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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The Mount Sinai Health System is New York City's largest academic medical system, encompassing eight hospitals, a leading medical school, and a vast network of ambulatory practices throughout the greater New York region. Mount Sinai is a national and international source of unrivaled education, translational research and discovery, and collaborative clinical leadership ensuring that we deliver the highest quality care—from prevention to treatment of the most serious and complex human diseases. The Health System includes more than 7,200 physicians and features a robust and continually expanding network of multispecialty services, including more than 400 ambulatory practice locations throughout the five boroughs of New York City, Westchester, and Long Island. The Mount Sinai Hospital is ranked No. 14 on U.S. News & World Report's "Honor Roll" of the Top 20 Best Hospitals in the country and the Icahn School of Medicine as one of the Top 20 Best Medical Schools in country. Mount Sinai Health System hospitals are consistently ranked regionally by specialty and our physicians in the top 1% of all physicians nationally by U.S. News & World Report.