Transduction of axotomized retinal ganglion cells by adenoviral vector administration at the optic nerve stump: an in vivo model system for the inhibition of neuronal apoptotic cell death.

Axotomy of the rat optic nerve leads to apoptotic cell death of retinal ganglion cells (RGCs). We have used adenoviral vectors to transduce RGCs from the cut optic nerve stump, a paradigm in which only those neurons are transduced which are directly affected by the axonal lesion. Transgenes encoded by the vectors were p35 and CrmA, which are potent intracellular anti-apoptotic proteins. We found that p35, but not CrmA exerted significant rescue effects on RGCs 14 days after axotomy. Expression of the transgenes was driven by the murine CMV (MCMV) promoter. The respective mRNAs were detectable 7 days but not 14 days after transduction. Since surviving RGCs were present beyond the time-point of detectable transcription of the p35 transgene, we conclude that apoptosis has been efficiently inhibited. In addition, we observed that transduction with two control vectors without a transgene in E1 also resulted in a minor but significant RGC rescue, implicating neuroprotective effects due to adenoviral transduction itself. This system will be useful in dissecting the pathways leading to neuronal cell death after axonal lesions and in the evaluation of the important question whether the cellular suicide program can be reverted to survival by therapeutic gene delivery.