In Vivo Bone Formation by Human Dental Pulp Cells Cultured without Cell Sorting and Osteogenic Differentiation Induction

Tissue engineering is in the process of making the shift from bench to bed. In a common strategy of tissue engineering, stem cells were sorted from primary cultured cells by cell surface markers, and then differentiated into the suitable cells for tissue regeneration using differentiation-inducing agents. The more simple strategy is the better in clinical application. This study showed that human dental pulp cells (hDPCs) cultured primarily under ordinary serum- supplemented condition without cell sorting and osteogenic differentiation induction possessed the capability to generate bone tissue in vivo. The alkaline phosphatase activity of hDPCs increased during in vitro cell culture, and the expression of osteocalcin was detected in the primary outgrowth culture of hDPCs. The hDPCs generated ectopic bone tissues on the border of the porous hydroxyapatite scaffold at 12 weeks after implantation in all 10 cases. This ectopic bone formation by hDPCs was observed regardless of the developing stage of tooth as a cell source, the type of culture medium, serum concentration and implantation site. We did not use cell sorting and osteogenic differentiation-inducing agents throughout this study. These results lead to set up a simple strategy of bone tissue engineering like not previous.