Transmission (TEM) and Scanning (SEM) electron microscopy
Models
Human retinal organoids
Human retinal pigment epithelial (RPE) cells
Derived from WT or CRISPR/Cas9 gene edited iPSCs
Timeline
Rapid
2-6 months
Accelerated in vitro evaluation of retinal toxicity
Newcells offers a fast and reliable retinal drug toxicity in vitro testing service using complex models developed in house: retinal organoids and RPE. The retinal toxicity service evaluates how new compounds affect cell viability, following photoreceptor degeneration or loss of RPE barrier function including outer segment photoreceptor phagocytosis. We also offer the comparison of several time points during differentiation. Our retinal toxicity service is fast, giving our clients insights into the ocular toxicity profile of their compounds and allowing them to evaluate possible rescue strategies.
Service outputs
Rapid retinal toxicity evaluation of compounds in iPSC-derived retinal organoids or RPE cells
Qualitative immunofluorescence on frozen retinal organoid sections using key markers
Time point comparisons
Assessment of the composition of retinal ganglion cells, photoreceptors, amacrine, horizontal cells and Muller glia using imaging techniques
Evaluation of photoreceptor and RPE degeneration
Analysis of loss of RPE barrier function & loss of phagocytosis of photoreceptor outer segment
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Human retinal models
96-well format
Rapid
Newcells Retinal Models
Accelerate your lead compound selection by understanding their mode of action in functional retinal tissue
1.
Recapitulate the architecture and function of the human retina
2.
Evaluate novel drugs safety profile in vitro
3.
Accelerate drug discovery & replace animal experiments
What is retinal toxicity and how can it be evaluated in vitro? Some drugs administered systematically may affect the function of the retina. Similarly, new treatments for eye diseases require careful safety evaluation. Retinal toxicity studies can be performed in animal models, or human ex-vivo models. However, these are limiting due to the number of experimental data points generated and limited predictivity in humans.
Newcells scientists have developed robust human iPSC-derived retinal tissue models. Retinal organoids are obtained through a carefully controlled differentiation process recapitulating the timeline of embryonic retinogenesis. At day 150, the organoids comprise all key cell types and are functional, allowing the evaluation of the cytotoxic effect of new compounds by simply adding them to the plate. The cell structure integrity and the gene expression profiles of key markers for the main cell types, such as photoreceptors, are then assessed. We also perform qualitative imaging and microscopy to provide a comprehensive drug toxicity profile. As our models are derived from human iPSCs, they are directly relevant to human clinical trials, and provide key data for transitional studies. The two main advantages of using in vitro retinal toxicity testing are the speed (as most simple studies can be carried out within one to two months) and the predictivity for human clinical trials.
These studies can be carried out in both our retinal organoids and RPE in vitro models for rapid evaluation of retinal toxicity of new compounds.
Modelling retinal drug toxicity: Retinal organoids have been tested for the response of known toxins such as thioridazine and doxorubicin. The intrinsic fluorescence of doxorubicin facilitates visualisation of the drug penetrating the retinal organoid (A). Exposure of the iPSC-derived retinal organoids to doxorubicin reduces cell viability in a dose-dependent manner (B).
(A) Newcells’ human iPSC-derived retinal organoids are permeable to small molecules. The penetration of doxorubicin, a naturally fluorescent small toxic molecule (red), into the retinal organoids increases over time (4h to 24h) demonstrating the permeability of the organoids to drugs.
(B) The retinal organoids were treated with increasing dose of doxorubicin over a period of 24h and cell viability was measured using an ATP assay. A dose-dependent decrease in cell viability was observed following increasing exposure to the drug.
During early drug development, drug screening is an essential step for the identification of lead compounds. This is usually performed as medium to high throughput. Newcells Biotech retinal organoids are suitable for in vitro drug screening since they are generated every 4-6 weeks (on-demand supply) in a 96-well plate format. They have been used to distinguish compounds which are toxic and non-toxic to the retina.
Dose-response plots of known cytotoxic and non-cytotoxic retinal agents. Retinal organoids were exposed to increasing concentrations of either cytotoxic or non-cytotoxic drugs and cell viability was measured over time. As expected, cell viability decreased upon increasing addition of Thioridazine and 4-hydrohytamoxifen, whilst non-cytotoxic drugs had no effect. The dose-response of cytotoxic and non-cytotoxic retinal agents was determined using CellTiter-Glo® 3D ATP assay.
Newcells provides a custom service evaluating retinal toxicity using our complex iPSC-derived human retinal models (retinal organoids or RPE)
Even though the differentiation process of retinal organoids is up to 210 days, our streamlined manufacturing process releases regular supply of tissue supporting short projects timelines. The robust data generated by our scientific experts will guide you in confidence for key decision-making steps during drug development.
An example of retinal drug toxicity screening includes a set of assays to assess cell viability, photoreceptor or RPE functionality and degeneration as well as key marker expression and localisation. We can also assess the safety of new viral vectors such as AAV.
Assay design
Models
Retinal organoids with photoreceptors (cone and rod), retinal ganglion cells, horizontal cells and amacrine cells (WT).
The retinal organoids are iPSC-derived, and they recapitulate the complex structure of the human retina with laminar cell organisation mimicking embryonic development. They contain the outer photoreceptor segment of the retina that responds to light.
Cone photoreceptor cells labelled with anti-Opsin (Red/Green) antibody.
Retinal pigment epithelium cells (RPE)
A functional monolayer in vitro model of retinal pigment epithelial cells generated from human iPSCs recapitulating phagocytosis of photoreceptor outer segments. The RPE cells are pigmented and displays typical cobblestone morphology.
RPE cells displaying cobblestone morphology. Cells were immunolabeled with tight-junction ZO-1 marker (shown in green) and co-stained with nuclei marker, Hoechst (shown in blue).
