A study on the activity of dermal multipotent stem cells in initiation of wound repair

Background: Wound healing is a process of cell-cell interaction and cell-extracellular matrix interaction. Dermal multipotent stem cells (dMSCs) have the abilities to promote survival and wound healing, but the potential function of dMSCs in wound healing, particularly in the initiation of wound repair, has not been fully understood. Methods: dMSCs and fibroblasts were isolated from neonatal rat dermis and were further purified and expanded. The cell cycles were determined with flow cytometry, while the radiosensitivity was measured by MTT assay. Rats were wounded with a 7-cm incision on the back skin and the wound fluids were collected by inserting two pieces of sterile polyvinyl alcohol sponge (1 cm in diameter and 0.4 cm in thickness) subcutaneously into the dorsum of each rat through the midline of incision on the 1, 2, 3 and 4 day after incision. The effects of wound fluids on the proliferation of dMSCs and fibroblasts were measured with MTT assays. dMSC’s abilities of adhesion and attachment and its migration in response to wound fluids collected on the 1 day after incision were explored by measuring the percentage of floating cells and the cells migrated into wounding area in vitro, respectively. Results: The isolated dMSCs were morphologically homogenous and highly proliferative. Most of the cultured dMSCs were quiescent with few apoptotic cells. Compared with fibroblasts, dMSCs were more sensitive to radiation and more proliferative in response to wound fluids, especially to the wound fluids collected on the 1 day after wounding. Moreover, their abilities to attach, adhere and migrate were significantly enhanced with the early-phase wound fluids. Conclusions: As primitive stem cells, dMSCs are very responsive to wound fluids, which suggests dMSCs’ important role in wound healing, especially in initiating wound repair.