Replicative senescence of vascular endothelial cells isolated from coronary patients is worsened by oxidative stress associated with risk factors for cardiovascular disease

Abstract

The p53‐p21 pathway can trigger senescence either by telomere shortening (replicative senescence via ATM) or following exposure to oxidative stress and DNA damages (stress‐induced senescence, SIS, via caveolin‐1). Our objective was to determine the main pathway in endothelial cells (EC) from coronary patients exposed to risk factors for cardiovascular diseases (CVD). EC were isolated from human internal mammary artery discarded during CABG (n = 56) and cultured in vitro until senescence. We quantified senescence by cytochemical detection of senescence‐associated b‐galactosidase, telomere length (RFL) by Southern blotting, gene expression of p53, p21, ATM and caveolin‐1 (Cav‐1) by qPCR and levels of lipid peroxidation (HNE) by immunofluorescence. Senescent EC displayed both telomeric instability markers (RFL shortening and increase in ATM, p<0.05) and oxidative stress markers (HNE and Cav‐1, p<0.05). mRNA levels of p53 were directly associated with the DNA damage response protein ATM and p21 (p<0.05) but not with Cav‐1 or HNE (p>0.05), suggesting that senescence is not exclusively directed by SIS. In conclusion, our data suggest that in human EC exposed to risk factors for CVD, there is a significant interplay between replicative senescence and SIS due to a state of cumulative cell damages. This study was supported by the Canadian Institutes of Health Research and the Fonds de la Recherche en Santé du Québec.