Differentially expressed genes between osteochondroprogenitor sub-populations

Cell based bone regeneration strategies offer promise for traumatic bone injuries, congenital defects, non-union fractures and other skeletal pathologies. Postnatal bone remodeling and fracture healing provide evidence that an osteochondroprogenitor cell is present in adult life which can differentiate to remodel or repair the fractured bone. However, cell based skeletal repair in the clinic is still in its infancy mostly due to poor characterization of progenitor cells and lack of knowledge about their in vivo behavior. Here we took a combined approach of high throughput screening, flow based cell sorting and in vivo transplantation to identify markers that identify osteochondroprogenitor cells. We show that the presence of tetraspanin CD9 enriches for osteochondroprogenitors within CD105+vemesenchymal cells and these cells readily form bone upon transplantation. In addition we have used Thy1.2 (CD90) and the ectonucleotidase CD73 to identify subsets within the CD9+ve population that lead to endochondral or intramembranous-like bone formation. Utilization of this unique cell surface phenotype to enrich for osteochondroprogenitor cells will allow for further characterization of the molecular mechanisms that regulate their osteogenic properties. Osteochondroprogenitor sub-populations were arrayed for differentially expressed genes. Osteochondroprogenitor cells were FACS sorted from E16.5 mouse embryonic limb suspension after staining with Flurochrome conjuigated antibodies