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To realize human induced pluripotent stem cell (hiPSC)-based cardiac regenerative therapy, evidence of therapeutic advantages in human-sized diseased hearts are indispensable. In combination with an efficient and simultaneous differentiation of various cardiac lineages from hiPSCs and cell sheet technology, we aimed to generate clinical-sized large cardiac tissue sheets (L-CTSs) and to evaluate the therapeutic potential in porcine infarct heart. We simultaneously induced cardiomyocytes (CMs) and vascular cells [vascular endothelial cells (ECs) and vascular mural cells (MCs)] from hiPSCs. We generated L-CTSs using 10cm-sized temperature-responsive culture dishes. We induced myocardial infarction (MI) in micromini-pigs (15–25 kg) and transplanted the L-CTSs (Tx) 2 weeks after MI induction (4 sheets/recipient) under immunosuppression (Tx: n = 5, Sham: n = 5). Self-pulsating L-CTSs were approximately 3.5cm in diameter with 6.8×106±0.8 of cells containing cTnT+-CMs (45.6±13.2%), VE-cadherin+-ECs (5.3±4.4%) and PDGFRβ+-MCs (14.4±20.7%), respectively (n = 5). In Tx group, echocardiogram indicated a significantly higher systolic function of the left ventricle (LV) compared to that in sham control (Sham vs Tx: fractional shortening: 24.2±8.6 vs 40.5±9.7%; p<0.05). Ejection fraction evaluated by left ventriculogram was significantly higher in Tx group (25.3±6.2% vs 39.8±4.2%; p<0.01). Speckle tracking echocardiogram showed a significant increase of circumference strain in infarct and border regions after transplantation. Fibrotic area was significantly lower in Tx group (23.8±4.5 vs 15.9±3.8%; P<0.001). Capillary density in the border region was significantly higher in Tx group (75.9±42.6/mm2 vs 137.4±44.8/mm2, p<0.001). These data indicate that the L-CTS transplantation attenuated LV remodeling. L-CTSs potentially restore cardiac dysfunction of human-sized infarct heart. [ABSTRACT FROM AUTHOR]

Blood vessels are essential components for many tissues and organs. Thus, efficient induction of endothelial cells (ECs) from human pluripotent stem cells is a key method for generating higher tissue structures entirely from stem cells. We previously established an EC differentiation system with mouse pluripotent stem cells to show that vascular endothelial growth factor (VEGF) is essential to induce ECs and that cyclic adenosine monophosphate (cAMP) synergistically enhances VEGF effects. Here we report an efficient and robust EC differentiation method from human pluripotent stem cell lines based on a 2D monolayer, serum-free culture. We controlled the direction of differentiation from mesoderm to ECs using stage-specific stimulation with VEGF and cAMP combined with the elimination of non-responder cells at early EC stage. This “stimulation-elimination” method robustly achieved very high efficiency (>99%) and yield (>10 ECs from 1 hiPSC input) of EC differentiation, with no purification of ECs after differentiation. We believe this method will be a valuable technological basis broadly for regenerative medicine and 3D tissue engineering. [ABSTRACT FROM AUTHOR]