Novel Targets and Therapeutic Interventions against Cerebral Ischemia-Reperfusion Injury

The cerebral ischemia/reperfusion (I/R) injury is a major challenge for the treatment of patients with acuteischemic stroke by intravenous (IV) thrombolysis and endovascular therapy. Currently, there is no effectiveintervention available to treat/prevent cerebral I/R injury. Emerging evidence suggests that thrombotic andinflammatory responses (thrombo-inflammation) and aberrant endoplasmic reticulum (ER) stress in the brainelicited by cerebral I/R contributes importantly to secondary brain injury and neurologic deterioration. In thisproposal we wish to develop a novel miRNA-based therapeutic strategy to simultaneously target thesepathological processes of cerebral I/R injury through distinct molecular mechanisms. Recently, decreasedexpression of miR-30c has been implicated in many pathological conditions in both patients and animal models.In preliminary studies, we show that miR-30c is highly expressed in blood platelets, cerebral microvessels, andcortical/hippocampal neurons in normal mice but its levels decline with age. miR-30c levels in both blood andbrain are markedly decreased after ischemic stroke and elevating miR-30c by single IV injection of syntheticmiR-30c mimic significantly protects against cerebral I/R injury. We further show that the increased expressionsof the direct target genes of miR-30c (including PAI-1 in both blood and brain, elF2α and caspase-3 in the brain)induced by cerebral I/R injury were significantly decreased by IV miR-30c mimic treatment. Based on theseexciting new findings from young adult mice, we propose the innovative hypothesis that miR-30c functions as acritical regulator of thrombo-inflammation and ER stress in the ischemic brain elicited by cerebral I/R injury, andthus targeting miR-30c represents a novel therapeutic approach for combating cerebral I/R injury. Followingupdated stroke Therapy Academic Industry Roundtable (STAIR) pre-clinical guidelines, we will test thishypothesis in aged male and female mice. Specifically, we will determine the efficacy and safety of IV miR-30cmimic as novel stroke therapeutics (Aim1). Using complementary approaches, i.e. the “gain-of-function” (miR-30c mimic) and “loss-of-function” (anti-sense Morpholino oligos that are designed to specifically compete withmiR-30c for binding sites of 3’UTR of each individual target gene and thus acts as a “target protector”), we willidentify PAI-1 as a key molecular target of miR-30c in regulation of post-stroke thrombo-inflammation (Aim 2),and identify elF2α and caspase 3 as key molecular targets of miR-30c in regulation of post-stroke neuronal ERstress and neuronal cell death (Aim 3). The long-term goal of these studies is to evaluate if targeting miR-30c isa viable option for stroke therapy in both male and female older populations at high risk for stroke.