Head of Bioengineering Novoheart, Medera Biopharm, United States
Abstract: Human ventricular cardiac tissue strips (hvCTS), composed of pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) in a 3D hydrogel matrix, provide in vitro human models for preclinical drug screening. Although collagen and fibrin are common hydrogels for cardiac tissue engineering, a quantitative comparison of these matrix materials has not been systematically examined. This study aims to compare the effects of collagen vs. fibrin matrix on hvCTS structure and the contractility and phenotype of the resident hPSC-cCMs. hvCTS fabricated using hPSC-CMs mixed with either a collagen type I (COL) or fibrin (FIB) hydrogel base were measured for contractility and excitation threshold from day 7-14 post-fabrication using an automated screening system. Developed force and maximum capture frequency were significantly higher, whereas passive tension and excitation threshold were significantly lower, for COL-hvCTS compared to FIB-hvCTS. The contraction rise time for COL-hvCTS was significantly shorter than FIB-hvCTS. The inotropic dose responses to isoprenaline and nifedipine were comparable for both hvCTS types when developed force was normalized to baseline. Gene ontology enrichment analysis of single cell-RNAseq data revealed that pathways related to oxidative metabolism were over-represented in COL-hvCTS, whereas pathways related to motility and adhesion were over-represented in FIB-hvCTS. Scanning electron microscopy (SEM) revealed a larger pore size distribution in the cell-free COL than the FIB matrix material, which is consistent with significantly faster medium permeation through COL- compared to FIB-layered Transwell plates. Hence, our results suggest hPSC-CMs in COL-hvCTS exhibit improved contractility and electrical coupling and are developmentally more mature compared to FIB-hvCTS. The superior contractility and maturity in COL-hvCTS could be attributable to the larger pore size and enhanced permeability in the collagen hydrogel base, facilitating nutrient diffusion and cell connectivity in hPSC-CMs. Such COL-hvCTS, with improved tissue contractility and maturity, could offer enhanced sensitivity for drug screening and disease modeling applications and to accelerate translation to clinical trials as our group has previously shown.
