[Influence of vascular endothelial growth factor on angiogenesis and neurogenesis]

Serum Levels of VEGF-A and Its Receptors in Patients in Different Phases of Hemorrhagic and Ischemic Strokes

Vascular endothelial growth factors (VEGFs) are important regulators of angiogenesis, neuroprotection, and neurogenesis. Studies have indicated the association of VEGF dysregulation with the development of neurodegenerative and cerebrovascular diseases. We studied the changes in serum levels of VEGF-A, VEGFR-1, and VEGFR-2 in patients at various phases of ischemic and hemorrhagic strokes. Quantitative assessment of VEGF-A, VEGFR-1, and VEGFR-2 in serum of patients with hemorrhagic or ischemic stroke was performed by enzyme immunoassay in the hyper-acute (1−24 h from the onset), acute (up to 1−7 days), and early subacute (7 days to 3 months) phases of stroke, and then compared with the control group and each other. Results of our retrospective study demonstrated different levels of VEGF-A and its receptors at various phases of ischemic and hemorrhagic strokes. In ischemic stroke, increased VEGFR-2 level was found in the hyper-acute (p = 0.045) and acute phases (p = 0.024), while elevated VEGF-A and reduced VEGFR-1 levels were revealed in the early subacute phase (p = 0.048 and p = 0.012, respectively). In hemorrhagic stroke, no significant changes in levels of VEGF-A and its receptors were identified in the hyper-acute phase. In the acute and early subacute phases there was an increase in levels of VEGF-A (p < 0.001 and p = 0.006, respectively) and VEGFR-2 (p < 0.001 and p = 0.012, respectively). Serum levels of VEGF-A and its receptors in patients with hemorrhagic and ischemic stroke indicate different pathogenic pathways depending on the phase of the disease.

[Effectiveness of anti-VEGF therapy for neovascular age-related macular degeneration in different types of exudative fluid localization]

PURPOSE

To assess the effectiveness of anti-VEGF therapy in different types of fluids localization in neovascular age-related macular degeneration (AMD).

MATERIAL AND METHODS

The study included 16 people (16 eyes) with exudative AMD. The study included patients with fibrovascular detachment of the retinal pigment epithelium (RPE), subretinal and intraretinal fluid. The patients were divided into two groups: in the first group, fibrovascular RPE detachment was combined with subretinal fluid (9 eyes); in the second group, fibrovascular RPE detachment was accompanied by both sub- and intraretinal fluid (7 eyes). All patients underwent standard ophthalmological examination, which included visometry, biomicroscopy, and ophthalmoscopy under conditions of drug-induced mydriasis. Additionally, OCT of the macular region and OCT-angiography were performed.

RESULTS

Over the entire observation period, the first group of patients received an average of 5.11 intravitreal injections (IVI), the second group - 5.14 IVI. Visual acuity was comparable in both groups at the beginning of the study. Subsequently, the treatment resulted in an increase in visual acuity after 3 months in the first (p=0.066) and second (p=0.043) groups, as well as after 12 months in both groups (p=0.043). In the first group of patients, after 12 months, an increase in RPE detachment was observed (p=0.942), which suggests that the disease activity remains underestimated on OCT when RPE detachment and subretinal fluid are combined. In the first group, complete resorption of subretinal fluid occurred in 2 people. In the second group, resorption of subretinal and intraretinal fluid occurred in 6 people.

CONCLUSION

Regardless of the subtype of fluid, anti-VEGF therapy is an effective method for treating exudative AMD. Intravitreal injections are necessary both in the presence of intra- and/or subretinal fluid, and fluid under RPE. The greatest difficulty is assessment of the fluid under the RPE.

A Fluorescent Aptasensor Based on Assembled G-Quadruplex and Thioflavin T for the Detection of Biomarker VEGF165

VEGF165, a regulator of angiogenesis, has been widely used as a serum biomarker for a number of human diseases, including cancer, rheumatoid arthritis, bronchial asthma, and diabetic eye disease. The rapid, accurate, and convenient detection of VEGF165 is a crucial step in effective healthcare monitoring, disease diagnosis, and prognosis assessment. In this study, a fluorescent aptasensor based on an assembled G-quadruplex and the signal molecule ThT was developed for VEGF165 detection. First, G-rich DNA fragments were assembled at both ends of the anti-VEGF165 aptamer, and the B-DNA form was converted into a G-quadruplex structure aptamer (G4-Apt). Then, ThT was introduced, and the G-quadruplex significantly enhanced the fluorescence intensity of the bound ThT. When VEGF165 was present, the higher affinity of the aptamer to the target protein allowed the G4-Apt/VEGF165 complex to form and release ThT, which emitted only weak fluorescence in the free state. Therefore, the aptasensor exhibited a good linear detection window from 1.56 to 25 nM VEGF165, with a limit of detection of 0.138 nM. In addition, the aptasensor was applied to detect VEGF165 in clinical serum samples, showing good accuracy, reproducibility, and stability. These results indicate that our developed fluorescent aptasensor can potentially be a reliable, convenient, and cost-effective approach for the sensitive, specific, and rapid detection of the VEGF165 biomarker.

Simultaneous Detection of VEGF and CEA by Time-Resolved Chemiluminescence Enzyme-Linked Aptamer Assay

BACKGROUND

As two important tumor markers, vascular endothelial growth factor (VEGF) and carcinoembryonic antigen (CEA) have a great value for clinical application in the early diagnosis of cancer. Due to the complex composition of biological samples, the results from combined detection of CEA and VEGF are often taken as a comprehensive indicator in order to make an accurate judgment on a disease. However, most of the current methods can only be used to detect the content of one biomarker. Therefore, it is necessary to explore a simple, rapid, low-cost, and highly sensitive method for the simultaneous detection of CEA and VEGF.

