Publications by authors named "Sacha Reichman"

24 Publications

  • Page 1 of 1

Reproducing diabetic retinopathy features using newly developed human induced-pluripotent stem cell-derived retinal Müller glial cells.

Glia 2021 Mar 8. Epub 2021 Mar 8.

Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France.

Muller glial cells (MGCs) are responsible for the homeostatic and metabolic support of the retina. Despite the importance of MGCs in retinal disorders, reliable and accessible human cell sources to be used to model MGC-associated diseases are lacking. Although primary human MGCs (pMGCs) can be purified from post-mortem retinal tissues, the donor scarcity limits their use. To overcome this problem, we developed a protocol to generate and bank human induced pluripotent stem cell-derived MGCs (hiMGCs). Using a transcriptome analysis, we showed that the three genetically independent hiMGCs generated were homogeneous and showed phenotypic characteristics and transcriptomic profile of pMGCs. These cells expressed key MGC markers, including Vimentin, CLU, DKK3, SOX9, SOX2, S100A16, ITGB1, and CD44 and could be cultured up to passage 8. Under our culture conditions, hiMGCs and pMGCs expressed low transcript levels of RLPB1, AQP4, KCNJ1, KCJN10, and SLC1A3. Using a disease modeling approach, we showed that hiMGCs could be used to model the features of diabetic retinopathy (DR)-associated dyslipidemia. Indeed, palmitate, a major free fatty acid with elevated plasma levels in diabetic patients, induced the expression of inflammatory cytokines found in the ocular fluid of DR patients such as CXCL8 (IL-8) and ANGPTL4. Moreover, the analysis of palmitate-treated hiMGC secretome showed an upregulation of proangiogenic factors strongly related to DR, including ANG2, Endoglin, IL-1β, CXCL8, MMP-9, PDGF-AA, and VEGF. Thus, hiMGCs could be an alternative to pMGCs and an extremely valuable tool to help to understand and model glial cell involvement in retinal disorders, including DR.
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http://dx.doi.org/10.1002/glia.23983DOI Listing
March 2021

Generation of a Transplantable Population of Human iPSC-Derived Retinal Ganglion Cells.

Front Cell Dev Biol 2020 27;8:585675. Epub 2020 Oct 27.

Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France.

Optic neuropathies are a major cause of visual impairment due to retinal ganglion cell (RGC) degeneration. Human induced-pluripotent stem cells (iPSCs) represent a powerful tool for studying both human RGC development and RGC-related pathological mechanisms. Because RGC loss can be massive before the diagnosis of visual impairment, cell replacement is one of the most encouraging strategies. The present work describes the generation of functional RGCs from iPSCs based on innovative 3D/2D stepwise differentiation protocol. We demonstrate that targeting the cell surface marker THY1 is an effective strategy to select transplantable RGCs. By generating a fluorescent GFP reporter iPSC line to follow transplanted cells, we provide evidence that THY1-positive RGCs injected into the vitreous of mice with optic neuropathy can survive up to 1 month, intermingled with the host RGC layer. These data support the usefulness of iPSC-derived RGC exploration as a potential future therapeutic strategy for optic nerve regeneration.
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http://dx.doi.org/10.3389/fcell.2020.585675DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7652757PMC
October 2020

Dynamic full-field optical coherence tomography: 3D live-imaging of retinal organoids.

Light Sci Appl 2020 17;9:140. Epub 2020 Aug 17.

Institut de la Vision, Sorbonne Université, INSERM, CNRS, F-75012 Paris, France.

Optical coherence tomography offers astounding opportunities to image the complex structure of living tissue but lacks functional information. We present dynamic full-field optical coherence tomography as a technique to noninvasively image living human induced pluripotent stem cell-derived retinal organoids. Coloured images with an endogenous contrast linked to organelle motility are generated, with submicrometre spatial resolution and millisecond temporal resolution, creating a way to identify specific cell types in living tissue via their function.
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http://dx.doi.org/10.1038/s41377-020-00375-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7429964PMC
August 2020

[Retinal organoids as a new tool for understanding and treating retinal diseases].

Med Sci (Paris) 2020 Jun-Jul;36(6-7):626-632. Epub 2020 Jul 2.

Institut de la Vision, Sorbonne Université, Inserm, CNRS, 17 rue Moreau, F-75012 Paris, France.

