The researchers found a clue to overcoming this barrier in their observations of rodent hair. Rodent papillae can be easily harvested, expanded, and successfully transplanted back into rodent skin, a method pioneered by Dr. Jahoda several years ago. The main reason that rodent hair is readily transplantable, the researchers suspected, is that their dermal papillae (unlike human papillae) tend to spontaneously aggregate, or form clumps, in tissue culture. The team reasoned that these aggregations must create their own extracellular environment, which allows the papillae to interact and release signals that ultimately reprogram the recipient skin to grow new follicles.
"This suggested that if we cultured human papillae in such a way as to encourage them to aggregate the way rodent cells do spontaneously, it could create the conditions needed to induce hair growth in human skin," said first author Claire A. Higgins, PhD, associate research scientist.
To test their hypothesis, the researchers harvested dermal papillae from seven human donors and cloned the cells in tissue culture; no additional growth factors were added to the cultures. After a few days, the cultured papillae were transplanted between the dermis and epidermis of human skin that had been grafted onto the backs of mice. In five of the seven tests, the transplants resulted in new hair growth that lasted at least six weeks. DNA analysis confirmed that the new hair follicles were human and genetically matched the donors.
"This approach has the potential to transform the medical treatment of hair loss," said Dr. Christiano. "Current hair-loss medications tend to slow the loss of hair follicles or potentially stimulate the growth of existing hairs, but they do not create new hair follicles. Neither do conventional h
|Contact: Karin Eskenazi|
Columbia University Medical Center