A systematic review investigating the association of microRNAs with human abdominal aortic aneurysms

Background and aims: There is increasing interest in identifying novel methods for abdominal aortic aneurysm (AAA) diagnosis. Non-coding RNA molecules such as microRNAs (miRNAs) are stable within the circulation and may serve as biomarkers for AAA. This systematic review aimed to identify miRNAs associated with a diagnosis of human AAA based on currently published original research. Methods: A systematic search of the MEDLINE and EMBASE databases identified studies assessing miRNA expression in abdominal aortic tissue or circulating blood from human AAA cases compared to non-aneurysmal controls. Data from included studies were extracted to assess methods and results after independent quality assessment by two reviewers. Results: 15 studies were included in this review. 11 studies obtained aortic tissue samples from 195 AAA cases and 104 controls with normal aortas. Nine studies obtained circulating blood samples from 526 AAA cases and 441 controls. miR-21 was differentially expressed in AAA tissue in five separate studies, with four studies reporting upregulation and one reporting downregulation. Seven other miRNAs were differentially expressed in AAA tissue in two separate studies. 15 circulating miRNAs were differentially expressed in two or more separate studies. miR-155 and miR-29b were the only miRNAs differentially expressed in two separate tissue-and blood-based studies. 11 studies offered mechanistic explanations of the role of miRNAs in AAA pathology through exploration of gene targets. Three studies assessed the diagnostic potential of circulating miRNAs with receiver operating characteristic curves. Only one study assessed the prognostic potential of circulating miRNAs in predicting AAA growth. Conclusions: Several miRNAs have been found to be associated with human AAA. Their utility as AAA biomarkers requires further investigation. (C) 2017 Published by Elsevier Ireland Ltd.