Generation of retinal organoids from pluripotent stem cells represents an important advance in the study of retinal development and offer new perspectives for the study of retinal diseases missing suitable animal models. Understanding the key stages of retinal development in vertebrates enabled to design protocols to generate self-organized three-dimensional structures derived from pluripotent stem cells and containing all retinal cell types. In addition to their application in basic research, such as the characterization of molecular and cellular mechanisms in retinal pathophysiology, these miniature organs also open up encouraging prospects in the field of cell therapy or the screening of therapeutic molecules, although some obstacles remain to be overcome.
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http://dx.doi.org/10.1051/medsci/2020098DOI Listing
October 2020

AAV-Mediated Gene Delivery to 3D Retinal Organoids Derived from Human Induced Pluripotent Stem Cells.

Int J Mol Sci 2020 Feb 3;21(3). Epub 2020 Feb 3.

Institut de la Vision, Sorbonne Université, INSERM, CNRS, 75012 Paris, France.

Human induced pluripotent stem cells (hiPSCs) promise a great number of future applications to investigate retinal development, pathophysiology and cell therapies for retinal degenerative diseases. Specific approaches to genetically modulate hiPSC would be valuable for all of these applications. Vectors based on adeno-associated virus (AAV) have shown the ability for gene delivery to retinal organoids derived from hiPSCs. Thus far, little work has been carried out to investigate mechanisms of AAV-mediated gene delivery and the potential advantages of engineered AAVs to genetically modify retinal organoids. In this study, we compared the early transduction efficiency of several recombinant and engineered AAVs in hiPSC-derived RPE cells and retinal organoids in relation to the availability of their cell-surface receptors and as a function of time. The genetic variant AAV2-7m8 had a superior transduction efficiency when applied at day 44 of differentiation on retinal organoids and provided long-lasting expressions for at least 4 weeks after infection without compromising cell viability. All of the capsids we tested transduced the hiPSC-RPE cells, with the AAV2-7m8 variant being the most efficient. Transduction efficiency was correlated with the presence of primary cell-surface receptors on the hiPS-derived organoids. Our study explores some of the mechanisms of cell attachment of AAVs and reports long-term gene expression resulting from gene delivery in retinal organoids.
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http://dx.doi.org/10.3390/ijms21030994DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7036814PMC
February 2020

Generation of human induced pluripotent stem cell lines from a patient with ITM2B-related retinal dystrophy and a non mutated brother.

Stem Cell Res 2019 12 5;41:101625. Epub 2019 Nov 5.

INSERM, CNRS, Institut de la Vision, Sorbonne Université, 17 rue Moreau, Paris, F-75012, France; CHNO des Quinze-Vingts, INSERM-DGOS CIC 1423, 28 rue de Charenton, Paris, F-75012, France. Electronic address:

Human induced pluripotent stem cell (iPSC) lines were generated from fibroblasts of a patient affected with an autosomal dominant retinal dystrophy carrying the mutation c.782A>C, p.Glu261Ala in ITM2B and from an unaffected brother. Three different iPSC lines were generated and characterized from primary dermal fibroblasts of the affected subject and two from the unaffected brother. All iPSC lines expressed the pluripotency markers, were able to differentiate into the three germ layers and presented normal karyotypes. This cellular model will provide a powerful tool to study this retinal dystrophy and better understand the role of ITM2B.
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http://dx.doi.org/10.1016/j.scr.2019.101625DOI Listing
December 2019

Restoration of visual function by transplantation of optogenetically engineered photoreceptors.

Nat Commun 2019 10 4;10(1):4524. Epub 2019 Oct 4.

Sorbonne Université, Institut de la Vision, INSERM, CNRS, 75012, Paris, France.

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 in the host retina, which depends on proper interaction with the underlying retinal pigment epithelium (RPE). Here, for an RPE-independent treatment approach, we introduce a hyperpolarizing microbial opsin into photoreceptor precursors from newborn mice, and transplant them into blind mice lacking the photoreceptor layer. These optogenetically-transformed photoreceptors are light responsive and their transplantation leads to the recovery of visual function, as shown by ganglion cell recordings and behavioral tests. Subsequently, we generate cone photoreceptors from human induced pluripotent stem cells, expressing the chloride pump Jaws. After transplantation into blind mice, we observe light-driven responses at the photoreceptor and ganglion cell levels. These results demonstrate that structural and functional retinal repair is possible by combining stem cell therapy and optogenetics.
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http://dx.doi.org/10.1038/s41467-019-12330-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6778196PMC
October 2019

Reprogramming of Adult Retinal Müller Glial Cells into Human-Induced Pluripotent Stem Cells as an Efficient Source of Retinal Cells.

