Program in Epithelial Stem Cells and Regeneration


The IRM Program in Epithelial Stem Cells and Regeneration works closely with Penn’s departments of dermatology, plastic surgery and ophthalmology. The ultimate goal of the program is to devise new treatments for diseases of the skin and cornea through the study of stem cells and regenerative medicine.


  • Discovery and isolation of stem cells in hair follicles, which are responsible for hair growth, and can regenerate hair follicles when injected  (Morris, et al.: Capturing and profiling hair follicle stem cells. Nature Biotechnology 22: 411-417, 2004).
  • Identification of key factors important for skin regeneration, hair growth and wound healing  (Ito, M., et al.: Wnt-dependent de novo hair follicle regeneration in adult mouse skin after wounding.  Nature 447: 316-321, 2007).
  • Discovery of stem cells in the cornea of the eye, which transformed the way corneal transplants are performed to treat certain types of blindness  (Cotsarelis, et al.: Existence of slow-cycling limbal epithelial basal cells that can be preferentially stimulated to proliferate: implications on epithelial stem cells. Cell 57: 201-209, 1989).
  • Demonstration of normal stem cell numbers in male pattern baldness leading to identification of prostaglandins as important in inhibiting hair growth in male pattern baldness  (Garza, et al.:Bald scalp in men with androgenetic alopecia retains hair follicle stem cells but lacks CD200-rich and CD34-positive hair follicle progenitor.  J Clin Invest 121(2): 613-622, February 2011.  Garza, L.A., et al.: Prostaglandin D2 inhibits hair growth and is elevated in bald scalp of men with androgenetic alopecia.  Science Translational Medicine 4(126 126ra34): 1-11, March 21, 2012).


  • Bioengineering of skin, teeth, corneas, mucous membranes, salivary glands, sweat glands and other associated tissues to replace tissue lost through injury or cancer treatment.
  • Conversion of induced pluripotent stem cells into different cell types in skin and eye to treat disease through tissue engineering.

“Stem cell research is critical to developing new skin tissues and, ultimately, changing the way we care for devastating wounds.”
George Cotsarelis, M.D., is Director of IRM Program Epithelial Stem Cells and Regeneration, and Albert M. Kligman Professor of Dermatology.  Dr. Cotsarelis discovered the stem cells in the cornea, which transformed the way cornea transplants are used to treat certain types of blindness.