Aqueous Vascular Endothelial Growth Factor Concentration Research Articles

Duration of Vascular Endothelial Growth Factor Suppression After Intravitreal Injection of Brolucizumab and Aflibercept in Macaque Eyes.

Purpose: To compare the duration of vascular endothelial growth factor (VEGF) suppression in the aqueous humor of macaque eyes after intravitreal injection of brolucizumab and aflibercept. Methods: Clinical dose of intravitreal brolucizumab (IVBr; 6.0 mg/50 μL) or intravitreal aflibercept (IVA; 2 mg/50 μL) was injected into the right eye of each of 8 macaques. Aqueous humor samples (150 μL) from both eyes were obtained just before injection and on days 1, 3, 7, 14, 21, 28, 42, 56, 84, and 112 after IVBr injection or IVA injection. VEGF concentrations were measured using enzyme-linked immunosorbent assays. Results: In the injected eyes, the mean VEGF suppression durations (range) were 4.9 (3-8) weeks for IVBr injection and 6.8 (6-8) weeks for IVA injection (P = 0.04). The VEGF concentrations returned to the preinjection level in the aqueous humor at 12 weeks both after IVBr and IVA injection. In the noninjected fellow eyes, the aqueous VEGF concentrations had decreased least at 1 day after IVBr injection and at 3 days after IVA injection, but were still detectable. The VEGF concentrations in the fellow eyes returned to the preinjection level in the aqueous humor at 1 week after IVBr injection and at 2 weeks after IVA injection. Conclusions: The duration of VEGF suppression in the aqueous humor after IVBr injection may be shorter than that after IVA injection, which may be related with clinical usage.

Detection of aqueous VEGF concentrations before and after intravitreal injection of anti-VEGF antibody using low-volume sampling paper-based ELISA

Intraocular vascular endothelial growth factor (VEGF) levels play an important role in the pathogenesis of blindness-related diseases, such as age-related macular degeneration (AMD). Here, we aimed to develop a paper-based enzyme-linked immunosorbent assay (P-ELISA) to analyze the suppression of aqueous VEGF concentrations following intravitreal injection (IVI) of anti-VEGF antibody (bevacizumab or ranibizumab). A total of 25 eyes with wet AMD, one with myopic neovascularization, and one with polypoidal choroidal vasculopathy were enrolled in this study. The limit of detection using P-ELISA was 0.03 pg/mL. Forty-six consecutive samples of aqueous humor were acquired. From all samples, 66.67% (10/15) achieved complete VEGF suppression (below the detection limit) within 5 weeks of receiving IVI of anti-VEGF antibody. Only 13.33% of samples (2/15) achieved complete VEGF suppression 5 weeks after receiving treatment. In some patients, elevated VEGF was still detected 5 weeks after receipt of anti-VEGF antibody, and all samples (10/10) were found to have elevated VEGF levels 49 days after treatment. Thus, we suggest that monthly IVI of anti-VEGF antibody may be required to ensure durable VEGF inhibition. Ultrasensitive P-ELISA can detect elevated VEGF at an earlier time point and may facilitate decision-making regarding appropriate treatment strategies.