Stem Cells Int 2019 15;2019:7858796. Epub 2019 Jul 15.

Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France.

The reprogramming of human somatic cells to induced pluripotent stem cells (iPSCs) has broad applications in regenerative medicine. The generation of self-organized retinal structures from these iPSCs offers the opportunity to study retinal development and model-specific retinal disease with patient-specific iPSCs and provides the basis for cell replacement strategies. In this study, we demonstrated that the major type of glial cells of the human retina, Müller cells, can be reprogrammed into iPSCs that acquire classical signature of pluripotent stem cells. These Müller glial cell-derived iPSCs were able to differentiate toward retinal fate and generate concomitantly retinal pigmented epithelial cells and self-forming retinal organoid structures containing retinal progenitor cells. Retinal organoids recapitulated retinal neurogenesis with differentiation of retinal progenitor cells into all retinal cell types in a sequential overlapping order. With a modified retinal maturation protocol characterized by the presence of serum and high glucose levels, our study revealed that the retinal organoids contained pseudolaminated neural retina with important features reminiscent of mature photoreceptors, both rod and cone subtypes. This advanced maturation of photoreceptors not only supports the possibility to use 3D retinal organoids for studying photoreceptor development but also offers a novel opportunity for disease modeling, particularly for inherited retinal diseases.
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http://dx.doi.org/10.1155/2019/7858796DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6664555PMC
July 2019

Defined Xeno-free and Feeder-free Culture Conditions for the Generation of Human iPSC-derived Retinal Cell Models.

J Vis Exp 2018 09 6(139). Epub 2018 Sep 6.

Institut de la Vision, Sorbonne Université, INSERM, CNRS, F-75012 Paris, France;

The production of specialized cells from pluripotent stem cells provides a powerful tool to develop new approaches for regenerative medicine. The use of human-induced pluripotent stem cells (iPSCs) is particularly attractive for neurodegenerative disease studies, including retinal dystrophies, where iPSC-derived retinal cell models mark a major step forward to understand and fight blindness. In this paper, we describe a simple and scalable protocol to generate, mature, and cryopreserve retinal organoids. Based on medium changing, the main advantage of this method is to avoid multiple and time-consuming steps commonly required in a guided differentiation of iPSCs. Mimicking the early phases of retinal development by successive changes of defined media on adherent human iPSC cultures, this protocol allows the simultaneous generation of self-forming neuroretinal structures and retinal pigmented epithelial (RPE) cells in a reproducible and efficient manner in 4 weeks. These structures containing retinal progenitor cells (RPCs) can be easily isolated for further maturation in a floating culture condition enabling the differentiation of RPCs into the seven retinal cell types present in the adult human retina. Additionally, we describe quick methods for the cryopreservation of retinal organoids and RPE cells for long-term storage. Combined together, the methods described here will be useful to produce and bank human iPSC-derived retinal cells or tissues for both basic and clinical research.
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http://dx.doi.org/10.3791/57795DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6235103PMC
September 2018

Characterization and Transplantation of CD73-Positive Photoreceptors Isolated from Human iPSC-Derived Retinal Organoids.

Stem Cell Reports 2018 09 9;11(3):665-680. Epub 2018 Aug 9.

