Enhanced wound-healing quality with bone marrow mesenchymal stem cells autografting after skin injury

Adult stem cells exist in various tissues and organs and have the potential to differentiate into different cell lineages, including bone, cartilage, fat, tendon, muscle, and epithelial cells of the gastrointestinal tract. Here, we report that the in vitro expanded and purified bone marrow mesenchymal stem cells (MSCs) might take on phenotypes with characteristics of vascular endothelial cells (7% on day 3 and 15% on day 1) or epidermal cells (3% on day 3 and 13% on day 1) after being cultured under different lineage-specific culture conditions. Also, in vivo grafting experiments showed that 5-bromodeoxyuridine-labeled MSCs could convert into the phenotypes of vascular endothelial cells (3.43, 3.46, and 2.94% on days 7, 14, and 28, respectively) in granulation tissues, sebaceous duct cells, and epidermal cells (0-1.49%) in regenerated skin, implying that these grafted MSCs might have transdifferentiated into the above three cell types. Animal autografting experiments with MSCs further confirmed that indices pertaining to wound healing quality, such as the speed of reepithelialization, the number of epidermal ridges and thickness of the regenerated epidermis, the morphology and the number and arrangement of microvasculature, fibroblasts and collagen, were much enhanced. Our results indicate that locally delivered bone marrow MSCs can enhance wound healing quality, and may generate de novo intact skin, resulting in perfect skin regeneration after full-thickness injury.