Bone marrow mesenchymal stem cells increase skin regeneration efficiency in skin and soft tissue expansion

Background: Skin and soft tissue expansion has limitations such as long hospitalization time and flap retraction after expansion. Our previous study suggested that bone marrow-derived stem cells contribute skin regeneration in skin and soft tissue expansion. In this study, the authors explored the feasibility of applying the bone marrow mesenchymal stem cells (BMMSCs) to the treatment of skin and soft tissue expansion and increasing the skin regeneration efficiency. Methods: Sixty silicone expanders were implanted in the backs of 15 pigs, and allogeneic BMMSCs were transplanted to skin shallow fascia layer (local transplantation, Group A) or via ear vein (systemic transplantation, Group B). Group C was the Sham operation control; and then the expanders were injected with normal saline (N.S.). Skin was obtained at different time points (days 0, 14, 21, 28, 35, and 42). The organizational structure changes of the target skin were observed in the expansion process. The distribution, differentiation, and paracrine function of labeled BMMSCs were detected. Results: Comparing with Group B (25.00 +/- 1.98 cm(2)) or Group C (24.00 +/- 1.10 cm(2), no transplantation), the expanded skin area of Group A (28.82 +/- 1.43 cm(2)) increased, with the morphology of epidermis thickened, and dermis thinned. The BMMSCs differentiated into vascular endothelial cells and dermal fibroblasts. The quantity of newborn cells was proportional to the number of transplanted cells. The gene expression of VEGF, bFGF, EGF, and SDF in Group A was higher than those in Group B or C. The most obvious changes were on day 35. Conclusions: The local transplanted BMMSCs could increase the skin regeneration efficiency in skin and soft tissue expansion and reduce skin shrinkage effectively after removing the expander. Growth factors, VEGF, bFGF, EGF, and SDF, are favorable to this process.