Isolated effect of material stiffness on valvular interstitial cell differentiation.

Previous methods for investigating material stiffness on cell behavior have focused on the use of substrates with limited ranges of stiffness and/or fluctuating surface chemistries. Using the co-polymer system of n-octyl methacrylate crosslinked with diethylene glycol dimethacrylate (DEGDMA/nOM), we developed a new cell culture platform to analyze the isolated effects of stiffness independent from changes in surface chemistry. Materials ranging from 25 kPa to 4,700 kPa were fabricated. Surface analysis including goiniometry and X-ray photoelectron spectroscopy (XPS) confirmed consistent surface chemistry across all formulations examined. The mechanosensitive cell type valvular interstitial cell (VIC) was cultured DEGDMA/nOM substrates of differing stiffness. Results indicate that order of magnitude changes in stiffness do not increase gene expression of VIC alpha-smooth muscle actin (SMA). However, structural organization of SMA is altered on stiffer substrates, corresponding with the appearance of the osteoblastic marker osteocalcin and nodule formation. This research presents the co-polymer DEGDMA/nOM as ideal substrate to investigate the influence of stiffness on VIC differentiation without the confounding effects of changing material surface chemistry. (c) 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 51-61, 2017.