Abstract
Engineered cardiac tissues fabricated from human induced pluripotent stem cells (hiPSCs) show promise for ameliorating damage from myocardial infarction, while also restoring function to the damaged left ventricular (LV) myocardium. For these constructs to reach their clinical potential, they need to be of a clinically relevant volume and thickness, and capable of generating synchronous and forceful contraction to assist the pumping action of the recipient heart. Design prerequisites include a structure thickness sufficient to produce a beneficial contractile force, prevascularization to overcome diffusion limitations and sufficient structural development to allow for maximal cell communication. Previous attempts to meet these prerequisites have been hindered by lack of oxygen and nutrient transport due to diffusion limits (100-200 μm) resulting in necrosis. This study employs a layer-by-layer (LbL) fabrication method to produce cardiac tissue constructs that meet these design prerequisites and mimic normal myocardium in form and function. Thick (>2 mm) cardiac tissues created from hiPSC-derived cardiomyocytes, -endothelial cells (ECs) and -fibroblasts (FBs) were assessed, in vitro, over a 4-week period for viability (<6% necrotic cells), cell morphology and functionality. Functional performance assessment showed enhanced t-tubule network development, gap junction communication as well as previously unseen, physiologically relevant conduction velocities (CVs) (>30 cm/s). These results demonstrate that LbL fabrication can be utilized successfully to create prevascularized, functional cardiac tissue constructs from hiPSCs for potential therapeutic applications.