Klf9 promotes the repair of myocardial infarction by regulating macrophage recruitment and polarization.

Summary: When a person has a heart attack, the heart gets hurt and needs to heal. Special white blood cells called macrophages act like a cleanup and repair crew. Scientists found that a special protein called Klf9 is like a boss that tells these cells where to go and what to do. Without Klf9, the heart doesn't heal well, leading to more damage and even death in mice. Klf9 helps the heart heal by making sure the right cells show up at the right time to fix the damage.