Abstract TP137: Suppression of Microrna Let-7a Expression Promotes Neurogenesis in Arginine Decarboxylase-neural Stem Cells After Ischemia

Abstract

Introduction: Neural stem cells (NSCs) have been studied as promising novel treatments for central nervous system (CNS) disorders due to the potential of differentiation into neuron. To increase the therapeutic efficiency of NSCs, we have focused on microRNA let-7a ( let-7a ), known as the regulator of diverse cellular mechanisms and agmatine, an endogenous primary amine synthesized from decarboxylation of L-arginine catalyzed by arginine decarboxylase (ADC) and a neurotransmitter reported to affect neuroprotection in CNS. The purpose of this study is to investigate the role of arginine metabolic enzyme which regulated let-7a in neural stem cell differentiation. Methods: Cortical NSCs were isolated from pregnant imprinting control region mice and used for experiments after 2-3 passages. After let-7a mimic and agmatine treatment, we performed by RT-PCR, western blot and immunocytochemistry. To confirm the effects of arginine metabolic enzyme and let-7a in vivo , mice were subjected to distal middle cerebral artery occlusion (dMCAO). Following dMCAO, mice were treated agmatine by intraperitoneal injection, let-7a mimic by osmotic pump and human ADC gene delivery into the NSCs using retroviral vector ( vh ADC)-NSCs via intracranial injection at the corpus callosum. Results: In vitro study suggested that high levels of let-7a promoted the expression of TLX and c-Myc, as well as repressed DCX and ERK expression. In addition, agmatine attenuated the expression of TLX and increased the expression of ERK by negatively regulating let-7a . Also, after dMCAO, we found that vh ADC-NSC and let-7a co-treatment group reduced the infarct volume, increased the expression of DCX, Neurogenin2, Olig2, and attenuated the expression of GFAP. Conclusion: In the present study, we found that agmatine can enhance NSC differentiation into neurons by modulating expression of let-7a . In vivo study showed that vh ADC-NSC and let-7a co-treatment promoted neurogenesis and inhibited glial differentiation in the treatment of neural stem cell transplantation in ischemic condition. Therefore, our study suggests that the therapeutic efficiency of the vh ADC-NSC on neural stem cell differentiation through suppression of let-7a of the CNS diseases.