Heart's Own Immune Cells Can Help It Heal (IMAGE) Washington University School of Medicine Caption The heart holds its own pool of immune cells capable of helping it heal after injury, according to new research in mice at Washington University School of Medicine in St. Louis. Most of the time when the heart is injured, these beneficial immune cells are supplanted by immune cells from the bone marrow, which are spurred to converge in the heart and cause inflammation that leads to further damage. In both cases, these immune cells are called macrophages, whether they reside in the heart or arrive from the bone marrow. Although they share a name, where they originate appears to determine whether they are helpful are harmful to an injured heart. In a mouse model of heart failure, the researchers showed that blocking the bone marrow's macrophages from entering the heart protects the organ's beneficial pool of macrophages, allowing them to remain in the heart, where they promote regeneration and recovery. The findings may have implications for treating heart failure in humans. Following injury, neonatal mouse hearts (middle) heal well, appearing similar to healthy heart tissue (top). But adult hearts form scar tissue following injury (bottom). Credit K. Lavine Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.