Polydimethylsiloxane lanes enhance sarcomere organization in human ESC-derived cardiomyocytes

Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) hold great potential in many areas of research such as cardiac tissue regeneration, cardiotoxicity screening and human heart disease models; however, before any of these applications can be realized, hESC-CMs need to progress from an immature phenotype to one that more closely resembles their adult counterparts in vivo. Current immature hESC-CMs can be characterized by their rounded morphology, disorganized contractile apparatus and circumferential gap junction expression. In an effort to improve the maturation of hESCCMs, prior work in our lab used micropatterned lanes of Matrigel and fibronectin extracellular matrix proteins on glass slides to control cell shape. From these experiments it was found that widths ranging from 30 to 80 μm promoted the best sarcomere development and nuclear alignment in a pure population of hESC-CMs. In this new system, a pure population of hESCCMs are seeded onto lanes of Matrigel on polydimethylsiloxane (PDMS) to investigate the portability of this technique to other substrate systems and how the substrate stimuli influences maturation. The same trend in nuclear alignment and sarcomere organization with lane width was observed when hESC-CMs were seeded onto lanes of Matrigel on PDMS as was found in the experiments utilizing glass as the substrate. By restricting cell adhesion and controlling substrate stiffness it may be possible to enhance the maturation of hESC-CMs in vitro which will provide a more physiological relevant phenotype that can then be used in the aforementioned applications.