[Effect of polydimethylsiloxane matrix elasticity on osteogenic differentiation of rat marrow stromal cells]

Objective: To investigate the effect of polydimethylsiloxane (PDMS) matrix elasticity on osteogenic differentiation of rat marrow stromal cells (rBMSC). Methods: A series of PDMS composite substrates with different elastic modulus were constructed by adjusting the relative concentrations of cross-linking agent. The Young's modulus was used to describe the elasticity of PDMS after measurement by atomic force microscope (AFM). After surface modification, rBMSC was seeded on PDMS matrix, and 7 days after rBMSC was cultured on the five different Young's moduli matrix, the differences of osteogenic differentiation of rBMSC were observed by the method of real-time PCR, Western blotting, and alkaline phosphatase assay. Results: The PDMS was suitable for cell culture after surface modification, and by altering the concentration of cross-linking agent, PDMS could mimic the majority of the tissues' elasticity in vivo. The related osteogenic differentiation markers expression showed significant difference between the five matrixes (P<0.05), including type Ⅰ collagen (Col-Ⅰ), osteocalcin (OCN), osteopontin (OPN) and bone morphogenetic protein 2 (BMP2). The expression of osteogenic markers was up-regulated in the group that the Young's modulus was (354.1±40.9) kPa (P<0.05). Conclusions: PDMS is a tunable elasticity matrix which could be used in the investigation of inducing rBMSCs into osteoblastic lineages. PDMS substrate stiffness has an obvious influence on rBMSC osteogenic differentiation.