Stem cells modified with a 'survival gene' could be used to treat heart attack patients, according to new research carried out on rats. Earlier studies using stem cells to treat heart damage in mice showed promise, but the transplanted cells did not live very long. However, US researchers have now found that by combining stem cell injections with gene therapy, they can successfully treat rats with damaged hearts. Their results are published in the journal Nature Medicine.
Scientists at the Brigham and Women's Hospital in Boston, US, first inserted a gene called Atk1 into bone marrow stem cells, and then injected the cells into rats with heart damage. After two weeks, the rats' hearts were working normally again. Team leader Victor Dzau thinks that the Atk1 gene, which makes a protein that stops cells from destroying themselves, allowed the stem cells to survive long enough to turn into heart muscle cells. Charles Murry, of the University of Washington in Seattle called the results 'pretty darned dramatic' saying the method could spell the end of the cell death problems that have hindered the field. However, he also expressed concerns that prolonging the lifespan of the injected cells could lead to an increased risk of cancer. But Dzau thinks the risk is low, as heart muscle cells do not divide very often.
Preliminary human trials in which heart attack patients were injected with their own bone marrow cells have also shown promise. However, it is not clear how the stem cells repair the muscle: whether they fuse with existing cells, grow into new cells or just trigger the repair of the damaged cells is unknown. Despite these uncertainties, advocates of the research say human stem cell trials should continue, because the need for new treatments is so great - an estimated 23 million people worldwide are affected by heart failure.