In many cases, heart disease can only be treated by heart transplantation.However, the number of hearts donated is small and many patients cannot be treated.Therefore, it is desired to establish a new treatment method to replace heart transplantation.Attempts to compensate for damage with cardiomyocytes made from human iPS cells have had some success, but the cell's epiphytic ability was low and there was room for improvement.So the group thought that transplantation might be necessary at the right stage of the many processes that make cardiomyocytes.

　To investigate this, the group transplanted cells at the 4th, 8th, 20th, and 30th days after the onset of cardiomyocyte differentiation into the heart of mice.When the progress was observed for 2 months, the cells 20 days after the start of differentiation showed the highest engraftment rate.Continued observations revealed that after 6 months, the myocardium had a characteristic structure, indicating that it had matured over a long period of time.
　This result was able to identify the most effective stage for transplanting cardiomyocytes made from iPS cells.In addition, from this finding, it is expected that detailed follow-up observations will be actively studied in the future. Research is likely to accelerate toward the establishment of treatments for heart disease using iPS cells.