Retinal pigment epithelium exhibits cell size, gene expression, and phagocytic activity alterations when exposed to retinoblastoma chemotherapeutics

Abstract Retinoblastoma (Rb) is a rare malignant disorder affecting the developing retina of children under the age of five. Chemotherapeutic agents used for treating Rb have been associated with defects of the retinal pigment epithelium (RPE), such as hyperplasia, gliosis, mottling, and visual acuity. Herein, we have developed two pluripotent stem cell (PSC)-RPE models to assess the cytotoxicity of known Rb chemotherapeutics such as Melphalan, Topotecan, and TW-37. Our findings demonstrate that these drugs alter the RPE cell size, decrease the monolayer barrier's trans-epithelial resistance and affect the cells' phagocytic activity. Our transcriptional analyses demonstrate an altered expression of genes involved in melanin and retinol processing, tight junction and apical-basal polarity pathways in both models. None of the drug treatments applied within the clinical range caused significant cytotoxic effects, changes to the apical-basal polarity, tight junction network or cell cycle. Together, our results demonstrate that although the most commonly used Rb chemotherapeutic drugs do not cause cytotoxicity in RPE, their application in vitro leads to compromised phagocytosis and strength of the barrier function, in addition to changes in gene expression that could alter the visual cycle.