Age-related macular degeneration: current treatments

Assessing REALTER simulator: analysis of ocular movements in simulated low-vision conditions with extended reality technology

Immersive technology, such as extended reality, holds promise as a tool for educating ophthalmologists about the effects of low vision and for enhancing visual rehabilitation protocols. However, immersive simulators have not been evaluated for their ability to induce changes in the oculomotor system, which is crucial for understanding the visual experiences of visually impaired individuals. This study aimed to assess the REALTER (Wearable Egocentric Altered Reality Simulator) system's capacity to induce specific alterations in healthy individuals' oculomotor systems under simulated low-vision conditions. We examined task performance, eye movements, and head movements in healthy participants across various simulated scenarios. Our findings suggest that REALTER can effectively elicit behaviors in healthy individuals resembling those observed in individuals with low vision. Participants with simulated binocular maculopathy demonstrated unstable fixations and a high frequency of wide saccades. Individuals with simulated homonymous hemianopsia showed a tendency to maintain a fixed head position while executing wide saccades to survey their surroundings. Simulation of tubular vision resulted in a significant reduction in saccade amplitudes. REALTER holds promise as both a training tool for ophthalmologists and a research instrument for studying low vision conditions. The simulator has the potential to enhance ophthalmologists' comprehension of the limitations imposed by visual disabilities, thereby facilitating the development of new rehabilitation protocols.

Potential oral VEGFR2 inhibitors: Treatment of wet age-related macular degeneration

Wet age-related macular degeneration (w-AMD) is one of the leading causes of vision loss in industrialized countries. A large body of evidence suggests that inhibitors targeting VEGFR2 may be effective in the treatment of w-AMD. The identification of an oral VEGFR2 inhibitor for the treatment of w-AMD provides an opportunity for a route of administration other than intravitreal injection. While screening potent VEGFR2 inhibitors at the enzyme and cellular levels, ensuring the safety of the compounds was our primary strategy for screening optimal compounds. Finally, compound 16 was identified, exhibiting enhanced inhibition of VEGFR2 enzyme and proliferation of BaF3-TEL-VEGFR2 cells compared to Vorolanib. Compound 16 had a weak inhibitory effect on human Ether-a-go-go-related gene (hERG) channel currents, showing a cardiac safety profile similar to Vorolanib. Compound 16 showed no significant toxicity to human liver cell LX-2, indicating a liver safety profile similar to Vorolanib. The water solubility of compound 16 was found to be higher than that of Vorolanib when tested at pH = 7.4. In addition, compound 16 was found to inhibit VEGFR2 phosphorylation in human umbilical vein endothelial cells (HUVECs) in a dose-dependent manner by WB assay. Furthermore, the in vitro preliminary evaluation of the drug-like properties of compound 16 showed remarkable plasma stability and moderate liver microsomal stability. Based on in vivo pharmacokinetic studies in ICR mice, compound 16 exhibited acceptable oral bioavailability (F = 20.2 %). Overall, these findings provide evidence that compound 16 is a leading potential oral drug candidate for w-AMD.

Age-Related Macular Degeneration - Therapies and Their Delivery

Age-related macular degeneration (ARMD) is a degenerative ocular disease that is the most important cause of irreversible vision loss in old-aged people in developed countries. Around fifty percent of vision impairments in developed countries are due to ARMD. It is a multifaceted disease that is associated with both genetic and environmental risk factors. The most important treatments option for ARMD includes laser photocoagulation, photodynamic therapy (PDT), Anti-VEGF Injections, and combination therapies. In this review, we also propose that topical ocular drug delivery with nanocarriers has more attention for the treatment of ARMD. The nanocarriers were specially designed for enhanced corneal residential time, prolonged drug release and action, and minimizing the frequency of administrations. Different types of nanocarriers were developed for the topical ocular delivery system, such as nanomicelles, nanoemulsions, nanosuspensions, liposomes, and polymeric nanoparticles. These topical ocular nanocarriers were administered topically, and they can fix the hydrophobic substances, increase solubility and improve the bioavailability of an administered drug. Hence the topical ocular delivery systems with nanocarriers provide a safe and effective therapeutic strategy and promising tool for the treatment of posterior segment ocular diseases ARMD.

Enhanced Biosafety of the Sleeping Beauty Transposon System by Using mRNA as Source of Transposase to Efficiently and Stably Transfect Retinal Pigment Epithelial Cells

