Intraocular Diseases Research Articles

Refinement for Ocular Ultrasound Images Quality by Utilizing Combination of Enhancement Techniques

Ultrasound has been used as a diagnostic modality for many intraocular diseases, due its safety, low cost, real time and wide availability. Unfortunately, ultrasound images suffer from speckle artifact that are tissue dependent. In this work, we will offer a method to reduce speckle noise and improve ultrasound image to raise the human diagnostic performance. This method combined undecimated wavelet transform with a wavelet coefficient mapping function: where UDWT used to eliminate the noise and a wavelet coefficient mapping function used to enhance the contrast of denoised images obtained from the first component. This methods can be used not only as a means for improving visual quality of medical images but also as a preprocessing module for computer-aided detection/diagnosis systems to improve the performance of screening and detecting regions of interest in images. The proposed method is experimentally evaluated via 60 ultrasound images of eye. It is demonstrated that the proposed method can further improve the image quality of ocular ultrasound; the results reveal the effectiveness and superiority of the proposed method.

Use of Rabbit Eyes in Pharmacokinetic Studies of Intraocular Drugs.

The intraocular route of drug administration enables the delivery of high concentrations of therapeutic drugs, while minimizing their systemic absorption. Several drugs are administered into the anterior chamber or vitreous, and the intraocular injection has been effective in curing various intraocular diseases. Rabbit eyes have been widely used for ophthalmic research, as the animal is easy to handle and economical compared to other mammals, and the size of a rabbit eye is similar to that of a human eye. Using a 30 G needle, drugs can be injected into the intracameral and intravitreal spaces of rabbit eyes. The eyeballs are then frozen until analysis, and can be divided into the aqueous humor, vitreous, and retina/choroid. The vitreous and retina/choroid samples can be homogenized and solubilized before analysis. Then, immunoassays can be performed to measure the concentrations of intraocular drugs in each compartment. Appropriate pharmacokinetic models can be used to calculate several parameters, such as the half-life and maximum concentration of the drug. Rabbit eyes can be a good model for pharmacokinetic studies of intraocular drugs.

Poly(ortho ester) nanoparticles targeted for chronic intraocular diseases: ocular safety and localization after intravitreal injection

Treatment of posterior eye diseases is more challenging than the anterior segment ailments due to a series of anatomical barriers and physiological constraints confronted by drug delivery to the back of the eye. In recent years, concerted efforts in drug delivery have been made to prolong the residence time of drugs injected in the vitreous humor of the eye. Our previous studies demonstrated that poly(ortho ester) (POE) nanoparticles were biodegradable/biocompatible and were capable of long-term sustained release. The objective of the present study was to investigate the safety and localization of POE nanoparticles in New Zealand white rabbits and C57BL/6 mice after intravitreal administration for the treatment of chronic posterior ocular diseases. Two concentration levels of POE nanoparticles solution were chosen for intravitreal injection: 1.5 mg/ml and 10 mg/ml. Our results demonstrate that POE nanoparticles were distributed throughout the vitreous cavity by optical coherence tomography (OCT) examination 14 days post-intravitreal injection. Intraocular pressure was not changed from baseline. Inflammatory or adverse effects were undetectable by slit lamp biomicroscopy. Furthermore, we demonstrate that POE nanoparticles have negligible toxicity assessed at the cellular level evidenced by a lack of glia activation or apoptosis estimation after intravitreal injection. Collectively, POE nanoparticles are a novel and nontoxic as an ocular drug delivery system for the treatment of posterior ocular diseases.

VEGF: From Discovery to Therapy: The Champalimaud Award Lecture.

