ABSTRACT
Mesenchymal stem cells (MSCs) are a population of plastic-adherent cells that has clonogenic capacity and multilineage differentiation potential in vitro. They can be isolated from bone marrow, adipose tissue, umbilical cord, and several other postnatal connective tissues [1]. Unlike the hematopoietic system, where the positive and negative selection of specific surface markers facilitates 600the isolation of hematopoietic stem cells (HSCs) from which a single HSC is capable of reconstituting the multilineage blood system in irradiated mice, the ability of a single MSC to reconstitute different mesenchymal compartments in vivo has not been demonstrated. Thus, the usage of “mesenchymal stem cell” to describe these cells is somewhat controversial since “stemness” implies self-renewal and multipotent capabilities, neither of which has been rigorously substantiated at the clonal level in vivo [1]. Nevertheless, MSCs are a promising cell source for regenerative medicine owing to their high ex vivo expansion rate, low immunogenicity, and their ability to give rise to committed progenies relevant for clinical applications, such as those in the mesenchymal (adipogenic, chondrogenic, osteogenic, tenogenic, myogenic, or endothelial) or even non-mesenchymal (neurogenic) lineages.
