Abstract Introduction Cell therapy for acute myocardial infarction (AMI) faces two challenges: cellular integration and post-transplantation arrhythmias. This project aims to produce human cardiac organoids (COs) in a scalable manner and validate their safety and efficacy in a translational swine model of AMI. Methods COs were derived from human induced pluripotent stem cells, differentiating into cardiomyocytes (CMs) and endothelial cells (ECs) in a single, scalable workflow using bioreactors. Twelve immunosuppressed animals underwent AMI induction and were randomized into: Short-term CO (8-day follow-up, n=2), Long-term Control (30-day follow-up, n=4), and Long-term CO (30-day follow-up, n=6) receiving 5-6 intramyocardial injections of 3500 COs (CO groups) or Plasmalyte (control group) 30 minutes post-AMI. CO integration into host tissue was analyzed by immunohistofluorescence (IF) against human nuclear antigen (HNA), cardiac troponin I, and von Willebrand factor at 8 and 30 days. Heart rhythm and arrhythmia were monitored for 8 (Short-term) or 15 (Long-term) days using an ECG Holter recorder. In long-term groups, cardiac function and scar size (LGE-FWHM) at 2 and 30 days post-AMI, and arrhythmic inducibility at 30 days were assessed via magnetic resonance imaging (MRI) and electroanatomic high-density mapping (HDM), respectively. Results After 10 days of culture, COs exhibited homogenous size, morphology, and cellular organization, with an external layer of ECs and a core of organized and mature CMs, supported by cardiac fibroblasts (Figure 1A). IF confirmed the presence of HNA-positive cells in the infarct and border zones at 8 and 30 days (Figure 1B), indicating the survival of transplanted COs. All animals maintained sinus rhythm without severe ventricular arrhythmias. While no significant differences in Long-term Control pigs were detected, paired t-student test of Long-term CO-treated animals demonstrated significant improvements over time in left ventricular (LV) stroke volume, LV ejection fraction (LVEF), percentage of LGE-FWHM mass, cardiac output, and cardiac index. Moreover, a trend toward improvement in LV mass, extracellular volume, indexed LV end-systolic volume, and indexed right ventricle end-diastolic volume was noticed (Table 1). HDM revealed smaller low-voltage areas in CO-treated animals compared to controls (0.5 ± 0.8 cm2 vs 1.3 ± 0.3 cm2, respectively), although statistical significance was not reached. Conclusions The scalable production of mature COs using this novel, single workflow is feasible. COs integrate rapidly into host tissue, remain viable for up to 30 days, and do not induce severe arrhythmias, demonstrating their safety. Although some improvements such as infarct size reduction and better LVEF, a larger sample size and different dose testing are needed to confirm their full impact on cardiac function.
Kalil et al. (Sat,) studied this question.