Abstract
Circulating microRNAs (miRNAs) have been used effectively as peripheral biomarkers and mechanistic targets for human diseases such as stroke, Alzheimer's, and cancer. The purpose of our study is to determine noninvasive, blood-based early detectable biomarkers for ischemic stroke (IS). Based on our previous global miRNA sequencing study, four miRNAs were previously unreported (novel) in IS condition. Among these, miRNA PC-5P-12969 was exclusively expressed in the IS condition; otherwise, it was not expressed in normal condition, and therefore, we focused on miRNA PC-5P-12969 for further studies. In the present study, we investigated novel miRNA PC-5P-12969 for its expression levels using quantitative real-time PCR assay (qRT-PCR) in an in vitro, oxygen, and glucose deprivation/reoxygenation (OGD/R)-treated mouse primary hippocampal neuronal cells (HT22) and in an in vivo using a photothrombotic stroke model. In an in vitro study of stroke-induced HT22 cells, we found a two fold increase of PC-5P-12969 expression levels, in agreement with our original global miRNA study. In the cerebral cortex of photothrombotic stroke mice, we found significantly upregulated levels of PC-5P-12969 in 4 hours and 1 day post-stroke relative to the control mice. However, we did not find any change in the expression of PC-5P-12969 in the cerebellum (unaffected in IS) of both stroke and control mice. Based on findings from this study, together with our earlier original global microRNA study results, we conclude that PC-5P-12969 is a potential candidate of the peripheral marker and also a drug target for IS. This is the first study validating that the miRNA PC-5P-12969, might be a potential biomarker for IS.