Retina

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Paschalis EI, Lei F, Zhou C, Chen XN, Kapoulea V, Hui P-C, Dana R, Chodosh J, Vavvas DG, Dohlman CH. Microglia Regulate Neuroglia Remodeling in Various Ocular and Retinal Injuries. J Immunol 2019;202(2):539-549.Abstract
Reactive microglia and infiltrating peripheral monocytes have been implicated in many neurodegenerative diseases of the retina and CNS. However, their specific contribution in retinal degeneration remains unclear. We recently showed that peripheral monocytes that infiltrate the retina after ocular injury in mice become permanently engrafted into the tissue, establishing a proinflammatory phenotype that promotes neurodegeneration. In this study, we show that microglia regulate the process of neuroglia remodeling during ocular injury, and their depletion results in marked upregulation of inflammatory markers, such as , , and in the retina, and abnormal engraftment of peripheral CCR2 CX3CR1 monocytes into the retina, which is associated with increased retinal ganglion cell loss, retinal nerve fiber layer thinning, and pigmentation onto the retinal surface. Furthermore, we show that other types of ocular injuries, such as penetrating corneal trauma and ocular hypertension also cause similar changes. However, optic nerve crush injury-mediated retinal ganglion cell loss evokes neither peripheral monocyte response in the retina nor pigmentation, although peripheral CX3CR1 and CCR2 monocytes infiltrate the optic nerve injury site and remain present for months. Our study suggests that microglia are key regulators of peripheral monocyte infiltration and retinal pigment epithelium migration, and their depletion results in abnormal neuroglia remodeling that exacerbates neuroretinal tissue damage. This mechanism of retinal damage through neuroglia remodeling may be clinically important for the treatment of patients with ocular injuries, including surgical traumas.
Pasovic L, Eidet JR, Olstad OK, Chen DF, Lyberg T, Utheim TP. Impact of Storage Temperature on the Expression of Cell Survival Genes in Cultured ARPE-19 Cells. Curr Eye Res 2017;42(1):134-144.Abstract

PURPOSE: The development of a suitable storage method for retinal pigment epithelium (RPE) is necessary in the establishment of future RPE replacement therapy, and storage temperature has proven to be pivotal for cell survival. ARPE-19, a widely used model for RPE, has been shown to yield the greatest number of viable cells when stored at 16°C compared to other storage temperatures. In this study, we analyze the gene expression profile of cultured ARPE-19 cells after seven days of storage at different temperatures in an effort to predict the gene-level consequences of storage of RPE transplants. MATERIALS AND METHODS: ARPE-19 cells were cultured until confluence and then stored in minimum essential medium at 4°C, 16°C, and 37°C for seven days. The total RNA was isolated and the gene expression profile was determined using DNA microarrays. The Results were validated using qPCR. RESULTS: Principal component and hierarchical clustering analyses show that the gene expression profiles of cell cultures stored at different temperatures cluster into separate groups. Cultures stored at 4°C cluster closest to the control cultures that were not stored and display the least change in gene expression after storage (157 differentially expressed genes). Cultures stored at 16°C and 37°C display a much larger change in differential gene expression (1787 and 1357 differentially expressed genes, respectively). At 16°C, the expression of several genes with proposed tumor suppressor functions was markedly increased. Changes in regulation of several known signaling pathways and of oxidative stress markers were discovered at both 16°C and 37°C, and activation of the angiogenesis marker vascular endothelial growth factor (VEGF) was discovered at 37°C. There was no evidence of the activation of inflammatory processes in stored cell cultures. CONCLUSION: ARPE-19 cultures stored at 16°C show the greatest propensity to modulate their gene expression profile in a manner that supports cell survival during storage.

