The team at Tel Aviv University used a patient's cell to create the heart, which has all the chambers and blood vessels of a natural one.
The process of printing the heart involved a biopsy of the fatty tissue that surrounds abdominal organs.
Researchers separated the cells in the tissue from the rest of the contents, namely the extracellular matrix linking the cells.
The cells were reprogrammed to become stem cells with the ability to differentiate into heart cells; the matrix was processed into a personalized hydrogel that served as the printing "ink."
Although the printed heart is only the size of a rabbit's, doctors believe the technology can be scaled up to engineer human ones for transplants.
The cells and hydrogel were first used to create heart patches with blood vessels and, from there, an entire heart.