Human Engineered Heart Tissue Patches Remuscularize the Injured Heart in a Dose-Dependent Manner

Human engineered heart tissue (EHT) transplantation represents a potential regenerative strategy for heart failure patients and has been successful in preclinical models. The clinical application requires upscaling adaptation to good manufacturing practices (GMP), and determination of the effective dose.

Cardiomyocytes were differentiated from three different human-induced pluripotent stem cell (hiPSC) lines including one reprogrammed under GMP conditions. Protocols for hiPSC expansion, cardiomyocyte differentiation, and EHT generation were adapted to substances available in GMP quality. EHT geometry was modified to generate patches suitable for transplantation in a small animal model and perspectively humans. Repair efficacy was evaluated at 3 doses in a cryo-injury guinea pig model. Human-scale patches were epicardially transplanted onto healthy hearts in pigs to assess technical feasibility.

They created mesh structured tissue patches for transplantation in guinea pigs (1.5x2.5 cm, 9-15x106 cardiomyocytes) and pigs (5x7 cm, 450 x106 cardiomyocytes). EHT patches coherently beat in culture and developed high force (mean 4.6 mN). Cardiomyocytes matured, aligned along the force lines, and demonstrated advanced sarcomeric structure and action potential characteristics closely resembling human ventricular tissue. EHT patches containing ~4.5, 8.5, 12x106, or no cells were transplanted 7 days after cryo-injury (n=18-19 per group). EHT transplantation resulted in a dose-dependent remuscularization (graft size: 0-12% of the scar). Only high-dose patches improved left-ventricular function (+8% absolute, +24% relative increase). The grafts showed time-dependent cardiomyocyte proliferation. While standard EHT patches did not withstand transplantation in pigs, the human-scale patch enabled successful patch transplantation.

EHT patch transplantation resulted in a partial remuscularization of the injured heart and improved left-ventricular function in a dose-dependent manner in a guinea pig injury model. Human scale patches were successfully transplanted in pigs in a proof-of-principle study. Heart disease is the number one cause of death worldwide. Although the mortality from acute myocardial infarction has decreased substantially over the last two decades, heart failure as its main sequelae remains a major disease burden. Cardiomyocyte (CM) renewal is limited to ~1% per year and even though there is evidence that CM proliferation increases slightly after injury this is by far too little to form a physiologically relevant number of new CMs. Regenerative strategies that aim to generate new myocardium are currently evaluated in preclinical and first clinical trials. Pluripotent stem cell-derived CMs have repeatedly demonstrated their potential to regenerate injured hearts in preclinical models. We have recently shown that transplantation of two stripe format human engineered heart tissues (EHTs) improved left-ventricular function in a guinea pig model. Yet, hurdles towards clinical translation remain. In particular, upscaling from small animal models to humans and adaptation to good manufacturing practices (GMP) represent challenges. Additionally, the optimal dose has not been defined yet. The current study describes the generation of EHT patches under GMP compatible conditions that can be scaled to a clinically relevant size, evaluated the effect of EHT-patch transplantation in a dose-finding study in guinea pigs, and assessed the possibility to transplant human scale EHT patches in pigs1.

Characterization of human-engineered heart tissue patches. A) Photographs of EHT patches demonstrating EHT development over a three-week culture period. B) Phalloidin staining of human EHT patches at day 1 and day 27 after casting. Insets show low magnification overviews. C) Serial longitudinal sections stained for dystrophin. Shown are sections from the upper and lower surface and the middle of the EHT patch, respectively. D) Phalloidin whole mount and alpha-actinin, myosin light chain, atrial isoform and myosin light chain, ventricular isoform staining in longitudinal sections after 21 days in culture.

  1. Querdel, E., Reinsch, M., Castro, L., Köse, D., Bähr, A., Reich, S., Geertz, B., Ulmer, B., Schulze, M., Lemoine, M. D., Krause, T., Lemme, M., Sani, J., Shibamiya, A., Stüdemann, T., Köhne, M., von Bibra, C. V., Hornaschewitz, N., Pecha, S., Nejahsie, Y., … Weinberger, F. (2021). Human Engineered Heart Tissue Patches Remuscularize the Injured Heart in a Dose-Dependent Manner. Circulation, 10.1161/CIRCULATIONAHA.120.047904. Advance online publication.