Pasquale LR, Khawaja AP, Wiggs JL, Kim J, Hysi P, Elze T, Lasky-Su J, Kang JH, Zeleznik O, and Consortium UKBEV. Metabolite and Lipid Biomarkers Associated With Intraocular Pressure and Inner Retinal Morphology: 1H NMR Spectroscopy Results From the UK Biobank. Invest Ophthalmol Vis Sci 2023;64(11):11.Abstract
PURPOSE: The purpose of this study was to assess metabolites associated with intraocular pressure (IOP) and inner retina structure. METHODS: We cross-sectionally assessed 168 non-fasting plasma metabolites measured by nuclear magnetic resonance (NMR) spectroscopy with IOP (n = 28,195), macular retinal nerve fiber layer thickness (mRNFL; n = 10,584), and macular ganglion cell inner plexiform layer thickness (mGCIPL; n = 10,554) in the UK Biobank. We used multiple linear regression models adjusting for various covariates with probit-transformed metabolite levels as predictors for each outcome. Each estimate represents the difference in outcome variable per standard deviation increase in the probit-transformed metabolite values. We used the number of effective (NEF) tests and false discovery rate (FDR) to adjust for multiple comparisons for metabolites and metabolite classes, respectively. RESULTS: In individual metabolite analysis, multiple amino acids, especially branched-chain amino acids, were associated with lower IOP (-0.12 mm Hg; 95% confidence interval = -0.16 to -0.07; NEF = 2.7E-05). Albumin, 3 hydroxybutyrate, lactate, and several lipids were associated with higher IOP (range = 0.07 to 0.18 mm Hg, NEF = ≤ 0.039). In IOP-adjusted analyses, five HDL-related metabolites were associated with thinner mRNFL (-0.15 microns for all metabolites, NEF = ≤ 0.027), whereas five LDL-related metabolites were associated with thicker mGCIPL (range = 0.17 to 0.20 microns; NEF = ≤ 0.044). In metabolite class analysis, the lipid components of lipoproteins (cholesterol, triglycerides, etc.) were not associated with our outcomes (FDR > 0.2 for all); yet multiple lipoproteins were significantly (FDR < 0.05) associated with all outcomes. CONCLUSIONS: Branched-chain amino acids were associated with lower IOP, HDL metabolites were associated with thinner mRNFL, and LDL metabolites were associated with thicker mGCIPL.
Patel NA, Al-Khersan H, Yannuzzi NA, Lin J, Smiddy WE. Reply. Ophthalmol Retina 2024;8(2):e4.
Patel M, Vavvas DG. Fundus autofluorescence in ampiginous choroiditis. Ophthalmic Surg Lasers Imaging Retina 2013;44(4):393-7.Abstract
Fundus autofluorescence (FAF) is being increasingly employed in the evaluation of retinal diseases. We report the first description of FAF findings during the natural history of ampiginous choroiditis and correlate these findings to fundus photography, infrared imaging, and cross-sectional optical coherence tomography. In a patient with a 12-month recurring, relapsing course of ampiginous choroiditis, there was a predictable pattern of FAF findings. At the time of presentation with a whitish-yellow, creamy clinical lesion, FAF reveals a diffuse, subtle hyperautofluorescence at the site of activity. As the clinical lesion fades, the FAF takes on a more intense, discrete, coalesced hyperautofluorescence, which decreases and becomes stippled over time, eventually giving way to a patch of hypoautofluorescence at the site of inactivity. Examination over the patient's long course suggests that FAF evolves predictably during exacerbations and remissions, and the FAF findings reveal activity well after the clinical lesion resolves. FAF is a simple, noninvasive, and effective modality for following the evolution of ampiginous choroiditis.
