Can photosynthetic bacteria treat heart diseases?

Science & Technology

The researchers from Stanford University are trying to find out if the photosynthetic bacteria can help generate oxygen in the body in case of heart failure. Heart failure is the top cause of death globally.

The genesis of this concept is the outcome of scientists’ search for new ways to deliver oxygen to the heart when blood flow is restricted. This condition, known as cardiac ischemia, is most often caused by coronary artery disease.

In experiments done with rats having cardiac disease, researchers found that by injecting a type of bacteria into the hearts of these anesthestized rats and then using light to trigger photosynthesis in the bacteria, the flow of oxygen can be increased which in turn improves the heart function. Bacteria take up the carbon dioxide produced in the body and use light to produce oxygen in the body.

Humans exhale carbon dioxide and plants convert it back to oxygen. When heart attack happens, the muscle is still trying to pump. There’s carbon dioxide but no oxygen. The scientists were trying to find out if there was any way to put plant cells next to heart cells and if these plant cells could produce oxygen from the existing carbon dioxide.

Researchers first tried grinding up spinach and kale and combining each with heart cells in a dish, but the chloroplasts, the photosynthetic organs, of those plants weren’t stable enough to survive outside of the plant cell.

So, next they tried photosynthetic bacteria (cyanobacteria/blue-green algae), since it has a more rugged structure necessary for living in water.

They repeated the same tests to see whether these photosynthetic bacteria had the ability to survive with heart cells in a dish. And, they did.

In the next round of experiments, the researchers injected the cyanobacteria into the beating hearts of anesthetized rats with cardiac ischemia. They then compared the heart function of rats with their hearts exposed to light (for less than 20 minutes) to those who were kept in the dark.

The group that received the bacteria plus light had more oxygen and the heart worked better. The bacteria dissipated within 24 hours, but the improved cardiac function continued for at least four weeks.

The researchers now plan to investigate how to apply this concept to humans and how to deliver a light source to the human heart. They are also examining the potential of using artificial chloroplasts to eliminate the need for bacteria.

The study has been published in Science Advances. The author of this study is Joseph Woo, MD, chair of cardiothoracic surgery at Stanford.

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