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Journal of Cellular and Molecular... Feb 2019Retinal Müller glial cells have the potential of neurogenic retinal progenitor cells, and could reprogram into retinal-specific cell types such as photoreceptor cells....
Retinal Müller glial cells have the potential of neurogenic retinal progenitor cells, and could reprogram into retinal-specific cell types such as photoreceptor cells. How to promote the differentiation of Müller cells into photoreceptor cells represents a promising therapy strategy for retinal degeneration diseases. This study aimed to enhance the transdifferentiation of rat Müller cells-derived retinal stem cells (MC-RSCs) into photoreceptor-like cells and explore the signalling mechanism. We dedifferentiated rat Müller cells into MC-RSCs which were infected with Otx2 overexpression lentivirus or control. The positive rate of photoreceptor-like cells among MC-RSCs treated with Otx2 overexpression lentivirus was significantly higher compared to control. Furthermore, pre-treatment with Crx siRNA, Nrl siRNA, or GSK-3 inhibitor SB-216763 reduced the positive rate of photoreceptor-like cells among MC-RSCs treated with Otx2 overexpression lentivirus. Finally, Otx2 induced photoreceptor precursor cells were injected into subretinal space of N-methyl-N-nitrosourea induced rat model of retinal degeneration and partially recovered retinal degeneration in the rats. In conclusion, Otx2 enhances transdifferentiation of MC-RSCs into photoreceptor-like cells and this is associated with the inhibition of Wnt signalling. Otx2 is a potential target for gene therapy of retinal degenerative diseases.
Topics: Animals; Cell Differentiation; Cell Transdifferentiation; Ependymoglial Cells; Female; Glycogen Synthase Kinase 3; Indoles; Lentivirus; Maleimides; Neurons; Otx Transcription Factors; Photoreceptor Cells; Rats; Rats, Sprague-Dawley; Retina; Retinal Degeneration; Stem Cells
PubMed: 30451368
DOI: 10.1111/jcmm.13995 -
Current Opinion in Cell Biology Oct 2014Optogenetics, the use of genetically encoded tools to control protein function with light, can generate localized changes in signaling within living cells and animals.... (Review)
Review
Optogenetics, the use of genetically encoded tools to control protein function with light, can generate localized changes in signaling within living cells and animals. For years it has been focused on channel proteins for neurobiology, but has recently expanded to cover many different types of proteins, using a broad array of different protein engineering approaches. These methods have largely been directed at proteins involved in motility, cytoskeletal regulation and gene expression. This review provides a survey of non-channel proteins that have been engineered for optogenetics. Existing molecules are used to illustrate the advantages and disadvantages of the many imaginative new approaches that the reader can use to create light-controlled proteins.
Topics: Animals; Cell Movement; Humans; Light; Optogenetics; Oxygen; Photoreceptor Cells; Phytochrome; Signal Transduction
PubMed: 25216352
DOI: 10.1016/j.ceb.2014.08.004 -
Advances in Experimental Medicine and... 2018Retinal degenerative diseases are a major cause of untreatable blindness due to a loss of photoreceptors. Recent advances in genetics and gene therapy for inherited... (Review)
Review
Retinal degenerative diseases are a major cause of untreatable blindness due to a loss of photoreceptors. Recent advances in genetics and gene therapy for inherited retinal dystrophies (IRDs) showed that therapeutic gene transfer holds a great promise for vision restoration in people with currently incurable blinding diseases. Due to the huge genetic heterogeneity of IRDs that represents a major obstacle for gene therapy development, alternative therapeutic approaches are needed. This review focuses on the rescue of cone function as a therapeutic option for maintaining central vision in rod-cone dystrophies. It highlights recent developments in better understanding the mechanisms of action of the trophic factor RdCVF and its potential as a sight-saving therapeutic strategy.
