[Heterogeneity of mesenchymal stem cells in culture in vitro]

Mesenchymal stem cells (MSC) are the ideal adult stem cells in cell/gene therapy and tissue engineering for their features of easily-handling, highly proliferative capacity in vitro, low immunogenicity and immunomodulatory ability. MSC, as a kind of cellular drug, have been utilized in a phase III clinical trial to treat refractory graft-versus-host disease (GVHD). However, the essences of MSC in culture remain elusive so far. Whether the cells expanded in vitro are stem cells per se, and if not, why expanded MSC maintain their multiple differentiation ability? And are the MSC cultivated in vitro homogeneous and if not, what the heterogeneity stands for? Focusing on the heterogeneity of MSC in culture in vitro, the above questions are briefly discussed in this review.