Ex vivo model of spontaneous neuroretinal degeneration for evaluating neuroprotection

Abstract

AbstractEx vivo neuroretina models are considered adequate tools for improving the knowledge of retinal physiology and pathobiology. Neuroretina explant cultures closely resemble in vivo conditions, thus, preserving complex in vivo neuronal connections and retaining the functionality of non‐neuronal cells of the retina. Furthermore, immunohistochemistry, electrophysiology and molecular biology techniques can be applied over retinal explant cultures.Although several cell culture‐based techniques have been developed to investigate retinal function, such as retinal cells primary cultures, co‐cultures with retinal pigment epithelium (RPE) cells, or 3D aggregates cultures, ex vivo models provide a better alternative to animal experimentation and are inexpensive and easy to develop. Limitations of these ex vivo systems include the absence of choroidal and retinal blood flow, the lack of vitreous and RPE, and the axotomy of the ganglion cells, which considerably limit the evaluation of the inner retina modifications. However, these limitations are also critical for the retina to degenerate spontaneously and progressively as the culture progresses.Neuroretina culture systems began to develop in the 1920 s, using chicken embryos' retinas and posteriorly mammalian retinas. In 1954, Trowell developed the membrane culture method, in which the retina was placed with the vitreous surface in contact with a supporting porous membrane and maintained at an air‐medium interface. In 1989, Caffé et al. cultured the neuroretina with the photoreceptors layer facing downward over porous membrane, the technique that is currently considered the gold standard. Since then, ex vivo mammal neuroretina cultures from rats, mice, hamsters, guinea pigs, rabbits, cats, dogs, pigs, cows or primate, have been used to describe the differentiation processes of post‐natal retinas; to provide valuable insights into retinal diseases processes; to test potential therapeutic substances; to examine the role of growth factors over retinal cells' dynamics; to assess nanostructured scaffolds and their potential cytotoxicity, and to evaluate potential advanced therapies.Although mammal neuroretina is an excellent alternative to the dependency on post‐mortem human eyes, ex vivo human neuroretina cultures have also been characterized. They have improved the current knowledge about photoreceptors, ganglion cells, glial cells and microglia dynamics. Furthermore, human tissues are theoretically better suited for translational research than animal cells and perhaps even animal models, which exponentially increases the usefulness of the neuroretina cultures, and the extrapolation of the results obtained, marking a promising future for the screening and evaluation of potential neuroprotectors.