Verification of the protective effect of transfecting brain-derived neurotrophic factor and B-cell lymphoma 2 genes on retina ganglion cells in a rat model of optic nerve injury

This pilot study investigated the protective effect of transfecting brain-derived neurotrophic factor (BDNF) and B-cell lymphoma 2 (bcl-2) genes in retinal ganglion cells (RGCs) using in vivo electroporation in an adult rat optic nerve transection model. Sprague-Dawley rats were randomly divided into five groups: BDNF(+)/bcl-2(+), BDNF(+), bcl-2(+), empty plasmid (EP), and no surgery (NS). The plasmids were intravitreally injected and electroporated into the left eye. Seven days later, optic nerve transection was performed in all groups except the NS group. Protein expression was examined using Western blotting, RGC survival was quantified using 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanine perchlorate (DiI) retrograde labeling, and apoptosis was assessed using terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) at multiple time points (7, 14, and 28 d after transfection). A significantly higher number of DiI (+) RGCs and lower number of apoptotic cells were observed in the BDNF(+)/bcl-2(+), BDNF(+), and bcl-2(+) groups compared to those in the EP group at all time points. The number of DiI (+) RGCs in the three treatment groups was significantly lower than that in the NS group. However, there were no significant differences among the three treatment groups. The protective effects of gene transfection tended to be strongest in the BDNF(+)/bcl-2(+) group, followed by the BDNF(+) group and then the bcl-2(+) group. Thus, all gene transfection treatments had a protective effect against the loss of DiI(+) RGCs induced by optic nerve transection but did not result in full recovery. This study also confirmed the value of in vivo electroporation. The findings of this pilot study provide a working base for the development of gene therapy for blinding optic nerve disorders.