Institut de la Vision, Sorbonne Université, INSERM, CNRS, 17, Rue Moreau, Paris 75012, France. Electronic address:

Photoreceptor degenerative diseases are a major cause of blindness for which cell replacement is one of the most encouraging strategies. For stem cell-based therapy using human induced pluripotent stem cells (hiPSCs), it is crucial to obtain a homogenous photoreceptor cell population. We confirmed that the cell surface antigen CD73 is exclusively expressed in hiPSC-derived photoreceptors by generating a fluorescent cone rod homeobox (Crx) reporter hiPSC line using CRISPR/Cas9 genome editing. We demonstrated that CD73 targeting by magnetic-activated cell sorting (MACS) is an effective strategy to separate a safe population of transplantable photoreceptors. CD73+ photoreceptor precursors can be isolated in large numbers and transplanted into rat eyes, showing capacity to survive and mature in close proximity to host inner retina of a model of photoreceptor degeneration. These data demonstrate that CD73+ photoreceptor precursors hold great promise for a future safe clinical translation.
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http://dx.doi.org/10.1016/j.stemcr.2018.07.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6135113PMC
September 2018

Chronic exposure to tumor necrosis factor alpha induces retinal pigment epithelium cell dedifferentiation.

J Neuroinflammation 2018 Mar 16;15(1):85. Epub 2018 Mar 16.

Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012, Paris, France.

Background: The retinal pigment epithelium (RPE) is a monolayer of pigmented cells with important barrier and immuno-suppressive functions in the eye. We have previously shown that acute stimulation of RPE cells by tumor necrosis factor alpha (TNFα) downregulates the expression of OTX2 (Orthodenticle homeobox 2) and dependent RPE genes. We here investigated the long-term effects of TNFα on RPE cell morphology and key functions in vitro.

Methods: Primary porcine RPE cells were exposed to TNFα (at 0.8, 4, or 20 ng/ml per day) for 10 days. RPE cell morphology, phagocytosis, barrier- and immunosuppressive-functions were assessed.

Results: Chronic (10 days) exposure of primary RPE cells to TNFα increases RPE cell size and polynucleation, decreases visual cycle gene expression, impedes RPE tight-junction organization and transepithelial resistance, and decreases the immunosuppressive capacities of the RPE. TNFα-induced morphological- and transepithelial-resistance changes were prevented by concomitant Transforming Growth Factor β inhibition.

Conclusions: Our results indicate that chronic TNFα-exposure is sufficient to alter RPE morphology and impede cardinal features that define the differentiated state of RPE cells with striking similarities to the alterations that are observed with age in neurodegenerative diseases such as age-related macular degeneration.
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http://dx.doi.org/10.1186/s12974-018-1106-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5857126PMC
March 2018

Noninvasive gene delivery to foveal cones for vision restoration.

JCI Insight 2018 01 25;3(2). Epub 2018 Jan 25.

Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France.

Intraocular injection of adeno-associated viral (AAV) vectors has been an evident route for delivering gene drugs into the retina. However, gaps in our understanding of AAV transduction patterns within the anatomically unique environments of the subretinal and intravitreal space of the primate eye impeded the establishment of noninvasive and efficient gene delivery to foveal cones in the clinic. Here, we establish new vector-promoter combinations to overcome the limitations associated with AAV-mediated cone transduction in the fovea with supporting studies in mouse models, human induced pluripotent stem cell-derived organoids, postmortem human retinal explants, and living macaques. We show that an AAV9 variant provides efficient foveal cone transduction when injected into the subretinal space several millimeters away from the fovea, without detaching this delicate region. An engineered AAV2 variant provides gene delivery to foveal cones with a well-tolerated dose administered intravitreally. Both delivery modalities rely on a cone-specific promoter and result in high-level transgene expression compatible with optogenetic vision restoration. The model systems described here provide insight into the behavior of AAV vectors across species to obtain safety and efficacy needed for gene therapy in neurodegenerative disorders.
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http://dx.doi.org/10.1172/jci.insight.96029DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5821199PMC
January 2018

Establishment of an induced pluripotent stem (iPS) cell line from dermal fibroblasts of an asymptomatic patient with dominant PRPF31 mutation.

Stem Cell Res 2017 12 7;25:26-29. Epub 2017 Oct 7.

Institut de la Vision, Sorbonne Universités, UPMC Univ Paris 06, INSERM UMR_S968, CNRS UMR7210, 75012 Paris, France. Electronic address:

A human iPS cell line was generated from fibroblasts of a phenotypically unaffected patient from a family with PRPF31-associated retinitis pigmentosa (RP). The transgene-free iPS cells were generated with the human OSKM transcription factors using the Sendai-virus reprogramming system. iPS cells contained the expected c.709-734dup substitution in exon 8 of PRPF31, expressed the expected pluripotency markers, displayed in vivo differentiation potential to the three germ layers and had normal karyotype. This cellular model will provide a powerful tool to study the unusual pattern of inheritance of PRPF31-associated RP.
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http://dx.doi.org/10.1016/j.scr.2017.10.007DOI Listing
December 2017

Generation of an induced pluripotent stem cell (iPSC) line from a patient with autosomal dominant retinitis pigmentosa due to a mutation in the NR2E3 gene.

