Incipient analysis of mesenchymal stem-cell-derived osteogenesis

Tissue regeneration strategies invoke cell-based therapies for effective ti ssue formation. Current assessment of mesenchymal stem cell (MSC) directed bone regeneration during in vivo assays is dependent-on histologic determin ation of bone formation. It was the aim of this study to determine the rela tionship between bone sialoprotein (BSP) expression and osteocalcin express ion with subsequent osteogenesis occurring in MSG-based implants. RT-PCR as sessment of human actin, collagen type I, BSP, and osteocalcin indicated th at undifferentiated cells did not express BSP or osteocalcin. Three weeks f ollowing implantation, human BSP could be identified in RNAs isolated from the retrieved implants. For every implant from which human BSP cDNA was amp lified, parallel implants harvested at 6 weeks demonstrated bone formation at the histologic level. This study confirms that, in the context of the se vere combined immunodeficiency disease (SCID) mouse model, culture-expanded , cryopreserved human MSCs have osteogenic potential and demonstrates that implanted cell gene expression can reveal the early onset of bone formation .