Inhibitory effects of IBI302 on experimental choroidal neovascularization

Objective To investigate the inhibitory effects of IBI302 on experimental choroidal neovascularization (CNV). Methods Affinity of IBI302 to vascular endothelial growth factor (VEGF) family cytokines (including VEGF-A165, VEGF-A121 and placental growth factor PlGF) and complements (C3b, C4b) was determined by enzyme-linked immunosorbent assay (ELISA). The antagonist effect of IBI302 on VEGF was measured by proliferation, migration and tube formation tests of human umbilical vein endothelial cells (HUVEC). The anti-complement activity of IBI302 was measured by hemolysis test mediated by complement classical pathway and alternative pathway. Rhesus laser-induced CNV model was divided into 5 groups including model control group, bevacizumab group, IBI302 0.25 mg group, IBI302 0.50 mg group and IBI302 1.25 mg group. Fluorescein angiography and optical coherence tomography were performed on these monkeys at 14 and 28 days after drug delivery to observe the fluorescein leakage area and retinal thickness. The aqueous VEGF concentration was measured at 29 days after drug delivery. Results IBI302 showed good affinity to VEGF-A165, VEGF-A121 and PlGF, as well as C3b and C4b. IBI302 significantly inhibited the proliferation, migration and tube formation of HUVEC induced by VEGF-A165. IBI302 inhibited the hemolysis induced by complements obviously. At 14 and 28 days after drug delivery, the area of fluorescein leakage and retinal thickness in IBI302 0.25 mg group, IBI302 0.50 mg group, IBI302 1.25 mg group were reduced. The differences of the area of fluorescein leakage and retinal thickness in three IBI302 groups were not significant (P>0.05). At 29 days after drug delivery, the VEGF concentration in the aqueous of rhesus monkey in bevacizumab group [(38.644±6.521) pg/ml] was decreased than that in model control group [(94.203±17.360) pg/ml], the difference was significant (P<0.05). The VEGF concentration in the aqueous of rhesus monkey in three IBI302 groups were less than 31.300 pg/ml. Conclusion IBI302 inhibited experimental CNV through blocking the activity of VEGF and complement. Key words: Choroidal neovascularization/prevention & control; Recombinant fusion proteins/antagonists & inhibitors; Animal experimentation

The changes of aqueous humor vascular endothelial growth factor and pigment epithelium-derived factor levels before and after intravitreal injection of ranibizumab in proliferative diabetic retinopathy

Background Intraocular neovascularization is a primary cause of visual reduce in proliferative diabetic retinopathy (PDR), and intravitreal injection of ranibizumab is one of treating approachs.Researching the mechanism of intravitreal injection of ranibizumab for PDR is a new target for the prevention and management of PDR. Objective This study was to determine the levels of vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF) in aqueous humor of PDR eyes before and after intravitreal injection of ranibizumab. Methods Self-controlled observational study was designed.Fifteen eyes of 15 PDR patients with type 2 diabetes mellitus were included in Fuzhou General Hospital of Nanjing Military Command from January to August 2014, and 1 eye combined with neovascular glaucoma and iris rubeosis.Aqueous samples of 0.1 ml at each time were collected before and 7 days after the injection of ranibizumab from all patients under the informed consent.The changes of aqueous VEGF and PEDF concentrations were detected and analyzed by enzyme-linked immunosorbent assay.This study complied with Declaration of Helsinki and the protocol was approved by this hospital. Results The freeVEGF concentrations before and 7 days after intravitreal injection were (179.4±136.5) pg/ml and (27.1±23.5) pg/ml, respectively, showing a significant reduce after intravitreal injection of ranibizumab (t=4.172, P=0.001). PEDF concentrations before and 7 days after intravitreal injection were (394.0±237.2) pg/ml and (267.7±199.6) pg/ml, respectively, showing a significant reduce after intravitreal injection of ranibizumab (t=5.443, P=0.000). Intraocular neovascularization vanished after intravitreal injection of ranibizumab and vitrectomy was carried out at the seventh day after intravitreal injection. Conclusions Free VEGF and PEDF levels in aqueous humor appear to be significantly decreased after intravitreal injection of ranibizumab, and ocular neovascularization disappears at same time, which avoids intraoperative bleeding during vitrectomy. Key words: Angiogenic factor/aqueous humor; Angiostatic proteins/aqueous humor; Diabetic retinopathy; Neovascularization; Vascular endothelial growth factor; Pigment epithelium-derived factor; Enzyme-linked immunosorbent assay; Ranibizumab

RETINAL BLOOD FLOW CORRELATES TO AQUEOUS VASCULAR ENDOTHELIAL GROWTH FACTOR IN CENTRAL RETINAL VEIN OCCLUSION.

