The role and mechanism of neurogenesis in neural stem/progenitor cells overexpressing arginine decarboxylase gene following ischemic injury

Abstract

Neural stem/progenitor cell (NSPCs) therapy is a promising therapeutic strategy for various central nervous system (CNS) diseases. However, transplanted NSPCs have not been sufficiently overcome the non-rich environment after ischemic injury. Arginine decarboxylase (ADC) is highly conserved gene act as acidic stress resistance systems in various organisms including Escherichia coli, plants and mammalians. However, it was poorly understood after mammalian CNS diseases. Therefore, the purpose of this study was to investigate the role of ADC-mNSPCs following ischemic injury.First, E14.5 fetal mice striatum derived NSPCs were cultured and transfected vhADC at DIV7. Highly expressed vhADC protein promoted agmatine synthesis under pathological conditions. Moreover, vhADC-mNSPCs promoted cell cycle arrest by intracellular Ca2+-induced CDK4 activation and the nucleocytoplasmic shuttling of phosphorylated pRB and E2F1 under pathological condition. Importantly, vhADC-mNSPCs were prevented mitochondrial membrane potential (ΔΨm) collapse although increased intracellular calcium levels. Moreover, siADC treated vhADC-mNSPCs were suppressed intracellular calcium levels under pathological condition. In addition, vhADC stimulated enhanced neuronal differentiation by increasing pSTAT1 expression via pP38 MAPK and pCREB signaling in mNSPCs. Therefore, vhADC stimulates cell cycle exit and neural differentiation in mNSPCs following oxygen-glucose depravation.Second, male Sprague-Dawley rats were subjected to 60 min middle cerebral artery occlusion (MCAO), which is well established model of focal cerebral ischemia. Experimental stroke damaged animal models were transplanted with over expressed vhADC contained striatum-derived neural stem/progenitor cells 7 days after ischemic injury. Behavior tests supported that vhADC-mNPCs promotes neurological functional repair compared with normal

mNPCs transplantation and vLXSN-mNPCs transplantation. Reflex response significantly regained to 80% in vhADC-mNPCs transplantation group, but experimental control group recorded 50% reflex response for 28 days after MCAO. Immunobloting and immunohistochemistry results suggested that vhADC-mNPCs promotes neural differentiation and synapse formation via higher density of MAP2/Synaptophysin/PSD95 positive expression in ipsilateral striatum, which could lead to functional recovery after certain CNS diseases. These results suggest that vhADC-mNSPCs may serve as a relevant cell therapy for various CNS diseases.