A Distinct miRNA Profile in Intimal Hyperplasia of Failed Arteriovenous Fistulas Reveals Key Pathogenic Pathways.

Intimal hyperplasia (IH) compromises the patency of arteriovenous fistula (AVF) vascular access in patients with end-stage kidney disease. Uncontrolled cell proliferation and migration, driven by inflammation, shear stress and surgery, are well-known triggers in IH. Recently, microRNAs (miRNAs) have emerged as regulators of core mechanisms in cardiovascular diseases and as potential markers of IH. This study was aimed at identifying a specific miRNA panel in failed AVFs and clarifying the miRNA involvement in IH. miRNA profiling performed in tissues from patients with IH (AVFs) and normal veins (NVs) highlighted a subset of four miRNAs significantly deregulated (hsa-miR-155-5p, hsa-miR-449a-5p, hsa-miR-29c-3p, hsa-miR-194-5p) between the two groups. These miRNAs were analyzed in tissue-derived cells (NVCs and AVFCs), human aortic smooth muscle cells (HAOSMCs) and human umbilical vein endothelial cells (HUVECs). The panel of hsa-miR-449a-5p, hsa-miR-155-5p, hsa-miR-29c-3p and hsa-miR-194-5p was up-regulated in AVFCs, HAOSMCs and HUVEC under inflammatory stimuli. Notably, overexpression of hsa-miR-449a-5p exacerbated the proliferative, migratory and inflammatory features of AVFCs. In vitro pharmacological modulation of these miRNAs with pioglitazone, particularly the down-regulation of hsa-miR-155-5p and hsa-miR-29c-3p, suggested their involvement in IH pathogenesis and a potential translational application. Overall, these findings provide new insights into the pathogenesis of AVF failure, reinforcing the miRNA contribution to IH detection and prevention.