Patel NA, Yannuzzi NA, Lin J, Smiddy WE. A Cost-Effectiveness Analysis of Intravitreal Aflibercept for the Prevention of Progressive Diabetic Retinopathy. Ophthalmol Retina 2022;6(3):213-218.Abstract
PURPOSE: To calculate costs required to prevent center-involved diabetic macular edema (CI-DME) or proliferative diabetic retinopathy (PDR), and to improve the diabetic retinopathy severity score (DRSS) with intravitreal anti-VEGF injections, as reported for aflibercept in 2 randomized control trials. DESIGN: Cost-effectiveness analysis modeling based on published data. SUBJECTS: None. METHODS: Results from PANORAMA and the Diabetic Retinopathy Clinical Research Network Protocol W were analyzed. Parameters collected included DRSS, risk reduction of PDR, risk reduction of CI-DME, and the number of treatments required. Costs were modeled based on 2020 Medicare reimbursement data practice settings of hospital-based facility and nonfacility. MAIN OUTCOME MEASURES: Cost to prevent cases of PDR and CI-DME and to improve DRSS stage. RESULTS: Over 2 years in Protocol W, the cost required to prevent 1 case of PDR was $83 000 ($72 400) in the facility (nonfacility) setting; in PANORAMA, the corresponding 2-year costs were $89 400 ($75 000) for the 2-mg aflibercept every 16 weeks (2Q16) arm, and $91 200 ($89 900) for the 2-mg aflibercept every 8 weeks as needed (2Q8PRN) arm. To prevent 1 case of CI-DME with vision loss in Protocol W, the cost was $154 000 ($133 000). For all CI-DME, with and without vision loss, in PANORAMA, the costs to prevent a case were $70 900 ($59 500) for the 2Q16 arm and $90 000 ($88 800) for the 2Q8PRN arm. In Protocol W, the overall accumulated total for cost/DRSS unit change at the 2-year point for facility (nonfacility) setting was $2700 ($2400)/DRSS. In the first year alone, it was $2100 ($1800)/DRSS and in the second year, it was $6100 ($5300)/DRSS. CONCLUSIONS: There is a considerable cost associated with the prevention of PDR and CI-DME with intravitreal aflibercept injections. A price per unit of change in DRSS is a new parameter that might serve as a benchmark in future utility analyses that could be used to bring the perspective to cost-utility considerations.
Patel NA, Acaba-Berrocal LA, Hoyek S, Fan KC, Martinez-Castellanos MA, Baumal CR, Harper AC, Berrocal AM, of (ROPIC) RPIC. Comparison in Retreatments between Bevacizumab and Ranibizumab Intravitreal Injections for Retinopathy of Prematurity: A Multicenter Study. Ophthalmology 2023;130(4):373-378.Abstract
PURPOSE: To compare the types and dosages of anti-vascular endothelial growth factors (VEGFs) to ascertain whether specific dosages or types of injection were associated with retreatment in clinical practice in the United States. DESIGN: Multicenter, retrospective, consecutive series. PARTICIPANTS: Patients with retinopathy of prematurity (ROP) treated with anti-VEGF injections from 2007 to 2021. METHODS: Sixteen sites from the United States participated. Data collected included demographics, birth characteristics, examination findings, type and dose of anti-VEGF treatment, retreatment rates, and time to retreatment. Comparisons of retreatment rates between bevacizumab and ranibizumab intravitreal injections were made. MAIN OUTCOME MEASURES: Relative rate of retreatment between varying types of anti-VEGF therapy, including bevacizumab and ranibizumab, and the various dosages used for each. RESULTS: Data from 873 eyes of 661 patients (61% male and 39% female) were collected. After exclusion of 40 eyes treated with laser before anti-VEGF injection and 266 eyes re-treated with laser at or beyond 8 weeks after the initial anti-VEGF treatment, 567 eyes of 307 patients (63% male and 37% female) remained and were included in the primary analysis. There was no difference between the no retreatment and retreatment groups in terms of birthweight, gestational age, age at first injection, ROP stages, or number of involved clock hours. The retreatment group had a larger percentage of aggressive ROP (34% vs. 18%, P < 0.001) and greater percentage of zone 1 ROP (49 vs. 34%, P = 0.001) than the no retreatment group. Ranibizumab use was associated with a higher rate of retreatment than bevacizumab use (58% vs. 37%, P < 0.001), whereas the rate of retreatment was not associated with a specific dose of ranibizumab (R2 = 0.67, P = 0.32). Meanwhile, lower doses of bevacizumab were associated with higher rates of retreatment compared with the higher doses (R2 = 0.84, P = 0.01). There was a dose-specific trend with higher doses trending toward lower retreatments for bevacizumab. CONCLUSIONS: In a multicenter study of ROP patients initially treated with anti-VEGF therapy, ranibizumab and lower-dose bevacizumab use were associated with an increased rate of retreatment when compared with higher-dose bevacizumab. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.
