Scientists grow beating rat heart in lab

January 14, 2008 Scientists from the University of Minnesota have successfully created a beating heart in a lab. The team was led by Dr. Doris Taylor, director of the University's Center for Cardiovascular Repair, used a process called "decellularization" in which the hearts were taken from newborn rats and stripped of their cells. The resulting non-living mass, called an extracellular matrix or ECM, contains no cells and therefore will not be rejected by its new owners. New muscle and endothelial cells are then injected into the ECM and stimulated electrically.

The first micro-contractions occurred within two days of the new cells being injected into the ECMs and visible contractions began to occur within seven to eight days. The rat hearts beat strongly enough to pump fluid out the aorta, although the force at which they beat was only equivalent to 2 percent of a normal adult rat or about 25 percent of a 16 week old human fetus.

The researchers will next be testing the process of pig hearts for which ECMs have already been created. A pig heart is roughly the size of a human heart. The eventual hope of the project is to be able to use the process on human hearts taken from cadavers or pig hearts with human cells injected, though it remains to be seen whether or not the process will work on a heart from a larger animal, such as a pig or human. The team also plans to experiment with the process on other organs such as kidneys, livers and lungs.