Stem Cell Res 2017 10 5;24:1-4. Epub 2017 Aug 5.

Institut de la Vision, Sorbonne Universités, UPMC Univ Paris 06, INSERM UMR_S968, CNRS UMR7210, 75012 Paris, France. Electronic address:

A human iPSC line was generated from fibroblasts of a patient affected with autosomal dominant Retinitis Pigmentosa (RP) carrying the mutation p.Gly56Arg in the NR2E3 gene. The transgene-free iPSCs were generated with the human OSKM transcription factors using the Sendai-virus reprogramming system. iPSCs contained the expected c.166G>A substitution in exon 2 of NR2E3, expressed the expected pluripotency markers, displayed in vivo differentiation potential to the three germ layers and had normal karyotype. This cellular model will provide a powerful tool to study the pathogenesis of NR2E3-associated RP. Resource table.
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http://dx.doi.org/10.1016/j.scr.2017.08.003DOI Listing
October 2017

Otx2-Genetically Modified Retinal Pigment Epithelial Cells Rescue Photoreceptors after Transplantation.

Mol Ther 2018 01 8;26(1):219-237. Epub 2017 Sep 8.

INSERM, U968, Paris 75012, France; Sorbonne Universités, UPMC Univ Paris 06 UMR_S 968, Institut de la Vision, Paris 75012, France; CNRS, UMR_7210, Paris 75012, France. Electronic address:

Inherited retinal degenerations are blinding diseases characterized by the loss of photoreceptors. Their extreme genetic heterogeneity complicates treatment by gene therapy. This has motivated broader strategies for transplantation of healthy retinal pigmented epithelium to protect photoreceptors independently of the gene causing the disease. The limited clinical benefit for visual function reported up to now is mainly due to dedifferentiation of the transplanted cells that undergo an epithelial-mesenchymal transition. We have studied this mechanism in vitro and revealed the role of the homeogene OTX2 in preventing dedifferentiation through the regulation of target genes. We have overexpressed OTX2 in retinal pigmented epithelial cells before their transplantation in the eye of a model of retinitis pigmentosa carrying a mutation in Mertk, a gene specifically expressed by retinal pigmented epithelial cells. OTX2 increases significantly the protection of photoreceptors as seen by histological and functional analyses. We observed that the beneficial effect of OTX2 is non-cell autonomous, and it is at least partly mediated by unidentified trophic factors. Transplantation of OTX2-genetically modified cells may be medically effective for other retinal diseases involving the retinal pigmented epithelium as age-related macular degeneration.
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http://dx.doi.org/10.1016/j.ymthe.2017.09.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5762984PMC
January 2018

Generation of Storable Retinal Organoids and Retinal Pigmented Epithelium from Adherent Human iPS Cells in Xeno-Free and Feeder-Free Conditions.

Stem Cells 2017 05 20;35(5):1176-1188. Epub 2017 Feb 20.

Institut de la Vision, Sorbonne Universités, INSERM, CNRS UMR 7210, UPMC Univ Paris 06, Paris, France.

Human induced pluripotent stem cells (hiPSCs) are potentially useful in regenerative therapies for retinal disease. For medical applications, therapeutic retinal cells, such as retinal pigmented epithelial (RPE) cells or photoreceptor precursors, must be generated under completely defined conditions. To this purpose, we have developed a two-step xeno-free/feeder-free (XF/FF) culture system to efficiently differentiate hiPSCs into retinal cells. This simple method, relies only on adherent hiPSCs cultured in chemically defined media, bypassing embryoid body formation. In less than 1 month, adherent hiPSCs are able to generate self-forming neuroretinal-like structures containing retinal progenitor cells (RPCs). Floating cultures of isolated structures enabled the differentiation of RPCs into all types of retinal cells in a sequential overlapping order, with the generation of transplantation-compatible CD73 photoreceptor precursors in less than 100 days. Our XF/FF culture conditions allow the maintenance of both mature cones and rods in retinal organoids until 280 days with specific photoreceptor ultrastructures. Moreover, both hiPSC-derived retinal organoids and dissociated retinal cells can be easily cryopreserved while retaining their phenotypic characteristics and the preservation of CD73 photoreceptor precursors. Concomitantly to neural retina, this process allows the generation of RPE cells that can be effortlessly amplified, passaged, and frozen while retaining a proper RPE phenotype. These results demonstrate that simple and efficient retinal differentiation of adherent hiPSCs can be accomplished in XF/FF conditions. This new method is amenable to the development of an in vitro GMP-compliant retinal cell manufacturing protocol allowing large-scale production and banking of hiPSC-derived retinal cells and tissues. Stem Cells 2017;35:1176-1188.
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http://dx.doi.org/10.1002/stem.2586DOI Listing
May 2017

