Human iPSC-cardiomyocyte-aggregate cell therapy in non-human primates and correlation of heart recovery with contractile and electrophysiological cardiomyocyte properties

Spatiotemporal transcriptomics of human cardiovascular progenitors in pig hearts identifies Midkine as a positive regulator of neovascularization

Efficacy of multi-layered human iPS cell-derived cardiovascular cell sheets in a pacing-induced canine dilated cardiomyopathy model

Dilated cardiomyopathy (DCM) is a progressive, intractable disease that leads to heart failure. Heart transplantation is the only curative treatment; however, access is limited by donor scarcity. Induced pluripotent stem cell (iPSC)-based therapies are attracting attention for DCM, but suitable large-animal models and robust preclinical data have been limited. We generated multi-layered cardiovascular cell sheets from human iPSCs by combining cardiomyocytes with endothelial and stromal cells and overcoming stacking limits using interleaved gelatin hydrogel microspheres, yielding a thicker cardiac tissue-like construct (product code: IHJ-301). To enable rigorous testing in non-ischemic heart failure, we established a modified canine rapid-pacing heart failure model that maintains depressed function without mortality by continuing pacing at a slightly reduced rate after induction (Step-Down Pacing Heart Failure model). IHJ-301 was implanted epicardially onto the left ventricular surface via thoracotomy, and cardiac function was assessed by echocardiography and right-heart catheterization. After 4 weeks of rapid pacing (230 ± 10 bpm), left ventricular ejection fraction (LVEF) was reduced from 77.8 ± 1.1% (pre-pacing) to 44.9 ± 1.9% (n = 11) (0 W). Continued pacing at 210 ± 10 bpm for additional 4 weeks resulted in no mortality and maintained depressed function (4 W LVEF 47.3 ± 2.6%). IHJ-301 was implanted at 0 W. At 4 weeks post-implantation (4 W), all animals in the IHJ-301 group (n = 5) showed greater functional improvement than sham (n = 6). Absolute changes from 0 W to 4 W were: ΔLVEF (%) 9.38 ± 1.47 vs. 1.90 ± 0.34; Δfractional shortening (%) 4.84 ± 0.75 vs. 0.97 ± 0.18; stroke volume (mL/beat) 1.21 ± 1.26 vs. −2.99 ± 0.60; cardiac output (L/min) 0.19 ± 0.19 vs. −0.58 ± 0.12 (all p < 0.05). We established a non-ischemic large-animal heart failure model that sustains depressed function for one month, enabling clear therapeutic readouts. IHJ-301 significantly improved multiple parameters of cardiac function, providing preclinical evidence that IHJ-301 could offer a promising therapeutic option for DCM.

In Vivo Bioincubation Promotes Maturation of Human iPSC-Derived Cardiomyocytes in Neonatal Rat and Pig Hearts

