BMP-2 peptide-functionalized nanopatterned substrates for enhanced osteogenic differentiation of human mesenchymal stem cells

A variety of biophysical and biochemical factors control stem cell differentiation. In this study, we developed a nanopatterned substrate platform to surface immobilize osteoinductive bone morphogenetic protein-2 (BMP-2) peptides. Specifically, polyurethane acrylate (PUA) substrates with nanometer-scale groove- and dot-shaped topography were fabricated. The nanopatterned PUA surface was uniformly coated with poly(glycidyl methacrylate) (pGMA) by initiated chemical vapor deposition (iCVD) followed by covalent immobilization of BMP-2 peptides. This approach resulted in much more efficient BMP-2 peptide immobilization than physical adsorption. The combined effects of biochemical signals from BMP-2 peptides and nanotopographical stimulation on osteogenic differentiation of hMSCs were examined in culture with and without soluble osteogenic factors. Results of Alizarin Red S staining, immunostaining, and quantitative real-time polymerase chain reaction revealed that hMSCs cultured on nanopatterned surfaces with immobilized BMP-2 peptides exhibited greater potential for osteogenic differentiation than hMSCs on a flat surface. Furthermore, the nanopatterned substrates with BMP-2 peptides directed osteogenic differentiation of hMSCs even without osteogenesis soluble inducing factors. Substrates with nanotopography and bioactive signals that induce differentiation of stem cells towards specific lineages could be used to develop functional stem cell culture substrates and tissue engineered scaffolds for therapeutic applications.