Biological drug therapy for ocular angiogenesis: Anti-VEGF agents and novel strategies based on nanotechnology

Sustained and Efficient Delivery of Antivascular Endothelial Growth Factor by the Adeno-associated Virus for the Treatment of Corneal Neovascularization: An Outlook for Its Clinical Translation

Corneal diseases represent 5.1% of all eye defects and are the fourth leading cause of blindness globally. Corneal neovascularization can arise from all conditions of chronic irritation or hypoxia, which disrupts the immune-privileged state of the healthy cornea, increases the risk of rejection after keratoplasty, and leads to opacity. In the past decades, significant progress has been made for neovascular diseases of the retina and choroid, with plenty of drugs getting commercialized. In addition, to overcome the barriers of the short duration and inadequate penetration of conventional formulations of antivascular endothelial growth factor (VEGF), multiple novel drug delivery systems, including adeno-associated virus (AAV)-mediated transfer have gone through the full process of bench-to-bedside translation. Like retina neovascular diseases, corneal neovascularization also suffers from chronicity and a high risk of recurrence, necessitating sustained and efficient delivery across the epithelial barrier to reach deep layers of the corneal stroma. Among the explored methods, adeno-associated virus-mediated delivery of anti-VEGF to treat corneal neovascularization is the most extensively researched and most promising strategy for clinical translation although currently although, it remains predominantly at the preclinical stage. This review comprehensively examines the necessity, benefits, and risks of applying AAV vectors for anti-VEGF drug delivery in corneal vascularization, including its current progress and challenges in clinical translation.

The impact of removing the epiretinal membrane and inner limiting membrane for sustained subretinal fluid by macular neovascularization refractory to anti-VEGF therapy

Purpose

Anti-vascular endothelial growth factor (VEGF) therapy is the most prevalent intervention for exudative lesions secondary to neovascular age-related macular degeneration (nAMD) and other macular neovascularization (MNV). However, in some cases refractory to the latest anti-VEGF agents is associated with epiretinal membrane (ERM) or vitreomacular traction. We applied a vitrectomy to remove those pathologies which may be effective for reducing the exudation.

Observations

In this case report, we present 2 cases with sustained subretinal fluid and macular neovascularization secondary to nAMD or dome-shaped macula that poorly responded to anti-VEGF therapy. In both cases, removing thin ERM or vitreomacular traction with an inner limiting membrane peeling promptly resolved the subretinal fluid and no recurrence was observed thereafter.

Conclusions and importance

Vitrectomy could be an effective modality for anti-VEGF drug-resistant MNV cases with vitreomacular traction or ERM even in the anti-VEGF era.

Innovative Nanotechnology in Drug Delivery Systems for Advanced Treatment of Posterior Segment Ocular Diseases

Funduscopic diseases, including diabetic retinopathy (DR) and age-related macular degeneration (AMD), significantly impact global visual health, leading to impaired vision and irreversible blindness. Delivering drugs to the posterior segment of the eye remains a challenge due to the presence of multiple physiological and anatomical barriers. Conventional drug delivery methods often prove ineffective and may cause side effects. Nanomaterials, characterized by their small size, large surface area, tunable properties, and biocompatibility, enhance the permeability, stability, and targeting of drugs. Ocular nanomaterials encompass a wide range, including lipid nanomaterials, polymer nanomaterials, metal nanomaterials, carbon nanomaterials, quantum dot nanomaterials, and so on. These innovative materials, often combined with hydrogels and exosomes, are engineered to address multiple mechanisms, including macrophage polarization, reactive oxygen species (ROS) scavenging, and anti-vascular endothelial growth factor (VEGF). Compared to conventional modalities, nanomedicines achieve regulated and sustained delivery, reduced administration frequency, prolonged drug action, and minimized side effects. This study delves into the obstacles encountered in drug delivery to the posterior segment and highlights the progress facilitated by nanomedicine. Prospectively, these findings pave the way for next-generation ocular drug delivery systems and deeper clinical research, aiming to refine treatments, alleviate the burden on patients, and ultimately improve visual health globally.

