Muscle protein worsens heart attack damage

Defined as a muscle protein whose enzymatic activity provides the energy for muscle contraction, myosin can be found in various places in the body, such as skeletal muscle and the heart. A team of scientists from The Scripps Research Institutein California (USA), were specifically interested in cardiac myosin.

Their findings, presented in a study published in the medical journal Arteriosclerosis, Thrombosis, and Vascular Biology, report the involvement of cardiac myosin in the damage caused by myocardial infarction. Thus, when a person has a heart attack, the protein would be released in the body and could then worsen the damage to heart tissue, causing thickening of the blood or the formation of a clot.

“We discovered another major biological activity of cardiac myosin”

To carry out their work, the scientists carried out experiments for three years to assess the activities of cardiac myosin ex-vivo (outside the organization), live (inside) and in vitro (in tube), relating to haemostasis and thrombosis.

“The real breakthrough of this study and that we discovered another major biological activity of cardiac myosinassures John H. Griffin, professor in the Department of Molecular Medicine at the Scripps Research Institute, in a article published on the institution’s website. No one suspected it acted as a procoagulant factor..” By administering an excess of cardiac myosin to mice undergoing infarctions, the scientists actually found that cardiac damage was multiplied by two.

Limit bleeding while avoiding excessive clotting

Blood clotting is essential to prevent bleeding after an injury. This is where procoagulant proteins, like collagen, come into play. Their role: to transform liquid blood into a semi-solid gel in order to limit bleeding, while avoiding excessive coagulation, as happens during deep vein thrombosis or when a blood clot causes a stroke.

“As with inflammation, a little clotting is fine, but it becomes dangerous if too much.explains John H. Griffin. While a small amount of cardiac myosin could help reduce bleeding in the heart, an excess of the protein could worsen the injury by promoting blood clots, which block oxygen supply and exacerbate heart tissue damage..”

“Cardiac myosin gives us a promising way forward”

The professor and his team are now working on the creation of a therapeutic compound that would target the procoagulant activity of cardiac myosin, in order to reduce the tissue damage caused by a heart attack. Objective: to eventually develop an anticoagulant drug that would only target coagulation induced by cardiac myosin, unlike a large number of already existing treatments, which act on the coagulation system of the entire human body.

Ideally, the drug the researchers are working on could be given to patients in hospitals immediately after an acute heart problem. “Cardiovascular disease is the leading cause of death for men, women, and people of most racial and ethnic groups in the United Statessays John H. Griffin. Novel drugs are needed for those at risk, and cardiac myosin gives us a promising way forward.”