In multiple sclerosis and several other brain disorders, the protective sheath around neurons called myelin breaks down, which in turn disrupts the transmission of nerve signals. Researchers at the VA Maryland Health Care System and the University of Maryland School of Medicine have found a new way to rebuild myelin with a type of stem cell that lives in hair follicles.
The researchers focused on stem cells that create melanocytes, which are the pigment-producing cells in mature hair follicles. They discovered that stem cells with a surface protein called CD34 can grow into the glial cells that form myelin. When they implanted CD34 positive stem cells in mice that had been engineered to lack myelin sheaths, the protective coatings formed around their neurons, they reported in the journal PLOS Genetics.
Why hair? Melanocytes that are found in hair actually originate from neural crest cells, which can also generate neurons and glial cells, the researchers explained in a statement. The same team had previously discovered two populations of melanocyte-producing stem cells in mature hair follicles. With further investigation, they discovered that only the CD34-positive cells turned into glial cells.
The researchers believe that if CD34-positive stem cells can be found in human hair, they could be examined as a potential source of new treatments for MS and other demyelinating diseases, as well as for nerve injuries.
Finding new ways to rebuild myelin is a priority among neurology researchers, who have been investigating a range of ideas for accomplishing that feat. Scientists at the University of Chicago have been working on making a safe derivative of an old blood pressure drug, Wytensin (guanabenz), ever since they discovered it protects myelin. Other approaches focus on using microRNAs to regenerate myelin and reprogramming skin cells from patients into myelin-repairing cells.
Examining the potential of skin cells in myelin repair is a priority of the Maryland team, too. They’re planning further studies designed to elucidate the potential sources, as well as the functions, of different cells that contribute to the protection and repair of neurons.
"In the future, we plan to continue our research in this area by determining whether these cells can enhance functional recovery from neuronal injury," said co-author Thomas Hornyak, M.D., Ph.D., associate professor of dermatology at the University of Maryland, in the statement. He added that they hope to "leverage genome-wide information" they gathered in this study to determine whether similar cells might be able to generate from skin cells.