Implantation of Spontaneously Beating Human iPS Cell-Derived ENGINEERED HEART TISSUE Does Not Provoke Ventricular Arrhythmias in a Guinea Pig Infarction Model

Objectives: Engineered heart tissue (EHT) is an in vitro generated three-dimensional, force generating cardiomyocyte network with morphological and functional properties of native myocardium. Incomplete coupling or spontaneous electrical activity of EHTs might provoke ventricular arrhythmias (VA) when transplanted onto a recipient's heart. The aim of this study was to investigate the occurrence of ventricular arrhythmias after implantation of human induced pluripotent stem cell (hiPSC)-derived EHT in a guinea pig infarction model.

Methods: Human iPSC were generated by retroviral reprogramming of dermal fibroblasts. Cardiac differentiation of hiPSC was performed by an embryoid body-based three-stage differentiation protocol. EHTs were created from hiPS-CM (5 × 10⁶ cardiomyocytes and 2 × 10⁶ hiPSC-endothelial cells per EHT). Left ventricular myocardial cryo-injury was induced in adult guinea pigs (n = 18) and telemetry sensors were implanted in all animals for continuous ECG monitoring. 7 days after cryo-injury, EHTs (Group I; 2 EHTs per animal, n = 10) or cell-free constructs (Group II; n = 8) were implanted.

Results: Cryo-injury resulted in large histologically verified transmural infarctions of the left ventricular wall. Dystrophin and MLC2V positive cross-striated muscle tissue was observed in the scar area of EHT transplanted animals. The human origin was demonstrated by staining for human Ku80, a human-specific marker. After induction of cryo-injury and before implantation of EHT or cell free constructs (7days), non-sustained or sustained ventricular arrhythmias were observed in 0 and 2 (33.3%) animals of Group I and II, respectively. After implantation of EHTs no sustained ventricular tachycardias were seen in any of the animals. However, 58 couplets, 15 triplets and 26 non-sustained ventricular tachycardias (NSVT) were observed in 5 animals (50%) during 28 days of follow-up. In the control group no VTs, but 9 NSVTs, 42 couplets and 15 triplets occurred in 6 (75%) animals during the same period of time. The incidence of VTs or NSVTs did not differ significantly between the two groups (Group I: 2.6, Group II: 1.2 ventricular arrhythmias per animal; p = 0.39).

Conclusion: Transplantation of hiPSC-derived EHTs in a guinea pig cryo-injury model generates new myocardium. Our telemetric data showed overall a low rate of arrhythmias in this model and provide no evidence for hiPSC-derived EHTs to induce ventricular arrhythmias.

 

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No conflict of interest has been declared by the author(s).