Biology subjects

Ader, M.

Publications and source records attributed to Ader, M..

8 recordsLinked to original sources

bioRxiv2026

IDENTIFICATION OF HUMAN PHOTORECEPTORS SUITABLE FOR CELL REPLACEMENT STUDIES IN A PRECLINICAL ACHROMATOPSIA MODEL

Cell replacement represents a potential treatment modality for retinal disorders characterized by photoreceptor loss. However, photoreceptor replacement approaches have not been clinically established. To take this forward, the main goal of this study was to systematically compare human photoreceptors of different ages and identify those that enable functional integration into the degenerative retina. Donor cells were isolated from iPSC-derived retinal organoids generated by a GMP-compliant protocol at differentiation days 120, 150, or 200 and transplanted subretinally into cone photoreceptor function loss 1 (Cpfl1) recipients, an inherited mouse model of cone degeneration. While younger photoreceptors showed slightly improved transplantation outcomes, donor photoreceptors of all culture stages displayed long-term survival, cone identity, structural integration into the host retina, and tight interactions with host Muller glia, including formation of a continuous outer limiting membrane. Transplanted photoreceptors showed signs of advanced maturation, including correct polarization with generation of apical inner- and outer segments, while basal synapses were formed with host bipolar cells. Electrophysiological assessment of host retinal ganglion cells revealed light-evoked responses in transplant-containing regions, providing evidence for functional incorporation of human photoreceptors into the mouse neuro-retinal circuitry. Thus, GMP-compliant human iPSC-derived photoreceptors are stable over a wide range of differentiation stages and constitute a robust cell source for retinal transplantation and functional repair. The findings provide important prerequisites for the development of standardized procedures towards clinical translation of photoreceptor replacement in the retina. Significant statementCell transplantation represents a potential therapy for retinal dystrophies. However, conditions allowing stable functional integration and maturation of donor photoreceptors have not been defined. We systematically compared GMP-compliant iPSC-derived photoreceptors of different culture times after transplantation into a retinal degeneration mouse model. Photoreceptors of all ages showed structural integration and advanced maturation in close interaction with host Muller glia and bipolar cells, allowing restoration of light-driven responses. Thus human photoreceptors isolated from retinal organoids represent a robust source for clinical development of cell replacement in the diseased retina.

neuroscience↗

bioRxiv2026

Transplanted human photoreceptors differentially survive, incorporate, and mature in mildly and severely degenerated mouse retinae

Photoreceptor transplantation is considered a disease-agnostic therapeutic strategy for retinal degenerative diseases with highly heterogenous genetic, molecular, and cellular pathologies. While integration of human photoreceptors enriched from stem cell-derived retinal organoids was noted in previous preclinical studies, the potential influence of retinal degeneration severity on transplantation efficiency has not been systematically assessed. Here, we employed mice presenting mild or severe retinal degeneration as recipients for human induced pluripotent stem cell-derived photoreceptors. Donor cells formed multi-cellular clusters that structurally integrated from 3 weeks post-transplantation (wpt) in mildly degenerated retinas, closely interacting with host Muller glia, resulting in proper maturation characterized by inner/outer segment and synapse formation by 26 wpt. In contrast, in severely degenerated hosts, donor photoreceptors remained mainly singularized and scattered in the subretinal space, showing limited structural integration or signs of maturation. Differential maturation of donor cells in mild vs. severe hosts was confirmed by single-cell RNA-sequencing analysis. However, transplantation at the beginning of the degeneration process of the severe model allowed structural integration and maturation of donor photoreceptors, despite complete loss of endogenous photoreceptors over time. The study thus shows that survival, integration, and maturation of donor photoreceptors depend on the degenerative retinal microenvironment shaping significantly transplantation efficiency.

neuroscience↗

bioRxiv2024

Extensive monolayer formation depends on a subpopulation of transplanted human iPSC-derived RPE cells

Loss of the retinal pigment epithelium (RPE) in the eye leads to photoreceptor dysfunction and death causing eventually vision loss. Cell replacement strategies using RPE cells derived in vitro from pluripotent stem cells (PSCs) are currently evaluated as a potential therapeutic strategy. Generation of polarized monolayers represents an essential prerequisite for proper RPE function, however, monolayer formation following transplantation of RPE cell suspensions has not been systematically assessed. Using the sodium iodate mouse model of acute RPE depletion, significant increase in monolayer formation capacity of passage (P) 1 vs. P2 human iPSC-derived RPE cells was observed three weeks after transplantation. Transplant-derived monolayers showed characteristic apicobasal polarity, RPE marker expression, phagocytosis function, and preservation of the host outer nuclear layer. The cell surface marker panel CD54+/PSA-NCAM- was identified to enrich for an RPE subpopulation with high potential for monolayer formation following transplantation. Results underline the importance of defining and isolating competent cell subpopulations for successful RPE transplantation.

neuroscience↗

bioRxiv2021

Extensive incorporation, polarisation and improved maturation of transplanted human cones in a murine cone degeneration model