Incorporation of immunotherapies and nanomedicine to better normalize angiogenesis-based cancer treatment

Neoadjuvant targeting of tumor angiogenesis has been developed and approved for the treatment of malignant tumors. However, vascular disruption leads to tumor hypoxia, which exacerbates the treatment process and causes drug resistance. In addition, successful delivery of therapeutic agents and efficacy of radiotherapy require normal vascular networks and sufficient oxygen, which complete tumor vasculopathy hinders their efficacy. In view of this controversy, an optimal dose of FDA-approved anti-angiogenic agents and combination with other therapies, such as immunotherapy and the use of nanocarrier-mediated targeted therapy, could improve therapeutic regimens, reduce the need for administration of high doses of chemotherapeutic agents and subsequently reduce side effects. Here, we review the mechanism of anti-angiogenic agents, highlight the challenges of existing therapies, and present how the combination of immunotherapies and nanomedicine could improve angiogenesis-based tumor treatment.

Niosome-encapsulated auraptene reduced the mRNA expression of VEGF-A and PDGFs genes in human retina-derived RPE cell line

AIM

To evaluate the effect of auraptene (AUR) treatment in forms of free and encapsulated in niosome nanoparticles by investigating the mRNA expression level of vascular endothelium growth factor (VEGF)-A and platelet-derived growth factors (PDGFs) in human retinal pigment epithelium (RPE) cell line.

METHODS

Niosome nanocarriers were produced using two surfactants Span 60 and Tween 80. RPE cell line was treated with both free AUR and niosome-encapsulated. Optimum dosage of treatments was calculated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Expression of VEGF-A and PDGF-A, PDGF-B, PDGF-C, PDGF-D genes was measured after total RNA extraction and cDNA synthesis, using real-time polymerase chain reaction (RT-PCR).

RESULTS

The highest entrapment efficiency (EE) was achieved by Span 60:cholesterol (1:1) with 64.3%. The half maximal inhibitory concentration (IC50) of free and niosome-encapsulated AUR were 38.5 and 27.78 µg/mL, respectively. Release study revealed that niosomal AUR had more gradual delivery to the cells. RT-PCR results showed reduced expression levels of VEGF-A, PDGF-A, PDGF-B, PDGF-C, and PDGF-D after treatment with both free and niosomal AUR.

CONCLUSION

Niosomal formulation of Span 60: cholesterol (1:1) is an effective drug delivery approach to transfer AUR to RPE cells. VEGF-A, PDGF-A, PDGF-B, PDGF-C, and PDGF-D are four angiogenic factors, inhibiting which by niosomal AUR may be effective in age-related macular degeneration.

Fostering the unleashing potential of nanocarriers-mediated delivery of ocular therapeutics

Ocular delivery is the most challenging aspect in the field of pharmaceutical research. The major hurdle for the controlled delivery of drugs to the eye includes the physiological static barriers such as the complex layers of the cornea, sclera and retina which restrict the drug from permeating into the anterior and posterior segments of the eye. Recent years have witnessed inventions in the field of conventional and nanocarrier drug delivery which have shown considerable enhancement in delivering small to large molecules across the eye. The dynamic challenges associated with conventional systems include limited drug contact time and inadequate ocular bioavailability resulting from solution drainage, tear turnover, and dilution or lacrimation. To this end, various bioactive-based nanosized carriers including liposomes, ethosomes, niosomes, dendrimer, nanogel, nanofibers, contact lenses, nanoprobes, selenium nanobells, nanosponge, polymeric micelles, silver nanoparticles, and gold nanoparticles among others have been developed to circumvent the limitations associated with the conventional dosage forms. These nanocarriers have been shown to achieve enhanced drug permeation or retention and prolong drug release in the ocular tissue due to their better tissue adherence. The surface charge and the size of nanocarriers (10-1000 nm) are the important key factors to overcome ocular barriers. Various nanocarriers have been shown to deliver active therapeutic molecules including timolol maleate, ampicillin, natamycin, voriconazole, cyclosporine A, dexamethasone, moxifloxacin, and fluconazole among others for the treatment of anterior and posterior eye diseases. Taken together, in a nutshell, this extensive review provides a comprehensive perspective on the numerous facets of ocular drug delivery with a special focus on bioactive nanocarrier-based approaches, including the difficulties and constraints involved in the fabrication of nanocarriers. This also provides the detailed invention, applications, biodistribution and safety-toxicity of nanocarriers-based therapeutcis for the ophthalmic delivery.