Neovascular age-related macular degeneration (nvAMD) is characterized by choroidal neovascularization (CNV), which leads to retinal pigment epithelial (RPE) cell and photoreceptor degeneration and blindness if untreated. Since blood vessel growth is mediated by endothelial cell growth factors, including vascular endothelial growth factor (VEGF), treatment consists of repeated, often monthly, intravitreal injections of anti-angiogenic biopharmaceuticals. Frequent injections are costly and present logistic difficulties; therefore, our laboratories are developing a cell-based gene therapy based on autologous RPE cells transfected ex vivo with the pigment epithelium derived factor (PEDF), which is the most potent natural antagonist of VEGF. Gene delivery and long-term expression of the transgene are enabled by the use of the non-viral Sleeping Beauty (SB100X) transposon system that is introduced into the cells by electroporation. The transposase may have a cytotoxic effect and a low risk of remobilization of the transposon if supplied in the form of DNA. Here, we investigated the use of the SB100X transposase delivered as mRNA and showed that ARPE-19 cells as well as primary human RPE cells were successfully transfected with the Venus or the PEDF gene, followed by stable transgene expression. In human RPE cells, secretion of recombinant PEDF could be detected in cell culture up to one year. Non-viral ex vivo transfection using SB100X-mRNA in combination with electroporation increases the biosafety of our gene therapeutic approach to treat nvAMD while ensuring high transfection efficiency and long-term transgene expression in RPE cells.

Mapping residual stereopsis in macular degeneration

Individuals with macular degeneration typically lose vision in the central region of one or both eyes. A binocular scotoma occurs when vision loss occurs in overlapping locations in both eyes, but stereopsis is impacted even in the non-overlapping region wherever the visual field in either eye is affected. We used a novel stereoperimetry protocol to measure local stereopsis across the visual field (up to 25° eccentricity) to determine how locations with functional stereopsis relate to the scotomata in the two eyes. Participants included those with monocular or binocular scotomata and age-matched controls with healthy vision. Targets (with or without depth information) were presented on a random dot background. Depth targets had true binocular disparity of 20' (crossed), whereas non-depth targets were defined by monocular cues such as contrast and dot density. Participants reported target location and whether it was in depth or flat. Local depth sensitivity (d') estimates were then combined to generate a stereopsis map. This stereopsis map was compared to the union of the monocular microperimetry estimates that mapped out the functional extent of the scotoma in each eye. The "union" prediction aligned with residual stereopsis, showing impaired stereopsis within this region and residual stereopsis outside this region. Importantly, the stereoblind region was typically more extensive than the binocular scotoma defined by the intersection (overlap) of the scotomata. This explains why individuals may have intact binocular visual fields but be severely compromised in tasks of daily living that benefit from stereopsis, such as eye-hand coordination and navigation.

Retinol-binding protein 4 in obesity and metabolic dysfunctions

Excessive increased adipose tissue mass in obesity is associated with numerous co-morbid disorders including increased risk of type 2 diabetes, fatty liver disease, hypertension, dyslipidemia, cardiovascular diseases, dementia, airway disease and some cancers. The causal mechanisms explaining these associations are not fully understood. Adipose tissue is an active endocrine organ that secretes many adipokines, cytokines and releases metabolites. These biomolecules referred to as adipocytokines play a significant role in the regulation of whole-body energy homeostasis and metabolism by influencing and altering target tissues function. Understanding the mechanisms of adipocytokine actions represents a hot topic in obesity research. Among several secreted bioactive signalling molecules from adipose tissue and liver, retinol-binding protein 4 (RBP4) has been associated with systemic insulin resistance, dyslipidemia, type 2 diabetes and other metabolic diseases. Here, we aim to review and discuss the current knowledge on RBP4 with a focus on its role in the pathogenesis of obesity comorbid diseases.

The synthesis of the very long chain polyunsaturated fatty acid (VLC-PUFA) 32:6 n-3

This article describes the synthesis of VLC-PUFA 32:6 n-3, D2-labeled 32:6 n-3, and the uptake of 32:6 n-3 into mouse retinal tissue.

Eye Movements in Macular Degeneration

In healthy vision, the fovea provides high acuity and serves as the locus for fixation achieved through saccadic eye movements. Bilateral loss of the foveal regions in both eyes causes individuals to adopt an eccentric locus for fixation. This review deals with the eye movement consequences of the loss of the foveal oculomotor reference and the ability of individuals to use an eccentric fixation locus as the new oculomotor reference. Eye movements are an integral part of everyday activities, such as reading, searching for an item of interest, eye-hand coordination, navigation, or tracking an approaching car. We consider how these tasks are impacted by the need to use an eccentric locus for fixation and as a reference for eye movements, specifically saccadic and smooth pursuit eye movements. Expected final online publication date for the Annual Review of Vision Science, Volume 7 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Tissue engineering approaches towards the regeneration of biomimetic scaffolds for age-related macular degeneration

Age-related macular degeneration (AMD) is the third major cause of blindness in people aged above 60 years. It causes dysfunction of the retinal pigment epithelium (RPE) and leads to an irreversible loss of central vision. The present clinical treatment options are more palliative in controlling the progression of the disease and do not functionally restore the degenerated RPE monolayer and photoreceptors. Currently, the clinical transplantation of RPE cells has shown poor engraftment potential due to the absence of an intact Bruch's membrane in AMD patients, thereby the vision is unable to be restored completely. Although tissue engineering strategies target the development of Bruch's membrane-mimetic substrates, the challenge still lies in the development of an ultrathin, biologically and mechanically equivalent membrane to restore visual acuity. Further, existing limitations such as cellular aggregation, surgical complications including retinal tissue damage, tissue rejection, disease transmission, inferior mechanical strength, and the loss of vision over time demand the search for an ideal strategy to restore the functional RPE. Hence, this review aims to provide insights into various approaches, from conventional cell therapy to 3D bioprinting, and their unmet challenges in treating AMD by outlining the pathophysiology of AMD and the host tissue response with respect to injury, treatment and preclinical animal models.

