The role of bFGF on the ability of MSC to activate endogenous regenerative mechanisms in an ectopic bone formation model.

The view depicting bone marrow (BM)-derived mesenchymal stem cells (MSC) as a uniform population differentiating into new-tissue builder cells is evolving toward the concept of a heterogeneous population of stem/progenitor cells secreting bioactive molecules, and contributing to establish an on-site regenerative microenvironment. We report that in an ectopic bone formation model the intrinsic MSC capability to activate endogenous regenerative mechanisms is critically dependent on the commitment level of implanted MSC. We demonstrate that the presence of bFGF in the culture medium during mouse MSC expansion in vitro is the key factor for the selection of subpopulations inducing host regenerative responses.