Feasibility Study Of Using Human Bone Marrow-derived Mesenchymal Stem Cells As Seeding Cells For Tissue Engineered Skin

Skin transplantation is the main means of treating skin defect caused by large-area burn or wound. In addition, deemed as the most effective in clinic treatment, autogenous skin transplantation has always been restricted for lack of autogenous skin source. Along with the development of tissue engineering, people has begun to realize the significance of developing new-type products to accelerate the concrescence of wound area and promote skin regeneration. Tissue engineering has three main factors, i.e. seeding cells, scaffold and extracelluar matrix(proper microenvironment), among which, the seeding cells has been viewed as the most crucial. An ideal seeding cell ought to have the following features: firstly, it has a convenient source; secondly, it has enough proliferation capacity to increase as many cell population as needed; thridly, it passages in vitro in the long term without changing the biological properties, and etc. This research finds out that human bone marrow-derived mesenchymal stem cells (BM-MSCs) are ideal as seeding cells. As one kind of adult stem cells, BM-MSCs has the self-renewal and differentiation potential. In certain conditions, they can differentiate into different embryonic layer cells as osteoblast, adipocyte, chondrocyte etc. Moreover, with low antigenicitiy and strong proliferation capacity, they are convenient to obtain. As well, the acquisition of BM-MSCs is not restricted from ethnics perspective.But there is seldom report of using MSCs in tissue engineered skin. Our experiments aim at finding out whether MSCs can differentiate into epidermal cells and whether they can be used as seeding cells in tissue engineering. Our previous research shows that BM-MSCs are likely to differentiate into epidermal cells. The current experiments range from repeating differentiation induction in vitro, to observing whether BM-MSCs can form epidermal layer or form epidermis together with epidermal cells with asymmetric scaffold in vitro. A large number of experiments are made, which show that although BM-MSCs succeed in advancing the concrescence of wound area, they have difficulty in differentiating into epidermal cells. In the end, the study proceeds with large-area burned patients to discuss whether BM-MSCs can be mobilized to blood to participate in the repair of burn wound and whether blood-bom MSCs can be used as the seeding cells of epidermis. The result shows the possibility exists while great efforts should be made in the method of separation and purification. The main findings and conclusions of the study are as follows:1. Both primary and passage human BM-MSCs, separated and cultivated with the method of Percoll gradient, showed typically fibroblast-like morphology and swirl growth with MSC's surface markers.2. There is possibility that BM-MSC differentiate into epidermal cells in vitro in inducing culture medium.3. Both BM-MSCs and BM-MSCs after directional inducing differentiation in vitro could promote the concrescence of skin wound area of naked mice. However, in special inducing culture medium, BM-MSCs neither performed the function of epidermal cells, nor emerged in the epidermal cells of the naked mice.4. Fibrin glue was useful to repeat the construction of symmetric porous scaffold and proofed the scaffold innocuous to MSCs. However, it is difficult to use BM-MSCs as seeding cells in the symmetric porous scaffold for the construction of tissue engineered skin.5. No MSCs were separated and cultured from peripheral blood of large-area burned patients in the way of density gradient centrifugation by use of Percoll separation medium. However, the possibility may exist.