Progress in developing rodent models of age-related macular degeneration (AMD)

Age-related macular degeneration (AMD) is the leading cause of irreversible central vision loss, typically affecting individuals from mid-life onwards. Its multifactorial aetiology and the lack of any effective treatments has spurred the development of animal models as research and drug discovery tools. Several rodent models have been developed which recapitulate key features of AMD and provide insights into its underlying pathology. These have contributed to making significant progress in understanding the disease and the identification of novel therapeutic targets. However, a major caveat with existing models is that they do not demonstrate the full disease spectrum. In this review, we outline advances in rodent AMD models from the last decade. These models feature various hallmarks associated with AMD, including oxidative stress, hypoxia, immune dysregulation, genetic mutations and environmental risk factors. The review summarises the methods by which each model was created, its pathological characteristics as well as its relation to the disease in humans.

Experimental Models in Neovascular Age Related Macular Degeneration

Neovascular age-related macular degeneration (vAMD), characterized by the neo-vascularization of the retro-foveolar choroid, leads to blindness within few years. This disease depends on angiogenesis mediated by the vascular endothelial growth factor A (VEGF) and to inflammation. The only available treatments consist of monthly intravitreal injections of antibodies directed against VEGF or VEGF/VEGFB/PlGF decoy receptors. Despite their relative efficacy, these drugs only delay progression to blindness and 30% of the patients are insensitive to these treatments. Hence, new therapeutic strategies are urgently needed. Experimental models of vAMD are essential to screen different innovative therapeutics. The currently used in vitro and in vivo models in ophthalmic translational research and their relevance are discussed in this review.

Protective effect of diphlorethohydroxycarmalol against oxidative stress-induced DNA damage and apoptosis in retinal pigment epithelial cells

Purpose: Reactive oxygen species (ROS) contribute to the onset and progression of disease pathogenesis in a variety of organs, including age-related macular degeneration (AMD). Diphlorethohydroxycarmalol (DPHC), a phlorotannin compound, is one of the major components of the brown alga Ishige okamurae Yendo, and has been shown to have strong antioxidant capacity. The purpose of this study was to evaluate the protective effects of DPHC against oxidative stress (hydrogen peroxide, H₂O₂)-induced DNA damage and apoptosis in cultured ARPE19 retinal pigment epithelial (RPE) cells. Materials and methods: Cell viability was assessed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide assay. Intracellular ROS generation was measured by flow cytometer using 2',7'-dichlorofluorescin diacetate. The magnitude of apoptosis was measured by flow cytometry using the annexin V/propidium iodide double staining. DNA damage was evaluated by DNA fragmentation assay, comet assay and 8-hydroxy-2'-deoxyguanosine (8-OHdG) analysis. To observe the mitochondrial membrane potential, 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethyl-imidacarbocyanine iodide staining was performed. In order to identify the underling mechanism of DPHC against H₂O₂-induced cellular alteration, we performed immune blotting. Results: The results of this study showed that the decreased survival rate brought about by H₂O₂ could be attributed to the induction of DNA damage and apoptosis accompanied by the increased production of ROS, which was remarkably reversed by DPHC. In addition, the loss of H₂O₂-induced mitochondrial membrane potential was significantly attenuated in the presence of DPHC. The inhibitory effect of DPHC on H₂O₂-induced apoptosis was associated with a reduced Bax/Bcl-2 ratio, the protection of the activation of caspase-9 and -3 and the inhibition of poly (ADP-ribose) polymerase cleavage, which was associated with the blockage of cytochrome c release to the cytoplasm. Conclusions: Our data proved that DPHC protects ARPE19 cells against H₂O₂-induced DNA damage and apoptosis by scavenging ROS and thus suppressing the mitochondrial-dependent apoptosis pathway. Therefore, this study suggests that DPHC has the therapeutic potential to prevent AMD by inhibiting oxidative stress-induced injury in RPE cells.

Use of Fundus Autofluorescence Combined with Optical Coherence Tomography for Diagnose of Geographic Atrophy in Age-Related Macular Degeneration

