miRNA-223-3p and let-7b-3p as potential blood biomarkers associated with the ischemic penumbra in rats

The present study aimed to identify commonalities in the microRNA (miRNA) expression profiles of the brain ischemic penumbra and the blood after hyperacute ischemic stroke and then to address whether the miRNA profile of blood has potential usefulness as a diagnostic biomarker of hyperacute ischemic stroke. Blood was collected from the jugular vein 4 h after permanent middle cerebral artery occlusion (pMCAO). After venous blood was collected, the rats were decapitated immediately, and brain ischemic penumbra samples were collected. Hematoxylin and eosin staining was used to observe the histopathological changes. Penumbra and blood miRNAs were measured by miRNA microarray and real-time polymerase chain reaction (PCR) analysis. MicroRNA profiles differed between hyperacute ischemic stroke and sham-operated rats. The expression of some miRNAs changed by more than 1.5-fold in the penumbra and blood 4 h after pMCAO; among those miRNAs, several were upregulated and several were downregulated. MiR-223-3p was found to be highly expressed in both the penumbra and the blood 4 h after pMCAO, and let-7b-3p was found to have low expression in both the penumbra and the blood 4 h after pMCAO. Moreover, miR-223-3p and let-7b-3p expression in blood and brain ischemic penumbra were positively correlated. The results show that select blood miRNAs may correlate with miRNA changes in the penumbra in a rat model of hyperacute ischemic stroke. Our findings suggest the potential usefulness of blood miR-223-3p and let-7b-3p as noninvasive biomarkers for the diagnosis of hyperacute ischemic stroke.