Patel NA, Acaba-Berrocal LA, Hoyek S, Fan KC, Martinez-Castellanos MA, Baumal CR, Harper AC, Berrocal AM, of Consortium RPI. Practice Patterns and Outcomes of Intravitreal Anti-VEGF Injection for Retinopathy of Prematurity: An International Multicenter Study. Ophthalmology 2022;129(12):1380-1388.Abstract
PURPOSE: To report practice patterns of intravitreal injections of anti-VEGF for retinopathy of prematurity (ROP) and outcomes data with a focus on retreatments and complications. DESIGN: Multicenter, international, retrospective, consecutive series. SUBJECTS: Patients with ROP treated with anti-VEGF injections from 2007 to 2021. METHODS: Twenfty-three sites (16 United States [US] and 7 non-US) participated. Data collected included demographics, birth characteristics, examination findings, and methods of injections. Comparisons between US and non-US sites were made. MAIN OUTCOME MEASURES: Primary outcomes included number and types of retreatments as well as complications. Secondary outcomes included specifics of the injection protocols, including types of medication, doses, distance from limbus, use of antibiotics, and quadrants where injections were delivered. RESULTS: A total of 1677 eyes of 918 patients (43% female, 57% male) were included. Mean gestational age was 25.7 weeks (range, 21.2-41.5 weeks), and mean birth weight was 787 g (range, 300-2700 g). Overall, a 30-gauge needle was most commonly used (51%), and the quadrant injected was most frequently the inferior-temporal (51.3%). The distance from the limbus ranged from 0.75 to 2 mm, with 1 mm being the most common (65%). Bevacizumab was the most common anti-VEGF (71.4%), with a dose of 0.625 mg in 64% of cases. Overall, 604 (36%) eyes required retreatment. Of those, 79.8% were retreated with laser alone, 10.6% with anti-VEGF injection alone, and 9.6% with combined laser and injection. Complications after anti-VEGF injections occurred in 15 (0.9%) eyes, and no cases of endophthalmitis were reported. Patients in the United States had lower birth weights and gestational ages (665.6 g and 24.5 weeks, respectively) compared with non-US patients (912.7 g and 26.9 weeks, respectively) (P < 0.0001). Retreatment with reinjection and laser was significantly more common in the US compared with the non-US group (8.5% vs. 4.7% [P = 0.0016] and 55% vs. 7.2% [P < 0.001], respectively). There was no difference in the incidence of complications between the 2 geographic subgroups. CONCLUSIONS: Anti-VEGF injections for ROP were safe and well tolerated despite a variance in practice patterns. Infants with ROP receiving injections in the US tended to be younger and smaller, and they were treated earlier with more retreatments than non-US neonates with ROP.
Patel AV, Papakostas TD, Vavvas DG. Under the Guise of Retinitis. JAMA Ophthalmol 2015;133(10):1205-6.