Activated monocytes resist elimination by retinal pigment epithelium and downregulate their OTX2 expression via TNF-α.

Aging Cell 2017 Feb 22;16(1):173-182. Epub 2016 Sep 22.

Institut de la Vision, 17 rue Moreau, 75012, Paris, France.

Orthodenticle homeobox 2 (OTX2) controls essential, homeostatic retinal pigment epithelial (RPE) genes in the adult. Using cocultures of human CD14 blood monocytes (Mos) and primary porcine RPE cells and a fully humanized system using human-induced pluripotent stem cell-derived RPE cells, we show that activated Mos markedly inhibit RPEOTX2 expression and resist elimination in contact with the immunosuppressive RPE. Mechanistically, we demonstrate that TNF-α, secreted from activated Mos, mediates the downregulation of OTX2 and essential RPE genes of the visual cycle among others. Our data show how subretinal, chronic inflammation and in particular TNF-α can affect RPE function, which might contribute to the visual dysfunctions in diseases such as age-related macular degeneration (AMD) where subretinal macrophages are observed. Our findings provide important mechanistic insights into the regulation of OTX2 under inflammatory conditions. Therapeutic restoration of OTX2 expression might help revive RPE and visual function in retinal diseases such as AMD.
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http://dx.doi.org/10.1111/acel.12540DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5242302PMC
February 2017

Rod-derived cone viability factor promotes cone survival by stimulating aerobic glycolysis.

Cell 2015 May;161(4):817-32

INSERM, U968, 75012 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, 75012 Paris, France; CNRS, UMR_7210, 75012 Paris, France. Electronic address:

Rod-derived cone viability factor (RdCVF) is an inactive thioredoxin secreted by rod photoreceptors that protects cones from degeneration. Because the secondary loss of cones in retinitis pigmentosa (RP) leads to blindness, the administration of RdCVF is a promising therapy for this untreatable neurodegenerative disease. Here, we investigated the mechanism underlying the protective role of RdCVF in RP. We show that RdCVF acts through binding to Basigin-1 (BSG1), a transmembrane protein expressed specifically by photoreceptors. BSG1 binds to the glucose transporter GLUT1, resulting in increased glucose entry into cones. Increased glucose promotes cone survival by stimulation of aerobic glycolysis. Moreover, a missense mutation of RdCVF results in its inability to bind to BSG1, stimulate glucose uptake, and prevent secondary cone death in a model of RP. Our data uncover an entirely novel mechanism of neuroprotection through the stimulation of glucose metabolism.
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http://dx.doi.org/10.1016/j.cell.2015.03.023DOI Listing
May 2015

Production of Retinal Cells from Confluent Human iPS Cells.

Methods Mol Biol 2016 ;1357:339-51

Institut de la Vision, Institut National de la Santé et de la Recherche Médicale, U968 , 17 Rue Moreau, 75012, Paris, France.

