Identification and characterization of microRNAs in vascular smooth muscle cells from patients with abdominal aortic aneurysms.

BACKGROUND:The role of microRNAs (miRs) in the development of various cardiovascular diseases was recently highlighted in several studies. However, the biological role of miRs in the pathogenesis of abdominal aortic aneurysms (AAAs) is still not well defined. The present study aims to identify and characterize miR expression in the aortic explant cultures of AAA patients. METHODS:A new microarray platform (miChip) using locked nucleic acid-modified capture probes with increased sensitivity and specificity was employed to detect the miR expression profile in human vascular smooth muscle cell cultures from AAA surgical samples. The array data were further validated by real-time quantitative reverse transcription polymerase chain reaction (qPCR) experiments with additional AAA and control aorta samples. Potential target genes of the differentially expressed miRs were predicted by bioinformatics analysis. Some of the results were confirmed by enzyme immunosorbent assay and Western blot analysis. RESULTS:Total RNA extracted from the explant of six AAAs and six normal aortas exhibited notably different miR profiles. A twofold difference of miR-516a-5p and miR-1260 was expressed in AAAs compared with normal aortic cultures (P < .05). The expression of miR-516a-5p was more than three times higher in AAAs, and miR-1260 expression was almost four times lower, as validated by qPCR. Additional qPCR performing on an extra 10 AAAs and 10 control aortas showed similar results. The expression of three predicted targets--secretory interleukin-3, vascular endothelial growth factor A, and collagen type 1, alpha 1 proteins--was significantly elevated in aneurysmal cultures compared with normal aortic cultures (P < .05). CONCLUSIONS:This miR microarray study displayed an altered expression of miR-516a-5p and miR-1260 in AAAs compared with control aortas. Functional annotations of the two miRs via bioinformatics approaches revealed that both are highly involved in some predefined mechanisms of AAA formation. Three of their target genes were also upregulated in AAAs. The results may be critical to elucidate the functional role of miRs in diseased aorta.

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