0922 GMT September 23, 2019
Scientists at the University of Texas Southwestern have uncloaked the molecular mechanisms underlying heart regeneration in the only mammals currently known to regrow a significant portion of their hearts after injury: Neonatal mice, Medical Xpress wrote.
These newborns have long held the secret to regenerating approximately 15 percent of their ventricular tissue, a capability that occurs within a fleeting window of about seven days after birth. Once that window closes, cardiac cells mature and mice forever lose the capacity to regrow injured regions of their hearts.
The research is underway at the university's Hamon Center for Regenerative Science and Medicine, where scientists have already made a series of breakthrough findings about cardiac regeneration.
Working collaboratively with another US team, the Texas researchers in 2011 were first in the world to announce the animals are actually capable of regrowing a significant amount of their heart tissue. The minuscule mice reboot their hearts by regenerating new cardiomyocytes, cells responsible for the potent contractile forces of the healthy organ.
Now, in a new development, the scientists have pinpointed genes, their protein products and a cascade of cells, including macrophages from the immune system, involved in the regeneration process. The advance may provide the recipe to aid ailing human hearts one day, team members said.
"Our work provides a detailed molecular blueprint of neonatal mouse heart regeneration, and represents a rich resource for the identification of genes that may facilitate cardiac repair in the face of injury," said Zhaoning Wang, lead author of a report on the team's latest research published in the Proceedings of the National Academy of Sciences.
The investigation is important, Wang said, because of the implications for potential human applications.
Heart disease is the leading cause of death worldwide, and once damaged, contractile cells do not regenerate. In a heart attack, an adult human heart can lose up to one billion cardiomyocytes because the cells are non-proliferating, which means they do not replenish themselves. Loss of cardiomyocytes leads to diminished heart contractility, scar formation and heart failure, Wang said.
By contrast, the neonatal mouse heart can efficiently regenerate healthy tissue, allowing the organ to function efficiently afterward. The animals lose the capability after the first week of life because regenerative components "undergo structural and functional maturation," Wang said.