Abstract TP95: Novel Biomarkers of Acute Ischemic Stroke Using MicroRNA Analysis

Background: Despite recent advances in treatment, early diagnosis and prognosis of acute ischemic stroke (AIS) suffers from significant limitations. Growing number of mostly case-control studies have determined that noncoding, micro-ribonucleic acid (miRNAs) play a role in the pathophysiologic processes related to cerebral ischemia and post-stroke recovery. This pilot project is a longitudinal study, which investigates difference in miRNA regulation in acute vs. chronic stage of ischemic stroke. Hypothesis: Expression of some miRNAs is significantly altered in acute stage of ischemic stroke. Methods: Blood and urine specimens collected during the acute phase (<72 hours) of ischemic stroke and at follow-up phases (within 3 months) were used to quantify the expression of five selected miRNAs (miRNA 21-5p; miRNA 124-5p, miRNA 126, miRNA 223, and miRNA 298) using 20 sample pairs (N=40) available with urine and blood specimens. Total RNA from frozen blood samples were isolated using the mir VANA RNA isolation kit (Ambion, USA). We extracted exosomal RNA from urine samples using exosome kit (Qiagen, USA). We ran miRNA expression assays using TaqMan probes (Applied Biosciences, USA) on 384-well microplates using QuantStudio 6 available in our lab. Each assay was run in duplicates using endogenous (U6) and blank controls. Results: The miRNA21-5p was significantly down-regulated (p<0.0001) at the acute phase in both blood and urine; inversely, miRNA124 was significantly upregulated (p<0.0001) at the acute phase vs. the chronic phase. The increased expression of miRNA 124-5p in both urine and serum strongly correlated with a lower stroke scale (NIHSS score (<8)), and its expression was significantly diminished with the increase in stroke severity (NIHSS >10). Expression of exosomal miRNA126 extracted from urine, was significantly upregulated (p<0.0001) during the acute phase, but remained unchanged at the acute and chronic phase (p=0.857) in serum. Conclusion: Our study showed the dysregulation of important miRNAs in acute stage of stroke. The upregulation of miRNA 124-5p in strokes with lower NIHSS may serve as early prognostic biomarker. Once replicated in larger scale studies, it will provide novel insights on understanding stroke pathophysiology.