The heart contains its own pool of immune cells capable of helping it heal after injury, according to new research in the US.

In a mouse model of heart failure, the researchers at Washington University School of Medicine in St. Louis, Missouri, 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.

"Researchers have known for a long time that the neonatal mouse heart can recover well from injury, and in some cases can even regenerate," said first author Kory J. Lavine, MD, PhD, instructor in medicine. "If you cut off the lower tip of the neonatal mouse heart, it can grow back. But if you do the same thing to an adult mouse heart, it forms scar tissue."

The findings may have implications for treating heart failure in humans. The study is available in The Proceedings of the National Academy of Sciences Early Edition.