Local endothelial dna repair defect causes aging-resembling endothelial-specific dysfunction.

We previously identified genomic instability as a causative factor for vascular aging. In the present study determined which vascular aging outcomes are due to local endothelial DNA damage, which was accomplished by genetic removal of ERCC1 DNA repair in mice (EC-KO mice). EC-KO showed a progressive decrease in microvascular dilation of the skin, increased microvascular leakage in the kidney, decreased lung perfusion, and increased aortic stiffness compared to WT. EC-KO showed expression of DNA damage and potential senescence marker p21 exclusively in the endothelium, as demonstrated in aorta. Also the kidney showed p21-positive cells. Vasodilator responses measured in organ baths were decreased in aorta, iliac and coronary artery EC-KO compared to WT, of which coronary artery was the earliest to be affected. Nitric oxide-mediated endothelium-dependent vasodilation was abolished in aorta and coronary artery, whereas endothelium-derived hyperpolarization and responses to exogenous nitric oxide were intact. EC-KO showed increased superoxide production compared to WT, as measured in lung tissue, rich in endothelial cells. Arterial systolic blood pressure was increased at 3 months, but normal at 5 months, at which age cardiac output was decreased. Since no further signs of cardiac dysfunction were detected this decrease might be an adaptation to prevent an increase of blood pressure. In summary, a selective DNA repair defect in the endothelium produces features of age-related endothelial dysfunction, largely attributed to loss of endothelium-derived nitric oxide. Increased superoxide generation might contribute to the observed changes affecting end organ perfusion, as demonstrated in kidney and lung.