The odontogenic differentiation of human dental pulp stem cells on nanofibrous poly(l-lactic acid) scaffolds in vitro and in vivo

The aim of this study was to investigate the odontogenic differentiation of human dental pulp stem cells (DPSCs) on nanofibrous (NF)-poly(l-lactic acid) (PLLA) scaffolds in vitro and in vivo. Highly porous NF-PLLA scaffolds which mimic the architecture of collagen type I fibers were fabricated by the combination of a phase-separation technique and a porogen-leaching method. The human DPSCs were then seeded onto the scaffolds and cultured in different media for odontogenic differentiation: “Control” medium without supplements; “DXM” medium containing 10−8 M dexamethasone (DXM), 50 μg ml−1 ascorbic acid and 5 mM β-glycerophosphate; “BMP-7 + DXM” medium containing 10−8 M DXM, 50 μg ml–1 ascorbic acid, 5 mM β-glycerophosphate plus 50 ng ml−1 bone morphogenetic protein 7 (BMP-7). For odontogenic differentiation study in vitro, alkaline phosphatase activity quantification, reverse transcription polymerase chain reaction, scanning electron microscopy, von Kossa staining and calcium content quantification were carried out. While both “DXM” medium and “BMP-7 + DXM” medium induced the DPSCs to odontoblast-like cells, the “BMP-7 + DXM” medium had greater inducing capacity than the “DXM” medium. Consistent with the in vitro studies, the “BMP-7 + DXM” group presented more extracellular matrix and hard tissue formation than the “DXM” group after 8 weeks of ectopic implantation in nude mice. Differentiation of DPSCs into odontoblast-like cells was identified by the positive immunohistochemical staining for dentin sialoprotein. In conclusion, odontogenic differentiation of DPSCs can be achieved on NF-PLLA scaffolds both in vitro and in vivo; the combination of BMP-7 and DXM induced the odontogenic differentiation more effectively than DXM alone. The NF-PLLA scaffold and the combined odontogenic inductive factors provide excellent environment for DPSCs to regenerate dental pulp and dentin.