Objective

There is an urgent and unmet need in the availability of in vitro models of human retina for pharmacological and toxicological studies. Application of animal models is limited by the fundamental, structural and functional differences between human and rodent retina. We used statistical modelling to evaluate the effects of key culture medium components on generation of retinal organoids from induced pluripotent stem cells (iPSCs) and used a known retinotoxin to demonstrate the applicability of our model for compounds screening. IPSCs from an unaffected subject were differentiated into retinal organoids with a modified 96 well plate format. In order to evaluate the effects of key variables on the expression of genes associated with the emergence of retinal cell phenotypes, we applied Design of Experiment methodology. At day 150 of differentiation, we found that retinoic acid, FBS and taurine were the most important single effectors. Retinoic acid at higher concentration gave rise to more cone photoreceptors (OPN1LW, OPN1SW, OPN1MW), whilst higher taurine had a positive effect for gene expression associated with appearance of horizontal, amacrine and bipolar cells (PROX1). Incubation of retinal organoids with moxifloxacin revealed dose-dependent toxicity and increased levels of apoptosis. Our system has an advantage of assessing compounding effects of various factors highlighting that optimal growth conditions will be a compromise between the requirements of the many cell types present in the retinal organoids. Variability between iPSC lines and clones to respond to differentiation protocols is widely reported and our approach provides a platform for scalable adaptation of culture conditions to multiple iPSC lines.