Carbamylated low-density lipoprotein induces oxidative stress and accelerated senescence in human endothelial progenitor cells

Carbamylated low-density lipoprotein (cLDL) plays a role in atherosclerosis. In this study we evaluate the effect of uremia on LDL carbamylation and the effect of cLDL and oxidized LDL (oxLDL; 200 mu g/ml) on number, function, and genomic stability of endothelial progenitor cells (EPCs) obtained from healthy volunteers. cLDL was generated after incubation of native LDL (nLDL) with uremic serum from patients with chronic kidney disease (CKD) stages 2-4. Oxidative stress was measured by flow cytometry and fluorescent microscopy, mitochondrial depolarization by flow cytometry, senescence by beta-galactosidase activity and telomere length, and DNA damage by phosphorylated histone H2AX (gamma H2AX). The percentage of cLDL by uremic serum was related to the severity of CKD. Compared with nLDL, cLDL induced an increase in oxidative stress (62 +/- 5 vs. 8 +/- 3%, P<0.001) and cells with mitochondrial depolarization (73 +/- 7 vs. 9 +/- 5%, P<0.001), and a decrease in EPC proliferation and angiogenesis. cLDL also induced accelerated senescence (73 +/- 16 vs. 12 +/- 9%, P<0.001), which was associated with a decrease in the expression of gamma H2AX (62 +/- 9 vs. 5 +/- 3%, P<0.001). The degree of injury induced by cLDL was comparable to that observed with oxLDL. This study supports the hypothesis that cLDL triggers genomic damage in EPCs, resulting in premature senescence. We can, therefore, hypothesize that EPCs injury by cLDL contributes to an increase in atherosclerotic disease in CKD.-Carracedo, J., Merino, A., Briceno, C., Soriano, S., Buendia, P., Calleros, L., Rodriguez, M., Martin-Malo, A., Aljama, P., Ramirez, R. Carbamylated low-density lipoprotein induces oxidative stress and accelerated senescence in human endothelial progenitor cells. FASEB J. 25, 1314-1322 (2011). www.fasebj.org