Abstract 687: Paracrine Function of Extracellular microRNA-191 in Diabetes Associated Impaired Wound Healing

MicroRNAs (miRNAs/miRs) stably circulate in blood and show biomarker potential under various pathological conditions. Additionally, miRNAs may exert paracrine effect upon cellular uptake.This study profiles plasma miRNAs of diabetic patients and investigates the paracrine mechanism of miRNA mediated wound repair.Plasma miRNAs and pro-inflammatory cytokines were profiled in type-2 diabetic patients with or without chronic wounds. Selected miRNA candidates were further validated in plasma samples obtained from controls (n=23), patients with PAD and chronic wound (PAD+W, n=27) or PAD alone (n=11) vs. that of 20 healthy controls by qRT-PCR. Inflammation mediated miRNA secretion and paracrine effects of released miRNAs on cellular functions were investigated in human endothelial or dermal cells respectively.Differential levels of the circulating miRNAs in diabetic PAD+W patients were revealed in miRNA array profiling. Among 41 miRNA candidates, miR-191 levels significantly increased in PAD+W patients compared to diabetic controls, whereas lower levels were observed in diabetic vs. healthy controls. Circulating CRP and cytokine levels were also high in PAD+W patients compared to diabetic controls. miR-191 significantly correlated with CRP in diabetic patients.Cytokine stimulation enhanced miR-191 secretion into culture supernatant from vascular endothelial cells. Moreover, co-culture assays maintained under pro-inflammatory stress demonstrated increased miR-191 levels in recipient dermal fibroblast cells when indirectly cultured with miRNA releasing endothelial cells compared to fibroblasts cultured alone. Luciferase reporter confirmed miR-191 binding to the 3’UTR of the ZO-1 transcript. miR-191 modulation in dermal fibroblasts inversely regulated ZO-1 expression and influenced scratch wound closure whereas in diabetic dermal microvascular endothelial cells, miR-191 overexpression compromised both tube formation and wound closure.Circulating miRNA patterns are influenced by underlying inflammation associated with chronic wounds in type-2 diabetic patients and miR-191 modulates essential cellular functions in a paracrine manner by targeting ZO-1 during wound healing.