When the flow of blood to the heart is blocked, heart cells don't get enough oxygen and begin to die; this is a heart attack, also called a myocardial infarction. Though there are some treatment options, like drugs that dissolve clots that are obstructing blood flow or dilate blood vessels, heart attacks are still a leading cause of death. The tissue damage that occurs during heart attacks can also cause lasting negative effects.
Researchers are now developing a therapeutic for heart attacks that helped a rat model of heart attack heal; it's a minimally invasive spray that uses exosomes. The work has been reported in ACS Nano.
Stem cells could be a way to repair heart tissues where cell death has occurred during a heart attack. But it's difficult and risky to direct stem cells to the heart. Membrane bound sacs called exosomes might may help. These sacs are enclosed by membranes made of lipids, and they can carry material like proteins and nucleic acids. Injections of exosomes have been tested, but they have frequently degraded before reaching the heart, so researchers thought that a spray that could be applied through a small incision might be an alternative.
To create the spray, the investigators isolated exosomes from mesenchymal stem cells and combined them with a protein that's involved in blood clotting, called fibrinogen. That mixture was added to another solution of protein that plays a role in blood clotting, thrombin.
This spray was tested on a rat model of heart attack by mixing the liquids to create a gel that contained exosomes, which was applied by a spray-tip needle through a small chest incision. The researchers found that injuries healed faster, and the effects lasted longer than exosomes that have previously been tested. This therapy was also less stressful than stem cell scaffolding, which is applied during open heart surgery.