Background: Human engineered heart tissue (EHT) transplantation represents a potential regenerative strategy for heart failure patients and has been successful in preclinical models. Clinical application requires upscaling, adaptation to good manufacturing practices (GMP) and determination of the effective dose. Methods: 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. Results: We created mesh structured tissue patches for transplantation in guinea pigs (1.5x2.5 cm, 9-15x10 6 cardiomyocytes) and pigs (5x7 cm, 450 x10 6 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, 12x10 6 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. Conclusions: 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.
It is highly debated how cyclic adenosine monophosphate-dependent regulation (CDR) of the major pacemaker channel HCN4 in the sinoatrial node (SAN) is involved in heart rate regulation by the autonomic nervous system. We addressed this question using a knockin mouse line expressing cyclic adenosine monophosphate-insensitive HCN4 channels. This mouse line displayed a complex cardiac phenotype characterized by sinus dysrhythmia, severe sinus bradycardia, sinus pauses and chronotropic incompetence. Furthermore, the absence of CDR leads to inappropriately enhanced heart rate responses of the SAN to vagal nerve activity in vivo. The mechanism underlying these symptoms can be explained by the presence of nonfiring pacemaker cells. We provide evidence that a tonic and mutual interaction process (tonic entrainment) between firing and nonfiring cells slows down the overall rhythm of the SAN. Most importantly, we show that the proportion of firing cells can be increased by CDR of HCN4 to efficiently oppose enhanced responses to vagal activity. In conclusion, we provide evidence for a novel role of CDR of HCN4 for the central pacemaker process in the sinoatrial node.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.