BioWorld International Correspondent

PARIS - Researchers at the French National Institute of Health and Medical Research (INSERM) in Paris have demonstrated for the first time that the skin of adult mammals contains stem cells capable of giving birth to all the cell lines necessary for regenerating the epidermis, the sebaceous glands and hair follicles. Most of these stem cells are to be found in the hair follicles.

The research team, led by Yves Barrandon, made the discovery in studies on mice, which possess about 50 hair follicles per square millimeter of skin compared with about five per square millimeter for humans. Earlier studies had concluded that hair follicles, which are deeply embedded in the dermis, effectively served as reservoirs of stem cells for the skin, with each follicle containing an estimated 1,000 to 1,500 stem cells.

Barrandon's research went further by locating these stem cells in a small zone in the upper part of the follicles and by retracing three different migration and differentiation paths upward and downward. They were thus able to establish that an adult mammal's skin contains all the skin's epithelial cell lines, not only those of the hair follicles, the hair itself and the sebaceous glands, but also those of the epidermis keratinocytes.

Barrandon said he was hopeful of finding the same phenomenon in human cells. If so, his discovery would have many different potential applications, not only in obvious areas, such as improving the appearance of skin grafts used to treat serious burns, speeding up the healing process for skin wounds and treating baldness, but also in combating skin cancer. In the area of carcinology, it could shed light on the transformation of certain follicle cells, whose corrupted activity is responsible for many carcinomas, so as to reverse the process. In addition, it could help protect hair follicle stem cells during chemotherapy to prevent the loss of hair that often results from such treatment.