Polymeric Nanoparticles for Retinal Drug Delivery

This is an Editorial and does not have an abstract. Please download the PDF or view the article in HTML.

Experimental and mathematical approaches for drug delivery for the treatment of wet age-related macular degeneration

Several chronic eye diseases affect the posterior segment of the eye. Among them age-related macular degeneration can cause vision loss if left untreated and is one of the leading causes of visual impairment in the world. Most treatments are based on intravitreally injected therapeutics that inhibit the action of vascular endothelial growth factor. However, due to the need for monthly injections, this method is associated with poor patient compliance. To address this problem, numerous drug delivery systems (DDSs) have been developed. This review covers a selection of particulate systems, non-stimuli responsive hydrogels, implants, and composite systems that have been developed in the last few decades. Depending on the type of DDS, polymer material, and preparation method, different mechanical properties and drug release profiles can be achieved. Furthermore, DDS development can be optimized by implementing mathematical modeling of both drug release and pharmacokinetic aspects. Several existing mathematical models for diffusion-controlled, swelling-controlled, and erosion-controlled drug delivery from polymeric systems are summarized. Compartmental and physiologically based models for ocular drug transport and pharmacokinetics that have studied drug concentration profiles after intravitreal delivery or release from a DDS are also reviewed. The coupling of drug release models with ocular pharmacokinetic models can lead to obtaining much more efficient DDSs for the treatment of age-related macular degeneration and other diseases of the posterior segment of the eye.

An Update on Strategies to Deliver Protein and Peptide Drugs to the Eye

In the past few decades, advancements in protein engineering, biotechnology, and structural biochemistry have resulted in the discovery of various techniques that enhanced the production yield of proteins, targetability, circulating half-life, product purity, and functionality of proteins and peptides. As a result, the utilization of proteins and peptides has increased in the treatment of many conditions, including ocular diseases. Ocular delivery of large molecules poses several challenges due to their high molecular weight, hydrophilicity, unstable nature, and poor permeation through cellular and enzymatic barriers. The use of novel strategies for delivering protein and peptides such as glycoengineering, PEGylation, Fc-fusion, chitosan nanoparticles, and liposomes have improved the efficacy, safety, and stability, which consequently expanded the therapeutic potential of proteins. This review article highlights various proteins and peptides that are useful in ocular disorders, challenges in their delivery to the eye, and strategies to enhance ocular bioavailability using novel delivery approaches. In addition, a few futuristic approaches that will assist in the ocular delivery of proteins and peptides were also discussed.

Immunotherapies targeting tumor vasculature: challenges and opportunities

Angiogenesis is a hallmark of cancer biology, and neoadjuvant therapies targeting either tumor vasculature or VEGF signaling have been developed to treat solid malignant tumors. However, these therapies induce complete vascular depletion leading to hypoxic niche, drug resistance, and tumor recurrence rate or leading to impaired delivery of chemo drugs and immune cell infiltration at the tumor site. Achieving a balance between oxygenation and tumor growth inhibition requires determining vascular normalization after treatment with a low dose of antiangiogenic agents. However, monotherapy within the approved antiangiogenic agents' benefits only some tumors and their efficacy improvement could be achieved using immunotherapy and emerging nanocarriers as a clinical tool to optimize subsequent therapeutic regimens and reduce the need for a high dosage of chemo agents. More importantly, combined immunotherapies and nano-based delivery systems can prolong the normalization window while providing the advantages to address the current treatment challenges within antiangiogenic agents. This review summarizes the approved therapies targeting tumor angiogenesis, highlights the challenges and limitations of current therapies, and discusses how vascular normalization, immunotherapies, and nanomedicine could introduce the theranostic potentials to improve tumor management in future clinical settings.

