Neovascular age-related macular degeneration: disease pathogenesis and current state of molecular biomarkers predicting treatment response-a scoping review

Age-related macular degeneration is a major cause of blindness, and the development of anti-vascular endothelial growth factor (VEGF) intravitreal treatments has revolutionised the management of the disease. At the same time, new challenges and unmet needs arose due to the limitations of the current therapeutic options. Neovascularisation development during the course of the disease has a complex pathogenetic mechanism, and several biomarkers and their association with treatment outcomes have been investigated. We reviewed the relevant literature about neovascularisation development and biomarkers related to response to treatment. Improving our knowledge on the field can improve patient outcomes and offer personalised care.

Clinical efficacy of subthreshold micropulse laser combined with anti-VEGF drugs in the treatment of diabetic macular edema: A meta-analysis

BACKGROUND

To systematically evaluate the efficacy and safety of subthreshold micropulse laser (SML) combined with anti-vascular endothelial growth factor (VEGF) drugs for the treatment of diabetic macular edema (DME).

METHODS

The randomized controlled trials on SML combined with anti-VEGF drugs for DME were retrieved from China National Knowledge Infrastructure, Wan Fang Data, VIP Data, Sino Med (China Biomedical Literature Database), PubMed, Web of Science, The Cochrane Library, and Embase by computer from inception to April 19, 2022. The observation group was treated with SML combined with anti-VEGF drugs, while the control group was treated with anti-VEGF agents alone or SML. And the references of the included literature were manually searched. The Meta-analysis was performed using Revman 5.4 and STATA SE 15.

RESULTS

This study finally included 15 randomized controlled trials involving 891 eyes for Meta-analysis. The results showed that there was no statistically significant difference between the 2 groups in best-corrected visual acuity at 1, 3, 6, 9, and 12 months after treatment. There was no statistical difference between the 2 groups in central macular thickness (CMT) at 1, 3, and 6 months after treatment (P > .05). CMT in the observation group was lower than that in the control group at 9 and 12 months (P < .05). There was no statistical difference between the 2 groups in total macular volume at 3, 6, 9, and 12 months in CMT (P > .05). The number of anti-VEGF drugs injections in the observation was lower than that in the control group (P < .05). The occurrence of complications between the 2 groups was not statistically significant difference (P > .05).

CONCLUSION

SML in combination with anti-VEGF drugs in patients with DME are comparable in reducing the number of anti-VEGF drugs injections and CMT, thereby reducing the financial burden on patients. It does not differ in best-corrected visual acuity and total macular volume.

[Long-term outcome of macular neovascularization secondary to choroidal osteoma with and without intravitreal anti-VEGF(vascular endothelial growth factor)- treatment]

BACKGROUND

Choroidal osteoma (CO) is a benign ossifying ocular tumor, which is unilateral in most cases. The CO may cause severe visual impairment, especially in the case of a secondary macular neovascularization (MNV).

OBJECTIVE

Based on a case series of patients with MNV secondary to CO, the variability of the clinical course with and without intravitreal anti-vascular endothelial growth factor (VEGF) treatment is presented.

METHODS

All patients diagnosed with secondary MNV due to CO between 2007 and 2023 were retrospectively assessed with respect to the clinical course.

RESULTS

In this study 7 eyes of 5 patients (4 women, 1 man) were diagnosed with secondary MNV due to CO. Intravitreal anti-VEGF treatment was carried out in 2 patients with unilateral MNV and 1 patient was treated in both eyes for bilateral MNV. In another case with bilateral MNV, only 1 eye was treated because of fibrosis in the other eye. A further case with unilateral CO and MNV scars at the initial diagnosis was left untreated. Overall, in 3 out of 5 eyes treated with intravitreal VEGF inhibition stabilization or improvement of visual acuity could be achieved.

CONCLUSION

In our case series intravitreal anti-VEGF treatment attained a functional stabilization or improvement in 3 out of 5 treated eyes. In one case of CO-associated MNV fibrosis rapidly developed without treatment. Therefore, the clarification for patients with CO about the lifelong risk for development of a secondary MNV is essential in individual cases for early treatment. As no standardized treatment scheme for intravitreal VEGF antibodies for CO-related MNV exists, the treatment is planned on an individual basis.

