(333f) Substrate Modulus and Pore Size of 3D Scaffolds Fabricated By Templated Fused Deposition Modeling Regulate Osteogenic Differentiation

The properties of the extracellular matrix, including elastic modulus, porosity, pore size, and curvature, are known to regulate cell fate in a number of physiological processes. Biomimetic 3D systems are needed for investigating interactions between cell populations and the microenvironment. Three dimensional polyurethane (PUR) scaffolds with tunable rigidity (10-900 MPa) and pore size (423-557 μm) were fabricated by a new template-Fused Deposition Modeling (t-FDM) process to investigate the effects of substrate modulus and pore size on osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells (BMSCs). Total protein assay indicated that modulus and pore size had minimal effects on cell proliferation. In contrast, BMSCs were more metabolically active and migrated faster on rigid substrates. Gene expression of osteogenic markers, including Runx2, Collagen-1, Fibronectin, and Osteopontin was up-regulated on rigid scaffolds. Mineralization of BMSCs on D21 was significantly up-regulated on rigid scaffolds with decreasing pore size, suggested by Alizarin Red S staining and SEM. These findings would guide the rational design of cell-responsive scaffolds that recapitulate the bone microenvironment for restoration and repair of bone damaged by trauma or disease.