Scientists discover key component to repair the molecular motor of human heart A team of scientists from Loyola University Chicago's Stritch School of Medicine have discovered a critical component for renewing the heart's molecular motor, which breaks down in heart failure. Approximately 6.2 million Americans have heart failure, an often fatal condition characterized by the heart's inability to pump enough blood and oxygen throughout the body. This discovery could represent a novel approach to repair the heart. Their findings, published in the May 19 issue of Nature Communications, show how a protein called BAG3 helps replace "worn-out" components of the cardiac sarcomere. The sarcomere is a microscopic structure inside every heart muscle cell that causes it to contract. All the cells then work together to make the heart pump blood around the body.