Patel NA, Hoyek S, Al-Khersan H, Fan KC, Yannuzzi NA, Davila J, Berrocal AM. Retinopathy of Prematurity Outcomes of Neonates Meeting Only a Single Screening Criterion: Proposal of the TWO-ROP Algorithm. Am J Ophthalmol 2023;252:147-152.Abstract
PURPOSE: To assess the rates of retinopathy of prematurity (ROP) and treatment-warranted ROP in a modern set of patients meeting 0 or 1 of the current ROP screening criteria. DESIGN: Retrospective cohort study. METHODS: Single-center study of 9350 infants screened for ROP from 2009 to 2019. Rates of ROP and treatment-warranted ROP were evaluated in group 1 (birth weight [BW] <1500 g and gestational age [GA] ≥30 weeks), group 2 (BW ≥1500 g and GA <30 weeks), and group 3 (BW ≥1500 g and GA ≥30 weeks). RESULTS: Of 7520 patients with reported BW and GA, 1612 (21.4%) patients met the inclusion criteria. The number of patients in groups 1, 2, and 3 was 466 (6.19%), 23 (0.31%), and 1123 (14.93%), respectively. The number of patients diagnosed with ROP was 20 (4.29%) in group 1, 1 (4.35%) in group 2, and 12 (1.07%) in group 3 (P < .001). The mean interval between birth and ROP diagnosis was 36.25 days (range 12-75 days) in group 1, 47 days in group 2, and 23.33 days (range 10-39 days) in group 3 (P = .05). No cases of stage 3, zone 1, or plus disease were recorded. No patients met the treatment criteria. CONCLUSIONS: Patients meeting 1 screening criterion had a low rate of ROP (<5%), with no stage 3, zone 1, or plus disease. No patients required treatment. We propose a possible algorithm (TWO-ROP) in appropriate neonatal intensive care units, with an amendment in screening protocol for this low-risk population to include only an outpatient screening examination within 1 week of discharge, or at 40 weeks if inpatient, to decrease the inpatient ROP screening burden while maintaining safety. Further external validation of this protocol would be required.
Pauleikhoff L, Boneva S, Boeck M, Schlecht A, Schlunck G, Agostini H, Lange C, Wolf J. Transcriptional Comparison of Human and Murine Retinal Neovascularization. Invest Ophthalmol Vis Sci 2023;64(15):46.Abstract
PURPOSE: Retinal neovascularization (RNV) is the leading cause of vision loss in diseases like proliferative diabetic retinopathy (PDR). A significant failure rate of current treatments indicates the need for novel treatment targets. Animal models are crucial in this process, but current diabetic retinopathy models do not develop RNV. Although the nondiabetic oxygen-induced retinopathy (OIR) mouse model is used to study RNV development, it is largely unknown how closely it resembles human PDR. METHODS: We therefore performed RNA sequencing on murine (C57BL/6J) OIR retinas (n = 14) and human PDR RNV membranes (n = 7) extracted during vitrectomy, each with reference to control tissue (n=13/10). Differentially expressed genes (DEG) and associated biological processes were analyzed and compared between human and murine RNV to assess molecular overlap and identify phylogenetically conserved factors. RESULTS: In total, 213 murine- and 1223 human-specific factors were upregulated with a small overlap of 94 DEG (7% of human DEG), although similar biological processes such as angiogenesis, regulation of immune response, and extracellular matrix organization were activated in both species. Phylogenetically conserved mediators included ANGPT2, S100A8, MCAM, EDNRA, and CCR7. CONCLUSIONS: Even though few individual genes were upregulated simultaneously in both species, similar biological processes appeared to be activated. These findings demonstrate the potential and limitations of the OIR model to study human PDR and identify phylogenetically conserved potential treatment targets for PDR.
Pearsall EA, Connor KM. Atypical Protein Kinase C: Breaking Down Barriers in Ocular Disease?. Am J Pathol 2018;188(10):2142-2146.Abstract
This commentary highlights the article by Lin et al that demonstrates the therapeutic potential of small-molecule atypical protein kinase C inhibitors in inflammatory ocular disease.
Peiris TJ, El Rami HE, Sun JK. CENTRAL SEROUS CHORIORETINOPATHY ASSOCIATED WITH STEROID ENEMA. Retin Cases Brief Rep 2021;15(1):15-17.Abstract
BACKGROUND/PURPOSE: To report a case of acute recurrent central serous chorioretinopathy that developed after a regimen of corticosteroid enemas and suppositories. METHODS: Observational case report. Fluorescein angiography and spectral domain optical coherence tomography. RESULTS: A 47-year-old male patient with ulcerative colitis managed through hydrocortisone enemas presented to clinic with a 1-day history of blurry vision of his left eye. Posterior segment examination revealed subretinal fluid in the superotemporal macula of the left eye extending centrally. After diagnosis of acute central serous chorioretinopathy, the patient was advised to taper steroid enemas and his visual symptoms and subretinal fluid resolved within the month. Seven years later, several months after using steroid suppositories for the first time since the original central serous chorioretinopathy episode, asymptomatic subretinal fluid accumulation with foveal sparing was found on routine ophthalmic examination. Three months later, most of this fluid had resolved with minimal residual subretinal fluid on clinical examination. CONCLUSION: Acute central serous chorioretinopathy may develop after corticosteroid enema or suppository use, a route of administration that has not been previously reported in association with the disease.