The aim of this study was to demonstrate the sensitivity of Optical coherence tomography (OCT) in detection of geographic atrophy (GA) secondary to exudative age related macular degeneration (AMD). In this retrospective case series study 77 patients (53% female, with mean ± standard deviation [SD] of 82.6±9.3 years) with 97 eyes (45 OS [left eyes]/52 OD [right eyes]) were included. This was a retrospective review of the charts of patients who presented with exudative AMD at the Pitié Salpetrière Hospital, Paris, France, between December 2016 and August 2017 that received intravitreal injections of anti-vascular endothelial growth factor (anti-VEGF) therapies. At baseline, following biomicroscopy examination, multimodal imaging was performed including, fluorescein angiography (FA), fundus auto-fluorescence (FAF), spectral domain optical coherence tomography (SD-OCT) and indocyanine green angiography (ICGA). During the follow-up, SD-OCT with/without FAF and FA were performed for each patient at 6, 12 and 18 months. For investigation of the prevalence of GA in eyes undergoing intravitreal injections with anti-VEGF therapy, FAF and SD-OCT images were qualitatively reviewed by four independent observers (two graders per group). Kappa coefficient of Cohen was calculated to determine agreement between the graders. The kappa coefficient of Cohen, for inter-rater agreement in the evaluation of FAF images was 0.468, indicating a moderate agreement between the first and second raters. Thus, the sensitivity and specificity of FAF for the diagnosis of GA were 70% and 57%, respectively. If atrophy was assessed with SD-OCT image analysis, the kappa coefficient for inter-rater agreement was 0.846, implying an acceptable agreement between both readers. The sensitivity and specificity of SD-OCT were 93% and 58% respectively. In conclusion, SD-OCT image analysis was more sensitive than FAF for identifying GA in patients treated for exudative AMD.

The Discovery of N-(1-Methyl-5-(trifluoromethyl)-1H-pyrazol-3-yl)-5-((6- ((methylamino)methyl)pyrimidin-4-yl)oxy)-1H-indole-1-carboxamide (Acrizanib), a VEGFR-2 Inhibitor Specifically Designed for Topical Ocular Delivery, as a Therapy for Neovascular Age-Related Macular Degeneration

A noninvasive topical ocular therapy for the treatment of neovascular or "wet" age-related macular degeneration would provide a patient administered alternative to the current standard of care, which requires physician administered intravitreal injections. This manuscript describes a novel strategy for the use of in vivo models of choroidal neovascularization (CNV) as the primary means of developing SAR related to efficacy from topical administration. Ultimately, this effort led to the discovery of acrizanib (LHA510), a small-molecule VEGFR-2 inhibitor with potency and efficacy in rodent CNV models, limited systemic exposure after topical ocular administration, multiple formulation options, and an acceptable rabbit ocular PK profile.

Translational considerations in injectable cell-based therapeutics for neurological applications: concepts, progress and challenges

Significant progress has been made during the past decade towards the clinical adoption of cell-based therapeutics. However, existing cell-delivery approaches have shown limited success, with numerous studies showing fewer than 5% of injected cells persisting at the site of injection within days of transplantation. Although consideration is being increasingly given to clinical trial design, little emphasis has been given to tools and protocols used to administer cells. The different behaviours of various cell types, dosing accuracy, precise delivery, and cell retention and viability post-injection are some of the obstacles facing clinical translation. For efficient injectable cell transplantation, accurate characterisation of cellular health post-injection and the development of standardised administration protocols are required. This review provides an overview of the challenges facing effective delivery of cell therapies, examines key studies that have been carried out to investigate injectable cell delivery, and outlines opportunities for translating these findings into more effective cell-therapy interventions.

Development and use of specific ELISA methods for quantifying the biological activity of bevacizumab, cetuximab and trastuzumab in stability studies

Bevacizumab (BVZ), cetuximab (CTX) and trastuzumab (TTZ) are monoclonal antibodies (mAbs) used worldwide for the treatment of several widespread kinds of cancer. They are marketed as medicines under their respective tradenames: Avastin(®), Erbitux(®) and Herceptin(®). The aim of this research was to develop in-house specific enzyme-linked immunosorbent assays (ELISA) to assess the long-term stability of these three mabs. These assays assess the biological functionality of the mAbs by quantifying their biological activity. For this purpose, we developed an indirect ELISA procedure whereby the specific antigens against which the mAbs are directed are used as specific "capturing" antibodies on the ELISA plates. We therefore used vascular endothelial growth factor (VEGF) in the ELISA for BVZ; human epidermal growth factor receptor (hEGFR) in the ELISA for CTX and human receptor HER2 (hHER2) in the ELISA for TTZ. After the mAbs had attached to their antigen, we used an anti-human IgG (whole molecule) peroxidase-conjugate and o-phenylenediaminedihydrochloride substrate. The reaction was stopped using sulphuric acid and absorbance was recorded at a wavelength of 450nm. The three ELISA methods were validated in terms of calibration models, range of the assay, limits of detection and quantitation, intra and interday precision and accuracy, and specificity by cross reactions. Forced degradation studies were also conducted on the medicines, providing useful information. Finally, the proposed ELISA were successfully used in a long-term stability study to quantify the remaining biological activity in medicines that had been opened and then stored under two different storage conditions, i.e. refrigerated at 4°C and frozen at -20°C. Results indicated that BVZ (Avastin(®)) is the most stable of the three in terms of its biological functionality.

