One issue with stem cell treatment is that only about 10 percent of the stem cells survive for more than about a day after injection, probably because they do not have a surface to adhere to, Traverse said.
In contrast, Christman's study showed that, in rats, the hydrogel scaffold stuck around for a couple of weeks before it dissolved. By that time, the scaffold has probably recruited enough stem cells and salvaged enough heart muscle cells to have a lasting benefit, Traverse said.
He and his colleagues are currently testing the use of stem cells in animals in combination with the pig intestine-derived material, which is U.S. Food and Drug Administration-approved. "We hope that we could potentially have an additive effect," Traverse said.
The current study by Christman and her colleagues administered the hydrogel to six pigs and gave an injection of salt solution or no injection to four "control" animals.
The researchers tested the heart function of the pigs by echocardiogram, or "echo," which uses ultrasound to take pictures of the heart.
Three months after the injections, the pigs that received the hydrogel showed improvements in measures of how well their hearts pumped blood, and reductions in measures of heart enlargement that can indicate heart failure. In contrast, most of the control animals had deteriorated heart function and signs of heart enlargement.
The researchers looked at heart tissue taken from the animals and found that the hydrogel-treated animals had thicker heart muscle in the region of the heart attack than the control animals. There were no differences in heart rhythm or in tissues from other organs after the injections in either the treated or control animals.
Although the true test will be how effective and safe the hydrogel is in people, the pig heart anatomy is very similar to humans, Christman noted.
"I imagine in 15 years from now when patients come in after a heart attack [and show signs of heart failure based on echo or MRI tests], they are going to get stem cells or biomaterial product or both to help prevent the development of heart failure," Traverse said.
The study was published in the Feb. 20 issue of Science Translational Medicine.
The research was funded in part by Ventrix Inc., a San Diego-based company that Christman cofounded and that has licensed the hydrogel and its delivery methods.
There's more on heart failure at the American Heart Association.
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