Induced pluripotent stem cells (iPSCs) are promising candidate cells for cardiomyogenesis in the failing heart. However, teratoma/tumour formation originating from undifferentiated iPSCs contaminating the graft is a critical concern for clinical application. Here, we hypothesized that brentuximab vedotin, which targets CD30, induces apoptosis in tumourigenic cells, thus increasing the safety of iPSC therapy for heart failure. Flow cytometry analysis identified consistent expression of CD30 in undifferentiated human iPSCs. Addition of brentuximab vedotin in vitro for 72 h efficiently induced cell death in human iPSCs, associated with a significant increase in G2/M phase cells. Brentuximab vedotin significantly reduced Lin28 expression in cardiomyogenically differentiated human iPSCs. Transplantation of human iPSC-derived cardiomyocytes (CMs) without treatment into NOG mice consistently induced teratoma/tumour formation, with a substantial number of Ki-67–positive cells in the graft at 4 months post-transplant, whereas iPSC-derived CMs treated with brentuximab vedotin prior to the transplantation did not show teratoma/tumour formation, which was associated with absence of Ki-67–positive cells in the graft over the same period. These findings suggest that in vitro treatment with brentuximab vedotin, targeting the CD30-positive iPSC fraction, reduced tumourigenicity in human iPSC-derived CMs, potentially providing enhanced safety for iPSC-based cardiomyogenesis therapy in clinical scenarios.

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Aims: Cardiomyocyte-derived induced pluripotent stem cells (iPSCs) may represent a promising therapeutic strategy for severely damaged myocardium. This study aimed to assess the efficacy and safety of clinical grade human iPSC-derived cardiomyocyte (hiPSC-CM) patches and conduct a pre-clinical proof-of-concept analysis. Methods and results: A clinical grade hiPSC line was established from peripheral blood mononuclear cells collected from a healthy volunteer homozygous for human leukocyte antigens and differentiated into cardiomyocytes using cytokines and chemical compounds. hiPSC-CMs were cultured on temperature-responsive culture dishes to fabricate the hiPSC-CM patch. The hiPSC-CMs expressed cardiomyocyte-specific genes and proteins while electrophysiological analyses revealed that hiPSC-CMs were similar to the human myocardium. In vitro safety studies using cell growth, soft agar colony formation, and undifferentiated cell assays indicated that tumourigenic cells were not present. Moreover, no genomic mutations were discovered using whole genome and exome sequencing analysis. Tumour formation was not detected in an in vivo tumourigenicity assay using NOG mice. General toxicity tests also showed no adverse events due to hiPSC-CM patch transplantation. An efficacy study using a porcine model of myocardial infarction demonstrated significantly improved cardiac function with angiogenesis and a reduction in interstitial fibrosis, which was enhanced by cytokine secretion from hiPSC-CM patches after transplantation. No lethal arrhythmias were observed. Conclusion: hiPSC-CM patches show promise for future translational research and clinical trials for ischaemic heart failure.

One of the major challenges in cell-based cardiac regenerative medicine is the in vitro construction of three-dimensional (3D) tissues consisting of induced pluripotent stem cell-derived cardiomyocyte (iPSC-CM) and a blood vascular network supplying nutrients and oxygen throughout the tissue after implantation. We have successfully built a vascularized iPSC-CM 3D-tissue using our validated cell manipulation technique. In order to evaluate an availability of the 3D-tissue as a biomaterial, functional morphology of the tissues was examined by light and transmission electron microscopy through their implantation into the rat infarcted heart. Before implantation, the tissues showed distinctive myofibrils within iPSC-CMs and capillary-like endothelial tubes, but their profiles were still like immature. In contrast, engraftment of the tissues to the rat heart led the iPSC-CMs and endothelial tubes into organization of cell organelles and junctional apparatuses and prompt development of capillary network harboring host blood supply, respectively. A number of capillaries in the implanted tissues were derived from host vascular bed, whereas the others were likely to be composed by fusion of host and implanted endothelial cells. Thus, our vascularized iPSC-CM 3D-tissues may be a useful regenerative paradigm which will require additional expanded and long-term studies.

The short- and mid-term outcome after valve surgery for active IE in patients with DM is worse because of the greater prevalence of infection-related death and IE recurrence.