Anxiety and depression in patients with advanced macular degeneration: current perspectives

Age-related macular degeneration (AMD) - despite advances in prevention and medical treatment options - remains prevalent among older adults, often resulting in functional losses that negatively affect the mental health of older adults. In particular, the prevalence of both anxiety and depression in patients with AMD is high. Along with medical treatment options, low vision rehabilitation and AMD-specific behavioral and self-management programs have been developed and have demonstrated effectiveness in improving the mental health of AMD patients. This article reviews the prevalence of anxiety and depression in patients with advanced AMD, discusses potential mechanisms accounting for the development of depression and anxiety in AMD patients, presents the state-of the-art of available interventions for addressing anxiety and depression in AMD patients, and delineates recommendations for eye care professionals regarding how to screen for these two prevalent mental health problems and how to facilitate appropriate treatment for patients with AMD.

Coaxial Electrospray of Ranibizumab-Loaded Microparticles for Sustained Release of Anti-VEGF Therapies

Age-related macular degeneration (AMD) is the leading cause of vision loss and blindness in people over age 65 in industrialized nations. Intravitreous injection of anti-VEGF (vascular endothelial growth factor) therapies, such as ranibizumab (trade name: Lucentis), provides an effective treatment option for neovascular AMD. We have developed an improved coaxial electrospray (CES) process to encapsulate ranibizumab in poly(lactic-co-glycolic) acid (PLGA) microparticles (MPs) for intravitreous injection and sustained drug release. This microencapsulation process is advantageous for maintaining the stability of the coaxial cone-jet configurations and producing drug-loaded MPs with as high as 70% encapsulation rate and minimal loss of bioactivitiy. The utility of this emerging process in intravitreous drug delivery has been demonstrated in both benchtop and in vivo experiments. The benchtop test simulates ocular drug release using PLGA MPs encapsulating a model drug. The in vivo experiment evaluates the inflammation and retinal cell death after intravitreal injection of the MPs in a chick model. The experimental results show that the drug-load MPs are able to facilitate sustained drug release for longer than one month. No significant long term microglia reaction or cell death is observed after intravitreal injection of 200 μg MPs. The present study demonstrates the technical feasibility of using the improved CES process to encapsulate water-soluble drugs at a high concentration for sustained release of anti-VEGF therapy.

Bicyclic [3.3.0]-Octahydrocyclopenta[c]pyrrolo Antagonists of Retinol Binding Protein 4: Potential Treatment of Atrophic Age-Related Macular Degeneration and Stargardt Disease

Antagonists of retinol-binding protein 4 (RBP4) impede ocular uptake of serum all-trans retinol (1) and have been shown to reduce cytotoxic bisretinoid formation in the retinal pigment epithelium (RPE), which is associated with the pathogenesis of both dry age-related macular degeneration (AMD) and Stargardt disease. Thus, these agents show promise as a potential pharmacotherapy by which to stem further neurodegeneration and concomitant vision loss associated with geographic atrophy of the macula. We previously disclosed the discovery of a novel series of nonretinoid RBP4 antagonists, represented by bicyclic [3.3.0]-octahydrocyclopenta[c]pyrrolo analogue 4. We describe herein the utilization of a pyrimidine-4-carboxylic acid fragment as a suitable isostere for the anthranilic acid appendage of 4, which led to the discovery of standout antagonist 33. Analogue 33 possesses exquisite in vitro RBP4 binding affinity and favorable drug-like characteristics and was found to reduce circulating plasma RBP4 levels in vivo in a robust manner (>90%).

Short-term results of switchback from aflibercept to ranibizumab in neovascular age-related macular degeneration in clinical practice

PURPOSE

This work was undertaken to analyze the efficacy of switchback from aflibercept to ranibizumab in patients with neovascular age-related macular degeneration (nAMD) who had previously switched from ranibizumab to aflibercept.

METHODS

This retrospective double-center study included 45 patients with nAMD who were previously treated with ranibizumab, then aflibercept, and then ranibizumab again, regardless of the number of intravitreal injections received. The primary outcome was change in best-corrected visual acuity (BCVA) measured on the Early Treatment Diabetic Retinopathy Study ETDRS chart before (T0) and after (T1) the switch, and 3 months after the switchback (T2). Secondary outcomes included changes in central foveal thickness (CFT) measured at T0, T1, and T2, as analyzed on spectral-domain optical coherence tomography (SD-OCT), and the percentage of patients gaining five letters or better.

RESULTS

Forty-seven eyes of 45 patients were switched back from aflibercept to ranibizumab. The mean BCVA was 67.4 ± 13.4 at T0, 66.7 ± 14.4 at T1, and 68.2 ± 13.9 at T2. BCVA was significantly improved between T1 and T2 (p = 0.0230), but not between T0 and T1 (p = 0.5153) or between T0 and T2 (p = 0.4248). The mean CFT decreased from 317.8 μm ± 89.6 at T0 to 306.9 μm ±68.0 at T1, and to 291.2 μm ± 76.6 at T2. The decrease in CFT was not statistically significant between either T0 and T1 or T1 and T2, but was significant between T0 and T2, when compared before switch and after switchback (p = 0.0027). However, when considering eyes that received three or more consecutive intravitreal injections of aflibercept before switchback, the statistical significance between T1 and T2 was lost, although a trend towards significance remained (p = 0.06). Thirteen eyes (27.7 %) gained five letters or more (range, 5-15 letters) after switchback.

