Experts claim to have uncovered what they think to be the root of baldness.
According to a Northwestern Medicine study, a newly found cause of balding in aging male and female mice could disclose a cause of hair loss in men and women as well. The findings add to our understanding of how hair and tissues age.
Hair stem cells lose the stickiness that keeps them fixed inside the hair follicle as they age, according to a study published in Nature Aging. The stem cells escape from their bulge position into the dermis when their adhesiveness wanes. They can’t thrive outside of their fragile habitat.
“The result is fewer and fewer stem cells in the hair follicle to produce hair,” explained 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 aging.”
Because mice and humans have numerous parallels in hair and stem cells, Yi believes the findings could apply to older men and women with thinning hair.
This is the first time scientists have observed hair follicle ageing in live animals, giving them a molecular glimpse of the aging process in real-time.
Scientists also uncovered two important genes that are responsible for increasing the adhesiveness of stem cells. In a new investigation, researchers are attempting to reintroduce these genes to determine whether this will correct hair loss.
Our hair follicles go through life and death cycles. To keep creating hair follicle cells during these regular cycles, a considerable number of stem cells remain permanently stuck in the stem cell compartment of hair follicles. Scientists identified what happens to these stem cells as they age, resulting in thinning hair and baldness, in this study.
“We believe this stem cell escape mechanism has never been reported before, because nobody could track the aging process in live animals,” Yi said.
Scientists have long known that as people age, their hair follicles shrink. But it wasn’t apparent how it happened. Many experts assumed it was related to cell death or the cells’ inability to divide as they became older.
“We discovered, at least in part, it is due to hair follicle stem cells migrating away from their niche,” Yi said. “Cell death also occurs during our observation. So, our discovery doesn’t dispute existing theories but provides a new mechanism.”
In live mice, scientists employed a long-wavelength laser to study hair follicle cells during ageing and labelled hair follicle cells, including stem cells, with green fluorescent protein. For several days, they observed the same hair follicle (in one case, they observed one hair follicle for 26 days and saw the entire process of hair follicle degradation). They noticed traces of a strange cell escape.
They next compared gene expression levels in follicle stem cells between young and aged mice. In aged hair follicle stem cells, they discovered the lower expression of adhesion-related genes.
The researchers then discovered a subset of genes that may control the expression of these cell adhesion genes. These two genes, FOXC1 and NFATC1, were genetically knocked off in mutant animals. As a result, hair loss began to accelerate around four months. These mice become fully bald in 12 to 16 months. Finally, researchers employed live imaging to capture the action of stem cells migrating away from the stem cell niche in these mutant animals.
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