Adenovirus vector-mediated in vivo gene transfer of nuclear factor erythroid-2p45-related factor 2 promotes functional recovery following spinal cord contusion

The aim of the present study was to investigate whether nuclear factor erythroid 2p45-related factor 2 (Nrf2) overexpression by gene transfer may protect neurons/glial cells and the association between neurons/glial cells and axons in spinal cord injury (SCI). In the present study, Nrf2 recombinant adenovirus (Ad) vectors were constructed. The protein levels of Nrf2 in the nucleus and of the Nrf2-regulated gene products heme oxygenase-1 (HO-1) and NAD (P)H-quinone oxidoreductase-1 (NQO1), were detected using western blot analysis in PC12 cells following 48 h of transfection. Furthermore, the expression of Nrf2 was localized using an immunofluorescence experiment, and the expression of Nrf2, HO-1 and NQO1 were detected using an immunohistochemical experiment in the grey matter of spinal cord in rats. Post-injury motor behavior was assessed via the Basso, Beattie and Bresnahan (BBB) locomotor scale method. In PC12 cells, subsequent to Ad-Nrf2 transfection, nuclear Nrf2, HO-1 and NQO1 levels were significantly increased compared with the control (P<0.01). There was statistically significant changes in the PC12-Ad-Nrf2 group [Nrf2 (1.146 +/- 0.095), HO-1 (1.816 +/- 0.095) and NQO1 (1.421 +/- 0.138)] compared with the PC12-control group [Nrf2 (0.717 +/- 0.055), HO-1 (1.264 +/- 0.081) and NQO1 (0.921 +/- 0.088)] and PC12-Ad-green fluorescent protein group [Nrf2 (0.714 +/- 0.111), HO-1 (1.238 +/- 0.053) and NQO1 (0.987 +/- 0.045); P<0.01]. The BBB scores of the rats indicated that they had improved functional recovery following the local injection of Ad-Nrf2. On the third day following the operation, BBB scores in the adenovirus groups (0.167 +/- 0.408) were significantly decreased compared with the SCI group (1 +/- 0.894; P<0.05). In the injured section of the spinal cord in the rats, the number of positive cells expressing Nrf2, HO-1 and NQO1 were raised compared with the control and SCI groups, indicating that the adenovirus vector-mediated gene transfer of Nrf2 promotes functional recovery following spinal cord contusion in rats.