The process of building a new heart in the laboratory took an interesting and unconventional turn at the University of Minnesota Center for Cardiovascular Repair. The preliminary findings of new research in rats might some day be translated to humans, forever changing heart transplantation.1
By using a process called whole organ decellularization, the University of Minnesota scientists used a detergent wash to remove all the cells from dead rat hearts and then injected the matrix that remained with a mixture of minced stem cells and progenitor cells from neonatal or newborn rat hearts. The researchers next pumped a solution of oxygen and nutrients through the remnant blood vessels; after four days they detected contractions in several hearts. In eight days, they had eight hearts beating normally enough to pump fluid out of the aorta. The best performing hearts were kept beating for 40 days.
Lead researcher Doris Taylor, MD, noted that the potential to grow human hearts in the lab is promising but the reality is many, many years off. John Mayer,MD, senior associate in cardiac surgery at Children's Hospital, Boston, says, “It's an important paper that advances the ball down the road,but it's a pretty long road.”
Cardiovascular researcher Kenneth Chien, MD,PhD, scientific director at Massachusetts General Hospital Cardiovascular Research Center in Boston, believes the study's “major merit is that it points to a very important role for the matrix in building. There may be a signature extracellular matrix component that will be required to make heart muscle.”
Dr. Chien says many questions must be answered before this unconventional process will find its way into clinical practice. Additionally, Dr. Mayer notes that it remains to be seen whether the procedure that was performed successfully using small animals can also be replicated in larger ones. He also wonders whether blood will flow freely, without clotting, through the reconstructed blood vessels.
Meanwhile, the Minnesota team is conducting similar experiments on pigs as a step toward human work.