[Tissue repairing cells that exist among mesenchymal stem cells; their potential for cell-based therapy].

Although adult stem cells are generally known to generate the cell types of the tissue in which they reside, mesenchymal stem cells (MSCs) are unique in that they differentiate not only into the same mesodermal-lineage such as bone, cartilage, and adipocytes, but also into other lineages of ectodermal and endodermal cells. Furthermore, a subpopulation of MSCs are known to integrate into damaged sites, differentiate into cell types specific to the integrated tissue and contribute to the tissue repair. As MSCs comprise heterogeneous cell populations, however, the cells responsible for wide-ranging differentiation as well as for tissue repair have not been identified. Recent evidence suggests that a subpopulation of human MSCs, which were named Muse cells, were shown to have the ability to differentiate into trilineage cells and to function as tissue repairing cells in vivo. This review summarizes recent advances in MSC properties and discuss about future perspectives.