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Chichagova V, Hallam D, Collin J, Buskin A, Saretzki G, Armstrong L, Yu-Wai-Man P, Lako M, Steel DH. Human iPSC disease modelling reveals functional and structural defects in retinal pigment epithelial cells harbouring the m.3243A > G mitochondrial DNA mutation. Sci Rep 2017; 7:12320. [PMID: 28951556 PMCID: PMC5615077 DOI: 10.1038/s41598-017-12396-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 09/08/2017] [Indexed: 01/19/2023] Open
Abstract
The m.3243A > G mitochondrial DNA mutation was originally described in patients with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes. The phenotypic spectrum of the m.3243A > G mutation has since expanded to include a spectrum of neuromuscular and ocular manifestations, including reduced vision with retinal degeneration, the underlying mechanism of which remains unclear. We used dermal fibroblasts, from patients with retinal pathology secondary to the m.3243A > G mutation to generate heteroplasmic induced pluripotent stem cell (hiPSC) clones. RPE cells differentiated from these hiPSCs contained morphologically abnormal mitochondria and melanosomes, and exhibited marked functional defects in phagocytosis of photoreceptor outer segments. These findings have striking similarities to the pathological abnormalities reported in RPE cells studied from post-mortem tissues of affected m.3243A > G mutation carriers. Overall, our results indicate that RPE cells carrying the m.3243A > G mutation have a reduced ability to perform the critical physiological function of phagocytosis. Aberrant melanosomal morphology may potentially have consequences on the ability of the cells to perform another important protective function, namely absorption of stray light. Our in vitro cell model could prove a powerful tool to further dissect the complex pathophysiological mechanisms that underlie the tissue specificity of the m.3243A > G mutation, and importantly, allow the future testing of novel therapeutic agents.
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Affiliation(s)
- Valeria Chichagova
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, NE1 3BZ, United Kingdom
| | - Dean Hallam
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, NE1 3BZ, United Kingdom
| | - Joseph Collin
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, NE1 3BZ, United Kingdom
| | - Adriana Buskin
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, NE1 3BZ, United Kingdom
| | - Gabriele Saretzki
- Institute for Cell and Molecular Biosciences and The Ageing Biology Centre, Campus for Ageing and Vitality, Newcastle University, NE4 5PL, United Kingdom
| | - Lyle Armstrong
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, NE1 3BZ, United Kingdom
| | - Patrick Yu-Wai-Man
- Cambridge Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0PY, United Kingdom
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, CB2 0XY, United Kingdom
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, NE1 3BZ, United Kingdom
- NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, EC1V 2PD, United Kingdom
| | - Majlinda Lako
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, NE1 3BZ, United Kingdom.
| | - David H Steel
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, NE1 3BZ, United Kingdom.
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Lee CJ, Fishman HA, Bent SF. Spatial cues for the enhancement of retinal pigment epithelial cell function in potential transplants. Biomaterials 2007; 28:2192-201. [PMID: 17267030 DOI: 10.1016/j.biomaterials.2007.01.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2006] [Accepted: 01/04/2007] [Indexed: 12/27/2022]
Abstract
Retinal pigment epithelial (RPE) cellular morphology and function are vital to the health of the retina. In age-related macular degeneration, RPE dysfunction and changes in Bruch's membrane occur. Thus, a potential cure is a dual-layer biomimetic transplant consisting of a layer of healthy RPE cells cultured on a support membrane. In this study, we investigated human anterior lens capsule as a replacement for Bruch's membrane and also explored different seeding methods as ways of inducing the desired cellular morphology and function. Using in vitro assays, we demonstrated that RPE cells cultured on lens capsule exhibited epithelial characteristics, such as the presence of actin belts and the formation of tight junctions in the monolayer. Bovine photoreceptor outer segments were also incubated with the RPE cells in order to quantify the binding and ingestion activity of the RPE cells. With these assays, we determined that cells seeded by centrifugation appeared to possess the most epithelial-like morphology, with the shortest overall length and the smallest elongation. They also exhibited enhanced metabolic activity, with a 1.5-fold increase over conventional gravity seeding. Thus, the spatial cues provided by centrifugation may assist cells in assuming native RPE function. Therefore, a dual-layer transplant, with RPE cells organized by centrifugation onto lens capsule, appears promising in achieving native retinal function.
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Affiliation(s)
- Christina J Lee
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305-5025, USA
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Wilt SD, Greaton CJ, Lutz DA, McLaughlin BJ. Mannose receptor is expressed in normal and dystrophic retinal pigment epithelium. Exp Eye Res 1999; 69:405-11. [PMID: 10504274 DOI: 10.1006/exer.1999.0714] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In normal retinas, the phagocytosis of shed photoreceptor outer segments is mediated in part through a mannose receptor protein located in the apical retinal pigment epithelium membrane. As dystrophic rats of the Royal College of Surgeons have a defect in which the retinal pigment epithelium (RPE) is unable to phagocytize the shed outer segments, it is hypothesized that mannose receptor expression will be lost with the progression of photoreceptor degeneration. Immunohistochemical and molecular techniques have been used to study the developmental expression of the mannose receptor in normal and dystrophic retinal pigment epithelium. By immunofluorescence, the mannose receptor is localized to the retinal pigment epithelium, apical membrane region, beginning around 5 days postnatally in both normal and dystrophic retinas. In immunoblots, bands at 175 kDa are labelled by an anti-mannose receptor antibody in apical membrane samples from both normal and dystrophic RPE at all developmental times sampled. RT-PCR analysis reveals that mannose receptor message is present in normal and dystrophic RPE samples at all developmental time points examined. The present study demonstrates that the expression of the mannose receptor begins prior to outer segment differentiation and the initiation of phagocytosis in both normal and dystrophic RPE. Expression of the mannose receptor continues to be unchanged during the progression of photoreceptor degeneration in the dystrophic retina.
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Affiliation(s)
- S D Wilt
- Departments of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, Louisville, KY 40202, USA
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