Replicative Senescence is Present in Cardiac Microvascular Endothelial Cells

Age-related decrease of angiogenesis in myocardium is a big challenge for us to achieve functional regeneration of infarcted myocardial tissues (MI) in aged peoples. Cardiac microvascular endothelial cells (CMECs) play a key role in cardiac angiogenesis upon the MI. However, whether or not cellular senescence is happening in CMECs has not yet been demonstrated clearly. In the present study, using the in vitro culture system, we found that increases in SA-beta-gal positive CMECs was associated with the increases of passage number of these cells. In addition, the telomere length of CMECs was shorter in older passage (passage 44) as compared with younger passage (passage 8). The rate of shortening was estimated as 147 bp per passage. Our findings indicated that CMECs were experiencing replicative senescence in vitro. A novel strategy to delay senescence in CMECs will be very helpful to improve the angiogenesis of aged hearts and the regeneration of MI tissues.