SAIF plays anti-angiogenesis via blocking VEGF-VEGFR2-ERK signal in tumor treatment

Shark cartilage was created as a cancer-fighting diet because it was believed to have an element that may suppress tumor growth. Due to overfishing, sharks have become endangered recently, making it impossible to harvest natural components from shark cartilage for therapeutic development research. Previously, we identified a peptide SAIF from shark cartilage with an-tiangiogenic and anti-tumor effects, successfully expressed it in Escherichia coli by using genetic engineering techniques. However, we did not elucidate the specific target of SAIF and its antiangiogenic molecular mechanism, which hindered its further drug development. Therefore, in this work, the exact mechanism of action was studied using various techniques, including cellular and in vivo animal models, computer-aided simulation, molecular target capture, and transcriptome sequencing analysis. With VEGF-VEGFR2 interaction and preventing the activation of VEGFR2/ERK signaling pathways, SAIF was discovered to decrease angiogenesis and hence significantly limit tumor development. The findings further demonstrated SAIF's strong safety and pharmaceutically potential. The evidence showed that SAIF, which is expressed by, is a potent and safe angiogenesis inhibitor and might be developed as a candidate peptide drug for the treatment of solid tumors such as hepatocellular carcinoma and other conditions linked with angiogenic overgrowth.

The role of ferroptosis in metabolic diseases

The annual incidence of metabolic diseases such as diabetes, non-alcoholic fatty liver disease (NAFLD), osteoporosis, and atherosclerosis (AS) is increasing, resulting in a heavy burden on human health and the social economy. Ferroptosis is a novel form of programmed cell death driven by iron-dependent lipid peroxidation, which was discovered in recent years. Emerging evidence has suggested that ferroptosis contributes to the development of metabolic diseases. Here, we summarize the mechanisms and molecular signaling pathways involved in ferroptosis. Then we discuss the role of ferroptosis in metabolic diseases. Finally, we analyze the potential of targeting ferroptosis as a promising therapeutic approach for metabolic diseases.

Inhibition of MMPs supports amoeboid angiogenesis hampering VEGF-targeted therapies via MLC and ERK 1/2 signaling

BACKGROUND

In the past decades studies on anti-tumoral drugs inhibiting matrix metalloproteinase (MMPs) were disappointing. Recently, we demonstrated that mature endothelial cells (ECs) and endothelial colony forming cells (ECFCs) can switch between invasion modes to cope with challenging environments, performing the "amoeboid angiogenesis" in the absence of proteases activity.

METHODS

We first set out to investigate by ELISA if the inhibitors of the main protease family involved in angiogenesis were differently expressed during breast cancer progression. We used Marimastat, a broad-spectrum MMP inhibitor, as a means of inducing amoeboid characteristics and studied VEGF role in amoeboid angiogenesis. Thus, we performed invasion and capillary morphogenesis assay, morphological, cell signaling and in vivo mouse studies.

RESULTS

Our data showed that TIMP1, TIMP2, alpha2-antiplasmin, PAI-1 and cystatin increase in breast cancer serum of patients with primary cancer and lymph node positive compared to healthy women. In vitro results revealed that the most high-powered protease inhibitors able to induce amoeboid invasion of ECFCs were TIMP1, 2 and 3. Surprisingly, Marimastat promotes ECFC invasion and tubular formation in vitro and in vivo, inducing amoeboid characteristics. We observed that the combination of Marimastat plus VEGF doesn't boost neither cell invasion nor vessel formation capacity. Moreover, inhibition of VEGF activity with Bevacizumab in the presence of Marimastat confirmed that amoeboid angiogenesis is independent from the stimulus of the main vascular growth factor, VEGF.

CONCLUSIONS

We underline the importance to consider the amoeboid mechanism of endothelial and cancer cell invasion, probably responsible for the failure of synthetic metalloproteinase inhibitors as cancer therapy and tumor resistance to VEGF-targeted therapies, to set-up new drugs to be used in cancer therapy.

