The hair follicle is dynamic, cycling between growth (anagen), regression (catagen), and resting (telogen) phases throughout life. We have demonstrated that nestin-expressing hair follicle stem cells give rise to follicle structures during early anagen or growth phase of the hair follicle. Nestin-expressing hair follicle stem cells appear in the hair follicular stem cell area, the permanent upper hair follicle immediately below the sebaceous glands and above the bulge area. The nestin-expressing hair follicle stem cells can differentiate into neurons, glia, keratinocytes, smooth muscle cells, and melanocytes in vitro. Furthermore, the hair follicle stem cells promote the recovery of peripheral nerve and spinal cord injury. We have termed these cells hair follicle pluripotent stem (hfPS) cells. These results suggest that hfPS cells provide an important accessible, autologous source of adult stem cells with potential for use in regenerative medicine.
