Efficacy of post‐injury anti‐miR‐181a and anti‐miR‐200c intravenous treatment in protection against experimental stroke in aged mice

Abstract

IntroductionStroke remains the second leading cause of death worldwide and the primary cause of long‐term disability in the US. To date, the only pharmacological treatment for stroke remains tissue plasminogen activator. A major factor for translational failure is likely overwhelming use of young adult rodent models despite the fact that stroke occurs predominantly in aged populations. MicroRNAs (miRs) are non‐coding RNAs that regulate protein translation, and we have previously demonstrated in young adult mice neuroprotection against experimental stroke with anti‐miR‐181a and anti‐miR‐200c. In the present study, to extend translational impact, we tested efficacy of post‐injury intravenous anti‐miR‐181a and anti‐miR‐200c in clinically relevant aged mice.MethodsAll studies were conducted in accordance with National Institutes of Health guidelines for the use of experimental animals, with protocols approved by the Stanford Animal Care and Use Committee. Animal treatment groups were randomized by coin flip, and all analyses were performed by an observer blinded to conditions. Transient focal cerebral ischemia was induced by suture occlusion of the middle cerebral artery (MCAO) for 1h in 20 month‐old male C57BL/6 mice (n=8 per cohort and treatment group). Sham surgery consisted of anesthesia and internal carotid exposure without suture occlusion (n=4 per group). Intravenous infusion: animals were re‐anesthetized and 30 pmol/g anti‐miR‐181a, anti‐miR‐200c or control (MM) in sterile saline (100 μl) was infused over 1 minute into the internal jugular vein at 2h reperfusion. Neurological status was assessed by 4‐point neurologic deficit score at 48h after MCAO. Infarct volume was assessed after sacrifice by anesthesia overdose at 48h after MCAO with triphenyl tetrazolium chloride staining. Infarct volume was calculated as percentage of hemisphere corrected for edema.ResultsMCAO in all groups resulted in significant decreases in neurological score and increased infarct volume relative to sham treated animals. Both anti‐miR‐181a and anti‐miR‐200c treatment resulted in significantly (p<0.05) higher neurological scores and significantly lower infarct volumes relative to MM‐control treated animals. No differences in neurological score or in infarct volume were observed between anti‐miR‐181a and anti‐miR‐200c treatments.ConclusionsBoth anti‐miR‐181a and anti‐miR‐200c are effective non‐invasive post‐stroke interventions to reduce injury in clinically‐relevant aged mice. Future investigations should be extended to testing in aged female cohorts and identifying relevant downstream targets of miR‐181a and miR‐200c.