Topics: Alternative Splicing; Amino Acid Sequence; Cell Communication; Cone-Rod Dystrophies; Dependovirus; Eye Proteins; Genetic Heterogeneity; Genetic Therapy; Genetic Vectors; Glycolysis; Humans; Models, Molecular; Precision Medicine; Protein Conformation; Retinal Cone Photoreceptor Cells; Retinal Rod Photoreceptor Cells; Sequence Alignment; Sequence Homology, Amino Acid; Thioredoxins; Translational Research, Biomedical; Treatment Outcome
PubMed: 29721982
DOI: 10.1007/978-3-319-75402-4_62 -
Stem Cell Research & Therapy Aug 2021Retinal regenerative therapies hold great promise for the treatment of inherited retinal degenerations (IRDs). Studies in preclinical lower mammal models of IRDs have...
BACKGROUND
Retinal regenerative therapies hold great promise for the treatment of inherited retinal degenerations (IRDs). Studies in preclinical lower mammal models of IRDs have suggested visual improvement following retinal photoreceptor precursors transplantation, but there is limited evidence on the ability of these transplants to rescue retinal damage in higher mammals. The purpose of this study was to evaluate the therapeutic potential of photoreceptor precursors derived from clinically compliant induced pluripotent stem cells (iPSCs).
METHODS
Photoreceptor precursors were sub-retinally transplanted into non-human primates (Macaca fascicularis). The cells were transplanted both in naïve and cobalt chloride-induced retinal degeneration models who had been receiving systemic immunosuppression for one week prior to the procedure. Optical coherence tomography, fundus autofluorescence imaging, electroretinography, ex vivo histology and immunofluorescence staining were used to evaluate retinal structure, function and survival of transplanted cells.
RESULTS
There were no adverse effects of iPSC-derived photoreceptor precursors on retinal structure or function in naïve NHP models, indicating good biocompatibility. In addition, photoreceptor precursors injected into cobalt chloride-induced retinal degeneration NHP models demonstrated an ability both to survive and to mature into cone photoreceptors at 3 months post-transplant. Optical coherence tomography showed restoration of retinal ellipsoid zone post-transplantation.
CONCLUSIONS
These findings demonstrate the safety and therapeutic potential of clinically compliant iPSC-derived photoreceptor precursors as a cell replacement source for future clinical trials.
Topics: Animals; Humans; Induced Pluripotent Stem Cells; Photoreceptor Cells, Vertebrate; Primates; Retinal Cone Photoreceptor Cells; Retinal Degeneration
PubMed: 34412697
DOI: 10.1186/s13287-021-02539-8 -
Current Biology : CB Oct 2016A quick guide to the diverse and unusual eyes of polychaete fan worms, by Michael Bok and Dan-Eric Nilsson.
A quick guide to the diverse and unusual eyes of polychaete fan worms, by Michael Bok and Dan-Eric Nilsson.
Topics: Animals; Biological Evolution; Eye; Photoreceptor Cells, Invertebrate; Polychaeta
PubMed: 27780053
DOI: 10.1016/j.cub.2016.06.032 -
The International Journal of... 2021Photoreceptor cells of the vertebrate neural retina originate in the neuroepithelium, and like other neurons, must undergo cell body translocation and polarity...
Photoreceptor cells of the vertebrate neural retina originate in the neuroepithelium, and like other neurons, must undergo cell body translocation and polarity transitions to acquire their final functional morphology, which includes features of neuronal and epithelial cells. We analyzed this process in detail in zebrafish embryos using confocal microscopy and electron microscopy. Photoreceptor progenitors were labeled by the transgenic expression of enhanced green fluorescent protein under the regulation of the photoreceptor-specific promoter , and structures of interest were disrupted using morpholino oligomers to knock-down specific genes. Photoreceptor progenitors detached from the basal retina at pre-mitotic stages, rapidly retracting a short basal process as the cell body translocated apically. They remained at an apical position indefinitely to form the outer nuclear layer (ONL), initially extending and retracting highly dynamic neurite-like processes, tangential to the apical surface. Many photoreceptor progenitors presented a short apical primary cilium. The number and length of these cilia was gradually reduced until nearly disappearing around 60 hpf. Their disruption by knocking-down and caused a notorious defect on basal process retraction. To assess the role of cell adhesion in the organization of photoreceptor progenitors, we knocked-down /N-cadherin and observed the cell behavior by time-lapse microscopy. The ectopic photoreceptor progenitors initially migrated in an apparent random manner, profusely extending cell processes, until they encountered other cells to establish cell rosettes in which they stayed, acquiring photoreceptor-like polarity. Altogether, our observations indicate a complex regulation of photoreceptor progenitor dynamics to form the retinal ONL, previous to the post-mitotic maturation stages.
