Polydopamine coating with static magnetic field promotes the osteogenic differentiation of human bone-derived mesenchymal stem cells on three-dimensional printed porous titanium scaffolds by upregulation of the BMP-Smads signaling pathway.

Bone regeneration has always been a hot topic for orthopedic surgeons. The role of polydopamine coating in promoting bone regeneration has attracted much attention. Static magnetic field (SMF) is considered an effective and noninvasive treatment for enhancing bone regeneration. However, the effect of polydopamine combined with SMF on bone regeneration on scaffolds is not clear. The aim of this study was to investigate the effects and potential mechanism of polydopamine coating combined with SMF on bone regeneration in three-dimensional printed scaffolds. The polydopamine coating (pTi group) was applied onto porous Ti6Al4V scaffolds (Ti group). Surface characterization was performed by scanning electron microscopy. The 100 mT SMF environment (pTi-SMF group) was established to enhance osteogenic differentiation of human bone-derived mesenchymal stem cells (hBMSCs) on polydopamine coating scaffolds. The cell viability and proliferation were significantly enhanced in the SMF environment (pTi-SMF vs. Ti: P=0.005). Improved morphology (pTi-SMF vs. pTi: P=0.024, pTi-SMF vs. Ti: P=0.001) and adhesion (Ti: x̅±s=1.585±0.324; pTi: x̅±s=2.164±0.314; pTi-SMF: x̅±s=4.634±0.247, P<0.001) of hBMSCs were observed in the pTi-SMF group. The high expression of osteogenesis-related RNA and protein (ALP: Ti, x̅±s=1.249±0.218; pTi, x̅±s=2.503±0.209; pTi-SMF, x̅±s=2.810±0.246. OCN: Ti, x̅±s=1.483±0.304; pTi, x̅±s=3.636±0.322; pTi-SMF, x̅±s=4.641±0.278. Runx2: Ti, x̅±s=1.372±0.227; pTi, x̅±s=3.054±0.229; pTi-SMF, x̅±s=3.914±0.253) was found in the pTi-SMF group (pTi-SMF vs. Ti: P<0.001). Proteomics was applied to explore the osteogenic mechanism of polydopamine coating combined with SMF. A total of 147 different proteins were identified between the pTi-SMF and Ti group. The osteogenic effect might be associated with the BMP-Smads signaling pathway (pTi-SMF vs. Ti: BMPR1A, P=0.001; BMPR2, P<0.001; Smad4, P=0.001; Smad1/5/8, P=0.008). In conclusion, the osteogenic differentiation of hBMSCs on polydopamine coating scaffolds could be enhanced by SMF stimulation by upregulation of the BMP-Smads signaling pathway. AJTR