Human induced pluripotent stem (hiPS) cells could be used as an unlimited source of retinal cells for the treatment of retinal degenerative diseases. Although much progress has been made in the differentiation of pluripotent stem cells towards different retinal lineages, the production of retinal cells from hiPS cells for therapeutic approaches require the development of easy and standardized protocols. In this chapter, we describe a simple and effective protocol for retinal differentiation of hiPS cells bypassing embryoid body formation and the use of exogenous molecules and substrates. In 2 weeks, confluent hiPS cells cultured in pro-neural medium can generate both retinal pigmented epithelial cells and self-forming neural retina-like structures containing retinal progenitor cells. These progenitors can be differentiated into all retinal cell types, including retinal ganglion cells and precursors of photoreceptors, which could find important applications in regenerative medicine. This differentiation system and the resulting hiPS-derived retinal cells will also offer opportunity to study the molecular and cellular mechanisms underlying human retinal development, and the establishment of in vitro models of human retinal degenerative diseases.
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http://dx.doi.org/10.1007/7651_2014_143DOI Listing
October 2016

[Production of in vitro retina from pluripotent human stem cells: a new therapeutic tool].

Med Sci (Paris) 2014 Oct 14;30(10):845-8. Epub 2014 Oct 14.

Institut de la vision, Inserm U968 ; Sorbonne Universités, UPMC-Paris 6, UMR_S968 ; CNRS, UMR 7210, 75012 Paris, France.

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http://dx.doi.org/10.1051/medsci/20143010009DOI Listing
October 2014

From confluent human iPS cells to self-forming neural retina and retinal pigmented epithelium.

Proc Natl Acad Sci U S A 2014 Jun 27;111(23):8518-23. Epub 2014 May 27.

Institut de la Vision, Institut National de la Santé et de la Recherche Médicale, U968;Sorbonne Universités, Université Pierre-et-Marie-Curie Paris 6, Unité Mixte de Recherche S968;Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7210, 75012 Paris, France;

Progress in retinal-cell therapy derived from human pluripotent stem cells currently faces technical challenges that require the development of easy and standardized protocols. Here, we developed a simple retinal differentiation method, based on confluent human induced pluripotent stem cells (hiPSC), bypassing embryoid body formation and the use of exogenous molecules, coating, or Matrigel. In 2 wk, we generated both retinal pigmented epithelial cells and self-forming neural retina (NR)-like structures containing retinal progenitor cells (RPCs). We report sequential differentiation from RPCs to the seven neuroretinal cell types in maturated NR-like structures as floating cultures, thereby revealing the multipotency of RPCs generated from integration-free hiPSCs. Furthermore, Notch pathway inhibition boosted the generation of photoreceptor precursor cells, crucial in establishing cell therapy strategies. This innovative process proposed here provides a readily efficient and scalable approach to produce retinal cells for regenerative medicine and for drug-screening purposes, as well as an in vitro model of human retinal development and disease.
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http://dx.doi.org/10.1073/pnas.1324212111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4060726PMC
June 2014

Cis-silencing of PIP5K1B evidenced in Friedreich's ataxia patient cells results in cytoskeleton anomalies.

Hum Mol Genet 2013 Jul 2;22(14):2894-904. Epub 2013 Apr 2.

Hôpital Robert Debré, INSERM UMR 676 Faculté de Médecine Denis Diderot, Université Paris 7, 75019 Paris, France.

Friedreich's ataxia (FRDA) is a progressive neurodegenerative disease characterized by ataxia, variously associating heart disease, diabetes mellitus and/or glucose intolerance. It results from intronic expansion of GAA triplet repeats at the FXN locus. Homozygous expansions cause silencing of the FXN gene and subsequent decreased expression of the encoded mitochondrial frataxin. Detailed analyses in fibroblasts and neuronal tissues from FRDA patients have revealed profound cytoskeleton anomalies. So far, however, the molecular mechanism underlying these cytoskeleton defects remains unknown. We show here that gene silencing spreads in cis over the PIP5K1B gene in cells from FRDA patients (circulating lymphocytes and primary fibroblasts), correlating with expanded GAA repeat size. PIP5K1B encodes phosphatidylinositol 4-phosphate 5-kinase β type I (pip5k1β), an enzyme functionally linked to actin cytoskeleton dynamics that phosphorylates phosphatidylinositol 4-phosphate [PI(4)P] to generate phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2]. Accordingly, loss of pip5k1β function in FRDA cells was accompanied by decreased PI(4,5)P2 levels and was shown instrumental for destabilization of the actin network and delayed cell spreading. Knockdown of PIP5K1B in control fibroblasts using shRNA reproduced abnormal actin cytoskeleton remodeling, whereas over-expression of PIP5K1B, but not FXN, suppressed this phenotype in FRDA cells. In addition to provide new insights into the consequences of the FXN gene expansion, these findings raise the question whether PIP5K1B silencing may contribute to the variable manifestation of this complex disease.
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http://dx.doi.org/10.1093/hmg/ddt144DOI Listing
July 2013

Expression of rod-derived cone viability factor: dual role of CRX in regulating promoter activity and cell-type specificity.

