Anisotropy in cell sheeting and cardiac differentiation

Treatment for myocardial infarction is largely limited to alleviating symptoms and preventing recurrence rather than directly repairing or replacing the damaged myocardial tissue. Consequently, one of the overarching goals of cardiac tissue engineering is to generate myocardial tissue that could be implanted as a patch over existing cardiac tissue to improve cardiac function. Advancements in pluripotent stem cell (PSC) technology and differentiation have made PSC-derived cardiomyocytes a viable cell source for engineered cardiac tissues. Because native cardiac tissue is directional in nature (i.e., anisotropic), biomaterial systems have been designed to organize PSC-derived cardiomyocytes to recapitulate this structure. The objective of this dissertation is to use aligned electrospun fibers as anisotropic substrates to generate aligned cell sheets and to evaluate how differentiating cardiomyocytes respond to degrees of anisotropy. We demonstrate that aligned electrospun fibers containing poly(N-isopropylacrylamide), a thermo-sensitive polymer commonly used for cell sheeting, and poly(capro lactone), a hydrophobic polymer commonly used in biomaterials, can be used to generate anisotropic cell sheets. Also shown is that the structure and functional behavior of PSCs-derived cardiomyocytes varies in a gradient-based manner on degree of substrate anisotropy at relatively early timepoints. As time progresses, cardiomyocyte alignment can be achieved on substrates that have a minimum threshold anisotropy. These electrospun, aligned fiber systems can be used in tissue engineering to generate viable cell sheets for cardiac tissue engineering or to precisely study cell sensitivity to differences in substrate anisotropy.