Harvard team grows heart muscle
Takes step toward goal of creating replacement parts
Harvard researchers have created a strip of pulsing heart muscle from mouse embryonic stem cells, a step toward the eventual goal of growing replacement parts for hearts damaged by cardiovascular disease.
The new work, to be published in the journal Science today, begins to confront what will be a major frontier for stem cell biology: translating recent basic science advances to meet the promise of regenerative medicine by finding ways to make such cells functional and potentially useful for therapies.
“I think over the last five years or so, we’ve made great progress in being able to guide stem cells into whatever cell type we want, in this case the heart,’’ said Dr. Deepak Srivastava, director of the Gladstone Institute of Cardiovascular Disease at the University of California at San Francisco, who was not involved in the research. The new work “has begun to think about how to assemble these types of cardiac cells into a 3-D fashion, for future use within a heart. It’s a long way from that right now . . . but it’s a first baby step toward that goal.’’
For years, scientists have been able to turn embryonic stem cells into a variety of heart cells, producing dramatic videos of cells beating in a dish. In the new work, stem cell biologists led by Dr. Kenneth R. Chien, director of the Massachusetts General Hospital Center for Cardiovascular Research, first isolated a progenitor cell that would only give rise to ventricular muscle cells - the working muscle that drives blood around the body, and the tissue that is damaged during a heart attack. Then, collaborating with biomedical engineers, they seeded those cells on a thin film that had been engineered in such a way that it encouraged them to begin to form cardiac muscle.
Kevin Kit Parker, a faculty member at the Wyss Institute for Biologically Inspired Engineering at Harvard, compared the strip of muscle to a Fruit Roll-Up, with cells lining the wrapper instead of fruit. In a video of the work, each time the cells contract, the film curls downward.
Parker is continuing to collaborate with Chien to find ways to do the same thing using human cells, and eventually to engineer a three-dimensional patch of muscle. Ultimately, the work raises the possibility that a patient’s own skin cells could be used to generate cells to repair their heart, turning adult cells into embryonic-like cells capable of turning into any cell in the body.
“This represents, we think, an important step moving from stem cell biology in the heart to regenerative cardiovascular medicine,’’ said Chien, who anticipates early stage clinical trials of cell therapy could begin within five years. “Basically, what we’ve got is proof of concept. There are still some challenges here.’’
Srivastava cautioned that there are still many problems that will need to be solved. Not only will enough cells need to be generated to repair a tissue; they will also need to be delivered to a patient in such a way that they integrate with heart muscle, contracting at the same time and contributing to the work the heart does.
“There are a lot of challenges ahead,’’ Srivastava said. “We will reach them, but it will take time.’’
Carolyn Y. Johnson can be reached at email@example.com.