1. Investigate dose dependent effects of autologous growth factor contents released from platelet concentrate on rate and amount of new bone formation formed by implanted autologous osteoblasts derived from bone marrow stromal cells. The results will be compared with osteoinductive effects of BMP-2
2. Investigate effects of growth factor contents released from platelet concentrate on apoptosis of bone forming cells in vivo
3. Explore a feasibility to use autologous mesenchymal stem cells and growth factors in enhancing host bone regeneration