Gene therapy shows the ability to restore neuronal dysfunction via therapeutic gene expression. The efficiency of gene expression and delivery to hypoxic injury sites is important for successful gene therapy. Therefore, we established a gene/stem cell therapy system using neuron-specific enolase promoter and induced neural stem cells in combination with valproic acid to increase therapeutic gene expression in hypoxic spinal cord injury.
To examine the effect of combined method on enhancing gene expression, we compared neuronal cell-inducible luciferase levels under normoxia or hypoxia conditions in induced neural stem cells with valproic acid. Therapeutic gene, vascular endothelial growth factor, expression with combined method was investigated in hypoxic spinal cord injury model. We verified gene expression levels and the effect of different methods of valproic acid administration in vivo.
The results showed that neuron-specific enolase promoter enhanced gene expression levels in induced neural stem cells compared to Simian Virus 40 promoter under hypoxic conditions. Valproic acid treatment showed higher gene expression of neuron-specific enolase promoter than without treatment. In addition, gene expression levels and cell viability were different depending on the various concentration of valproic acid. The gene expression levels were increased significantly when valproic acid was directly injected with induced neural stem cells in vivo.
In this study, we demonstrated that the combination of neuron-specific enolase promoter and valproic acid induced gene overexpression in induced neural stem cells under hypoxic conditions and also in spinal cord injury depending on valproic acid administration in vivo. Combination of valproic acid and neuron-specific enolase promoter in induced neural stem cells could be an effective gene therapy system for hypoxic spinal cord injury.
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This work was partly supported by the Brain Korea 21 PLUS Project for Medical Science, Yonsei University; Basic Science Research Program through the National Research Foundation of Korea (NRF) (No. 2015R1D1A1A02059821); and a National Research Foundation of Korea Grant, funded by the Korean Government (NRF-2015R1A6A3A01018883). This research was also supported by grants from the National Research Foundation of Korea (2013M3A9B4076483 and 2016K1A3A1A61006001) and KRIBB research initiative program funded by the Ministry of Science and ICT.
Conflict of interest
The authors declare no financial conflicts of interest.
The Animal Care and Use Committee of the Medical Research Institute of Yonsei University College of Medicine approved all protocols (IACUC approval 291 No. 2017-0114) in the current study.
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Yun, Y., Baek, D., Lee, D. et al. Combined Method of Neuronal Cell-Inducible Vector and Valproic Acid for Enhanced Gene Expression under Hypoxic Conditions. Tissue Eng Regen Med (2019). https://doi.org/10.1007/s13770-019-00223-w
- Induced neural stem cells (iNSCs)
- Neuron-specific enolase promoter (pNSE)
- Valproic acid (VPA)
- Spinal cord injury (SCI)