Shear Stress Regulates Osteogenic Differentiation of Human Dental Pulp Stem Cells via the p38 Pathway

This study aimed to investigate the effects of shear stress on osteogenic differentiation of human dental pulp stem cells (hDPSCs). The hDPSCs were subjected to shear stress for 24 h before osteogenic induction for 21 days. The mRNA expression of osteogenic markers such as RUNX2, OSX, ALP, COL1A1, OCN, and OPN was evaluated by real-time RT-PCR. Alkaline Phosphatase (ALP) activity and Alizarin Red S (ARS) staining were investigated to confirm osteogenic differentiation and mineralization of hDPSCs, respectively. The protein expression of osterix was shown by immunofluorescence staining and Western blotting. RNA sequencing was performed to investigate how shear stress affects the osteogenic differentiation of hDPSCs, which was validated through p38 inhibitor (SB203580) treatment. Real-time RT-PCR revealed that shear stress enhanced osteogenic marker-gene expression. The increased osterix protein expression was detected on Day 14 in the shear-stress loading group compared to the static group. Shear stress enhanced ALP activity and mineralization, observed on Days 14 and 21. A volcano plot exhibited up- and downregulated genes, while the p38 inhibitor markedly inhibited osteogenic differentiation of hDPSCs triggered by shear stress. In conclusion, shear stress promotes the osteogenic differentiation of hDPSCs through the p38 mitogen-activated protein kinase signaling pathway.