Title : Developing iPSC-derived 3D Outer Blood-Retinal Barrier Disease Models of Choroideremia for Gene Therapy Evaluation
Abstract:
Inherited retinal dystrophies (IRD) impact millions of people and are leading causes of blindness globally. IRDs can be caused by over 300 different genetic mutations and many of the individual disorders are rare diseases with low prevalence and few treatment options. One treatment modality for IRDs is adenoassociated virus (AAV) based gene therapy and the success of FDA-approved Luxturna has been promising. However, gene therapy for other IRDs has not been so successful. Choroideremia (CHM) is one such rare inherited disease, primarily affecting the blood-retinal barrier. Many AAV gene therapies for choroideremia are being developed yet fail to meet primary endpoints. To explore why these therapies may be less efficacious in diseases such as choroideremia, we have engineered a 3D bioprinted multi-cellular outer blood retinal barrier model. We develop a vascularized choroid by bioprinting human iPSC derived fibroblasts and primary pericytes and endothelial progenitor cells on the basal side of a 96 well plate transwell membrane. Once this vascular structure has been established, we seed the apical side of the membrane with human iPSC derived immature retinal pigment epithelial cells (RPE). These RPE are matured for 7 weeks to form hexagonal cells and an RPE-choroid like barrier. With our optimized conditions, the vasculature remains healthy and stable for at least 7 weeks and is dependent on cellular interactions with the RPE. Thus, we have produced a more physiologically relevant model for studying diseases of the outer blood retinal barrier. The use of human iPSC-derived cell types allows for modular addition of patient derived iPSC cells and evaluating cell-cell interactions in healthy versus disease settings. Additionally, disease models developed in our 96 well format can be used for high-throughput screening of small molecules as well as gene therapy variants. This work provides a platform for studying many therapies across many diseases, accelerating drug discovery for rare inherited retinal dystrophies.