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) hold great promise for cardiac regenerative medicine and disease modeling. However, hiPSC-CMs generated through conventional in vitro differentiation exhibit immature, fetal-like phenotypes. While in vivo bioincubation in neonatal rodent hearts promotes hiPSC-CM maturation toward adult-like phenotypes, studies in large animal models remain limited, particularly with detailed morphological characterization. In this study, we investigated bioincubation of fluorescently labeled hiPSC-CMs in both neonatal rat and pig hearts. Human iPSCs were differentiated into cardiomyocytes expressing GFP or RFP reporters and subsequently injected intramyocardially into neonatal rats (GFP-labeled) and pigs (RFP-labeled). After 4–8 weeks of bioincubation, fluorescent hiPSC-CMs were isolated using large-particle fluorescence-activated cell sorting (COPAS), which preserves cellular morphology of adult-like cardiomyocytes. Immunostaining for cardiac troponin T revealed well-organized sarcomeric structures in multinucleated hiPSC-CMs. Bioincubated hiPSC-CMs displayed rod-shaped morphology with binucleation, characteristic features of mature adult cardiomyocytes. Quantitative analysis demonstrated that bioincubated hiPSC-CMs from rat hearts exhibited sarcomere length and cell circularity comparable to native rat adult cardiomyocytes, though with higher intra-cellular variability in sarcomere organization. Histological examination confirmed successful engraftment of RFP-positive hiPSC-CMs within pig myocardium, with engrafted cells also displaying mature adult-like features. These findings provide critical proof-of-concept data for bioincubation in large animal models and support further investigation for disease modeling, drug screening, and regenerative cell therapies. SIGNIFICANCE STATEMENT Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) offer tremendous potential for cardiac disease modeling and regenerative therapies, but their clinical application is limited by their immature characteristics. Here we show that in vivo bioincubation in neonatal rat hearts enables hiPSC-CMs to achieve structural maturity, exhibiting features of adult cardiomyocytes, including organized sarcomeres, rod-shaped morphology, and multinucleation. We further provided proof-of-concept evidence for engraftment in neonatal pig hearts for maturation, supporting feasibility in large animal models. The use of large-particle cell sorting enables recovery of intact, adult-sized cardiomyocytes for subsequent analysis. These findings establish a practical and scalable platform for generating structurally mature human cardiomyocytes through in vivo bioincubation.

Intramyocardial injection of allogeneic human induced pluripotent stem cell-derived cardiomyocytes in advanced ischemic heart failure: an early-stage randomized trial.

Robust Myocardial Regeneration After Selective Cardiomyocyte Loss Is Driven by Cardiac Stem Cell Activation Through the miR-221–p57 Axis

A central unresolved and highly contested question in cardiac biology is whether the adult mammalian heart, believed to have a very limited endogenous cardiomyocyte (CM) regenerative capacity, can be coaxed into an effective regenerative response after acute CM loss. Using TgMyh6MCM:R26stop-DTA mice, we show that selective diffuse ablation of ∼15% of left ventricular CMs causes acute heart failure but is followed by complete structural and functional recovery within 28 days. Recovery is accomplished by robust generation of new mononucleated CMs, replacing ∼1/10 of the left ventricular CM compartment. This CM regeneration is produced by the activation of resident cardiac stem cells (CSCs), which exit quiescence, proliferate, produce new CMs, and subsequently return to quiescence. Depletion of the putative CSCs blocks repair, whereas transplantation of either clonogenic or primary CSCs through the systemic circulation fully restores myocardial regeneration and function, establishing that the CSCs home, nest and differentiate in the damaged myocardium and, therefore, are the main effectors of regeneration in this setting. Mechanistically, we show that miR-221-dependent repression of p57 governs the transition from quiescence--to activation—to differentiation—to quiescence of the CSCs, defining a reversible regulatory program which, under the proper conditions, endows the adult myocardium with robust CM regenerative competence.

Clinical landscape of human pluripotent stem cell-derived cardiomyocyte therapy.

Heart failure is a major clinical and economic burden that afflicts 60 million individuals worldwide. Guideline-directed medical therapies can slow disease progression, but they cannot restore the loss of cardiomyocytes. Over the past two decades, human pluripotent stem cell (hPSC)-based technology has emerged as a leading approach to overcome limited cardiac regenerative capacity, offering a scalable source of functional human cardiomyocytes. The field is now at a pivotal translational stage, as advances in differentiation and tissue engineering have enabled hPSC-based products to enter first-in-human clinical trials. In this review, we summarize the pathophysiological rationale for cell-based therapy in heart failure with reduced ejection fraction. Then, we examine the preclinical foundations of distinct hPSC-derived product formats, including cell suspensions, epicardial sheets, engineered heart muscle, and cardiac spheroids, each with distinct tradeoffs and translational considerations. We conclude by providing updates on ongoing and recently completed clinical trials, evaluating their safety, feasibility, and preliminary efficacy outcomes.