Newborn Mice’s Hearts Can Heal Themselves, Study Finds
By SINDYA N. BHANOO

An adult zebra fish can regenerate a damaged heart with no scar formation. This remarkable phenomenon has been seen in other fish and amphibians as well, but never before in a mammal.

Now researchers from the University of Texas Southwestern Medical Center report in the current issue of Science that the mammalian newborn heart can fully heal itself.

Dr. Hesham Sadek, a cardiologist at the medical center, and his colleagues worked with mice and found that if a portion of the heart was removed within the first week of life, the heart grew back completely.

The researchers removed about 15 percent of lowest portion of the heart, known as the apex, in laboratory mice. Within three weeks, the lost tissue regenerated itself and the hearts were healed.

“But by seven days this remarkable regenerative is lost and instead of regrowing that tissue back, there is heart failure,” said Dr. Sadek said. “In humans, it may be a few months after birth that this is lost.”

The newborn’s uninjured beating heart cells, known as cardiomyocytes, may be the source of new cells. Or stem cells may be contributing to the process, according to the report.

The study offers hope that doctors will one day be able to cure heart disease. If newborn children are also able to regenerate their hearts, there may be a way to restart this ability in adults.

“We’re looking at a few genes that could regulate this process, and then we can look for drugs that activate the genes,” Dr. Sadek said. “Maybe we can remind the heart how to do this.”