Human organotypic retinal cultures (HORCs) as a chronic experimental model for investigation of retinal ganglion cell degeneration

Abstract

There is a growing need for models of human diseases that utilise native, donated human tissue in order to model disease processes and develop novel therapeutic strategies. In this paper we assessed the suitability of aged human retinal explants as a potential model of chronic retinal ganglion cell (RGC) degeneration. Our results confirmed that RGC markers commonly used in rodent studies (NeuN, βIII Tubulin and Thy-1) were appropriate for labelling human RGCs and followed the expected differential expression patterns across, as well as throughout, the macular and paramacular regions of the retina. Furthermore, we showed that neither donor age nor post-mortem time (within 24 hours) significantly affected the initial expression levels of RGC markers. In addition, the feasibility of using human post mortem donor tissue as a long-term model of RGC degeneration was determined with RGC protein being detectable up to 4 weeks in culture with an associated decline in RGC mRNA and significant, progressive, apoptotic labelling of NeuN + cells. Differences in RGC apoptosis might have been influenced by medium compositions indicating that media constituents could play a role in supporting axotomised RGCs. We propose that using ex vivo human explants may prove to be a useful model for testing the effectiveness of neuroprotective strategies.

Retinal explant culture: A platform to investigate human neuro‐retina

“…A later study by Niyadurupola et al focussed on the distribution and expression of thy1 under different neurotoxic stress conditions in adults . In an extension to this study, the distribution of RGCs using different markers were assessed and the utility of post‐mortem human retinal explants for long‐term study of RGCs was demonstrated …”

“…More recently, adult human retinal explants have been used for the study of human retinal ganglion cells (RGCs), photoreceptors and glial cells . Other retinal neurons like the amacrine cells, horizontal cells and bipolar cells have not been studied extensively either due to difficulties in culture or due to a perceived subordinate role in retinal pathology.…”

“…This is the most suitable choice retinal experimentation as they produce reproducible retinal fragments. The macular and para‐macular regions have been used to compare the differential gene expression in different regions of human retina …”

“…A number of supplements, including hormones, growth factors, serum substitutes, cofactors, lipids and buffers have been included in the retinal explant culture media to promote the growth of explants, especially retinal neurons, whilst maintaining the pH. Glutamine, B‐27 and N2 are the most commonly used supplements in human retinal explant culture . A number of growth factors like neuronal growth factor, fibroblast growth factor and epidermal growth factor have been incorporated in the retinal culture media, specifically to enhance the survival of retinal neurons.…”

Modeling Human Glaucoma: Lessons from the in vitro Models

“…The opportunity to investigate whole tissue cultures poses clear advantages compared to a monolayer of cultured cells, allowing the study of cell-to-cell interactions and maintaining an anatomical structure under EHP [28] . Exposure of retinal tissue obtained from human postmortem donors to EHP may also prove to be a useful model for testing the effectiveness of neuroprotective strategies [29,30] . Additionally, the use of EHP systems also promotes the reduction of animal use and the experimental variability intrinsic to animal models of glaucoma ( table 1 ).…”