In their previous work, the scientists created a technique in which they use a detergent solution to strip a donor organ of cells that might set off an immune response in the recipient. They did that in mouse hearts, but for this study, the researchers used it on human hearts. They stripped away many of the cells on 73 donor hearts that were deemed unfit for transplantation. Then the researchers took adult skin cells and used a new technique with messenger RNA to turn them into pluripotent stem cells, the cells that can become specialized to any type of cell in the human body, and then induced them to become two different types of cardiac cells.