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Dr. Yunyuan Li has completed his Ph.D. in 2005 from the University of Alberta, Canada. He is a currently a senior researcher at Burn and Wound Healing Research Laboratory at the University of British Columbia, Canada. His research interests were focused on the roles of hematopoietic cell-derived multi-potent stem cells in skin wound healing, hair follicle regeneration, and inflammation. Till now, Dr. Li has published over 40 articles in peer-reviewed journals.
Non-healing and chronic wounds cause tremendous suffering and debilitation .To look for new strategies to improve healing of damage skin tissue and understand the mechanism underlining a complex wound healing process, in last a few years, we have conducted a serial of studies to identify healing promoting factors. We found that the macrophage colony-stimulating factor (M-CSF) released from proliferating skin cells could induce a subset of hematopoietic cells to be dedifferentiated into multipotent stem cells. Interestingly, hematopoietic cell-derived, stage specific embryonic antigen (SSEA)-1 and-3 positive, multipotent stem cells were transiently present in the wound site after skin injury. In this study, we further explored the roles of these hematopoietic cell-derived multipotent stem cells to repair injured skin and hair regeneration in a mouse model. Hematopoietic cell-derived multipotent stem cells were generated by culture mouse splenocytes in a medium containing M-CSF. Skin excisional wounds were generated by punch biopsy in mice which received nothing (control) or one million splenocyte-derived stem cells by intra-dermal or tail vein injection simultaneously. Injected stem cells expressing GFP or labeled with a fluorescent dye Dil were used for cell tracing. Immunofluorescent staining was used to identify the cell source in healing skin tissue. Results revealed that addition of M-CSF or its antibody to increase or reduce the number of hematopoietic cell-derived stem cells at the wound site could accelerate or slow skin wound healing in mice. We also demonstrated that injected hematopoietic cell-derived stem cells could be differentiated into fibroblasts, keratinocytes and blood vessel-like structures in vivo. These blood cell-derived skin cells were the major contributions of healing skin. Furthermore, our results suggested that hematopoietic cell-derived multipotent stem cells could participate in new hair follicle regeneration. In conclusion, hematopoietic cells are the major contributions and cell source for skin tissue repair and hair regeneration.