PurposeIntraocular vascular diseases are leading causes of adult vision loss, and in the mid-1900s, I. C. Michaelson postulated that the retina releases a soluble, diffusible factor that causes abnormal vascular growth and leakage. What became known as “Factor X” eluded investigators for decades.MethodsThe field of cancer research, where Judah Folkman pioneered the concept of angiogenesis, provided the inspiration for the work honored by the 2014 Champalimaud Vision Award. Recognizing that tumors recruit their own blood supply to achieve critical mass, Dr Folkman proposed that angiogenic factors could be therapeutic targets in cancer. Napoleone Ferrara identified vascular endothelial growth factor (VEGF) as such an angiogenic agent: stimulated by hypoxic tumor tissue, secreted, and able to induce neovascularization. VEGF also was a candidate for Factor X, and the 2014 Champalimaud Laureates and colleagues worked individually and collaboratively to identify the role of VEGF in ocular disease.ResultsThe Champalimaud Laureates correlated VEGF with ocular neovascularization in animal models and in patients. Moreover, they showed that VEGF not only was sufficient, but it also was required to induce neovascularization in normal animal eyes, as VEGF inhibition abolished ocular neovascularization in key animal models.ConclusionsThe identification of VEGF as Factor X altered the therapeutic paradigms for age-related macular degeneration (AMD), diabetic retinopathy, retinal vein occlusion, and other retinal disorders.Translational RelevanceThe translation of VEGF from discovery to therapy resulted in the most successful applications of antiangiogenic therapy to date. Annually, over one million patients with eye disease are treated with anti-VEGF agents.

Corticosteroid implants for chronic non-infectious uveitis.

Uveitis is a term used to describe a heterogeneous group of intraocular inflammatory diseases of the anterior, intermediate, and posterior uveal tract (iris, ciliary body, choroid). Uveitis is the fifth most common cause of vision loss in high-income countries, accounting for 5% to 20% of legal blindness, with the highest incidence of disease in the working-age population.Corticosteroids are the mainstay of acute treatment for all anatomical subtypes of non-infectious uveitis and can be administered orally, topically with drops or ointments, by periocular (around the eye) or intravitreal (inside the eye) injection, or by surgical implantation. To determine the efficacy and safety of steroid implants in people with chronic non-infectious posterior uveitis, intermediate uveitis, and panuveitis. We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) (Issue 10, 2015), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to November 2015), EMBASE (January 1980 to November 2015), PubMed (1948 to November 2015), Latin American and Caribbean Health Sciences Literature Database (LILACS) (1982 to November 2015), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com) (last searched 15 April 2013), ClinicalTrials.gov (www.clinicaltrials.gov), and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic search for studies. We last searched the electronic databases on 6 November 2015.We also searched reference lists of included study reports, citation databases, and abstracts and clinical study presentations from professional meetings. We included randomized controlled trials comparing either fluocinolone acetonide (FA) or dexamethasone intravitreal implants with standard-of-care therapy with at least six months of follow-up after treatment. We included studies that enrolled participants of all ages who had chronic non-infectious posterior uveitis, intermediate uveitis, or panuveitis with vision that was better than hand-motion. Two review authors independently reviewed studies for inclusion. Two review authors independently extracted data and assessed the risk of bias for each study. We included data from two studies (619 eyes of 401 participants) that compared FA implants with standard-of-care therapy. Both studies used similar standard-of-care therapy that included administration of prednisolone and, if needed, immunosuppressive agents. The studies included participants from Australia, France, Germany, Israel, Italy, Portugal, Saudi Arabia, Spain, Switzerland, Turkey, the United Kingdom, and the United States. We assessed both studies at high risk of performance and detection bias.Only one study reported our primary outcome, recurrence of uveitis at any point during the study through 24 months. The evidence, judged as moderate-quality, showed that a FA implant probably prevents recurrence of uveitis compared with standard-of-care therapy (risk ratio (RR) 0.29, 95% confidence interval (CI) 0.14 to 0.59; 132 eyes). Both studies reported safety outcomes, and moderate-quality evidence showed increased risks of needing cataract surgery (RR 2.98, 95% CI 2.33 to 3.79; 371 eyes) and surgery to lower intraocular pressure (RR 7.48, 95% CI 3.94 to 14.19; 599 eyes) in the implant group compared with standard-of-care therapy through two years of follow-up. No studies compared dexamethasone implants with standard-of-care therapy. After considering both benefits and harms reported from two studies in which corticosteroids implants were compared with standard-of-care therapy, we are unable to conclude that the implants are superior to traditional systemic therapy for the treatment of non-infectious uveitis. These studies exhibited heterogeneity in design and outcomes that measured efficacy. Pooled findings regarding safety outcomes suggest increased risks of post-implant surgery for cataract and high intraocular pressure compared with standard-of-care therapy.