As laser speckle flowgraphy can measure blood flow distribution in the ocular fundus, the authors analyzed the relationship between retinal blood flow and aqueous vascular endothelial growth factor (VEGF) concentration in central retinal vein occlusion. This prospective observational study examined 45 eyes of 45 patients with central retinal vein occlusion before treatment. Blood flow in large vessels around and at the optic disk, aqueous VEGF concentration, and arteriovenous passage time were examined. Blood flow was evaluated as mean blur rate by laser speckle flowgraphy. Fluorescein angiography found 20 ischemic and 25 nonischemic type eyes. Aqueous VEGF concentration in the ischemic type was significantly higher than that in the nonischemic type (P = 0.01). Arteriovenous passage time was significantly correlated to the logarithm of the aqueous VEGF concentration (P = 0.0001). Mean blur rate of the affected eye/mean blur rate of the unaffected eye of the ischemic type was significantly lower than the nonischemic type (P = 0.039). Additionally, mean blur rate was significantly correlated both to the logarithm of the aqueous VEGF concentration (P < 0.0001) and to the arteriovenous passage time (P = 0.0001). Laser speckle flowgraphy may be useful for predicting aqueous VEGF concentration and severity of central retinal vein occlusion.

Suppression of Intraocular Vascular Endothelial Growth Factor During Aflibercept Treatment of Age-Related Macular Degeneration

To determine the duration of suppression of aqueous humor concentrations of vascular endothelial growth factor (VEGF) in eyes with neovascular age-related macular degeneration (AMD) treated with aflibercept. Nonrandomized prospective clinical study. Twenty-seven eyes of 27 neovascular AMD patients receiving intravitreal aflibercept injections on a pro re nata regimen driven by spectral-domain optical coherence tomography (SD OCT) were included in this study. A total of 132 aqueous humor specimens were collected before intravitreal aflibercept injections and their VEGF-A concentrations assayed by multiplex bead analysis. Mean aqueous humor VEGF concentrations before treatment initiation were 90.6 ± 37.1 pg/mL (range 23.4-190.3 pg/mL). Intravitreal injection of aflibercept suppressed the aqueous VEGF concentrations to below the lower limit of quantification (<4 pg/mL) in all patients. The mean duration of VEGF suppression below the lower limit of quantification was >71 ± 18 days. The earliest time after injection at which the VEGF concentration recovered to above the lower limit of quantification was 55 days in 1 patient and >56 days, the recommended aflibercept treatment interval, in 20 patients. The aqueous VEGF recovery status of 6 patients was uncertain after 56 days. On average, VEGF concentrations in the aqueous humor were suppressed below the lower limit of quantification after intravitreal aflibercept injections for about 10 weeks. This aqueous suppression time suggests durable VEGF inhibition for most patients dosed with aflibercept every 8 weeks.

Electroretinograms and level of aqueous vascular endothelial growth factor in eyes with hemicentral retinal vein occlusion or branch retinal vein occlusion

Hemicentral retinal vein occlusion (hCRVO) is a disease related to CRVO but not to branch retinal vein occlusion (BRVO). We reported a significant correlation between aqueous vascular endothelial growth factor (VEGF) levels and the implicit time of 30-Hz flicker electroretinogram (ERG) in CRVO eyes. The purpose of this study was to compare aqueous VEGF levels and ERG components between hCRVO and BRVO eyes. The medical records of patients with macular edema secondary to hCRVO (12 eyes) or BRVO (16 eyes) and received an intravitreal injection of bevacizumab (IVB) at the Nagoya University Hospital from July 2009 to May 2013 were reviewed. Full-field ERGs were recorded before the IVB. Aqueous humor was collected just before the IVB to measure VEGF concentration. Differences in aqueous VEGF level and ERG components between hCRVO and BRVO eyes were determined. Mean aqueous VEGF concentration in hCRVO eyes was significantly higher than that in BRVO eyes (504 vs. 148 pg/ml, P < 0.05). The implicit time of 30-Hz flicker ERG was significantly longer in hCRVO than in BRVO eyes (33.5 vs. 29.8 ms, P < 0.01). The significant difference in VEGF levels in aqueous and implicit times of 30-Hz flicker ERG suggest that retinal ischemia is more manifest in hCRVO than in BRVO eyes.