Peiris TJ, Indaram M, Koo E, Soul JS, Hunter DG. Congenital muscular dystrophy-dystroglycanopathy, type A, featuring bilateral retinal dysplasia and vertical angle kappa. J AAPOS 2018;22(3):242-244.e1.Abstract
Muscular dystrophy-dystroglycanopathy type A (MDDGA3), one of a group of diseases collectively known as congenital muscular dystrophies, is an alpha-dystroglycanopathy with characteristic brain and ocular abnormalities. We report the case of a 9-month-old boy with developmental delay whose family sought evaluation for esotropia. Subsequent examination, imaging, and testing revealed significant motor and cognitive delay, marked weakness with appendicular spasticity, and a diffuse brain malformation. In addition, the patient had poor visual acuity, nystagmus, optic nerve hypoplasia, bilateral retinal dysplasia and retinal dragging with a large vertical angle kappa, and an avascular peripheral retina. Genetic testing revealed two known heterozygous mutations in the POMGnT1 gene confirming MDDGA3. He was treated with botulinum toxin injections for his strabismus and continues to be followed, with planned laser ablation of the peripheral avascular retina.
Peng Y-R, Shekhar K, Yan W, Herrmann D, Sappington A, Bryman GS, van Zyl T, Do MTH, Regev A, Sanes JR. Molecular Classification and Comparative Taxonomics of Foveal and Peripheral Cells in Primate Retina. Cell 2019;176(5):1222-1237.e22.Abstract
High-acuity vision in primates, including humans, is mediated by a small central retinal region called the fovea. As more accessible organisms lack a fovea, its specialized function and its dysfunction in ocular diseases remain poorly understood. We used 165,000 single-cell RNA-seq profiles to generate comprehensive cellular taxonomies of macaque fovea and peripheral retina. More than 80% of >60 cell types match between the two regions but exhibit substantial differences in proportions and gene expression, some of which we relate to functional differences. Comparison of macaque retinal types with those of mice reveals that interneuron types are tightly conserved. In contrast, projection neuron types and programs diverge, despite exhibiting conserved transcription factor codes. Key macaque types are conserved in humans, allowing mapping of cell-type and region-specific expression of >190 genes associated with 7 human retinal diseases. Our work provides a framework for comparative single-cell analysis across tissue regions and species.
Pennock S, Kazlauskas A. Vascular endothelial growth factor A competitively inhibits platelet-derived growth factor (PDGF)-dependent activation of PDGF receptor and subsequent signaling events and cellular responses. Mol Cell Biol 2012;32(10):1955-66.Abstract
Certain platelet-derived growth factor (PDGF) isoforms are associated with proliferative vitreoretinopathy (PVR), a sight-threatening complication that develops in a subset of patients recovering from retinal reattachment surgery. Although these PDGF isoforms are abundant in the vitreous of patients and experimental animals with PVR, they make only a minor contribution to activating PDGF receptor α (PDGFRα) and driving experimental PVR. Rather, growth factors outside of the PDGF family are the primary (and indirect) agonists of PDGFRα. These observations beg the question of why vitreal PDGFs fail to activate PDGFRα. We report here that vitreous contains an inhibitor of PDGF-dependent activation of PDGFRα and that a major portion of this inhibitory activity is due to vascular endothelial cell growth factor A (VEGF-A). Furthermore, recombinant VEGF-A competitively blocks PDGF-dependent binding and activation of PDGFR, signaling events, and cellular responses. These findings unveil a previously unappreciated relationship between distant members of the PDGF/VEGF family that may contribute to pathogenesis of a blinding eye disease.