Role of the Immune System in Renal Transplantation, Types of Response, Technical Approaches and Current Challenges

Advances over the last decades have made renal transplantation an important therapy for patients with end-stage renal disease, as the incidences of acute rejection and short-term transplant loss have been significantly reduced. However, long-term transplant survival remains a challenge in the renal transplantation community. The main causes of long-term graft loss are acute and chronic rejection, as well as the complications related to immunosuppression therapy. In spite of the breakthroughs achieved in recent years, histology is the gold standard technique to confirm the activation of the immune system against the graft with all the ensuing problems that taking biopsies brings to immunosuppressed patients. For this reason, several assays have been developed to try to monitor the immune function, but they show serious constraints owing to the fact that they require substantial laboratory work, they are not clinically available and they provide controversial results, so the combination of multiple assays is often needed to obtain a reliable diagnosis. Thus, the aim of this review is to perform a retrospective study of the immune system in renal transplantation, with special emphasis on the cutting-edge technological developments for monitoring, classification and early detection of rejection episodes in order to contribute to a better adjustment of immunosuppressive therapies and, hence, to a more personalized medicine that improves the quality of life of patients.

Design, Synthesis and Cytotoxicity Screening of New Thiazole Derivatives as Potential Anticancer Agents through VEGFR-2 Inhibition

Z-configurated isomers are kinetically preferred molecules. Compounds with Z-configuration are contained in many natural products, biologically active compounds and as synthons for organic synthesis. Two series of new thiazole-based analogs were synthesized from appropriate starting materials hydrazinecarbothioamide derivatives (Z)-2a,b to be evaluated for their inhibitory activity towards VEGFR-2. The prepared thiazole compounds 3a-5b were screened for their cytotoxic potency against the MDA-MB-231 breast cancer cell line and their percentage inhibition against VEGFR-2. Compound 4d exhibited good VEGFR-2 inhibitory activity. A DNA flow cytometry analysis was conducted, and compound 4d demonstrated cell cycle arrest at the G1 and G2/M phases of the cell cycle profile and an apoptosis-inducing effect by increasing the percentage of pre-G1 phase. Compound 4d was further evaluated for its apoptosis-inducing effect by studying the effect on mitochondrial membrane potential (MMP) and p53 activation. It was found to boost the level of p53 and reduce the level of MMP compared with the untreated control cells.

Clinical Effect of Tongmai Fuming Decoction on Neovascular Ophthalmopathy

Background

The incidence of neovascular eye disease is increasing year by year, seriously threatening human vision health and becoming an urgent public health problem. Tongmai fuming decoction as an experienced prescription can treat ischemic eye disease.

Objective

To investigate the therapeutic effect of Tongmai fuming decoction combined with anti-VEGF therapy on neovascular ophthalmopathy.

Methods

52 patients (62 eyes) with neovascular ophthalmopathy who met the inclusion criteria from January 2018 to July 2020 were randomly divided into the control and observation groups. The control group was given an intravitreal injection of antivascular endothelial growth factor (VEGF) drugs once a day combined with on-demand treatment. The observation group was treated with traditional Chinese medicine Tongmai fuming decoction in addition to the treatment of anti-VEGF drugs. The best-corrected visual acuity (BCVA) was examined before and after treatment, and optical coherence tomography angiography (OCTA) was used to examine the mean retinal thickness and neovascularization in the macular area. Patients were followed for one year and the number of anti-VEGF injections was recorded.

Results

After treatment, the average thickness of BCVA and macular retina in the two groups significantly improved. The BCVA of the control group was 0.59 ± 0.39 3 months after treatment, and that of the experimental group was 0.42 ± 0.25 3 months after treatment. The average thickness of the macular retina in the control group was 304.8 ± 79.7 3 months after treatment, and that in the experimental group was 267.7 ± 64.6 3 months after treatment; The average number of injections of anti-VEGF therapy in the control group was 2.32 ± 1.15 times, and that in the experimental group was 1.74 ± 0.76 times. There was a significant difference between the two groups.