CONCLUSIONS

A short-term benefit of switchback from one anti-VEGF agent to another was observed in patients with nAMD who had shown no benefit from the initial switch.

Management of neovascular age-related macular degeneration: current state-of-the-art care for optimizing visual outcomes and therapies in development

Contemporary management of neovascular age-related macular degeneration (AMD) has evolved significantly over the last few years. The goal of treatment is shifting from merely salvaging vision to maintaining a high quality of life. There have been significant breakthroughs in the identification of viable drug targets and gene therapies. Imaging tools with near-histological precision have enhanced our knowledge about pathophysiological mechanisms that play a role in vision loss due to AMD. Visual, social, and vocational rehabilitation are all important treatment goals. In this review, evidence from landmark clinical trials is summarized to elucidate the optimum modern-day management of neovascular AMD. Therapeutic strategies currently under development, such as gene therapy and personalized medicine, are also described.

Design, synthesis, and evaluation of nonretinoid retinol binding protein 4 antagonists for the potential treatment of atrophic age-related macular degeneration and Stargardt disease

Accumulation of lipofuscin in the retina is associated with pathogenesis of atrophic age-related macular degeneration and Stargardt disease. Lipofuscin bisretinoids (exemplified by N-retinylidene-N-retinylethanolamine) seem to mediate lipofuscin toxicity. Synthesis of lipofuscin bisretinoids depends on the influx of retinol from serum to the retina. Compounds antagonizing the retinol-dependent interaction of retinol-binding protein 4 (RBP4) with transthyretin in the serum would reduce serum RBP4 and retinol and inhibit bisretinoid formation. We recently showed that A1120 (3), a potent carboxylic acid based RBP4 antagonist, can significantly reduce lipofuscin bisretinoid formation in the retinas of Abca4^–/– mice. As part of the NIH Blueprint Neurotherapeutics Network project we undertook the in vitro exploration to identify novel conformationally flexible and constrained RBP4 antagonists with improved potency and metabolic stability. We also demonstrate that upon acute and chronic dosing in rats, 43, a potent cyclopentyl fused pyrrolidine antagonist, reduced circulating plasma RBP4 protein levels by approximately 60%.

Current treatment limitations in age-related macular degeneration and future approaches based on cell therapy and tissue engineering

Age-related macular degeneration (AMD) is the leading cause of blindness in the Western world. With an ageing population, it is anticipated that the number of AMD cases will increase dramatically, making a solution to this debilitating disease an urgent requirement for the socioeconomic future of the European Union and worldwide. The present paper reviews the limitations of the current therapies as well as the socioeconomic impact of the AMD. There is currently no cure available for AMD, and even palliative treatments are rare. Treatment options show several side effects, are of high cost, and only treat the consequence, not the cause of the pathology. For that reason, many options involving cell therapy mainly based on retinal and iris pigment epithelium cells as well as stem cells are being tested. Moreover, tissue engineering strategies to design and manufacture scaffolds to mimic Bruch's membrane are very diverse and under investigation. Both alternative therapies are aimed to prevent and/or cure AMD and are reviewed herein.

Choice of Cell Source in Cell-Based Therapies for Retinal Damage due to Age-Related Macular Degeneration: A Review

Background. Age-related macular degeneration (AMD) is a complex disorder that affects primarily the macula involving the retinal pigment epithelium (RPE) but also to a certain extent the photoreceptor layer and the retinal neurons. Cell transplantation is a promising option for AMD and clinical trials are underway using different cell types. Methods. We hypothesize that instead of focusing on a particular cell source for concurrent regeneration of all the retinal layers and also to prevent exhaustive research on an array of cell sources for regeneration of each layer, the choice should depend on, precisely, which layer is damaged. Results. Thus, for a damage limited to the retinal pigment epithelial (RPE) layer, the choice we suggest would be RPE cells. When the damage extends to rods and cones, the choice would be bone marrow stem cells and when retinal neurons are involved, relatively immature stem cell populations with an inherent capacity to yield neuronal lineage such as hematopoietic stem cells, embryonic stem cells, or induced pluripotent stem cells can be tried. Conclusion. This short review will prove to be a valuable guideline for those working on cell therapy for AMD to plan their future directions of research and therapy for this condition.

An Update on Intravitreal Injections for Macular Diseases: Friend or Foe?

The purpose of this article is to review the role of intravitreal injections of medications in the treatment of the two common macular diseases, macular edema and age related macular degeneration (AMD). We perform literature search by search engine Pubmed till May 2011, using keywords 'intravitreal injections', 'age-related macular degeneration' and 'macular edema' to retrieve relevant review articles and original papers. To conclude, with advance in technology, intravitreal injections of medications may have become an integral part of our ability to treat a wide range of macular diseases. The use of ranibizumab, pegaptanib in the treatment of neovascular AMD and TA in the treatment of various causes of macular edema have shown promising results in a number of prospective randomized controlled trials, with low risk of complications reported.

