Hopes Raised for Heart Treatment

Researchers at Massachusetts General Hospital (MGH) have discovered in mice what they believe to be cardiac master cells, which have the potential of developing into the three different types of heart tissue. The breakthrough study, which will be published in the Dec. 15 issue of the journal Cell, raises hopes for new and far more effective drug and regenerative treatments for heart diseases.

Scientists at Children’s Hospital Boston also independently discovered a different stem cell line that develops into two main cell types that form the heart.

The results of the studies challenge the previous notion that the heart’s different cell types are so diverse that they must generate from disparate sources.

“This is the first study that shows that a single cell can give rise to all cardiac tissues and structures,” said Kenneth R. Chien ’73, the senior author of the paper and the director of the Cardiovascular Research Center at MGH, a Harvard Medical School teaching hospital.

Current therapies for recovering damaged heart tissue due to disorders such as heart attacks involve injection of bone marrow or blood cells and are largely ineffective, experts say. However, the findings of the MGH and Children’s Hospital studies could move scientists closer to being able to regenerate damaged heart tissues using stem cell therapies.

Deepak Srivastava, the director of the Gladstone Institute of Cardiovascular Disease at the University of California, San Francisco, cautioned that further research will be necessary before the discovery can be translated into specific treatments.

“The biggest hurdle in any treatment will be to guide these progenitor cells to develop into the appropriate tissue, deliver them to the correct part of the organ, and then have them actually incorporated by the heart,” Srivastava said.

The team identified the master cardiac cell in mice and showed that it can develop into cardiac muscle cells that power the heart, endothelial cells that make up blood vessels, and the smooth muscle cells that allow the vessels to expand and contract. Using the same scientific techniques, the researchers hope to show human embryonic stem cells can develop into similar cardiac master cells in humans.

Chien said he believes Harvard’s institutional support for this research is crucial for further discoveries in the field because governmental support of stem cell research is lagging due to a continued ban on using federal funds to finance human embryonic stem cell research.

“This research makes a compelling case that we should aggressively expand our attention and focus on human embryonic stem cell lines,” Chien said.

—Staff writer Anupriya Singhal can be reached at asinghal@fas.harvard.edu.