Biomimetic Extracellular Matrix-Incorporated Scaffold Induces Osteogenic Gene Expression in Human Marrow Stromal Cells

Engineering biomaterials mimicking the biofunctionality of the extracellular matrix (ECM) is important in instructing and eliciting cell response. The native ECM is highly dynamic and has been shown to support cellular attachment, migration, and differentiation. The advantage of synthesizing an ECM-based biomaterial is that it mimics the native cellular environment. However, the ECM has tissue-specific composition and patterned arrangement. In this study, we have employed biomimetic strategies to develop a novel collagen/chitosan template that is embedded with the native ECM of differentiating human marrow stromal cells (HMSCs) to facilitate osteoblast differentiation. The scaffold was characterized for substrate stiffness by magnetic resonance imaging and nanoindentation and by immunohistochemical analysis for the presence of key ECM proteins. Gene expression analysis showed that the ECM scaffold supported osteogenic differentiation of undifferentiated HMSCs as significant changes were observed in the expression levels of growth factors, transcription factors, proteases, receptors, and ECM proteins. Finally, we demonstrate that the scaffold had the ability to nucleate calcium phosphate polymorphs to form a mineralized matrix. The results from this study suggest that the threedimensional native ECM scaffold directly controls cell behavior and supports the osteogenic differentiation of mesenchymal stem cells.