Ocular Immunity and Inflammation.

Complex immunologic mechanisms are involved in multiple intraocular diseases. The field of immunology has aided greatly in better understanding and treating inflammation in the posterior segment. While traditional therapy has relied on drugs such as corticosteroids and antimetabolites that exert there effects by multiple mechanisms, the more recently developed biologic immune modulators involve specific mechanisms of action with the potential to significantly reduce side effects relative to more traditional agents. Better understanding of diseases such as age-related macular degeneration or diabetic retinopathy has led to the appreciation of immune mechanisms involved in these diseases and has suggested potential targets for therapy.

Functional Expression of Toll‐Like Receptors in Human Retinal and Choroidal Vascular Endothelial Cells

PurposeToll‐like receptors (TLRs) are a family of proteins that initiate the innate immune response in reaction to invading microbes. Studies confirm the expression of TLRs in a variety of ocular tissues and cells, and it has also been suggested that selected TLRs may be associated with geographic atrophy and neovascularisation in age‐related macular degeneration, diabetic retinopathy and other vascular and inflammatory diseases of the ocular posterior segment. However, TLR expression and localisation in the retinal and choroidal vasculature has not been defined.MethodsIn this study the gene (mRNA) expression of TLRs 1‐10 was investigated using RT‐PCR and comparative qPCR and the protein expression and localisation of selected TLRs (3, 4, 6 and 9) were examined using western blotting, flow cytometry and immunofluorescent staining.ResultsPCR showed gene expression of TLR1‐6 and 9 in human choroidal endothelial cells (hCEC) and TLR2‐6, 9 and 10 in human retinal endothelial cells (hREC). Western blotting detected TLR3, 4 and 9 proteins in both hCEC and hREC with higher levels in hCEC, whilst TLR6 protein was not detectable in either cell type. Flow cytometry detected all four TLRs (3, 4, 6 and 9) on the cell surface and intracellularly, TLR6 expression was detectable but low. The expression and localisation of TLR3, 4 and 9 were confirmed by immunofluorescent staining and TLR functionality tested by expression of IL‐6 (ELISA) in response to TLR ligands.ConclusionsThis study has, for the first time, identified the differential expression and localisation of TLRs in intraocular endothelial cells. This profiling will help inform our understanding of different retinal and choroidal vascular diseases, as well as the development of future treatments for intraocular vascular diseases.

Functional Expression of Toll‐Like Receptors in Human Retinal and Choroidal Vascular Endothelial Cells

PurposeToll‐like receptors (TLRs) are a family of proteins that initiate the innate immune response in reaction to invading microbes. Studies confirm the expression of TLRs in a variety of ocular tissues and cells, and it has also been suggested that selected TLRs may be associated with geographic atrophy and neovascularisation in age‐related macular degeneration, diabetic retinopathy and other vascular and inflammatory diseases of the ocular posterior segment. However, TLR expression and localisation in the retinal and choroidal vasculature has not been defined.MethodsIn this study the gene (mRNA) expression of TLRs 1‐10 was investigated using RT‐PCR and comparative qPCR and the protein expression and localisation of selected TLRs (3, 4, 6 and 9) were examined using western blotting, flow cytometry and immunofluorescent staining.ResultsPCR showed gene expression of TLR1‐6 and 9 in human choroidal endothelial cells (hCEC) and TLR2‐6, 9 and 10 in human retinal endothelial cells (hREC). Western blotting detected TLR3, 4 and 9 proteins in both hCEC and hREC with higher levels in hCEC, whilst TLR6 protein was not detectable in either cell type. Flow cytometry detected all four TLRs (3, 4, 6 and 9) on the cell surface and intracellularly, TLR6 expression was detectable but low. The expression and localisation of TLR3, 4 and 9 were confirmed by immunofluorescent staining and TLR functionality tested by expression of IL‐6 (ELISA) in response to TLR ligands.ConclusionsThis study has, for the first time, identified the differential expression and localisation of TLRs in intraocular endothelial cells. This profiling will help inform our understanding of different retinal and choroidal vascular diseases, as well as the development of future treatments for intraocular vascular diseases.