Pennock S, Kim D, Mukai S, Kuhnle M, Chun DW, Matsubara J, Cui J, Ma P, Maberley D, Samad A, Van Geest RJ, Oberstein SL, Schlingemann RO, Kazlauskas A. Ranibizumab is a potential prophylaxis for proliferative vitreoretinopathy, a nonangiogenic blinding disease. Am J Pathol 2013;182(5):1659-70.Abstract
Proliferative vitreoretinopathy (PVR) exemplifies a disease that is difficult to predict, lacks effective treatment options, and substantially reduces the quality of life of an individual. Surgery to correct a rhegmatogenous retinal detachment fails primarily because of PVR. Likely mediators of PVR are growth factors in vitreous, which stimulate cells within and behind the retina as an inevitable consequence of a breached retina. Three classes of growth factors [vascular endothelial growth factor A (VEGF-A), platelet-derived growth factors (PDGFs), and non-PDGFs (growth factors outside of the PDGF family)] are relevant to PVR pathogenesis because they act on PDGF receptor α, which is required for experimental PVR and is associated with this disease in humans. We discovered that ranibizumab (a clinically approved agent that neutralizes VEGF-A) reduced the bioactivity of vitreous from patients and experimental animals with PVR, and protected rabbits from developing disease. The apparent mechanism of ranibizumab action involved derepressing PDGFs, which, at the concentrations present in PVR vitreous, inhibited non-PDGF-mediated activation of PDGF receptor α. These preclinical findings suggest that available approaches to neutralize VEGF-A are prophylactic for PVR, and that anti-VEGF-based therapies may be effective for managing more than angiogenesis- and edema-driven pathological conditions.
Perepelkina T, Kegeles E, Baranov PY. Optimized conditions and use of synthetic matrix for retinal differentiation from pluripotent cells. Tissue Eng Part C Methods 2019;Abstract
PURPOSE: Since it was first introduced in 2011, three-dimensional "Sasai" method for retinal differentiation became a strategy of choice for retinal tissue and neuron production. It is based on the recapitulation of retinal development and requires several stages: aggregate formation, neuroectoderm induction, and eye field induction, followed by retinal maturation. In order to achieve the consistency of retinal differentiation needed for drug discovery and cell transplantation we have attempted to improve spheroid formation as well as approach xeno-free conditions. METHODS: In this study we compared the effect of cell culture plate shape and material, medium viscosity, lipid and bovine serum albumin concentrations on aggregate formation from mouse embryonic stem cells. We have also assessed the possibility of substituting Matrigel with the synthetic vitronectin-mimicking oligopeptide. RX-GFP mES cell line used for experiments. The dose-response of synthetic ECM has been assessed and quantified by live fluorescence microscopy, immunohistochemistry, flow cytometry and qPCR for early retinal development genes (Rx, Pax6, Lhx2, Sox2, Six6). RESULTS: The comparison of seeding conditions at 24hr. post seeding showed the dose-dependent effects of lipids (lipids concentration of 2% resulted in 100% efficiency of aggregate formation and significant increase in size to 532.8 ± 31.87um, p< 0.05); and viscosity (methylcellulose concentration of 0.06% in OV medium showed 100% efficiency and increase in aggregate size 532±19.23 um, p<0.01). The addition of synthetic matrix resulted in retinal differentiation (34.47% of RX as detected by flow cytometry compared to 33.8%, observed with Matrigel). The early retinal genes expression at day 7 was confirmed by qPCR. CONCLUSIONS: We present the optimized conditions for 3D retinal differentiation including the option of xeno-free extracellular matrix. These defined medium conditions significantly decrease the variability within and between batches and allow substantial scale up of retinal tissue and cell production for drug discovery, disease modeling and transplantation purposes.