Ocular antisense oligonucleotide delivery by cationic nanoemulsion for improved treatment of ocular neovascularization: an in-vivo study in rats and mice

The efficacy of an antisense oligonucleotide (ODN17) cationic nanoemulsion directed at VEGF-R2 to reduce neovascularization was evaluated using rat corneal neovascularization and retinopathy of prematurity (ROP) mouse models. Application of saline solution or scrambled ODN17 solution on eyes of rats led to the highest extent of corneal neovascularization. The groups treated with blank nanoemulsion or scrambled ODN17 nanoemulsion showed moderate inhibition in corneal neovascularization with no significant difference with the saline and scrambled ODN17 control solution groups, while the groups treated with ODN17 solution or Avastin® (positive ODN17 control) clearly elicited marked significant inhibition in corneal neovascularization confirming the results reported in the literature. The highest significant corneal neovascularization inhibition efficiency was noted in the groups treated with ODN17 nanoemulsion (topical and subconjunctivally). However, in the ROP mouse model, the ODN17 in PBS induced a 34% inhibition of retinal neovascularization when compared to the aqueous-vehicle-injected eyes. A significantly higher inhibition of vitreal neovascularization (64%) was observed in the group of eyes treated with ODN17 nanoemulsion. No difference in extent of neovascularization was observed between blank nanoemulsion, scrambled ODN17 nanoemulsion, vehicle or non-treated eyes. The overall results indicate that cationic nanoemulsion can be considered a promising potential ocular delivery system and an effective therapeutic tool of high clinical significance in the prevention and forthcoming treatment of ocular neovascular diseases.

Complement component C5a promotes expression of IL-22 and IL-17 from human T cells and its implication in age-related macular degeneration

BACKGROUND

Age related macular degeneration (AMD) is the leading cause of irreversible blindness in elderly populations worldwide. Inflammation, among many factors, has been suggested to play an important role in AMD pathogenesis. Recent studies have demonstrated a strong genetic association between AMD and complement factor H (CFH), the down-regulatory factor of complement activation. Elevated levels of complement activating molecules including complement component 5a (C5a) have been found in the serum of AMD patients. Our aim is to study whether C5a can impact human T cells and its implication in AMD.

METHODS

Human peripheral blood mononuclear cells (PBMCs) were isolated from the blood of exudative form of AMD patients using a Ficoll gradient centrifugation protocol. Intracellular staining and enzyme-linked immunosorbent assays were used to measure protein expression. Apoptotic cells were detected by staining of cells with the annexin-V and TUNEL technology and analyzed by a FACS Caliber flow cytometer. SNP genotyping was analyzed by TaqMan genotyping assay using the Real-time PCR system 7500.

RESULTS

We show that C5a promotes interleukin (IL)-22 and IL-17 expression by human CD4+ T cells. This effect is dependent on B7, IL-1β and IL-6 expression from monocytes. We have also found that C5a could protect human CD4+ cells from undergoing apoptosis. Importantly, consistent with a role of C5a in promoting IL-22 and IL-17 expression, significant elevation in IL-22 and IL-17 levels was found in AMD patients as compared to non-AMD controls.

CONCLUSIONS

Our results support the notion that C5a may be one of the factors contributing to the elevated serum IL-22 and IL-17 levels in AMD patients. The possible involvement of IL-22 and IL-17 in the inflammation that contributes to AMD may herald a new approach to treat AMD.

Baicalein significantly protects human retinal pigment epithelium cells against H₂O₂-induced oxidative stress by scavenging reactive oxygen species and downregulating the expression of matrix metalloproteinase-9 and vascular endothelial growth factor

PURPOSE

Age-related macular degeneration is a leading cause of blindness in the elderly. At a later stage, neovascular or exudative age-related macular degeneration can lead to severe central vision loss that is related to aging-associated cumulative oxidative stress of the human retinal pigment epithelium (hRPE) cells. Early prevention with antioxidants is mandatory. The aim of this study was to determine whether and how baicalein can act as an antioxidant.

METHODS

The methods used included lactate dehydrogenase, 2′,7′-dichloro-fluorescein diacetate, or enzyme-linked immunosorbent assay to measure cell viability, oxygen free radical levels, or the levels of vascular endothelial growth factor (VEGF)/matrix metalloproteinase-9 (MMP-9), respectively.

RESULTS

H₂O₂ dose-dependently reduced the cell viability of hRPE cells. This negative effect was dose-dependently (with a lower effect at 20µM) and significantly counteracted by pretreatment with baicalein (50µM). Treatment with H₂O₂ significantly stimulated the formation of oxygen free radicals. This increase was dose-dependently and significantly blunted by baicalein. Further, treatment with a sublethal dose of H₂O₂ was associated with an upregulation in the levels of VEGF and MMP-9. The increases in these proteins were also dose-dependently (with a lower effect at 20µM) and significantly (50µM) blunted by pretreatment with baicalein.

CONCLUSION

This study supports an antioxidative role for baicalein whereby it protects hRPE cells against H₂O₂-induced oxidative stress by downregulating the levels of VEGF and MMP-9, which are increased by H₂O₂.

