BMP2 cross-linked by transglutaminase 2 to collagen-plla scaffold promotes osteogenic differentiation in mesenchymal stem cells

Transglutaminase 2 (TG2) was used to attach biologically-active BMP2 to collagen type I-coated poly-l-lactic acid (PLLA) nanofibrous scaffolds. Irreversibly cross-linked BMP2 retained its activity and induced Smad-dependent gene expression in cells seeded on PLLA–BMP2 scaffolds. These modified scaffolds promote osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBMSCs) cultured in low-serum and growth factor free medium and support deposition of the calcified matrix and induction of the molecular osteogenic markers Runx2, osteopontin, osteonectin and bone sialoprotein. Importantly, the PLLA–BMP2 scaffolds did not support chondrogenic differentiation in hBMSCs as there was no expression of chondrogenic markers aggrecan, Sox 9, and collagen type II, and no deposition of cartilaginous glycosaminoglycan-rich matrix. Thus, TG2-mediated cross-linking of BMP2 to a scaffold is a novel approach to induce osteoblast-specific programming of hBMSCs in a spatially controlled manner.