Conclusion

Tongmai fuming decoction and anti-VEGF therapy have a synergistic effect in the treatment of neovascular ophthalmopathy, which can reduce the treatment times of anti-VEGF drugs.

The protein biosynthesis inhibitor vioprolide A evokes anti-angiogenic and pro-survival actions by targeting NOP14 and decreasing VEGF receptor 2- and TAZ-signaling

Angiogenesis contributes to the progression of several diseases including cancer or age-related macular degeneration and is crucially driven by pathologically hyperactive endothelial cells (ECs). Targeting angiogenic processes in ECs thus represents a promising strategy to treat these conditions. Vioprolide A (vioA) is a myxobacterial cyclic depsipeptide that targets the nucleolar protein 14 (NOP14) and possesses strong anti-cancer and anti-inflammatory actions. Here, we present evidence that vioA promotes anti-angiogenic actions in vivo and in ECs in vitro. VioA reduced the choroidal neovascularization after laser-induced photocoagulation in mice in vivo, the sprouting of choroidal explant cultures ex vivo and key angiogenic features of ECs in vitro. Mechanistically, vioA decreased VEGFR2 protein levels and phosphorylation leading to impaired downstream pro-angiogenic signaling. Concurrently, vioA influenced TAZ signaling by diminishing its nuclear translocation and protein level, resulting in a reduced expression of pro-angiogenic target genes and dynamic cytoskeletal remodeling. Surprisingly, vioA induced pro-survival signaling in ECs by activating Akt and inhibiting p53-dependent apoptosis. Knockdown of the cellular target NOP14 further revealed a partial involvement in the anti-angiogenic and pro-survival actions of vioA. Taken together, our study introduces vioA as an interesting anti-angiogenic compound that warrants further investigations in preclinical studies.

The Therapeutic Benefits of Nanoencapsulation in Drug Delivery to the Anterior Segment of the Eye: A Systematic Review

Background: Although numerous nanoparticle formulations have been developed for ocular administration, concerns are being raised about a possible mismatch between potential promises made by the field of nanoparticle research and demonstration of actual therapeutic benefit. Therefore, the primary focus of this present review was to critically assess to what extent nanoencapsulation of ocular drugs improved the therapeutic outcome when treating conditions in the anterior segment of the eye.

Methods: A systematic search was conducted using Medline, PubMed, and Embase databases as well as Google Scholar for published peer-reviewed articles in English focusing on conventional nanoparticles used as drug delivery systems to the anterior segment of the eye in in vivo studies. The major therapeutic outcomes were intraocular pressure, tear secretion, number of polymorphonuclear leucocytes and pupil size. The outcome after encapsulation was compared to the non-encapsulated drug.

Results: From the search, 250 results were retrieved. Thirty-eight studies met the inclusion criteria. Rabbits were used as study subjects in all but one study, and the number of animals ranged from 3 to 10. Coated and uncoated liposomes, lipid-based and polymeric nanoparticles, as well as micelles, were studied, varying in both particle size and surface charge, and encapsulating a total of 24 different drugs, including 6 salts. The majority of the in vivo studies demonstrated some improvement after nanoencapsulation, but the duration of the benefit varied from less than 1 h to more than 20 h. The most common in vitro methods performed in the studies were drug release, transcorneal permeation, and mucin interaction.

Discussion: Nanoparticles that are small and mucoadhesive, often due to positive surface charge, appeared beneficial. Although in vitro assays can unravel more of the hidden and sophisticated interplay between the encapsulated drug and the nanoparticle structure, they suffered from a lack of in vitro—in vivo correlation. Therefore, more research should be focused towards developing predictive in vitro models, allowing rational design and systematic optimization of ocular nanoparticles with minimal animal experimentation.

