Abstract
Abstract: :
Purpose: To explore the feasibility of nonviral gene transfer to ocular tissues. Methods: Adult mice were given periocular (10 µl), intravitreous (1 µl), or subretinal (1 µl) injection of a plasmid containing a CMV/LacZ expression cassette (500 ng/µl) in PBS with or without electroporation, or the CMV/LacZ plasmid (200 ng/µl) in OMEM containing LipofectAMINE2000 (400 µg/ml). Electroporation was also done after subretinal injection of a plasmid (500 µg/ml PBS) containing LacZ driven by the vitelliform macular dystrophy 2 (VMD2) promoter (VMD2/LacZ). Staining for LacZ was done on whole eyes or ocular frozen sections 3 or 14 days after injections. Results: Three days after subretinal injection of CMV/LacZ plasmid in LipofectAMINE2000 or CMV/LacZ in PBS combined with electroporation, there was widespread, although not uniform, LacZ expression in RPE cells throughout the region where the retina was detached from the subretinal injection. Injection of VMD2/LacZ plasmid in PBS plus electroporation also resulted in LacZ staining of RPE cells, although less extensive than that seen with the CMV/LacZ plasmid. Ocular sections showed intense staining for LacZ in RPE cells. Three days after subretinal injection of CMV/LacZ plasmid in PBS without electroporation, there was no detectable LacZ staining of RPE cells. Fourteen days after subretinal injection of CMV/LacZ plasmid in LipofectAMINE2000 or CMV/LacZ in PBS combined with electroporation, there was much less, but still detectable, LacZ staining in RPE cells. For intravitreous and periocular routes, electroporation was needed to achieve LacZ staining in ganglion cells or periocular tissues, respectively. Conclusions:High levels of transgene expression can be achieved in RPE cells after subretinal injection of plasmids containing expression cassettes with lipid vehicle or with aqueous vehicle plus electroporation. Expression is transient, but lasts at least 2 weeks. Electroporation, but not lipid vehicle, results in transduction after intravitreous or periocular injections. These data suggest that nonviral ocular gene transfer may be feasible for some applications and should be investigated further.
Keywords: gene transfer/gene therapy • retinal pigment epithelium • retina