"We think that these cells normally play an important role in the remodeling of the heart after birth, when the newborn heart no longer relies upon the mother's circulation and oxygenation," Chien said. "We believe the isl1+ progenitor cells are left over from fetal development so that they can insure the closure of any existing small heart defects and the formation of a completely mature heart in newborns."
The UCSD team noted in the Nature paper that the next research steps with the isl1+ cells will be cellular transplantation in living animals to study their role in endogenous repair after cardiac injury.