Aqueous vascular endothelial growth factor and ranibizumab concentrations after monthly and bimonthly intravitreal injections of ranibizumab for age-related macular degeneration

To evaluate vascular endothelial growth factor (VEGF) and ranibizumab concentrations in eyes with age-related macular degeneration (AMD) after monthly and bimonthly intravitreal ranibizumab (IVR) injections. Aqueous humor samples were obtained from 26 eyes with AMD before and after IVR injections. Nine eyes received three monthly injections and 17 eyes received two bimonthly injections. The VEGF and ranibizumab concentrations were measured by enzyme-linked immunosorbent assay. The aqueous VEGF concentrations in the monthly injection group decreased below the lowest detectable limit in eight of nine eyes 1 month after the first injection and seven of nine eyes 1 month after the second injection (P < 0.001, mean baseline value, 94.7 pg/ml); the aqueous VEGF concentrations in the bimonthly injection group decreased below the lowest detectable limit in two of 17 eyes 2 months after the first injection (P < 0.001, mean baseline value, 152.4 pg/ml). The mean aqueous ranibizumab concentrations with monthly injections were 71.2 ng/ml 1 month after the first injection, and 96.3 ng/ml 1 month after the second injection. The mean aqueous ranibizumab concentrations in the bimonthly injection group were 2.5 ng/ml in 15 of 17 eyes, and below the lowest detectable limit in two of 17 eyes 2 months after the first injection. In this pilot study with limited follow-up, intravitreal injection of ranibizumab can suppress aqueous VEGF completely for 1 month in most cases. Its effect does not last for 2 months enough to suppress VEGF completely in most cases, although aqueous VEGF at 2 months after intravitreal injection of ranibizumab is less than that before injection in most cases.

Correlation between vascular endothelial growth factor and nonperfused areas in macular edema secondary to branch retinal vein occlusion

PurposeTo determine the role of vascular endothelial growth factor (VEGF) in macular edema secondary to branch retinal vein occlusion (BRVO).Patients and methodsAqueous humor samples were collected from 52 eyes with macular edema secondary to BRVO before intravitreal drug injections and from 62 control eyes with cataract. VEGF was measured using an enzyme-linked immunosorbent assay. Fluorescein angiography showed capillary nonperfused areas (NPAs). Macular edema was evaluated by optical coherence tomography as the central retinal thickness.ResultsThe mean aqueous VEGF levels in eyes with BRVO and control eyes with cataract were, respectively, 290.5 pg/mL ± 294.9 pg/mL (range 81.9 pg/mL–1567.3 pg/mL) and 118.0 pg/mL ± 50.1 pg/mL (range 24.6 pg/mL–241.1 pg/mL), which differed significantly (P < 0.0001). The mean VEGF level in eyes with BRVO without apparent NPA was 171.4 pg/mL ± 52.5 pg/mL (range 90.9 pg/mL–299.9 pg/mL), which was significantly higher than controls (P = 0.001). VEGF levels were correlated positively with the size of NPA (P = 0.0002) but not with the central retinal thickness.ConclusionThe aqueous VEGF concentration in patients with macular edema secondary to BRVO increased significantly and was correlated significantly with the size of NPA. Aqueous VEGF increased even in eyes without apparent NPA.

