Multiscale Tunable Hybrid Biomaterials for Engineering Human iPSC-Based Cardiac Microphysiological Systems

Thesis (Ph.D.)--University of Washington, 2019Human induced pluripotent stem cells (hiPSCs) offer tremendous potential for use in engineering human tissues for disease modeling, drug development, and cell therapy. However, differentiated cardiomyocytes are phenotypically immature, reducing assay reliability when translating in vitro results to clinical studies and precluding hiPSC-derived cardiac tissues from therapeutic use in vivo. To address this, we have developed hybrid hydrogels comprised of decellularized myocardial extracellular matrix (dECM) and reduced graphene oxide (rGO) to provide a more instructive microenvironment for proper cellular and tissue development. A tissue-specific protein profile was preserved post-decellularization, and through the modulation of rGO content and degree of reduction, the mechanical and electrical properties of the hydrogels could be tuned. Engineered heart tissues (EHTs) generated using dECM-rGO hydrogel scaffolds and hiPSC-derived cardiomyocytes exhibited significantly increased twitch forces even after only 14 days of culture, and the expression of genes that regulate contractile function were also increased. Similar improvements in various aspects of electrophysiological function, such as calcium-handling, action potential duration, and conduction velocity, were also induced by the hybrid biomaterial. Notably, this included a drastic upregulation of genes encoding potassium ion channels and connexin 43 gap junction proteins. dECM-rGO hydrogels could be used as a bioink to bioprint cardiac tissues in a high-throughput manner, and these tissues were utilized to assess the proarrhythmic potential of cisapride. The onset of action potential duration prolongation and beat interval irregularities was observed in dECM-rGO tissues at clinical doses, indicating that the enhanced maturation of these tissues corresponded well with a capability to produce physiologically-relevant drug responses. Taken together, this research demonstrates the versatility of dECM-rGO hydrogels and the feasibility of combining the unique pro-maturation material properties of both components to engineer more functionally developed tissues that are suitable for modeling the adult human myocardium