Gene Therapy in Ophthalmology: Validation on Cultured Retinal Cells and Explants from Postmortem Human Eyes

Abstract

Gene therapy studies in primates can provide important information regarding vector tropism, specific cellular expression, biodistribution, and safety prior to clinical trials. In this study, we report the assessment of transduction efficiency of recombinant adeno-associated virus (rAAV) vectors using human postmortem retina. Transductions were performed using two in vitro models prepared from human tissue: dissociated cell cultures and retinal explants. These models were used to assess cellular tropism and selectivity of rAAV vectors encoding for fluorescent proteins under the control of different promoters. These promoters were a ubiquitous cytomegalovirus promoter and a cell type–specific promoter targeting expression in ON bipolar cells. The results demonstrate that this in vitro approach can limit the use of living primates for the validation of gene therapy in vision and ophthalmology. Fradot and colleagues propose a new ex vivo approach for the preclinical assessment of gene transfer efficacy in the retina. The authors use human postmortem retinas to generate two in vitro models prepared from human tissue: dissociated cell cultures and retinal explants. These models were used to assess cellular tropism and selectivity of rAAV vectors encoding fluorescent proteins under the control of different promoters. The authors claim that this work paves the way for the wider use of postmortem human retina in other studies, even if these models cannot fully replace in vivo testing in primates.