Effect of Vitrectomy on Aqueous VEGF Concentration and Pharmacokinetics of Bevacizumab in Macaque Monkeys

To evaluate the effect of vitrectomy on the concentration of vascular endothelial growth factor (VEGF) and the pharmacokinetics of intravitreally injected bevacizumab in the aqueous humor in cynomolgus macaques. Pars plana lensectomy and a standard three-port vitrectomy were performed in one eye each of six macaques. After a minimal 12-week healing period, the vitrectomized eyes received an intravitreal injection of bevacizumab (1.25 mg/50 μL). Aqueous humor and venous blood samples were obtained from the macaques just before vitrectomy, just before injection of bevacizumab, on days 1, 3, and 7, and during weeks 2, 4, 6, and 8 after the injection. The bevacizumab and VEGF concentrations were measured by using enzyme-linked immunosorbent assay. The VEGF concentrations in the aqueous humor ranged from 52.6 to 113.9 pg/mL (mean ± standard deviation [SD], 81.7 ± 27.0 pg/mL) before vitrectomy and 20.7 to 72.7 pg/mL (mean ± SD, 51.4 ± 20.5 pg/mL) 3 months after vitrectomy, a difference that reached significance (P = 0.03). The aqueous VEGF concentrations decreased to less than 9.0 pg/mL, the lower limit of detection, in all eyes between 1 and 7 days after injection of bevacizumab. The mean half-life of 1.25 mg intravitreally injected bevacizumab was 1.5 ± 0.6 days (range, 1.0-2.4 days) in the aqueous humor. The VEGF concentration in the aqueous humor decreased and the half-life of the intravitreally injected bevacizumab was shorter in vitrectomized eyes.

Aqueous humor vascular endothelial growth factor in dogs: association with intraocular disease and the development of pre‐iridal fibrovascular membrane

To examine the concentrations of vascular endothelial growth factor (VEGF) in aqueous humor of dogs with intraocular disease and to evaluate the association of aqueous humor VEGF with pre-iridal fibrovascular membrane (PIFM) formation. Two hundred and twenty six aqueous humor samples and 101 plasma samples were collected from 178 dogs with a variety of intraocular diseases (including cataract, primary glaucoma, uveitic glaucoma, aphakic/pseudophakic glaucoma, retinal detachment, lens luxation, and intraocular neoplasia), and aqueous humor was collected from 13 ophthalmically normal control dogs. Systemic disease status and administration of select medications were recorded. Aqueous and plasma VEGF was assayed via enzyme-linked immunosorbant assay validated for canine VEGF. Available histopathology samples were examined for the presence of PIFM. Where present, PIFMs were categorized as none, cellular, vascular or fibrous, and fibrovascular. Data were evaluated by mixed model anova, with application of Tukey-Kramer adjustment for multiple comparisons. There was no association between aqueous humor and plasma VEGF levels. Compared with normal controls, aqueous humor VEGF was significantly elevated for all intraocular diseases (P < 0.05) except for primary and diabetic cataracts. Systemic disease and administered medications had no significant effect on aqueous humor VEGF concentration. Compared to dogs without PIFM, aqueous humor VEGF was significantly higher in dogs with fibrovascular PIFM (P = 0.001), but not cellular (P = 0.1704) or fibrous/vascular PIFM (P = 0.0667). These findings confirm that VEGF is commonly elevated in aqueous humor of dogs with intraocular disease and likely plays a role in the causation or progression of a variety of intraocular disorders, including the development of PIFM.

Significant Correlation between Electroretinogram Parameters and Ocular Vascular Endothelial Growth Factor Concentration in Central Retinal Vein Occlusion Eyes

Central retinal vein occlusion (CRVO) leads to retinal ischemia, which then induces an upregulation of vascular endothelial growth factor (VEGF). The aim of this study was to determine whether a significant correlation exists between the ocular VEGF levels and the amplitudes and implicit times of different components of the electroretinogram (ERG) in eyes with a CRVO. The medical records of the 20 consecutive patients who had macular edema secondary to CRVO and were examined at the Nagoya University Hospital from November 2008 to February 2010 were reviewed. Because all the patients were scheduled to receive an intravitreal injection of bevacizumab (IVB), it was possible to collect samples of the aqueous humor before the IVB. The correlation between the different components of the ERGs and the VEGF concentration in the aqueous was determined. The mean VEGF concentration of the aqueous humor was 416 pg/mL with a range of 100-1260 pg/mL. The b/a ratio of the single flash ERGs (P = 0.049; ρ = -0.45), implicit times of the cone a-wave (P = 0.028; ρ = 0.50), cone b-wave (P = 0.0059; ρ = 0.63), and 30 Hz flicker ERGs (P = 0.0058; ρ = 0.63) were significantly correlated with the VEGF concentration in the aqueous. The significant correlations between the different components of the ERGs and the aqueous VEGF concentration indicate that full-field ERGs can be used to detect the CRVO patients at a high risk of developing neovascularization of the iris.