Topics: Animals; Cadherins; Cilia; Photoreceptor Cells; Retina; Zebrafish
PubMed: 32930348
DOI: 10.1387/ijdb.200113fz -
Neurotoxicity Research May 2018Antibiotics such as gentamicin (an aminoglycoside) and penicillin (a beta-lactam antibiotic) are routinely used in retinal cell and explant cultures. In many cases,...
Antibiotics such as gentamicin (an aminoglycoside) and penicillin (a beta-lactam antibiotic) are routinely used in retinal cell and explant cultures. In many cases, these in vitro systems are testing parameters regarding photoreceptor transplantation or preparing cells for transplantation. In vivo, milligram doses of gentamicin are neurotoxic to the retina. However, little is known about the effects of antibiotics to retina in vitro and whether smaller doses of gentamicin are toxic to retinal cells. To test toxicity, retinal cells were dissociated from tiger salamander, placed in culture, and treated with either 20 μg/ml gentamicin, 100 μg/ml streptomycin, 100 U/ml antibiotic/antimycotic, 0.25 μg/ml amphotericin B, or 100 U/ml penicillin G. All dosages were within manufacturer's recommended levels. Control cultures had defined medium only. Cells were fixed at 2 h or 7 days. Three criteria were used to assess toxicity: (1) survival of retinal neurons, (2) neuritic growth of photoreceptors assessed by the development of presynaptic varicosities, and (3) survival and morphology of Mueller cells. Rod cells were immunolabeled for rod opsin, Mueller cells for glial fibrillary acidic protein, and varicosities for synaptophysin. Neuronal cell density was reduced with all pharmacological treatments. The number of presynaptic varicosities was also significantly lower in both rod and cone photoreceptors in treated compared to control cultures; further, rods were more sensitive to gentamicin than cones. Penicillin G (100 U/ml) was overall the least inhibitory and amphotericin B the most toxic of all the agents to photoreceptors. Mueller cell survival was reduced with all treatments; reduced survival was accompanied by the appearance of proportionally fewer stellate and more rounded glial morphologies. These findings suggest that even microgram doses of antibiotic and antimycotic drugs can be neurotoxic to retinal cells and reduce neuritic regeneration in cell culture systems.
Topics: Analysis of Variance; Animals; Anti-Bacterial Agents; Cell Count; Cell Survival; Cells, Cultured; Ependymoglial Cells; Glial Fibrillary Acidic Protein; Neurons; Photoreceptor Cells; Presynaptic Terminals; Retina; Urodela
PubMed: 29098663
DOI: 10.1007/s12640-017-9826-6 -
ELife Apr 2022Electrical coupling, mediated by gap junctions, contributes to signal averaging, synchronization, and noise reduction in neuronal circuits. In addition, gap junctions...
Electrical coupling, mediated by gap junctions, contributes to signal averaging, synchronization, and noise reduction in neuronal circuits. In addition, gap junctions may also provide alternative neuronal pathways. However, because they are small and especially difficult to image, gap junctions are often ignored in large-scale 3D reconstructions. Here, we reconstruct gap junctions between photoreceptors in the mouse retina using serial blockface-scanning electron microscopy, focused ion beam-scanning electron microscopy, and confocal microscopy for the gap junction protein Cx36. An exuberant spray of fine telodendria extends from each cone pedicle (including blue cones) to contact 40-50 nearby rod spherules at sites of Cx36 labeling, with approximately 50 Cx36 clusters per cone pedicle and 2-3 per rod spherule. We were unable to detect rod/rod or cone/cone coupling. Thus, rod/cone coupling accounts for nearly all gap junctions between photoreceptors. We estimate a mean of 86 Cx36 channels per rod/cone pair, which may provide a maximum conductance of ~1200 pS, if all gap junction channels were open. This is comparable to the maximum conductance previously measured between rod/cone pairs in the presence of a dopamine antagonist to activate Cx36, suggesting that the open probability of gap junction channels can approach 100% under certain conditions.
