Photosynthetic bacteria injected into the heart during a heart attack could keep heart cells alive by providing an essential source of oxygen, a new study in rats finds.
Why it matters:
During a heart attack, the artery that supplies blood to the heart is blocked and heart tissue begins to die. Blood flow can be restored by reopening the artery, but patients often don’t undergo this procedure until an hour or two after their first symptoms. So researchers are very interested in alternate ways to get oxygen to heart muscle when blood flow is obstructed.
The researchers tapped the freshwater cyanobacterium Synechococcus elongatus, a photosynthetic type of bacteria.
While blocking blood flow to rats’ hearts for 60 minutes, researchers injected their hearts with cyanobacteria and shone a spotlight on the organ to induce photosynthesis. Rats who received the treatment had less heart damage 24 hours later, and improved heart function four weeks later.
And in a different test, the researchers found that performing the therapy in the light resulted in a nearly 30 percent increase in cardiac output compared to performing the therapy in the dark. The injection also didn’t seem to set off an immune response in the rats. The research was published in Science Advances on Wednesday.
“This is, as far as we know, the first time anyone has actually harnessed the equivalent of a plant cell to try to help a mammalian cell,” said study author Dr. Joseph Woo, a cardiothoracic surgeon and professor at Stanford University. “We’re essentially creating a solar-energy-powered heart.”
Woo sees potential for applying the technique to other conditions associated with reduced blood flow, such as stroke.
But keep in mind:
If such a technique were ever going to work for human patients, it would need to be modified to make it less invasive — that is, delivering bacteria to the heart via the bloodstream rather than direct injection, and also figuring out a way to provide light to the bacteria without opening up the skin to expose the heart. To avoid injecting patients with live bacteria, the researchers would also like to develop a synthetic version of the photosynthesizing machinery present in cyanobacteria.
What they’re saying:
Yale cardiac surgeon Dr. Arnar Geirsson, who wasn’t involved with the study, was enthusiastic about the technique, which he said could lead to “a paradigm shift in how you potentially treat any type of disease that involves a lack of oxygen and nutrients.”
“They’re really thinking outside the box,” he said. “The concept of using this mechanism to potentially treat conditions or diseases is very, very unique.” He pointed out, however, that because bacteria can cause an immune response in animals, in-depth research is needed before moving to human patients.
The bottom line:
The delivery of oxygen-producing bacteria to a site of blocked blood flow is a promising new approach for preventing tissue death, if researchers can clear some important hurdles.