Stimulation of TLR4 Increases Angiogenic and Anti‐Angiogenic Gene Expression in Choroidal Endothelial Cells

PurposeThe Toll‐like receptor (TLR) family initiate the innate immune response in reaction to invading microbes. Studies confirm the expression of TLRs in a variety of ocular tissues and cells, and it has also been suggested that selected TLRs may be associated with geographic atrophy and neovascularisation in age‐related macular degeneration, diabetic retinopathy and other vascular and inflammatory diseases of the ocular posterior segment. However, the exact mechanisms of TLR stimulation and the mechanism of endothelial inflammatory and angiogenic effects have not been defined.MethodsMicroarray analysis was performed on primary human choroidal endothelial cells stimulated with LPS, a specific TLR ligand. Microarray results were validated using qPCR and the functional significance of increased factors were investigated using proliferation and migration assays.ResultsMicroarray indicated a large increase in expression of angiogenic (e.g. CCL2, IL‐8) and anti‐angiogenic (e.g. CXCL10, CXCL11) molecules. The fold change in expression of these molecules was validated using qPCR and the secretion using ELISA. Reported angiogenic molecules were confirmed to have a pro‐angiogenic effect in vitro.ConclusionsThis profiling of factors increased during TLR4 stimulation will help inform our understanding of inflammation in choroidal vascular diseases, as well as the development of future treatments for intraocular vascular diseases.

Ocular Inflammatory Diseases: Molecular Pathogenesis and Immunotherapy.

Uveitis is a diverse group of potentially sight-threatening intraocular inflammatory diseases of infectious or autoimmune etiology and accounts for more than 10% of severe visual handicaps in the United States. Pathology derives from the presence of inflammatory cells in the optical axis and sustained production of cytotoxic cytokines and other immuneregulatory proteins in the eye. The main therapeutic goals are to down-regulate the immune response, preserve the integrity of the ocular architecture and eventually eliminate the inciting uveitogenic stimuli. Current therapy is based on topical or systemic corticosteroid with or without second line agents and serious adverse effects of these drugs are the impetus for development of less toxic and more specific therapies for uveitis. This review summarizes the pathophysiology of uveitis, molecular mechanisms that regulate the initiation and progression of uveitis and concludes with emerging strategies for the treatment of this group of potentially blinding diseases.

Topical administration of a suppressor of cytokine signaling-1 (SOCS1) mimetic peptide inhibits ocular inflammation and mitigates ocular pathology during mouse uveitis

Uveitis is a diverse group of potentially sight-threatening intraocular inflammatory diseases and pathology derives from sustained production of pro-inflammatory cytokines in the optical axis. Although topical or systemic steroids are effective therapies, their adverse effects preclude prolonged usage and are impetus for seeking alternative immunosuppressive agents, particularly for patients with refractory uveitis. In this study, we synthesized a 16 amino acid membrane-penetrating lipophilic suppressor of cytokine signaling 1 peptide (SOCS1-KIR) that inhibits JAK/STAT signaling pathways and show that it suppresses and ameliorates experimental autoimmune uveitis (EAU), the mouse model of human uveitis. Fundus images, histological and optical coherence tomography analysis of eyes showed significant suppression of clinical disease, with average clinical score of 0.5 compared to 2.0 observed in control mice treated with scrambled peptide. We further show that SOCS1-KIR conferred protection from ocular pathology by inhibiting the expansion of pathogenic Th17 cells and inhibiting trafficking of inflammatory cells into the neuroretina during EAU. Dark-adapted scotopic and photopic electroretinograms further reveal that SOCS1-KIR prevented decrement of retinal function, underscoring potential neuroprotective effects of SOCS1-KIR in uveitis. Importantly, SOCS1-KIR is non-toxic, suggesting that topical administration of SOCS1-Mimetics can be exploited as a non-invasive treatment for uveitis and for limiting cytokine-mediated pathology in other ocular inflammatory diseases including scleritis.

