Abstract
Cardiomyocytes undergo cell division during the fetal period but do not divide after birth; thus, they grow into adult heart cells by enlarging their size. Therefore, heart failure occurs when a certain number of cardiomyocytes are lost owing to myocardial infarction, myocarditis, sarcoidosis, etc. Through scientific efforts, we have developed methods to safely and efficiently generate induced pluripotent stem (iPS) cells from peripheral blood T cells, generate ventricle-specific cardiomyocytes from iPS cells, and remove residual iPS cells and non-cardiomyocytes using the "metabolic selection method" and purify the cardiomyocytes from iPS cell derivatives. We have also developed the technology to mass-produce and efficiently engraft cardiomyocytes by generating cardiomyocyte spheroids and have developed devices suitable for cell transplantation. We have confirmed the safety and efficacy of these techniques by performing preclinical studies (oncogenesis, arrhythmogenicity, etc.) using immunodeficient mice, rats, pigs, and monkeys. Based on these technologies, we have successfully regenerated human ventricular muscle-specific cardiomyocytes with purity greater than 99%. We have also confirmed that the regenerated myocardium transplanted into immunodeficient mice maintained autonomic beating for more than a year without tumor formation. We are planning to conduct clinical trials to transplant iPS cell-derived cardiomyocytes into patients with heart failure associated with ischemic heart disease, which will, in the near future, enable clinical applications using HLA-deficient iPS cells and iPS cells generated from the patient's own lymphocytes to generate regenerative cardiomyocytes without rejection. It would also help establish personalized medicine for heart failure and usher in the long-awaited treatment for intractable severe heart failure using ventricular muscle supplementation.