In an act of transformation worthy of any magician, scientists have converted scar tissue in the hearts of living mice into beating heart cells. If the same trick works in humans (and we’re still several years away from a trial), it could lead us to a long-sought prize of medicine – a way to mend a broken heart.
Our hearts are made of several different types of cell. These include muscle cells called cardiomyocytes, which contract together to give hearts their beats, and connective cells called cardiac fibroblasts, which provide support. The fibroblasts make up half of a heart, but they become even more common after a heart attack. If hearts are injured, they replace lost cardiomyocytes with scar tissue, consisting of fibroblasts. In the short-term, this provides support for damaged tissue. In the long-term, it weakens the heart and increases the risk of even further problems.
Hearts can’t reverse this scarring. Despite their vital nature, they are terrible at healing themselves. But Deepak Srivastava from the Gladstone Institute of Cardiovascular Disease can persuade them to do so with the right chemical cocktail. In 2010, he showed that just three genes – Gata4, Mef2c and Tbx5 (or GMT)– could transform fibroblasts into new cardiomyocytes.
This only worked in cells growing in a laboratory dish, but it was a start. Srivastava’s team have now taken the next step. By injecting living mice with GMT, they turned some of the rodents’ fibroblasts into cardiomyocytes. Since hearts are already loaded with fibroblasts, Srivastava’s technique simply conscripts them into muscle duty. Best of all, the technique worked even better in the animals than in isolated cells. No transplants. No surgeries. No stem cells. Just add three genes, and watch sick hearts turn into healthier ones.
“This is a permanent fix,” says Benoit Bruneau, a heart specialist who works at the same institute but was not involved in this study. “The net result is a much smaller scar and restored cardiac function. Honestly, I would have thought a few years ago that this was science fiction.”
by Ed Yong, Discover Magazine | Read more:
Image: by 20after4
