Scientists Transform Human Scar Tissue into Beating Heart Cells

There may be a way to regenerate cells that have suffered in the wake of a heart attack. Scientists have discovered that the class of cells that form human scar tissue can be transformed into those that resemble beating heart cells. The findings could have major implications for patients that have suffered from heart attacks in the future.

After a heart attack occurs, cells within the region that was most affected shut down and stop beating. More specifically, they become entombed in scar tissue. Reversing this process could potentially be lifesaving for patients, which is why researchers examined the phenomenon a bit further.

Last year, scientists transformed scar-forming heart cells, part of a class of cells known as fibroblasts, into beating heart-muscle cells in live mice. Now, they've done the same to human cells in a petri dish. In mice, the researchers injected just three genes, together known as GMT, into the hearts of live mice that had been damaged by a heart attack. This made them reason that the same three genes could have the same effect on human cells. Yet initial experiments proved otherwise.

The scientists weren't to be deterred, though. Instead, the researchers looked for additional genes to help initiate the transformation. They then injected all candidate genes into human fibroblasts and then systematically removed each one to see which were necessary for reprogramming. In the end, they found that injecting a cocktail of five genes, including GMT in addition to the genes ESRRG and MESP1, could reprogram the fibroblasts.

"While almost all the cells in our study exhibited at least a partial transformation, about 20 percent of them were capable of transmitting electrical signals--a key feature of beating heart cells," said Ji-dong Fu, one of the researchers, in a news release. "Clearly, there are some yet-to-be-determined barriers preventing a more complete transformation for many of the cells. For example, success rates might be improved by transforming the fibroblasts within living hearts rather than in a dish--something we also observed during our initial experiments in mice."

Currently, the researchers plan to test the five-gene cocktail in the hearts of other mammals. They hope that, in the future, a combination of small, drug-like molecules could be developed to replace the cocktail and offer a safe and easier method of delivery to patients.

The findings are published in the journal Stem Cell Reports and Nature.