Topics: Animals; Connexins; Gap Junctions; Ion Channels; Mice; Photoreceptor Cells, Vertebrate; Retina; Retinal Cone Photoreceptor Cells; Retinal Rod Photoreceptor Cells
PubMed: 35471186
DOI: 10.7554/eLife.73039 -
Scientific Reports Sep 2021Vertebrate photoreceptors contain large numbers of closely-packed mitochondria which sustain the high metabolic demands of these cells. These mitochondria populations...
Vertebrate photoreceptors contain large numbers of closely-packed mitochondria which sustain the high metabolic demands of these cells. These mitochondria populations are dynamic and undergo fusion and fission events. This activity serves to maintain the population in a healthy state. In the event of mitochondrial damage, sub-domains, or indeed whole mitochondria, can be degraded and population homeostasis achieved. If this process is overwhelmed cell death may result. Death of photoreceptors contributes to loss of vision in aging individuals and is associated with many eye diseases. In this study we used serial block face scanning electron microscopy of adult Macaca fascicularis retinae to examine the 3D structure of mitochondria in rod and cone photoreceptors. We show that healthy-looking photoreceptors contain mitochondria exhibiting a range of shapes which are associated with different regions of the cell. In some photoreceptors we observe mitochondrial swelling and other changes often associated with cellular stress. In rods and cones that appear stressed we identify elongated domains of mitochondria with densely-packed normal cristae associated with photoreceptor ciliary rootlet bundles. We observe mitochondrial fission and mitochondrion fragments localised to these domains. Swollen mitochondria with few intact cristae are located towards the periphery of the photoreceptor inner-segment in rods, whilst they are found throughout the cell in cones. Swollen mitochondria exhibit sites on the mitochondrial inner membrane which have undergone complex invagination resulting in membranous, electron-dense aggregates. Membrane contact occurs between the mitochondrion and the photoreceptor plasma membrane in the vicinity of these aggregates, and a series of subsequent membrane fusions results in expulsion of the mitochondrial aggregate from the photoreceptor. These events are primarily associated with rods. The potential fate of this purged material and consequences of its clearance by retinal pigment epithelia are discussed.
Topics: Animals; Cell Membrane; Imaging, Three-Dimensional; Macaca fascicularis; Microscopy, Electron, Scanning; Mitochondria; Mitochondrial Membranes; Retinal Cone Photoreceptor Cells; Retinal Rod Photoreceptor Cells
PubMed: 34552195
DOI: 10.1038/s41598-021-98409-7 -
Archivos de La Sociedad Espanola de... Jun 2021Our visual system has evolved to provide us with an image of the scene that surrounds us, informing us of its texture, colour, movement, and depth with an enormous... (Review)
Review
Our visual system has evolved to provide us with an image of the scene that surrounds us, informing us of its texture, colour, movement, and depth with an enormous spatial and temporal resolution, and for this purpose, the image formation (IF) dedicates the vast majority of our retinal ganglion cell (RGC) population and much of our cerebral cortex. On the other hand, a minuscule proportion of RGCs, in addition to receiving information from classic cone and rod photoreceptors, express melanopsin and are intrinsically photosensitive (ipRGC). These ipRGC are dedicated to non-image-forming (NIF) visual functions, of which we are unaware, but which are essential for aspects related to our daily physiology, such as the timing of our circadian rhythms and our pupillary light reflex, among many others. Before the discovery of ipRGCs, it was thought that the IF and NIF functions were distinct compartments regulated by different RGCs, but this concept has evolved in recent years with the discovery of new types of ipRGCs that innervate subcortical IF regions, and therefore have IF visual functions. Six different types of ipRGCs are currently known. These are termed M1-M6, and differ in their morphological, functional, molecular properties, central projections, and visual behaviour responsibilities. A review is presented on the melanopsin visual system, the most active field of research in vision, for which knowledge has grown exponentially during the last two decades, when RGCs giving rise to this pathway were first discovered.
Topics: Circadian Rhythm; Retinal Cone Photoreceptor Cells; Retinal Ganglion Cells; Retinal Rod Photoreceptor Cells; Vision, Ocular
PubMed: 34092284
DOI: 10.1016/j.oftale.2020.06.020