Once human photoreceptors die, they do not regenerate, thus photoreceptor transplantation has emerged as a potential treatment approach for blinding diseases. Improvements in transplant organization, donor cell maturation and synaptic connectivity to the host will be critical in advancing this technology to clinical practice. Unlike the unstructured grafts of prior cell suspension transplantations into end-stage degeneration models, we describe extensive incorporation of iPSC retinal organoid-derived human photoreceptors into mice with cone dysfunction. This incorporative phenotype was validated in both cone-only as well as pan-photoreceptor transplantations. Rather than forming a glial barrier, Muller cells extend throughout the graft, even forming a common outer limiting membrane. Donor-host interaction appears to promote polarisation as well as development of morphological features critical for light detection, namely formation of inner and well stacked outer segments oriented towards the RPE. Putative synapse formation and graft function is evident both at a structural and electrophysiological level. Overall, these results show that human photoreceptors interact readily with a partially degenerated retina. Moreover, incorporation into the host retina appears to be beneficial to graft maturation, polarisation and function. HighlightsO_LIGeneration of the first human iPSC cone reporter line C_LIO_LIHuman cones extensively incorporate into the retina of mice with cone degeneration C_LIO_LIDonor cone age and time in vivo are important factors for transplant incorporation C_LIO_LIIncorporation into the host retina correlates with graft polarisation C_LIO_LIImproved photoreceptor maturation after transplantation in vivo vs. in vitro C_LIO_LIRe-establishment of cone-mediated light-responses in the cone deficient mouse C_LI

neuroscience↗

bioRxiv2021

Label-free imaging flow cytometry: analysis and sorting of enzymatically dissociated tissues

Biomedical research often relies on identification and isolation of specific cell types using molecular biomarkers and sorting methods such as fluorescence or magnetic activated cell sorting. Labelling processes potentially alter the cells properties and should be avoided, especially when purifying cells for clinical applications. A promising alternative is the label-free identification of cells based on their physical properties. Sorting real-time deformability and fluorescence cytometry (soRT-FDC) is a microfluidic technique for label-free analysis and sorting of single cells. In soRT-FDC, bright-field images of cells are analyzed by a deep neural net (DNN) to obtain a sorting decision, but sorting was so far only demonstrated for blood cells which show clear morphological differences and are naturally in suspension. Most cells, however, grow in tissues, requiring dissociation before cell sorting which is associated with additional challenges including survival, changes in morphology, or presence of aggregates. Here, we introduce methods for robust analysis and sorting of single cells from mammalian nervous tissue and provide DNNs which are capable of distinguishing visually similar cells. Exemplarily, we employ the DNN for image-based sorting to enrich photoreceptor cells from dissociated retina for transplantation into the mouse eye. Results provide evidence that the combination of machine learning and soRT-FDC allows label-free enrichment of target cells from dissociated tissues.

biophysics↗

bioRxiv2020

Transplanted pluripotent stem cell-derived photoreceptor precursors elicit conventional and unusual light responses in mice with advanced retinal degeneration

Retinal dystrophies often lead to blindness. Developing therapeutic interventions to restore vision is therefore of paramount importance. Here we demonstrate the ability of pluripotent stem cell-derived cone precursors to engraft and restore light responses in the Pde6brd1 mouse, an end-stage photoreceptor degeneration model. Up to 1.5% of precursors integrated into the host retina, differentiated into cones and formed synapses with bipolar cells. Half of the transplanted mice exhibited visual behaviour and 33% showed binocular light sensitivity. The majority of ganglion cells exhibited contrast-sensitive ON, OFF or ON-OFF light responses and even motion sensitivity. Many cells also exhibited unusual responses (e.g. light-induced suppression), presumably reflecting remodelling of the neural retina. Our data indicate that despite relatively low engraftment yield, engrafted pluripotent stem cell-derived cone precursors can elicit light responsiveness even at advanced degeneration stages. Further work is needed to improve engraftment yield and counteract retinal remodelling to achieve useful clinical applications.

neuroscience↗

bioRxiv2019

Rod nuclear architecture determines contrast transmission of the retina and behavioral sensitivity in mice

Rod photoreceptors of nocturnal mammals display a striking inversion of nuclear architecture, which has been proposed as an evolutionary adaptation to dark environments. However, the nature of visual benefits and underlying mechanisms remains unclear. It is widely assumed that improvements in nocturnal vision would depend on maximization of photon capture, at the expense of image detail. Here we show that retinal optical quality improves 2-fold during terminal development, which, confirmed by a mouse model, happens due to nuclear inversion. We further reveal that improved retinal contrast-transmission, rather than photon-budget or resolution, leads to enhanced contrast sensitivity under low light condition. Our findings therefore add functional significance to a prominent exception of nuclear organization and establish retinal contrast-transmission as a decisive determinant of mammalian visual perception. One Sentence SummaryOur study reveals that chromatin compaction in rod cells augments contrast sensitivity in mice.

biophysics↗

bioRxiv2018

Restoration of visual function by transplantation of optogenetically engineered photoreceptors

A major challenge in the treatment of retinal degenerative diseases, with the transplantation of replacement photoreceptors, is the difficulty in inducing the grafted cells to grow and maintain light sensitive outer segments (OS) in the host retina, which depends on proper interaction with the underlying retinal pigment epithelium (RPE). For a RPE-independent treatment approach, we introduced a hyperpolarizing microbial opsin into photoreceptor precursors from new-born mice, and transplanted them into blind mice lacking the photoreceptor layer. These optogenetically transformed photoreceptors were light responsive and their transplantation lead to the recovery of visual function, as shown by ganglion cell recordings and behavioral tests. Subsequently, we generated cone photoreceptors from human induced pluripotent stem cells (hiPSCs), expressing the chloride pump Jaws. After transplantation into blind mice, we observed light-driven responses at the photoreceptor and ganglion cell level. These results demonstrate that structural and functional retinal repair is possible by combining stem cell therapy and optogenetics.

bioengineering↗