Expression of Toll-like receptors in human retinal and choroidal vascular endothelial cells

Toll-like receptors (TLRs) are a family of proteins that initiate the innate immune response in reaction to invading microbes. Studies confirm the expression of TLRs in a variety of ocular tissues and cells, and it has also been suggested that selected TLRs may be associated with geographic atrophy and neovascularisation in age-related macular degeneration, diabetic retinopathy and other vascular and inflammatory diseases of the ocular posterior segment. However, TLR expression and localisation in the retinal and choroidal vasculature has not been defined. A better understanding of differential TLR expression in the choroid and retina, particularly in endothelial cells would improve our knowledge of vascular and inflammatory diseases in the posterior segment of the eye. In this study the gene (mRNA) expression of TLRs 1–10 was investigated using RT-PCR and comparative qPCR and the protein expression and localisation of selected TLRs (3, 4, 6 and 9) were examined using western blotting, flow cytometry and immunofluorescent staining. PCR showed gene expression of TLR1-6 and 9 in human choroidal endothelial cells (hCEC) and TLR2-6, 9 and 10 in human retinal endothelial cells (hREC). Western blotting detected TLR3, 4 and 9 proteins in both hCEC and hREC with higher levels in hCEC, whilst TLR6 protein was not detectable in either endothelial cell type. Flow cytometry detected all four TLRs (3, 4, 6 and 9) on the cell surface and intracellularly, TLR6 expression was detectable but low. The expression and localisation of TLR3, 4 and 9 were confirmed by immunofluorescent staining in endothelial cells and whole tissue sections and their functionality tested by expression of IL-6 (ELISA) in response to stimulation with specific TLR ligands. This study has, for the first time, identified the differential expression and localisation of TLRs in intraocular endothelial cells. This profiling will help inform our understanding of different retinal and choroidal vascular diseases, as well as the development of future treatments for intraocular vascular diseases.

Bacterial Spectrum and Antibiotic Resistance Patterns of Ocular Infection: Differences between External and Intraocular Diseases.

This study aimed to compare the differences of microbial spectrum and antibiotic resistance patterns between external and intraocular bacterial infections in an eye hospital in South China. A total of 737 bacteria isolates from suspected ocular infections were included in this retrospective study covering the period 2010–2013. The organisms cultured from the ocular surface (cornea, conjunctiva) accounted for the majority of the isolates (82.77%, n = 610), followed by the intraocular (aqueous humor, vitreous fluid), which accounted for 17.23% (n = 127). The top three species accounting for the external ocular infections were S. epidermidis (35.25%), P. aeruginosa (8.03%), and S. simulans (4.43%). The top three species for the intraocular infections were S. epidermidis (14.96%), S. hominis (8.66%), and B. subtilis (7.87%). The bacteria from the external ocular surface were more sensitive to neomycin, while those from the intraocular specimens were more sensitive to levofloxacin (P < 0.01). Multidrug resistance was found in 89 bacteria (12.08%), including isolates from both external (13.28%) and intraocular samples (6.30%). The results of this study indicate that the bacteria spectrum of external and intraocular infections is variable in the setting. A high percentage of bacterial organisms were found to be primarily susceptible to neomycin for external infection and levofloxacin for intraocular infection.

HIV infection in patients with intraocular inflammation

HIV infection in patients with intraocular inflammation

Ultrasound diagnostics in ophthalmology (standardized echography)

Ultrasound diagnostics have been one of the most important noninvasive supplementary diagnostic procedures in ophthalmology for many decades and are indispensable for many intraocular and orbital diseases. When the echography examination and analysis of the echograms obtained are correctly carried out, ultrasound diagnostics are characterized by a high measure of specificity and sensitivity.

Diagnosis of intraocular lesions using vitreous humor and intraocular perfusion fluid cytology: Experience with 83 Cases.