PLoS One 2010 Oct 7;5(10):e13075. Epub 2010 Oct 7.

Department of Genetics, INSERM, U968, Paris, France.

Background: RdCVF and RdCVF2, encoded by the nucleoredoxin-like genes NXNL1 and NXNL2, are trophic factors with therapeutic potential that are involved in cone photoreceptor survival. Studying how their expression is regulated in the retina has implications for understanding both their activity and the mechanisms determining cell-type specificity within the retina.

Methodology/principal Findings: In order to define and characterize their promoters, a series of luciferase/GFP reporter constructs that contain various fragments of the 5'-upstream region of each gene, both murine and human, were tested in photoreceptor-like and non-photoreceptor cell lines and also in a biologically more relevant mouse retinal explant system. For NXNL1, 5'-deletion analysis identified the human -205/+57 bp and murine -351/+51 bp regions as having promoter activity. Moreover, in the retinal explants these constructs drove expression specifically to photoreceptor cells. For NXNL2, the human -393/+27 bp and murine -195/+70 bp regions were found to be sufficient for promoter activity. However, despite the fact that endogenous NXNL2 expression is photoreceptor-specific within the retina, neither of these DNA sequences nor larger upstream regions demonstrated photoreceptor-specific expression. Further analysis showed that a 79 bp NXNL2 positive regulatory sequence (-393 to 315 bp) combined with a 134 bp inactive minimal NXNL1 promoter fragment (-77 to +57 bp) was able to drive photoreceptor-specific expression, suggesting that the minimal NXNL1 fragment contains latent elements that encode cell-type specificity. Finally, based on bioinformatic analysis that suggested the importance of a CRX binding site within the minimal NXNL1 fragment, we found by mutation analysis that, depending on the context, the CRX site can play a dual role.

Conclusions/significance: The regulation of the Nucleoredoxin-like genes involves a CRX responsive element that can act as both as a positive regulator of promoter activity and as a modulator of cell-type specificity.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0013075PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2951342PMC
October 2010

The homeobox gene CHX10/VSX2 regulates RdCVF promoter activity in the inner retina.

Hum Mol Genet 2010 Jan 20;19(2):250-61. Epub 2009 Oct 20.

Department of Genetics, Institut de la Vision, INSERM Université Pierre et Marie Curie-Paris 6, UMR-S 968, Paris, France.

Rod-derived Cone Viability Factor (RdCVF) is a trophic factor with therapeutic potential for the treatment of retinitis pigmentosa, a retinal disease that commonly results in blindness. RdCVF is encoded by Nucleoredoxin-like 1 (Nxnl1), a gene homologous with the family of thioredoxins that participate in the defense against oxidative stress. RdCVF expression is lost after rod degeneration in the first phase of retinitis pigmentosa, and this loss has been implicated in the more clinically significant secondary cone degeneration that often occurs. Here, we describe a study of the Nxnl1 promoter using an approach that combines promoter and transcriptomic analysis. By transfection of selected candidate transcription factors, chosen based upon their expression pattern, we identified the homeodomain proteins CHX10/VSX2, VSX1 and PAX4, as well as the zinc finger protein SP3, as factors that can stimulate both the mouse and human Nxnl1 promoter. In addition, CHX10/VSX2 binds to the Nxnl1 promoter in vivo. Since CHX10/VSX2 is expressed predominantly in the inner retina, this finding motivated us to demonstrate that RdCVF is expressed in the inner as well as the outer retina. Interestingly, the loss of rods in the rd1 mouse, a model of retinitis pigmentosa, is associated with decreased expression of RdCVF by inner retinal cells as well as by rods. Based upon these results, we propose an alternative therapeutic strategy aimed at recapitulating RdCVF expression in the inner retina, where cell loss is not significant, to prevent secondary cone death and central vision loss in patients suffering from retinitis pigmentosa.
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http://dx.doi.org/10.1093/hmg/ddp484DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2796890PMC
January 2010