NOS3 and endothelial dysfunction: In this review, we summarize recent findings on endothelial dysfunction in AAA pathogenesis including clinical evidence of a dysfunctional endothelium in AAA patients, the relationship between biomechanical stress and ECs in AAA, endothelial nitric oxide synthase (eNOS) uncoupling in AAA, and a transcriptional profile of EC dysfunction in AAA revealed by single-cell RNA sequencing (scRNA-seq).