Mount Sinai Researchers Discover That Muscle Surrounding Hair Follicles Is Essential to New Hair Growth
Latest Discovery Could Aid in the Development of Treatment for Hair Loss
Mount Sinai researchers have discovered the function of a muscle surrounding hair follicles that is essential to the hair cycle process and could be key to the prevention of future hair loss, according to a study published in the journal Science in January.
The muscle, called the dermal sheath, has been recognized by scientists for decades, but little was understood about its role until now.
Hair grows in lifelong cycles of follicle growth, regression, and rest, followed by shedding of the old hair shaft and renewed hair growth from the stem cell reservoir. The Mount Sinai researchers discovered in mice that the dermal sheath is a smooth muscle that contracts during the follicle regression phase to physically relocate dermal papilla cells from the follicle base to the stem cells in the upper follicle. The dermal papilla provides essential signals for activation of the stem cells.
The research team also showed that this contraction machinery is present in human hair follicles, suggesting that similar mechanisms occur in people.
The research team found that the dermal sheath is the main driver in cell movement during the regression process before regeneration of the follicle and new hair shaft growth can begin. When the sheath’s contraction is blocked, the follicle regression and dermal papilla relocation are impeded. Manipulating the contraction presents an opportunity to treat hair loss by stalling the hair cycle and preventing loss of existing hair.
“Blocking the newly discovered muscle and its contraction cannot cure baldness caused by hair loss diseases. Instead, blocking contraction and arresting the destruction phase of the cycle has the potential to retain the existing hair shaft that is otherwise lost when a new hair shaft is produced and before hair loss sets in,” said Michael Rendl, MD, Professor of Cell, Developmental and Regenerative Biology, and Dermatology, and Associate Director, Black Family Stem Cell Institute, at the Icahn School of Medicine at Mount Sinai; and senior author of the study. “We are excited about the possibility of stopping follicle regression and preventing the loss of the existing hair. Our studies continue to make this possible in the future.”
The study was funded by grants from the National Institutes of Health (NIAMS) and the stem cell research initiative of the New York State Department of Health (NYSTEM).
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Mount Sinai Health System is one of the nation’s leading integrated academic health systems and one of the largest in the New York metropolitan area. Its comprehensive system includes seven hospitals, more than 400 outpatient practices, over 600 research and clinical laboratories, the Icahn School of Medicine at Mount Sinai, the Graduate School of Biomedical Sciences, and the Mount Sinai Phillips School of Nursing. Together, the Health System comprises approximately 48,000 employees, more than 9,000 physicians, and 8,600 nurses.
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