The effect of fibroblast growth factor 7 on human dental pulp stem cells for differentiation to AQP5-positive and αSMA-positive cells in vitro and in vivo

Objectives Transplantation of stem cells into wounds has become popular in regeneration therapies. As stem cells for transplantation, human dental pulp stem cells (hDPSCs) are known to be pluripotent cells that are relatively easy to collect from the pulp of deciduous or wisdom teeth. The purpose of this study was to investigate whether hDPSCs treated with fibroblast growth factor 7 (FGF7) would contribute to the regeneration of wounded rat submandibular glands (SMGs). Materials and methods In in vitro studies, hDPSCs were treated with or without FGF7 and mRNA expression levels were examined at days 3, 7 and 14 using qRT-PCR. The target genes analyzed were BMI1 as an undifferentiated marker, AQP5 as an acinar cell marker, CK19 as a ductal epithelial cell marker, alpha SMA as a myoepithelial cell marker and VIMENTIN as a fibroblast marker. In in vivo studies, hDPSCs treated with or without FGF7 for 14 days were mixed with type I collagen gels and were transplanted into wounded rat SMGs. Hematoxylin-Eosin and immunohistochemical staining were performed at days 3 and 7, and the numbers of positive cells were counted. The primary antibodies used were against BMI1, AQP5, alpha SMA, PanCK and VIMENTIN. Results In the in vitro studies, mRNA levels of BMI1 were decreased and alpha SMA were increased at days 3, 7 and 14, while AQP5 was increased at day 14 in the FGF7 group. In the in vivo studies, the proliferation of hDPSCs and cell islands was observed at day 7 in the FGF7 group. Few BMI1-positive cells were observed, while numbers of AQP5-positive and alpha SMA-positive cells were increased at days 3 and 7 in the FGF7 group. Moreover, cell islands were AQP5-positive. Conclusion These results suggest that FGF7-treated hDPSCs differentiate into AQP5-positive and alpha SMA-positive cells. Moreover, AQP5-positive cell aggregations were formed.