MINNEAPOLIS, January 14, 2008—University of Minnesota researchers have created a beating heart in the laboratory, a medical first. If perfected, the technique may be used to generate new hearts for patients.

Using detergents, they stripped away the cells from rat hearts until only the nonliving matrix was left; they then repopulated the matrix with fresh heart cells.

"The results were a home run," says Doris Taylor, M.D., director of the University's Center for Cardiovascular Repair and a principal investigator on the study. "We knew that cell therapy—that is, transplanting cells into the heart—is not a panacea. So we started thinking, 'Is there a way to use cells to engineer heart tissue?'"

The idea, she says, was to create whole new blood vessels or organs by implanting a patient's own cells into a matrix derived from a donor organ. This approach ought to bypass the problem of organ rejection because the matrix, being devoid of cells, can't provoke an immune response.

The process, called whole organ recellularization, can be done "with virtually any organ," Taylor says. 

The main hurdle in creating new hearts wasn't finding the right cells, but recreating the vastly complex architecture of the heart, Taylor explains. In puzzling it over, she and Harald Ott, M.D., a research associate in the center (now a surgical resident at Harvard Medical School and first author of the study), hit on a way to get nature to solve the problem for them.

To remove cells from fresh rat hearts, the researchers pumped solutions of detergents through the network of blood vessels that normally nourish the organ. The treatment popped all the cells like balloons and washed away the debris, leaving the matrix of protein fibers that form the backbone of a living heart's connective tissue. It's called the extracellular matrix, or ECM.

"We just took nature's own building blocks to build a new organ," says Ott. Still, "When we saw the first contractions we were speechless."

The naked ECM's looked like "ghost hearts": eerily white, rubbery "skeletons" that retained the organ's original 3-D structure. Among the surviving features was the tubing of blood vessels, which came in handy later.

U of M news release

Star Tribune article