Efficient VEGF gene expression using hypoxia-inducible neuron-specific vector system

Abstract

Since neurons play a critical role in the central nervous system, neuron-target gene expression system is important for gene therapy. Ischemic neurons following injury affect disruption of neurovascular unit which is mediated by astrocyte. Also reactive astrocyte contributes to astrogliosis that aggravate traumatic environment. Therefore, controllable gene expression system that expressed in neurons selectively more than glial cells and other cell types is necessary. We used neuron-specific enloase (NSE) promoter to target neurons. NSE is one of glycolytic isoenzymes and abundant in adult brain neurons due to their characteristics of expression in matured neurons. Because NSE is expressed high in various neuronal cell types, we can design neuron-target gene expression system using NSE promoter. Also, to improve gene expression under hypoxic ischemic environment like spinal cord injury (SCI), the combination of erythropoietin (Epo) enhancer and NSE promoter was used. Vascular endothelial growth factor (VEGF) is an angiogenic peptide and has neuroprotective effects as well as angiogenesis. VEGF is considered good therapeutic gene because it protects injured neurons and promotes sprouting of blood vessels to support cell survival. In this study, the use of NSE promoter increases the expression of luciferase reporter gene and VEGF gene. The luciferase and VEGF gene expression is the highest with the plasmid vector including Epo enhancer under hypoxic conditions and also showed proliferation effect. With this hypoxia-inducible neuron-specific gene expression system, applied gene or cell therapy is promising to regenerate SCI.