Effect of scaffold stiffness on myoblast differentiation

Successful tissue engineering requires optimization of scaffold stiffness for a given application and cell type. Here, we investigated the effect of scaffold stiffness on myoblast cells, demonstrating the ability of cells to affect and to sense their mechanical microenvironment. Myoblasts were cultured on composite three-dimensional poly-lactic acid (PLLA)/poly-lactic co glycolic acid (PLGA) porous scaffolds of varied elasticity. The elasticity was controlled by changing the ratio of PLLA versus PLGA in the scaffolds. Cell organization, myotube formation, and cell viability were affected by scaffold stiffness. PLLA-containing scaffolds (100% to 25% PLLA) provided stiffness that supported myotube formation, while neat PLGA scaffold failed to support myotube formation and cell viability. Furthermore, scaffold stiffness correlated to its size/area reduction upon culturing experiments, suggesting different shrinkage degree by cell forces. Inhibition of scaffold shrinking by affixing device resulted in spacious cell organization with normal cell morphology. This may suggest that scaffold shrinkage led to cellular degeneration and shape deformation. Our results indicate that compliant scaffolds are insufficient to withstand cell forces. On the other hand, excessively firm scaffold could not lead to parallel oriented myotube organization. Hence, optimal scaffold stiffness can be tailored by PLLA/PLGA blending to direct specific stages of myoblast differentiation and organization.