Mesenchymal Stem cell therapy with GHRH receptor analog resolves post-stroke vasogenic edema via modulating AQP4 and mitochondria-ER crosstalk

BACKGROUND: Post-stroke edema is one of the fatal consequences of ischemic stroke where increased intracranial pressure can exacerbate neurological dysfunction leading to mortality. To date, conventional post-stroke therapy has failed to manage cerebral edema and render neuroprotection. Earlier, our lab reported the benefits of intra-arterially administered mesenchymal stem cells (IA MSCs) in alleviating post-stroke vasogenic edema. Recently, post-stroke neuroendocrine regulation involving growth hormone releasing hormone receptor (GHRH-R) analog is gaining attention as one of the potential targets for stroke intervention, adjunctive to the existing conventional therapies. Therefore, the current study aims to explore the combined therapeutic potential of IA MSCs and GHRH-R analogs in resolution of cerebral vasogenic edema following ischemic stroke. METHODS: IA MSCs in combination with GHRH-R analogs at a dose of 10 µg/rat/day. In the short-term study, animals were subjected to neurobehavioral assessments following euthanasia at 24 h post-stroke. Next, infarct size, neuronal viability and extent of apoptosis were assessed by triphenyl-tetrazolium-chloride staining, Nissl staining and TUNEL assay. Protein expressions were evaluated by western blot and immunofluorescence assay, and finally morphological analysis of cellular organelles were performed by transmission electron microscopy. The study was extended for 3-days and 7-days with sustained release GHRH-R agonist (MR-409) using osmotic pump following IA MSCs administration post-stroke. Animals were subjected to different cognitive and behavioral tests. Further blood specimens and vital organs were subjected to toxicological analysis. Finally, expressions of different water channel genes and proteins were checked using transcriptomic analysis and immunofluorescence assay, respectively. RESULTS: Post-stroke administration of IA MSCs and MR-409 combination reduced mitochondria-endoplasmic reticulum (ER) distance, modulated AQP4 expression, leading to reduction in blood-brain-barrier (BBB) disruption in the short term along with resolving vasogenic edema in the long term. CONCLUSION: The study provides indirect preliminary evidence of combined administration of IA MSCs with sustained release GHRH-R agonist towards increasing the mitochondria-endoplasmic reticulum association, altering the expression of AQP4, maintaining BBB integrity and alleviating post-stroke vasogenic edema.