Distribution of murine adipose-derived mesenchymal stem cells in vivo following transplantation in developing mice

Systemic delivery of mesenchymal stem cells (MSCs) or stromal cells in vivo is attractive because it offers means of disseminating therapeutic cells to various tissues and organs in vivo. In the present study, we investigated the distribution and engraftment of the murine adipose-derived mesenchymal stem cells (ADSCs) without exposure to or exposed to bone microenvironment or transforming growth factor-beta1 (TGF-beta1) prior to transplantation into developing mice. The ADSCs harvested from the murine inguinal fat pad exhibited potential for differentiation toward osteogenic and adipogenic cell lineages in vitro. Fourteen days after systemic transplantation of the ADSCs marked with enhanced green fluorescent protein (EGFP) into developing mice, minimal donor GFP(+) cells were detected in the skeletal tissues in a limited number of the recipient mice. Exposure of the ADSCs to bone microenvironment for 7 or 14 days prior to transplantation into developing mice enhanced their migration and survival in the bones of the recipient mice. Exposure of ADSCs to TGF-beta1 prior to systemic transplantation exerted similar effects on cell migration and engraftment in various tissues, including the bones of the recipient developing mice. At 28 days following systemic transplantation, the ADSCs exposed to bone microenvironment were restricted mostly to the skeletal tissues of the recipient mice. Donor cells retrieved from the bones of the recipient mice at 28 days following cell transplantation expressed the differentiation markers Runx2 and Osterix (Osx). These data suggest that exposure of ADSCs to bone microenvironment or to TGF-beta1 prior to transplantation enhances their survival in the skeletal tissues following transplantation.