Cardiac Cells Renew Throughout Life in Humans
Second study suggests new strategy for improving stem cell recruitment, heart function and survival post-heart injury
FRIDAY, April 3 (HealthDay News) -- Cardiac muscle cells continue to renew after birth and throughout life in humans, according to a study in the April 3 issue of Science. In a related study in the April 3 issue of Cell Stem Cell, inhibition of DPP-IV combined with treatment with granulocyte colony stimulating factor increases the recruitment of stem cells to the heart, increases the formation of new blood vessels, and improves survival and cardiac function in mice surgically induced to have a myocardial infarction.
Olaf Bergmann, M.D., from the Karolinska Institute in Stockholm, Sweden, and colleagues measured carbon-14 levels in the DNA of human myocardial cells to date the cells. By analyzing genomic DNA from individuals born before and after the onset of nuclear bomb testing in 1955, the researchers found that cardiomyocytes do renew after birth. About 1 percent of cardiomyocytes turned over at 25 years of age, which gradually fell to 0.45 percent turnover at 75 years of age. However, they note that less than 50 percent of cardiomyocytes turn over during a normal life span.
In the second study, Marc-Michael Zaruba from Ludwig-Maximilians-University in Munich, Germany, and colleagues examined whether the homing of stem cells known as endothelial progenitors to damaged heart tissue by stromal-cell-derived factor, type I (SDF-1) could be improved by inhibiting a protein that promotes the breakdown of SDF-1, CD26/dipeptidylpeptidase IV (DPP-IV), finding that it was linked to increased recruitment of stem cells to the heart, increased formation of new blood vessels, and improved survival and cardiac function in mice surgically induced to have a myocardial infarction.
"The capacity to generate cardiomyocytes in the adult human heart suggests that it may be rational to work toward the development of therapeutic strategies aimed at stimulating this process in cardiac pathologies," Bergmann and colleagues write.