Peterson SL, Li Y, Sun CJ, Wong KA, Leung KS, de Lima S, Hanovice NJ, Yuki K, Stevens B, Benowitz LI. Retinal Ganglion Cell Axon Regeneration Requires Complement and Myeloid Cell Activity within the Optic Nerve. J Neurosci 2021;41(41):8508-8531.Abstract
Axon regenerative failure in the mature CNS contributes to functional deficits following many traumatic injuries, ischemic injuries, and neurodegenerative diseases. The complement cascade of the innate immune system responds to pathogen threat through inflammatory cell activation, pathogen opsonization, and pathogen lysis, and complement is also involved in CNS development, neuroplasticity, injury, and disease. Here, we investigated the involvement of the classical complement cascade and microglia/monocytes in CNS repair using the mouse optic nerve injury (ONI) model, in which axons arising from retinal ganglion cells (RGCs) are disrupted. We report that central complement C3 protein and mRNA, classical complement C1q protein and mRNA, and microglia/monocyte phagocytic complement receptor CR3 all increase in response to ONI, especially within the optic nerve itself. Importantly, genetic deletion of C1q, C3, or CR3 attenuates RGC axon regeneration induced by several distinct methods, with minimal effects on RGC survival. Local injections of C1q function-blocking antibody revealed that complement acts primarily within the optic nerve, not retina, to support regeneration. Moreover, C1q opsonizes and CR3+ microglia/monocytes phagocytose growth-inhibitory myelin debris after ONI, a likely mechanism through which complement and myeloid cells support axon regeneration. Collectively, these results indicate that local optic nerve complement-myeloid phagocytic signaling is required for CNS axon regrowth, emphasizing the axonal compartment and highlighting a beneficial neuroimmune role for complement and microglia/monocytes in CNS repair.SIGNIFICANCE STATEMENT Despite the importance of achieving axon regeneration after CNS injury and the inevitability of inflammation after such injury, the contributions of complement and microglia to CNS axon regeneration are largely unknown. Whereas inflammation is commonly thought to exacerbate the effects of CNS injury, we find that complement proteins C1q and C3 and microglia/monocyte phagocytic complement receptor CR3 are each required for retinal ganglion cell axon regeneration through the injured mouse optic nerve. Also, whereas studies of optic nerve regeneration generally focus on the retina, we show that the regeneration-relevant role of complement and microglia/monocytes likely involves myelin phagocytosis within the optic nerve. Thus, our results point to the importance of the innate immune response for CNS repair.
Phadikar P, Saxena S, Ruia S, Lai TYY, Meyer CH, Eliott D. The potential of spectral domain optical coherence tomography imaging based retinal biomarkers. Int J Retina Vitreous 2017;3:1.Abstract

BACKGROUND: Biomarker", a merged word of "biological marker", refers to a broad subcategory of medical signs that objectively indicate the state of health, and well-being of an individual. Biomarkers hold great promise for personalized medicine as information gained from diagnostic or progression markers can be used to tailor treatment to the individual for highly effective intervention in the disease process. Optical coherence tomography (OCT) has proved useful in identifying various biomarkers in ocular and systemic diseases. MAIN BODY: Spectral domain optical coherence tomography imaging-based biomarkers provide a valuable tool for detecting the earlier stages of the disease, tracking progression, and monitoring treatment response. The aim of this review article is to analyze various OCT based imaging biomarkers and their potential to be considered as surrogate endpoints for diabetic retinopathy, age related macular degeneration, retinitis pigmentosa and vitreomacular interface disorder. These OCT based surrogate markers have been classified as retinal structural alterations (macular central subfield thickness and cube average thickness); retinal ultrastructural alterations (disruption of external limiting membrane and ellipsoid zone, thinning of retinal nerve fiber layer and ganglion cell layer); intraretinal microangiopathic changes; choroidal surrogate endpoints; and vitreoretinal interface endpoints. CONCLUSION: OCT technology is changing very quickly and throughout this review there are some of the multiple possibilities that OCT based imaging biomarkers will be more useful in the near future for diagnosis, prognosticating disease progression and as endpoint in clinical trials.

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