A heart attack occurs when the flow of oxygen-rich blood to a section of the heart muscle is blocked. If the blood flow is not restored quickly the heart muscle or tissue dies. A new study by researchers at Cornell University and the University of Bonn has found that stem cells are capable of regenerating into new heart cells very early in life- but the same cells lose that regenerative ability in adults.
In a study carried out on lab mice, undifferentiated stem cells grew into new heart cells in a two-day-old mouse, but not in adult mice. The finding settles a controversy on whether stem cells could be used to aid the recovery of an adult mammalian heart after the formation of an infarct, an area of tissue death, caused by artery blockage.
Researchers found out that the two-day old mice grew new heart cells and almost completely recovered from the infarction, caused by tissue death in an area, due to local lack of oxygen. This proved that the injury did not inhibit the stem cells from growing into new heart cells. But when the same procedure was carried out in adult mice, no new heart cells, called myocytes were formed, though new blood vessels were created.
The stem cells found in the adult heart "have lost the ability to become heart cells, and are only capable of forming new vessels," said Micheal Kotlikoff, senior author of the paper and dean of Cornell's College of Veterinary Medicine. Single stem cells differentiate into all tissues at the start of life, but with time, they become "developmentally restricted" or specialized to form only certain tissues.
The paper will appear August 29 in the Proceedings of the National Academy of Sciences.
by RTT Staff Writer
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