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).
About the Mount Sinai Health System
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 advances medicine and health through unrivaled education and translational research and discovery to deliver care that is the safest, highest-quality, most accessible and equitable, and the best value of any health system in the nation. The Health System includes approximately 7,300 primary and specialty care physicians; 13 joint-venture ambulatory surgery centers; more than 415 ambulatory practices throughout the five boroughs of New York City, Westchester, Long Island, and Florida; and more than 30 affiliated community health centers. The Mount Sinai Hospital is ranked on U.S. News & World Report's "Honor Roll" of the top 20 U.S. hospitals and is top in the nation by specialty: No. 1 in Geriatrics and top 20 in Cardiology/Heart Surgery, Diabetes/Endocrinology, Gastroenterology/GI Surgery, Neurology/Neurosurgery, Orthopedics, Pulmonology/Lung Surgery, Rehabilitation, and Urology. New York Eye and Ear Infirmary of Mount Sinai is ranked No. 12 in Ophthalmology. Mount Sinai Kravis Children's Hospital is ranked in U.S. News & World Report’s “Best Children’s Hospitals” among the country’s best in four out of 10 pediatric specialties. The Icahn School of Medicine is one of three medical schools that have earned distinction by multiple indicators: ranked in the top 20 by U.S. News & World Report's "Best Medical Schools," aligned with a U.S. News & World Report "Honor Roll" Hospital, and No. 14 in the nation for National Institutes of Health funding. Newsweek’s “The World’s Best Smart Hospitals” ranks The Mount Sinai Hospital as No. 1 in New York and in the top five globally, and Mount Sinai Morningside in the top 20 globally.