but provides a new mechanism.”
Source: Northwestern University