Dissection of cardiovascular development and disease pathways in zebrafish

The use of animal models in medicine has contributed significantly to the development of drug treatments and surgical procedures for the last century, in particular for cardiovascular disease. In order to model human disease in an animal, an appreciation of the strengths and limitations of the system are required to interpret results and design the logical sequence of steps toward clinical translation. As the world's population ages, cardiovascular disease will become even more prominent and further progress will be essential to stave off what seems destined to become a massive public health issue. Future treatments will require the imaginative application of current models as well as the generation of new ones. In this review, we discuss the resources available for modeling cardiovascular disease in zebrafish and the varied attributes of this system. We then discuss current zebrafish disease models and their potential that has yet to be exploited.

Association of age-related macular degeneration with age-related hearing loss

Objective:

To assess the association between age-related macular degeneration and age-related hearing loss in Turkish subjects aged 50 years or older.

Study design and setting:

Prospective, case–control study within a tertiary university hospital.

Subjects and methods:

Fifty subjects with age-related macular degeneration and 43 healthy subjects underwent ophthalmological and otolaryngological examination. Statistical analyses were conducted for the poorer eye and ear, comparing age-related hearing loss and pure tone average in the macular degeneration group versus controls.

Results:

Median pure tone average was significantly poorer in the macular degeneration group (35 dBHL) compared with controls (23 dBHL). In the macular degeneration group, hearing loss was significantly greater in dry type (43 dBHL) than wet type (32 dBHL) cases. There was a significant difference between the prevalence of varying degrees of hearing loss in the macular degeneration versus control groups, being respectively: mild, 50 and 35 per cent; moderate, 20 and 5 per cent; and severe, 6 and 0 per cent. There was a weak, but significant correlation between each patient's visual acuity and pure tone average results (rs = −0.37, p < 0.001).

Conclusion:

Age-related hearing loss is more common in patients with age-related macular degeneration. Such patients should be questioned regarding hearing difficulty, and referred to an otolaryngologist if appropriate.

Patient characteristics and treatment of neovascular age-related macular degeneration in France: the LUEUR1 observational study

BACKGROUND

Age-related macular degeneration is the primary cause of blindness in developed countries. Current treatments of this degenerative disease mainly include laser, photodynamic therapy with verteporfin and administration of anti-vascular endothelial growth factors. The LUEUR (LUcentis® En Utilisation Réelle) study is composed of a cross-sectional part (LUEUR1), which examined the current management of wet AMD in France, and a follow-up part (LUEUR2), which will assess the development of patients treated for wet AMD over 4 years. Here we describe the results of LUEUR1.

METHODS

Patients with wet AMD were enrolled during a routine medical examination in LUEUR1, a cross-sectional, observational, prospective, multicentre study. Investigators recorded patient demographics, visual acuity, characteristics of wet AMD lesions, date of AMD diagnosis, comorbidities, previous treatments, treatments prescribed at inclusion, and low vision rehabilitation.

RESULTS

A total of 72 investigators recruited 1,019 patients with wet AMD, corresponding to 1,405 eyes affected by the disease. The mean age of patients was 78.7 ± 7.3 years. Most were female (62.3%) and non-smokers (66.9%). The mean visual acuity was 49.12 ± 24.18 Early Treatment Diabetic Retinopathy Study letters. Most eyes showed occult (52.8%) and subfoveal (84.6%) choroidal neovascularisation. Bilateral wet AMD affected 37.9% of patients. The median time since diagnosis was 12 months. Ranibizumab-based therapy (67.3%) and photodynamic therapy (29.8%) were the most frequent previous treatments. Prior to inclusion, 5.6% of patients had low vision rehabilitation. When a treatment was prescribed on the day of inclusion, it was most often ranibizumab (89.0% of all treatments at inclusion).

CONCLUSIONS

The results of this study illustrate the impact of anti-vascular endothelial growth factor therapies on the treatment of wet AMD in a real-life context. Specifically, ranibizumab-based therapy appears to have largely replaced laser photocoagulation and verteporfin-based photodynamic therapy.

Multifunctional microbubbles for image-guided antivascular endothelial growth factor therapy

We synthesize multifunctional microbubbles (MBs) for targeted delivery of antivascular endothelial growth factor (antiVEGF) therapy with multimodal imaging guidance. Poly-lactic-co-glycolic acid (PLGA) MBs encapsulating Texas Red dye are fabricated by a modified double-emulsion process. Simultaneous ultrasound and fluorescence imaging are achieved using Texas Red encapsulated MBs. The MBs are conjugated with Avastin, an antiVEGF antibody for treating neovascular age-related macular degeneration (AMD). The conjugation efficiency is characterized by enzyme-linked immunosorbent assay (ELISA). The efficiency for targeted binding of Avastin-conjugated MBs is characterized by microscopic imaging. Our work demonstrates the technical potential of using multifunctional MBs for targeted delivery of antiVEGF therapy in the treatment of exudative AMD.