Intrinsically Cross-Linked ECM-Like Multilayers for BMP-2 Delivery Promote Osteogenic Differentiation of Cells

Surface coatings prepared by layer-by-layer technique permit loading of growth factors (GFs) and their spatially controlled release. Here, native chondroitin sulfate (nCS), oxidized CS (oCS100), or mixture of both (oCS50) are combined with collagen I (Col I) to fabricate polyelectrolyte multilayers (PEMs) that exhibit structural, mechanical, and biochemical cues like the natural extracellular-matrix. The use of oCS enables intrinsic cross-linking of PEM that offers higher stability, stiffness, and better control of bone morphogenetic protein-2 (BMP-2) release compared to nCS. oCS100 PEMs have enhanced stiffness, promote Col I fibrillization, and present BMP-2 in a matrix-bound manner. oCS50 PEMs show intermediate effects on osteogenesis, soft surface, high water content but also moderately slow BMP-2 release profile. C2C12 myoblasts used for osteogenesis studies show that oCS PEMs are more stable and superior to nCS PEMs in supporting cell adhesion and spreading as well as in presenting BMP-2 to the cells. oCS PEMs are triggering more osteogenesis as proved by the quantitative real-time polymerase chain reaction, immune and histochemical staining. These findings show that intrinsic cross-linking in oCS/Col I multilayers provides a successful tool to control GFs delivery and subsequent cell differentiation which opens new opportunities in regenerative therapies of bone and other tissues.