Ocular distribution of AAV variants after intravitreal and intracameral injections in mouse

Abstract

Purpose : Gene therapy is a possible therapeutic strategy for many eye diseases. Delivering the therapeutic transgene to the desired cell type remains a challenge. The present study examined different AAVs for transgene delivery location and effectiveness in mouse eye.

Methods : Ten weeks old male C57BL/6J mice were injected intravitreally (IVT) in OS and intracamerally (IC) in OD eyes with 1ul AAV virus at 2E10 vector genome (vg) per eye, n=5 for each virus. AAVs tested were AAV2 CAG eGFP, AAV2 Y3F CAG eGFP, AAV2 Y4F CAG eGFP, AAVrh10 scCBh eGFP. Optical coherence tomography (OCT) of anterior chamber and retina, fundus autofluorescence (FA) imaging of cornea and retina were performed at baseline, day 7, 21 and 42 using Spectralis (Heidelberg Engineering, Germany). At the end of study, 3 eyes were processed for histological sectioning, 2 eyes were flat mounted to evaluate GFP expression.

Results : Seven days after IC injection, FA signal was observed in all corneas (20/20). Cornea edema was found in 30% of eyes (6/20), mild subretinal lesions in 45% of eyes (9/20). Three weeks post injection, cornea edema resolved in 50% of eyes (3/6). All subretinal lesions were (9/9) reduced or recovered. At week six, 10% of eyes (2/20) had persistent vitreous cell clusters (indicating inflammation) and 10% of eyes (2/20) had persistent cornea abnormality. Interestingly, FA signal was observed in retina in 65% of eyes (13/20) at day 21. At six weeks the retina FA signal was reduced in 6 eyes, remained the same in 4 eyes and increased in 5 eyes.
For IVT injected eyes, FA signal was observed in all retinas (20/20) seven days post injection. 80% of eyes (16/20) had vitreous cell clusters and 35% of eyes (7/20) had subretinal lesions at one week. These changes were reduced in 81% of eyes (13/16) three weeks and six weeks post injection. Persistent retina abnormalities were observed in 3% of eyes (3/20) through entire duration of experiment. The FA signal in retina remained similar on day 42. Retinas in eyes injected with AAVrh10 scCBh eGFP remained at normal thickness through the entire experiment while other viruses significantly increased retina thickness at day 7.

Conclusions : Based on these results, there is a wide variety of tropisms and inflammatory potential among different vector designs. Choosing among the vectors will require further careful analysis considering the criteria utilized here and additional ones.

This is a 2020 ARVO Annual Meeting abstract.