The roles of mesenchymal stem cells in tissue repair and disease modification.

Mesenchymal stem cells (MSCs) are multi-potent cells which have been widely used for tissue regeneration and immunomodulation. The infusion of autologous and allogenic MSCs has been proved to be safe and effective in tissue repair and disease modulation. The inherent homing ability of MSCs ensures the transplanted cells migrating into the damaged tissue areas, but only a small percentage of the transplanted (allogenic) MSCs survive for long. However, the beneficial effects of MSCs transplantation could be noted within 1-2 days that are unlikely due to their proliferation and differentiation. The regulatory roles of MSCs in tissue repair are rather more important than their direct involvement of repair processes. The most important effect of transplanted MSCs is their immunomodulation function through crosstalk with the immune cells or the paracrine actions. The active factor secreted by MSCs may vary in the different disease conditions or tissue niches, and are under dynamic changes in various local environments. To understand and define the MSCs secretion factors in various disease settings could be a future research direction, and the findings could lead to potential new MSCs-based therapeutic products.