MicroRNA expression in the blood and brain of rats subjected to transient focal ischemia by middle cerebral artery occlusion

Background and Purpose - Several hundred small RNAs called microRNAs (miRNAs) have been identified and characterized from various organisms, including humans. In humans, some of these miRNAs have been found to regulate (patho) physiologic conditions such as tumor progression/regression, cholesterol and glucose homeostasis, etc. In this report, we present data on the miRNAs expressed under ischemic conditions in both the brain and blood of rats subjected to middle cerebral artery occlusion (MCAo). Methods - Sprague-Dawley rats subjected to MCAo were reperfused for either 24 or 48 hours, and both blood and brain samples were harvested. miRNA expression profiling and oligonucleotide microarray were carried out, and the data were validated by quantitative real-time polymerase chain reaction and correlated with published data on protein and gene expression in MCAo rats. Results - We report here for the first time the involvement of miRNA regulation in brain pathogenesis associated with MCAo. Comparison with the corresponding DNA microarray data revealed that the target mRNA expression is correlated with the regulation of miRNA. We have also provided evidence that some of the miRNAs that are highly expressed in the ischemic brain can be detected in blood samples. Conclusions - Further studies are needed to evaluate the possible use of miRNAs as biomarkers in stroke and related pathologies.