ESTABLISHMENT OF A 3D IN VITRO MODEL OF RETINITIS PIGMENTOSA
The retina can be affected by different types of diseases, with or without origin in genetic changes, which can compromise its morphological structure and the survival of specific cells. Among these diseases, retinitis pigmentosa (RP) is a hereditary disease related to around 100 mutations, especially in genes that encode proteins necessary for phototransduction in rod photoreceptors. Mutation in phosphodiesterase 6 β (PDE6β) alters cellular activity that results in apoptosis, but a new cell death pathway has recently been related to RP, necroptosis. Necroptosis can be considered as a 'programmed necrosis', can influence the transcription of inflammatory genes, with literature on necroptosis in RP being scarce. This work aims to establish a 2D and 3D model of RP in vitro, which can recapitulate the loss of photoreceptors that occurs during the progression of RP. Obtaining this model will help test new molecules and gene manipulations to establish therapeutic strategies for treating RP. As a starting point, we standardized the formation of neurospheres, composed of retinal progenitor cells. In a second step, we tested protocols for differentiation into rods, an arrangement called photosphere. In parallel, we performed 2D mixed retinal cultures of WT (C57BL/6J) and PDE6β knockout (RD1) to standardize experiments with light stimulation. We used LEDs in the cell incubator to stimulate mixed retinal cultures exposed to 200 lux and 12,000 lux for 2 and 5 hours. Cell cultures performed from WT and RD1 animals had no change in cell viability by MTT and PrestoBlue at 200 lux. In cell cultures stimulated with 12,000 lux, we observed a significant decrease in cell viability with PrestoBlue and increased TUNEL labeling. Double-labeling experiments showed that the TUNEL-positive cells were predominantly rods. LDH, RIPK3 markers and activated capase-3 were increased. In conclusion, to accelerate the induction of cell death in the photoreceptors of the RD1 model in vitro, a 2D light assay was standardized in addition to the 3D cell culture with differentiation of retinal precursors into a predominantly photoreceptor sphere, which we call the photosphere.