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Gene Therapy


  • Transduction efficiency of viral vector
  • Cell tropism identification
  • In vitro safety prediction
  • Cell viability assessment
  • Therapy efficacy


  • Human retinal organoids
  • Human retinal pigment epithelial (RPE) cells
  • dervided from heathy donor, patient cells or CRISPR/Cas9 gene edited iPSCs


  • 2-6 months

Accelerated in vitro preclinical evaluation of viral vectors for retinal gene therapy development

Newcells retinal organoids and RPE models are valuable tools for in vitro preclinical selection of new retinal gene therapy vectors. They allow rapid in vitro evaluation of the best combination of vector capsid, promoter, and transgene. They also enable initial safety and efficacy testing to be carried out using the exact same promoter or gene as those to be used in clinical trials. Our retinal models have been validated for their use in screening and selection of optimal adeno-associated viral (AAV) vectors with increased photoreceptor tropism for retinal gene therapy.

Service outputs

  • Evaluation of AAV vectors transduction efficiency in iPSC-derived retinal organoids or RPE cells
  • Determination of AAV vector cell tropism and transduction of photoreceptor-like cells
  • Cell viability assessment post-transduction

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Localization and distribution of Müller glia cells (CRALBP, red) in retinal organoids. Nuclear DAPI staining (blue).
Localization and distribution of Müller glia cells (CRALBP, red) in retinal organoids. Nuclear DAPI staining (blue).

Gene therapy vector tropism

Viral vector optimisation

In vitro evaluation

Newcells Retinal Model

Accelerate your lead compound selection by understanding their mode of action in functional retinal tissue


Recapitulate the architecture and function of the human retina


Evaluate gene therapy vectors and novel drugs for retinal diseases in vitro


Accelerate drug discovery by replacing animal experiments

AAV vector evaluation in vitro for retinal gene therapy Close Open

Newcells’ retinal organoids have shown their potential to be used as an informative in vitro model for the evaluation of new retinal gene therapy vectors for retinal diseases.

Our organoids have been used to screen AAV gene therapy vectors in a collaboration with a team at the University of Oxford. This study confirmed robust and efficient transduction of human photoreceptor-like cells by AAV vectors highlighting improved transduction capability of AAV2 7m8 in retinal organoids when using the ubiquitous CAG promoter. With several cell types present within the organoids, the experiments were able to specifically show the targeted cell types, demonstrating that a CAG-driven transgene transduced a broad range of cell types, while GRK1-driven transgenes show a more restricted photoreceptor-specific expression (A). The work also demonstrated the viability of the retinal organoids were not affected by AAV transduction (B).

(A) Live cell imaging of reporter gene expression up to 27 days post-transduction. Arrows indicate the areas where the onset of reporter gene expression first appeared, allowing evaluation of which cell types each AAV vector transduced preferentially.
(B) Retinal organoid viability following transduction by AAV. ATP assay was assessed as an indicator of viability at 27 days post-transduction with AAV vectors. Data analysed using a one-way analysis of variance indicated no significant influence of AAV treatment on ATP levels and viability (F=1.107, P =0.3908) relative to control retinal organoids.

These studies can be carried out in both our retinal organoids and RPE in vitro models to allow rapid evaluation of new retinal gene therapy vectors.


Tropism of AAV Vectors in Photoreceptor-Like Cells of Human iPSC-Derived Retinal Organoids

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Transduction efficiency in RPE Close Open
Dose- and time- dependent increase in GFP signal in AAV-transduced RPE. Percentage of GFP-positive cells over 28 days post transduction with AAV5-CAG-EGFP:WPR at two different doses. Scale: 150 µm.
Service overview Close Open

Newcells provides a custom service evaluating AAV vectors in our laboratories. With our regular supply of tissue, our projects timelines are short. The robust data generated by our scientific experts will guide you in confidence for key decision-making steps during drug development.

An example of viral vector testing service includes a set of assays to assess transduction efficiency, cell tropism and post-transduction cell viability.

Assay design

Retinal organoids with photoreceptors (cone and rod), retinal ganglion cells, horizontal cells and amacrine cells.

Retina pigment epithelium (RPE) cells (2D cobblestones monolayer).

Assay format

96-well plates (retinal organoids)

24-well plates (RPE)



Assay readout
  • Cell viability assay (ATP depletion assay, LDH release and microscopy)
  • Qualitative immunofluorescence with cell specific markers & cell death markers
  • AAV transduction efficiency
Time points and replicates
  • Post-transduction (typically up to 28 days)
  • Triplicates per vector and per concentration

Models to choose from for this service

Retinal organoids

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.

Find out more
A microscope image of retinal organoids
Cone photoreceptor cells labelled with anti-Opsin (Red/Green) antibody.

Retinal pigment epithelium cells (RPE)

A functional 2D 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.

Find out more
Image of RPE model
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).


Is this the service for you? Speak to one of our experts about your requirements.

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