The objective of the study was to evaluate the use of vitreous humor and/or intraocular perfusion fluid (IPF) from pars plana vitrectomy as a diagnostic and therapeutic procedure for intraocular diseases. The cytologic findings with respect to the clinical data, the anatomical findings, and the final diagnosis in 83 cases that underwent intraocular cytologic examinations at the Kansai Medical University Takii Hospital were evaluated. For cytologic examination, the Papanicolaou stain, Giemsa stain, and in some cases, molecular biology and immunocytochemical techniques were used. Most of the clinical diagnoses were uveitis or endophthalmitis. Sixty-eight cases (81.9%) were negative on cytodiagnosis, while 15 cases (18.9%) were positive or suspicious for malignancy. Negative cases included infections and intraocular sarcoidosis (IOS), and all of the positive or suspicious cases were intraocular lymphomas. Some of these latter cases were also diagnosed using immunocytochemical staining or molecular biological procedures as ancillary techniques, performed using vitreous body cytology from IPF. An early diagnosis and treatment of intraocular diseases is necessary to maintain an acceptable degree of quality of life. For an accurate diagnosis, it is necessary to understand the anatomy of the eye. Giemsa staining is recommended in addition to Papanicolaou staining for cytologic diagnostic evaluation of intraocular diseases. Furthermore, for the diagnosis of clonality in intraocular lymphomas, it is often necessary to use ancillary molecular biological procedures, using vitreous fluid.

Activation of the Liver X Receptor Inhibits Th17 and Th1 Responses in Behcet’s Disease and Vogt-Koyanagi-Harada Disease

Behcet's disease (BD) and Vogt-Koyanagi-Harada (VKH) syndrome are two intraocular inflammatory diseases that are caused by an aberrant T lymphocyte response. Th17 cells, mainly producing the cytokine IL-17, and Th1 cells, characterized by the production of the index cytokine IFN-γ, are the CD4(+) T lymphocyte subsets implicated in the pathogenesis of both BD and VKH. Suppressing the excessive response of these Th17 and Th1 cells has been reported to be an effective therapeutic approach to treat these patients and continuous efforts are being undertaken to find new methods to modulate the function of these cells. Evidence is emerging that the Liver X receptor (LXR) is an important regulator of inflammatory and immune responses and the study reported here was designed to investigate the role of LXR activation in BD and VKH. Here we demonstrate that the frequency of Th17 and Th1 cells along with the relevant cytokines IL-17, IFN-γ and corresponding transcriptional factors RORC, T-bet were all decreased following LXR activation by the agonist GW3965. LXR controlled the expression of inflammatory cytokines through an effect on NF-kappa B (NFκb) phosphorylation. Data from our study provide evidence for an association between a decreased LXR expression and disease activity in both BD and VKH, due to the fact that a lower LXR activation may result in an enhanced Th1 and Th17 immune response. Our study suggests that enhancing LXR activation may offer a potential therapeutic approach targeting aberrant immune responses by inhibiting Th1 and Th17 cell responses.

Development of gene therapy for treatment of age-related macular degeneration.

Intraocular neovascular diseases are the leading cause of blindness in the Western world in individuals over the age of 50. Age-related macular degeneration (AMD) is one of these diseases. Exudative AMD, the late-stage form, is characterized by abnormal neovessel development, sprouting from the choroid into the avascular subretinal space, where it can suddenly cause irreversible damage to the vulnerable photoreceptor (PR) cells essential for our high-resolution, central vision. The molecular basis of AMD is not well understood, but several growth factors have been implicated including vascular endothelial growth factor (VEGF), and the advent of anti-VEGF therapy has markedly changed the outcome of treatment. However, common to all current therapies for exudative AMD are the complications of repeated monthly intravitreal injections, which must be continued throughout one's lifetime to maintain visual benefits. Additionally, some patients do not benefit from established treatments. Strategies providing long-term suppression of inappropriate ocular angiogenesis are therefore needed, and gene therapy offers a potential powerful technique. This study aimed to develop a strategy based on RNA interference (RNAi) for the sustained attenuation of VEGF. We designed a panel of anti-VEGF short hairpin RNAs (shRNA), and based on the most potent shRNAs, microRNA (miRNA)-mimicked hairpins were developed. We demonstrated an additive VEGF silencing effect when we combined the miRNAs in a tricistronic miRNA cluster. To meet the requirements for development of medical treatments for AMD with long-term effects, the shRNA/miRNA is expressed from vectors based on adeno-associated virus (AAV) or lentivirus (LV). Both vector systems have been found superior in terms of transduction efficiency and persistence in gene expression in retinal cells. The capacity of AAV-encoded RNAi effector molecules to silence endogenous VEGF gene expression was evaluated in mouse models, including the model of laser-induced choroidal neovascularization (CNV), and we found that subretinal administration of self-complementary (sc)-AAV2/8 encoding anti-VEGF shRNAs can impair vessel formation. In parallel, a significant reduction of endogenous VEGF was demonstrated following injection of scAAV2/8 vectors expressing multiple anti-VEGF miRNAs into murine hind limb muscles. Furthermore, in an ongoing project we have designed versatile, multigenic LV vectors with combined expression of multiple miRNAs and proteins, including pigment epithelium-derived factor (PEDF), a multifunctional, secreted protein that has anti-angiogenic and neurotrophic functions. Co-expression of miRNAs and proteins from a single viral vector increases safety by minimizing the viral load necessary to obtain a therapeutic effect and thereby reduces the risk of insertional mutagenesis as well as the immune response against viral proteins. Our results show co-expression of functional anti-VEGF-miRNAs and PEDF in cell studies, and in vivo studies reveal an efficient retinal pigment epithelium (RPE)-specific gene expression following the incorporation of the vitelliform macular dystrophy 2 (VMD2) promoter, demonstrating the potential applicability of our multigenic LV vectors in ocular anti-VEGF gene therapy, including combination therapy for treatment of exudative AMD. In conclusion, these highly promising data clearly demonstrate that viral-encoded RNAi effector molecules can be used for the inhibition of neovascularization and will, in combination with the growing interest of applying DNA- or RNA-based technologies in the clinic, undoubtedly contribute to the development of efficacious long-term gene therapy treatment of intraocular neovascular diseases.

