Comprehensive Evaluation of Surface Potential Characteristics on Mesenchymal Stem Cells' Osteogenic Differentiation

The surface electric potential of biomaterials has been extensively proven to play a critical role in stem cells' fate. However, there are ambiguous reports on the relation of stem cells' osteogenic capacity to surface potential characteristics (potential polarity and intensity). To address this, we adopted a surface with a wide potential range and both positive/negative polarity in a comprehensive view to get insight into surface potential-regulating cellular osteogenic differentiation. Tb _xDy_{1- x}Fe₂ alloy/poly(vinylidene fluoride-trifluoroethylene) magnetoelectric films were prepared, and the film could provide controllable surface potential characteristics with positive or negative polarity and potential (ϕ_ME) intensity variation from 0 to ±120 mV as well as keep the surface chemical composition and microstructure unchanged. Cell culture results showed that osteogenic differentiation of mesenchymal stem cells on both positive and negative potential films was obviously upregulated when the /ϕ_ME/ intensities were set from 0-55 mV. Differently, the highest upregulated osteogenic differentiation on the positive potential films corresponded to the /ϕ_ME/ intensity from 35-55 mV and was better than that on the negative potential films whereas the highest on the negative potential films corresponded to the /ϕ_ME/ intensity from 0-35 mV and was better than that on the positive potential films. This fact could illustrate why previous reports appeared ambiguously; i.e., the comparative result in osteogenic differentiation between the positive and negative potential films strongly depends on the selection of surface potential intensity. On the basis of assaying of the exposed functional sites (RGD and PHSRN) of the adsorbed fibronectin (FN) and the expression of cellular integrin α5 and β1 subunits, the difference in the behavior between the positive and negative potential films was attributed to the distinct conformation of adsorbed fibronectin (FN) and the opposite changing trend with /ϕ_ME/ for the two films, which triggers the osteogenesis-related FAK/ERK signaling pathway to a different extent. This study could provide new cognition for the in-depth understanding of the regulation mechanism underlying surface potential characteristics in cell behaviors.