Minimally Invasive Spray Could Help to Repair Damage after Heart Attacks

Heart attacks, or myocardial infarctions, can be fatal. Modern surgical techniques, diagnostics, and medications have greatly improved early survival from these events, but the five-year mortality rate remains high due to the long-term effects of permanently damaged heart tissue.

Researchers have explored stem-cell therapy as a way to regrow tissue after a heart attack. But introducing stem cells directly to the heart could trigger an immune response or result in tumor growth. Therefore, researchers have tried injecting exosomes, i.e., vesicles containing proteins, lipids, and genetic material secreted by stem cells, into the heart. However, the exosomes often break down before they can have therapeutic effects. There are also cardiac patches or scaffolds that help implanted exosomes last longer, but they usually must be placed during open-heart surgery.

Yafeng Zhou, Medical Center of Soochow University, Suzhou, China, and colleagues have developed a minimally invasive exosome spray that could help to repair hearts after myocardial infarction. The team used an exosome solution that could be sprayed onto the heart via a tiny incision, avoiding major surgery. The researchers mixed exosomes from mesenchymal stem cells with fibrinogen, a protein involved in blood clotting. They added the resulting solution to a small, double-barreled syringe that also contained a separate solution of thrombin, another clotting protein. When the team sprayed the solutions out of the syringe onto a rat’s heart through a small chest incision, the liquids mixed and formed an exosome-containing gel that stuck to the heart. An endoscope inserted through a second small incision was used to guide the spray needle.

In rats that had recently had a heart attack, the exosome spray lasted longer, healed injuries better, and boosted the expression of beneficial proteins more than heart-injected exosomes alone. In pigs, the spray caused less severe immune reactions and surgical stress than open-heart surgery. According to the researchers, the spray could provide a promising strategy to deliver therapeutic exosomes for heart repair.