MBG-Modified β-TCP Scaffold Promotes Mesenchymal Stem Cells Adhesion and Osteogenic Differentiation via a FAK/MAPK Signaling Pathway

The beta-TCP scaffold has been widely used as a bone graft substitute, but the traditional PMMA molding method induced undesirable mechanical strength and poor interconnectivity still have not been addressed until now. In this study, a MBG-based PU foam templating method was developed to fabricate beta-TCP scaffolds with desirable microtopography. The MBG gel, as both binder and modifier, prepared by a modified sol gel method with controlled viscosity is incorporated with beta-TCP powder and thereafter is impregnated into PU foam. The resultant hybrid scaffolds exhibited interconnected macropores (200 - 500 mu m) and distinctive micropores (0.2-1.5 mu m), especially for the TCP/25MBG (with 25 wt % content MBG). As expected, the compression strength of beta-TCP/MBG composite scaffolds was enhanced with increasing MBG content, and TCP/50MBG (with SO wt % content MBG) exhibited almost 100-fold enhancement compared to the pure beta-TCP. Intriguingly, the cell affinity and osteogenic capacity of rBMSCs were also dramatically improved the best on TCP/25MBG. Further investigation found that the subtle, grainy-like microtopography, not the chemical composition, of the TCP/25MBG favored the adsorption of Fn and expression of integrin (alpha 5/beta 1 and further facilitated FA formation and the expression of p-FAK, following activation of the MAPK/ERK signaling pathway and ultimately upregulated expression of osteogenic genes. Further in vivo experiments confirmed the promoted osteogenesis of TCP/25MBG in vivo. The results suggest that such a novel MBG-based PU foam templating method offers new guidance to construct hierarchically porous scaffolds, and the prepared MBG-modified beta-TCP scaffold will have great potential for future use in bone tissue regeneration.