Influence of Physical Properties of Biomaterials on Cellular Behavior

In this study, we evaluated the effect of hydrogel structural properties on proliferation and biosynthesis activity of encapsulated chondrocytes. Hydrogels with varying structural and mechanical properties were prepared by photopolymerizing PEGDA precursors having MWs of 3.4 kDa, 6 kDa, 10 kDa, and 20 kDa and were characterized for their swelling ratio, network structure, morphology, and mechanical properties. The effect of hydrogel structural properties on the cellular activity of encapsulated chondrocytes was studied over four weeks. Varying the molecular weight of PEGDA precursors exhibited a significant effect on the structural and mechanical properties of the hydrogels. Large mesh size was found to support cell proliferation. However, extracellular matrix (ECM) accumulation varied with the precursor molecular weight. Both PEGDA 6 kDa and 10 kDa hydrogels supported GAG accumulation, while PEGDA 10 kDa and 20KDa hydrogels supported collagen accumulation. Chondrocytes cultured in PEGDA 10 kDa hydrogels expressed a relative increase in collagen type II and aggrecan expression while maintaining low collagen type I expression. Increasing mesh size of the hydrogels resulted in an increase in cellular proliferation exhibiting the strong correlation between mesh size and cell growth, while mesh size had a differential effect on ECM accumulation and expression of cartilage specific markers.