Cardiopatch platform enables maturation and scale-up of human pluripotent stem cell-derived engineered heart tissues

Abstract

Despite increased use of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) for drug development and disease modeling studies, methods to generate large, functional heart tissues for human therapy are lacking. Here we present a “Cardiopatch” platform for 3D culture and maturation of hiPSC-CMs that after 5 weeks of differentiation show robust electromechanical coupling, consistent H-zones, I-bands, and evidence for T-tubules and M-bands. Cardiopatch maturation markers and functional output increase during culture, approaching values of adult myocardium. Cardiopatches can be scaled up to clinically relevant dimensions, while preserving spatially uniform properties with high conduction velocities and contractile stresses. Within window chambers in nude mice, cardiopatches undergo vascularization by host vessels and continue to fire Ca2+ transients. When implanted onto rat hearts, cardiopatches robustly engraft, maintain pre-implantation electrical function, and do not increase the incidence of arrhythmias. These studies provide enabling technology for future use of hiPSC-CM tissues in human heart repair.

Advanced maturation of human cardiac tissue grown from pluripotent stem cells

“…A recent study 31 reported large (7x7 mm to 36x36 mm) and thin (50μm) human heart tissues grown without exogenous stimulation that displayed less developed ultrastructure, no evidence of oxidative metabolism, slightly negative FFR, comparable APD and conduction velocity, and approximately 4-fold higher force per unit cross-sectional tissue area. It would be instructive to explore how the different tissue geometries (very thin patches vs. cylindrical muscle) and culture protocols (no external stimulation vs. intensity training) between that 31 and this current study contributed to the measured structural and functional tissue outcomes.…”

“…Even our best methods have limited ability to emulate the physiology of adult myocardium 1–11,31 , with the excitation-contraction coupling (requiring t-tubules), positive force frequency relationship (requiring mature calcium handling), and efficient energy conversion (requiring oxidative metabolism) notably absent 2–3,5,6,8–10 . Adult ventricular myocytes are uniquely organized for beating function, with densely packed sarcomeres, mitochondria, t-tubules, and sarcoplasmic/endoplasmic reticulum (SR/ER).…”

“…Human iPS-CMs can be matured by long-term culture, electrical, hydrodynamic and mechanical stimulation 8,9,15–17,31 . Recent studies indicate that the in vitro culture may not follow the developmental paradigm: high stimulation frequencies benefit maturation in vitro 9 , while the native heart beats more slowly following birth 5,13 .…”

“…It would be instructive to explore how the different tissue geometries (very thin patches vs. cylindrical muscle) and culture protocols (no external stimulation vs. intensity training) between that 31 and this current study contributed to the measured structural and functional tissue outcomes.…”

In Vitro Tissue‐Engineered Skeletal Muscle Models for Studying Muscle Physiology and Disease

“…[179] Alternatively, oxygen and nutrient delivery to tissues can be improved by dynamic culture in which media is displaced or agitated to improve mass transfer around the tissue. [180] In engineered skeletal and cardiac muscle tissues, dynamic culture on a rocking platform significantly increased force generation and improves overall tissue organization, [181–183] yielding engineered neonatal rat muscles with the highest specific forces reported to date and comparable to those of native neonatal muscle. [151] While dynamic culture conditions are a cheap, simple, and effective method to increase nutrient delivery in media volumes greater than 1 mL, the miniaturized organ-on-a-chip models with small media volume will require the use of microfluidic perfusion systems to both enhance nutrient delivery to engineered muscle and enable paracrine communication among multiple microtissues/organs.…”