Low-dose melittin is safe for intravitreal administration and ameliorates inflammation in an experimental model of uveitis

Uveitis is a group of sight-threatening ocular inflammatory disorders, whose mainstay of therapy is associated with severe adverse events, prompting the investigation of alternative treatments. The peptide melittin (MEL) is the major component of Apis mellifera bee venom and presents anti-inflammatory and antiangiogenic activities, with possible application in ophthalmology. This work aims to investigate the potential of intravitreal MEL in the treatment of ocular diseases involving inflammatory processes, especially uveitis. Safety of MEL was assessed in retinal cells, chick embryo chorioallantoic membranes, and rats. MEL at concentrations safe for intravitreal administration showed an antiangiogenic activity in the chorioallantoic membrane model comparable to bevacizumab, used as positive control. A protective anti-inflammatory effect in retinal cells stimulated with lipopolysaccharide (LPS) was also observed, without toxic effects. Finally, rats with bacille Calmette-Guerin- (BCG) induced uveitis treated with intravitreal MEL showed attenuated disease progression and improvement of clinical, morphological, and functional parameters, in addition to decreased levels of proinflammatory mediators in the posterior segment of the eye. These effects were comparable to the response observed with corticosteroid treatment. Therefore, MEL presents adequate safety profile for intraocular administration and has therapeutic potential as an anti-inflammatory and antiangiogenic agent for ocular diseases.

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Melittin at low concentration is safe for intravitreal administration.

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The antiangiogenic effect of melittin on the chorioallantoic membrane model is comparable to bevacizumab.

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Melittin protects retinal cells from inflammatory response induced by lipopolysaccharide.

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Melittin improves clinical, functional and morphological signs of inflammation in rats with BCG-induced uveitis.

Rapamycin and Resveratrol Modulate the Gliotic and Pro-Angiogenic Response in Müller Glial Cells Under Hypoxia

Hypoxia and hypoxia-reoxygenation are frequently developed through the course of many retinal diseases of different etiologies. Müller glial cells (MGCs), together with microglia and astrocytes, participate firstly in response to the injury and later in the repair of tissue damage. New pharmacological strategies tend to modulate MGCs ability to induce angiogenesis and gliosis in order to accelerate the recovery stage. In this article, we investigated the variation in autophagy flux under hypoxia during 4 h, employing both gas culture chamber (1% O₂) and chemical (CoCl₂) hypoxia, and also in hypoxia-reoxygenation. Then, we delineated a strategy to induce autophagy with Rapamycin and Resveratrol and analysed the gliotic and pro-angiogenic response of MGCs under hypoxic conditions. Our results showed an increase in LC3B II and p62 protein levels after both hypoxic exposure respect to normoxia. Moreover, 1 h of reoxygenation after gas hypoxia upregulated LC3B II levels respect to hypoxia although a decreased cell survival was observed. Exposure to low oxygen levels increased the protein expression of the glial fibrillary acid protein (GFAP) in MGCs, whereas Vimentin levels remained constant. In our experimental conditions, Rapamycin but not Resveratrol decreased GFAP protein levels in hypoxia. Finally, supernatants of MGCs incubated in hypoxic conditions and in presence of the autophagy inductors inhibited endothelial cells (ECs) tubulogenesis. In agreement with these results, reduced expression of vascular endothelial growth factor (VEGF) mRNA was observed in MGCs with Rapamycin, whereas pigment epithelium-derived factor (PEDF) mRNA levels significantly increased in MGCs incubated with Resveratrol. In conclusion, this research provides evidence about the variation of autophagy flux under hypoxia and hypoxia-reoxygenation as a protective mechanism activated in response to the injury. In addition, beneficial effects were observed with Rapamycin treatment as it decreased the gliotic response and prevented the development of newly formed blood vessels.