In situ covalently cross-linked PEG hydrogel for ocular drug delivery applications.

Avastin(®) has been clinically proved to be effective in the treatment of intraocular neovascularization diseases. However, the short half-life of Avastin(®) need frequent administration to maintain its therapeutic efficiency. In this paper, we attempted to develop an in situ PEG hydrogels with great biocompatibility for sustained release of Avastin(®) to inhibit the corneal neovascularization. PEG hydrogels was formed via thiol-maleimide reaction using 4-arm PEG-Mal and 4-arm PEG-SH. The transparent hydrogel was rapidly formed under physiological conditions. By varying the concentration of 4-arm PEG-SH, PEG hydrogel with different gelling time, pore size, swelling ratio and mechanical property could be obtained. In vitro cytotoxicity indicated that the developed PEG hydrogel had no apparent cytotoxicity on L-929 cells after 7 days of incubation. In vitro release study showed the encapsulated Avastin(®) was sustained release from PEG hydrogels within a period of 14 days study. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis further confirmed that the released Avastin(®) did not undergo apparent hydrolysis within 14 days. As a conclusion, we could conclude that the developed PEG hydrogels as an injectable hydrogels might be suitable for extended Avastin(®) release to treat the corneal neovascularization.

Controlled release bevacizumab in thermoresponsive hydrogel found to inhibit angiogenesis.

Age-related macular degeneration (ARMD) and intraocular neovascular diseases have been treated clinically by anti-VEGF antibody drug bevacizumab. However, the use of bevacizumab in the treatment of retinal neovascular diseases has been limited due to the short half-life and frequent injections. In this research, novel amphiphilic hydrophilic-hydrophobic block copolymers of methoxy-poly (ethylene glycol)-block-poly (lactic-co-glycolic acid) were synthesized with ring-opening polymerization, and cross-linked with 2,2-bis (2-oxazoline) (BOX). The aqueous solution of the block copolymers can reverse the sol-gel-sol phase transition. After 1 month of intravitreal injection, the histomorphology of a rabbit's retina was preserved, which indicated the mPEG-PLGA-BOX hydrogel had no cytotoxicity in vivo. Released bevacizumab from the mPEG-PLGA-BOX hydrogel inhibited the RF/6A (Maraca mulatta retina epithelial cell) and HUVEC cell growth, and anti-angiogenesis in 3-D cultures, which showed the bioactivity of the anti-VEGF agent, were maintained in the hydrogel within the release process. In conclusion, the mPEG-PLGA-BOX hydrogel had a sol-gel behavior phase transition, and its intraocular biocompatibility and the characteristics of biodegradability and bioactivity appear to be a promising intravitreal injection carrier for bevacizumab delivery.