BACKGROUNDThe seed cell is a core problem in bone tissue engineering research. Recent research indicates that human dental pulp stem cells (hDPSCs) can differentiate into osteoblasts in vitro, which suggests that they may become a new kind of seed cells for bone tissue engineering. The aim of this study was to evaluate the osteogenic differentiation of hDPSCs in vitro and bone-like tissue formation when transplanted with three-dimensional gelatin scaffolds in vivo, and hDPSCs may become appropriate seed cells for bone tissue engineering.

METHODSWe have utilized enzymatic digestion to obtain hDPSCs from dental pulp tissue extracted during orthodontic treatment. After culturing and expansion to three passages, the cells were seeded in 6-well plates or on three-dimensional gelatin scaffolds and cultured in osteogenic medium. After 14 days in culture, the three-dimensional gelatin scaffolds were implanted subcutaneously in nude mice for 4 weeks. In 6-well plate culture, osteogenesis was assessed by alkaline phosphatase staining, Von Kossa staining, and reverse transcription-polymerase chain reaction (RT-PCR) analysis of the osteogenesis-specific genes type I collagen (COL I), bone sialoprotein (BSP), osteocalcin (OCN), RUNX2, and osterix (OSX). In three-dimensional gelatin scaffold culture, X-rays, hematoxylin/eosin staining, and immunohistochemical staining were used to examine bone formation.

RESULTSIn vitro studies revealed that hDPSCs do possess osteogenic differentiation potential. In vivo studies revealed that hDPSCs seeded on gelatin scaffolds can form bone structures in heterotopic sites of nude mice.

CONCLUSIONSThese findings suggested that hDPSCs may be valuable as seed cells for bone tissue engineering. As a special stem cell source, hDPSCs may blaze a new path for bone tissue engineering.