Pharmacokinetics of Bevacizumab and Its Effect on Vascular Endothelial Growth Factor after Intravitreal Injection of Bevacizumab in Macaque Eyes

To evaluate the pharmacokinetics of intravitreally injected bevacizumab in the systemic circulation and the aqueous humor and its effect on vascular endothelial growth factor (VEGF) in the aqueous humor. Bevacizumab (1.25 mg/50 microL) was injected into the vitreous cavity of the right eyes of three cynomolgus macaques. Aqueous humor and serum were obtained from the macaques just before injection and on days 1, 3, and 7 and weeks 2, 4, 6, and 8 after injection. The bevacizumab and VEGF concentrations were measured using enzyme-linked immunosorbent assay. Aqueous VEGF concentrations ranged from 63.2 to 106 pg/mL (mean, 80.0 +/- 22.6 pg/mL) before injection; decreased to <31.2 pg/mL, the lower limit of detection, in all eyes between 1 and 28 days after injection; and returned to the preinjection concentration at 42 days. Aqueous VEGF concentrations in the fellow eyes did not change throughout the experiment. Aqueous bevacizumab concentrations in the treated eyes reached a mean peak concentration of 49,500 +/- 10,900 ng/mL the day after injection and gradually declined, whereas those in the untreated eyes peaked at 3 days, with a mean concentration of 18.5 +/- 25.5 ng/mL, and declined to below 0.156 ng/mL, the limit of detection at 2 weeks. A maximum mean bevacizumab concentration of 1430 +/- 186 ng/mL was achieved in the serum 1 week after injection. Intravitreal injection of bevacizumab decreased the VEGF concentration in the treated eyes for at least 4 weeks and had no or a minimal effect on the untreated fellow eyes.

Intracameral bevacizumab effectively reduces aqueous vascular endothelial growth factor concentrations in neovascular glaucoma

Vascular endothelial growth factor (VEGF) concentrations in both the aqueous and vitreous are raised in ocular ischaemia secondary to exudative age-related macular degeneration, diabetes mellitus and other retinal vascular diseases.1...

Correlation of increased vascular endothelial growth factor with neovascularization and permeability in ischemic central vein occlusion.

To establish a role for vascular endothelial growth factor (VEGF) during the onset and clinical course of neovascularization of the iris (NVI) in ischemic central retinal vein occlusion. Sixteen patients with ischemic central retinal vein occlusion were followed up for 12 months by clinical examination, retinal and iris angiography, and serial anterior chamber sampling of aqueous humor. Aqueous VEGF level was determined by enzyme-linked immunoassay, and permeability changes were estimated by capillary zone electrophoretic assessment of aqueous albumin. A correlation was found between aqueous VEGF concentrations and the onset, persistence, and regression of NVI; extent of retinal capillary nonperfusion; and vascular permeability. The NVI occurred when aqueous VEGF concentrations were 849 to 1569 pg/mL and regressed fully when they fell below 550 pg/mL. Aqueous concentrations of serum albumin, a marker of increased permeability, correlated with increased VEGF. Placental growth factor was found at low levels only when VEGF levels exceeded 330 pg/mL. The NVI remained VEGF-dependent during the course of the disease, regressing only if VEGF concentrations were reduced after laser ablation of hypoxic retina. The close temporal correlation between aqueous VEGF levels and the course of neovascularization and permeability in human ischemic central retinal vein occlusion indicates that increased aqueous VEGF level may predict the need for treatment, and that anti-VEGF therapy at an early stage of ischemic central retinal vein occlusion may be therapeutically beneficial.