METHODS

Based on specific aptamers and magnetic separation, a time-resolved chemiluminescence enzyme-linked aptamer assay was developed for the simultaneous detections of CEA and VEGF in serum samples.

RESULTS

Under the optimal conditions, the linear range of the calibration curve for VEGF was from 0.5 to 80 ng mL-1, and the limit of detection was 0.1 ng mL-1. The linear range of the calibration curve for CEA was 0.5 to 160 ng mL-1, and the limit of detection was 0.1 ng mL-1. The established method was applied to detect VEGF and CEA in serum samples. The results were consistent with those of commercial kits.

CONCLUSION

The method has high sensitivity and can quickly obtain accurate results, which could greatly improve the measurement efficiency, reduce the cost, and also reduce the volume of sample consumed. It can be seen that the method established in this study has important application value and broad application prospect in clinical diagnosis.

[Antioxidant nutraceuticals for glaucoma]

Glaucoma is the leading cause of irreversible blindness in the world. Intraocular pressure (IOP) is currently the only proven modifiable risk factor for POAG. IOP-independent mechanisms contributing to the development of glaucomatous neurodegeneration include oxidative stress, excitotoxicity, mitochondrial dysfunction, and impaired ocular blood flow. In this regard, there has recently been growing interest in the use of various antioxidant dietary supplements as neuroprotective therapy for glaucoma. The issue of the effectiveness and safety of these biologically active additives is an urgent scientific problem reflected in numerous studies. This article reviews current concepts of oxidative/nitrosative stress, the role of reactive oxygen species (ROS)/reactive nitrogen (Nr) and their participation in the development of POAG, as well as experimental models and clinical studies using essential fatty acids, natural compounds and a number of other antioxidant substances that can counteract oxidative stress in glaucoma.

[Modern approaches to treatment of postsurgical macular edema]

Postsurgical macular edema, known as Irvine-Gass syndrome, is one of the possible causes of reduced visual acuity in ophthalmic surgery. The article reviews and summarizes data on the main approaches to the treatment of this pathology, discusses the main groups of drugs used to manage postoperative macular edema.

A highly sensitive colorimetric aptasensor for the detection of the vascular endothelial growth factor in human serum

Early detection of cancer is of great significance for disease prevention and diagnosis. However, the levels of most cancer markers are quite low in the early stages of disease, so it is urgent to develop a highly sensitive detection method. In this study, a label-free and highly sensitive colorimetric strategy was developed for the detection of the vascular endothelial growth factor₁₆₅ (VEGF₁₆₅) in human serum. First, a convenient biosensor was constructed by immobilizing VEGF₁₆₅ on a microplate, where aptamers bound with VEGF₁₆₅ to form a complex. Then, streptavidin labeled-horseradish peroxidase (HRP-SA) combined with the complex via the interaction between streptavidin and biotin, thus catalyzing the 3,3',5,5'-tetramethylbenzidine (TMB) and H₂O₂ system to produce colored products. In the presence of target, immobilized VEGF₁₆₅ and target competitively bound with the aptamers, resulting in a reduction of the colorimetric signal. Moreover, the optical density (OD) signal decreased with the increase of target concentration. The strategy showed a broad linear range (0.1-100 ng/mL) and a rather low detection limit of 10 pg/mL with good precision and selectivity. Further, the proposed method was successfully applied in detecting VEGF₁₆₅ in human serum. The detection results of serum samples showed that the proposed assay had a high correlation with CLEIA kits (r = 0.971, P = 0.001). It has potential for application in clinical research and diagnosis.

[Anti-VEGF drugs in the treatment of neovascular glaucoma]

Neovascular glaucoma (NVG) is the most frequently occurring type of secondary glaucoma characterized by significant decrease in visual functions. Its pathogenesis consists mainly of ischemia of the posterior segment, which is often secondary to proliferative diabetic retinopathy or ischemic central retinal vein occlusion. Development of neovascularization in the eye is associated with processes that change homeostatic balance between proangiogenic (vascular endothelial growth factor (VEGF)) and antiangiogenic (pigment epithelium-derived factor (PEDF)) factors. The aim of the therapy is to reduce the production of aqueous humour. Application of antiangiogenic preparations in patients with NVG as adjuvant therapy is the method of choice for both prevention and treatment of the disease. The article reviews literature on current possibilities of using anti-VEGF drugs in the treatment of NVG.

Anti-angiogenic activity and mechanism of a chemically sulfated natural glucan from Phellinus ribis

A sulfated polysaccharide named PRP-S16 was obtained by sulfation of a glucan from Phellinus ribis using the chlorosulfonic acid method. PRP-S16 could significantly block the formation of new vessels in chicken chorioallantoic membrane (CAM). It could also inhibit the proliferation, migration, and tube formation and significantly reduced the mRNA expression of vascular endothelial growth factor (VEGF) in EA.hy926 endothelial cells. Western blotting indicated that PRP-S16 down regulated the protein expression of VEGF and VEGF receptor-1 (VEGFR-1), and inhibited the phosphorylation of VEGFR-2, protein kinase B (Akt) and extracellular signal-regulated kinase (ERK1/2) in EA.hy926 cells. These findings suggest that the mechanism of action of the anti-angiogenesis activity of PRP-S16 is related to the inhibition of VEGF-induced signaling pathway. PRP-S16 might be utilized as an effective antagonist in combating diseases associated with angiogenesis.