Inducible Transgene Expression After Intraocular Injection of an Inducible Expression Cassette Packaged in Adeno-Associated Viral (AAV) Vector

Abstract

Purpose: : To explore the feasibility of inducible expression of transgenes after AAV-mediated ocular gene transfer.

Methods: : An expression cassette containing a novel regulatory system based upon alternative splicing of a human mutant β-globin intron-2 with GFP as reporter was packaged in AAV2 vector and injected into the subretinal space of BALB/c mice or vitreous of C57BL/6 mice. After 6 weeks mice that had been given a subretinal injection of vector were given a subretinal injection of oligo or mismatched oligo and expression of GFP was assessed on choroidal flat mounts after 1, 7, or 14 days. Mice that had been given an intravitreous injection of vector were given multiple intravitreous injection of oligo or mismatched oligo and GFP expression was assessed on retinal flat mounts.

Results: : After subretinal injection of vector, subsequent subretinal injection of oligo resulted in prominent expression of GFP in RPE cells in 4 of 4 mice, while subretinal injection of mismatched oligo showed only faint background fluorescence. After intravitreous injection of vector, subsequent injections of oligo resulted in GFP expression in ganglion cells, greatest in the quadrant of the retina where the oligo injections were done, while mice injected with mismatched oligos showed only faint background fluorescence.

Keywords: gene transfer/gene therapy • retina