Novel therapies for proliferative retinopathies

Proliferative retinopathies, such as neovascular age–related macular degeneration and proliferative diabetic retinopathy, are a special health issue due to their contribution to irreversible blindness. Although the promoting conditions and physiopathology of proliferative retinopathies are different, these feature a highly detrimental angiogenesis driven by the overproduction of vascular endothelial growth factor (VEGF). This article describes the mechanism of action of ocular antiangiogenic therapies currently found in clinical development. Systems classify accordingly as (a) novel anti-VEGF systems, (b) molecules targeting non-VEGF pathways, and (c) gene therapies. Whereas most therapies are designed to neutralize VEGF, there is a significant set of products with diverse complexity and mechanism of action. Anti-VEGF therapies are still the most studied approach to tackle angiogenesis. Therapies targeting non-VEGF pathways, however, are highlighted because they could be an option for patients nonresponsive to anti-VEGF therapies. Finally, gene therapy is a promissory technology platform but still is subject to demonstrate safety and efficacy.

Systems biology of angiogenesis signaling: Computational models and omics

Angiogenesis is a highly regulated multiscale process that involves a plethora of cells, their cellular signal transduction, activation, proliferation, differentiation, as well as their intercellular communication. The coordinated execution and integration of such complex signaling programs is critical for physiological angiogenesis to take place in normal growth, development, exercise, and wound healing, while its dysregulation is critically linked to many major human diseases such as cancer, cardiovascular diseases, and ocular disorders; it is also crucial in regenerative medicine. Although huge efforts have been devoted to drug development for these diseases by investigation of angiogenesis‐targeted therapies, only a few therapeutics and targets have proved effective in humans due to the innate multiscale complexity and nonlinearity in the process of angiogenic signaling. As a promising approach that can help better address this challenge, systems biology modeling allows the integration of knowledge across studies and scales and provides a powerful means to mechanistically elucidate and connect the individual molecular and cellular signaling components that function in concert to regulate angiogenesis. In this review, we summarize and discuss how systems biology modeling studies, at the pathway‐, cell‐, tissue‐, and whole body‐levels, have advanced our understanding of signaling in angiogenesis and thereby delivered new translational insights for human diseases.

This article is categorized under:

Cardiovascular Diseases > Computational Models

Cancer > Computational Models

Ten Years of Knowledge of Nano-Carrier Based Drug Delivery Systems in Ophthalmology: Current Evidence, Challenges, and Future Prospective

The complex drug delivery barrier in the eye reduces the bioavailability of many drugs, resulting in poor therapeutic effects. It is necessary to investigate new drugs through appropriate delivery routes and vehicles. Nanotechnology has utilized various nano-carriers to develop potential ocular drug delivery techniques that interact with the ocular mucosa, prolong the retention time of drugs in the eye, and increase permeability. Additionally, nano-carriers such as liposomes, nanoparticles, nano-suspensions, nano-micelles, and nano-emulsions have grown in popularity as an effective theranostic application to combat different microbial superbugs. In this review, we summarize the nano-carrier based drug delivery system developments over the last decade, particularly review the biology, methodology, approaches, and clinical applications of nano-carrier based drug delivery system in the field of ocular therapeutics. Furthermore, this review addresses upcoming challenges, and provides an outlook on potential future trends of nano-carrier-based drug delivery approaches in ophthalmology, and hopes to eventually provide successful applications for treating ocular diseases.

Ocular Therapeutics and Molecular Delivery Strategies for Neovascular Age-Related Macular Degeneration (nAMD)

Age-related macular degeneration (AMD) is the leading cause of vision loss in geriatric population. Intravitreal (IVT) injections are popular clinical option. Biologics and small molecules offer efficacy but relatively shorter half-life after intravitreal injections. To address these challenges, numerous technologies and therapies are under development. Most of these strategies aim to reduce the frequency of injections, thereby increasing patient compliance and reducing patient-associated burden. Unlike IVT frequent injections, molecular therapies such as cell therapy and gene therapy offer restoration ability hence gained a lot of traction. The recent approval of ocular gene therapy for inherited disease offers new hope in this direction. However, until such breakthrough therapies are available to the majority of patients, antibody therapeutics will be on the shelf, continuing to provide therapeutic benefits. The present review aims to highlight the status of pre-clinical and clinical studies of neovascular AMD treatment modalities including Anti-VEGF therapy, upcoming bispecific antibodies, small molecules, port delivery systems, photodynamic therapy, radiation therapy, gene therapy, cell therapy, and combination therapies.