Abstract Body: (Background)
Stroke has become a leading cause of mortality and disability worldwide. However, except rehabilitation, there is no effective therapy during chronic phase after ischemic stroke.
Interestingly, it has been reported that young cerebrospinal fluid (CSF) restores oligodendrogenesis and memory in aged mice. However, if specific components in CSF could contribute to functional recovery during chronic phase of ischemic stroke remains unclear. We tried to distinguish a specific microRNA in CSF and identify its potential therapeutic functions.
(Method)
Rats were subjected to permanent left middle cerebral artery occlusion (pMCAO). Brains and CSF were collected at 3, 7, 14, 28 days after pMCAO. MicroRNA in CSF was evaluated by microRNA Array. A specific microRNA was selected based on heatmap and volcano plot. IPA analysis was used to distinguish possibly related signaling pathways.
Mimic/ inhibitor of this microRNA was applied respectively to primary cultured astrocytes and neurons soon after 3 hours’ oxygen glucose deprivation (OGD). Associated proteins were tested through western blot at 96 hours after OGD.
In vivo, time course of pStat3 was assessed in peri-infarct cortical area. At 7 days after pMCAO, mimic of this microRNA was applied to CSF through Cisterna Magna. behavioral tests were assessed at 7, 14, 21, 28 days after pMCAO. At 28 days after pMCAO, brains were harvested for ischemia volume calculation and immunofluorescence.
(Result)
miR-204-5p was significantly upregulated in CSF at 7 days after pMCAO and selected as target microRNA. According to IPA analysis, miR-204-5p might be associated with Stat3 signaling pathway.
Based on results of astrocyte culture, GFAP was significantly decreased by applying miR-204-5p mimic. Regarding neuron culture, pStat3, MAP2 showed a tendency to increase by applying miR-204-5p mimic.
In vivo, pStat3 significantly increased at 3 days and began to decrease from 7 days after pMCAO. miR-204-5p mimic group showed a tendency of ameliorated functional dysfunction, smaller ischemia volume at 28 days after pMCAO. In peri-infarct area, compared with non-treatment group, GFAP was significantly decreased, and pStat3 showed tendency to increase in miR-204-5p mimic group.
(Conclusion)
Applying miR-204-5p mimic into CSF contributed to functional recovery via activating Stat3 signalling pathway and reducing astrocytosis, which might be a candidate of exosome or liposome preparation for future clinical trials.