Effect of microaneurysms on the anti-VEGF treatment for diabetic macular edema: A retrospective cross-sectional study

Although anti-vascular endothelial growth factor (VEGF) treatment is effective for treating diabetic macular edema (DME), the effect of the microaneurysm (MA) status on the therapeutic efficacy of an anti-VEGF treatment remains unclear. Our current study investigated the effects of the number and the presence or absence of leaking MAs on DME and the efficacy of anti-VEGF therapy. A total of 51 eyes of 47 DME patients were administered anti-VEGF treatment. Fluorescence angiography results were used to determine the number of MAs and the presence or absence of leakage, with these findings matched to the optical coherence tomography maps. The correlation between the number of MAs and the retinal thicknesses and the influence of the leaking MAs was examined in order to definitively determine the effect of the anti-VEGF treatment. There was a correlation between the number of MAs and the retinal thickness of the sector in both the 6 mm (correlation coefficients: 0.42) and 3 mm (0.34) sectors (P < .001). There was also a correlation between the number of MAs and the retinal thickness in both the 6 mm (0.31) and 3 mm (0.24) sectors after undergoing the treatment (P < .01). There was a significant difference between the mean thickness of the leaking versus the non-leaking MAs in the 6 mm (388 ± 87 μm) and 3 mm (477 ± 108 μm) sectors before treatment (P < .01). There was also a significant difference for the retinal thickness between the sectors with and without leaking MAs after the treatment (P < .01). The degree of retinal edema before treatment is associated with the number of MAs and the presence of leaking MAs. Anti-VEGF treatment is less effective for focal macular edema with large numbers of MAs, which includes leaking MAs.

Utilization of response surface design for development and optimization of rosuvastatin calcium-loaded nano-squarticles for hair growth stimulating VEGF and IGF production: in-vitro and in-vivo evaluation

INTRODUCTION

Countless individuals experience negative emotions as hair loss pattern affects their self-esteem and well-being. Rosuvastatin calcium (Ca-RUV) was reported to stimulate the growth of the hair in the applied area, hence, it was selected as a potential hair loss treatment drug.

SIGNIFICANCE

This study aims to develop and optimize (Ca-RUV) loaded squarticles (SQRs) and assess their ability to deliver and release Ca-RUV in the hair follicle for the promotion of hair growth.

METHODS

A response surface design was utilized to study the effect of varying Pluronic® F68 (PF68) and the percentage of liquid lipids within the core of the SQRs and the effects of particle size, entrapment efficiency, and drug released percentage after 24 h (%Q24) were assessed. The optimized formula was subjected to DSC, XRD, and in-vivo evaluation in rats.

RESULTS

SQRs stabilized by 0.8% PF68 and contained 37.5% liquid lipids showed an acceptable particle size (250 nm), drug entrapment efficiency (75%), and %Q24 (100%). The in-vivo studies illustrated the ability of the formula to regrow hair in animals after 10 days due to the elevation of the vascular endothelial growth factor (VEGF) and insulin-like growth factor 1 (IGF-1) to their normal values and by 9% and 54%, respectively, relative to standard therapy minoxidil (5%).

CONCLUSION

Thus, it can be concluded that the optimized formula of Ca-RUV loaded SQRs showed superior in-vivo results in the promotion of hair growth in a shorter period relative to the marketed product. Therefore, the formula can offer a viable option for the treatment of hair loss.

Dexamethasone intravitreal implant in diabetic macular oedema refractory to anti-vascular endothelial growth factors: the AUSSIEDEX study

AIM

To evaluate effectiveness of dexamethasone intravitreal implant 0.7 mg (DEX) monotherapy in the AUSSIEDEX study non-responder subgroup, defined by diabetic macular oedema (DME) refractory to anti-vascular endothelial growth factor (anti-VEGF) agents.

METHODS

This prospective, open-label, observational, real-world study included pseudophakic and phakic (scheduled for cataract surgery) eyes that did not achieve a ≥5-letter best corrected visual acuity (BCVA) gain and/or clinically significant central subfield retinal thickness (CRT) improvement after 3-6 anti-VEGF injections for DME (N=143 eyes), regardless of baseline BCVA and CRT. After an initial DEX injection (baseline visit), reinjection was permitted at ≥16-week intervals.

PRIMARY ENDPOINTS

changes in mean BCVA and CRT from baseline to week 52. Safety assessments included adverse events.

RESULTS

Of 143 eyes, 53 (37.1%) and 89 (62.2%) switched to DEX after 3-6 (early) and >6 (late) anti-VEGF injections, respectively; 1 (0.7%) had missing information. With 2.3 injections (mean) over 52 weeks, the change in mean BCVA from a baseline of 57.8 letters was not significant at week 52. Mean CRT improved significantly from a baseline of 417.8 μm at week 52 (mean change -60.9 μm; p<0.001). Outcomes were similar in eyes switched to DEX early and late. No unexpected adverse events were reported; no filtration surgeries were required.

CONCLUSION

To date, AUSSIEDEX is the largest prospective, real-world study of DEX monotherapy for treatment-naïve or anti-VEGF-refractory DME. Following early or late switch from anti-VEGF agents, DEX significantly improved anatomic outcomes at 52 weeks without new safety concerns, supporting use in anti-VEGF-refractory DME.

TRIAL REGISTRATION NUMBER

NCT02731911.

Effect of repeated intravitreal anti-vascular endothelial growth factor drugs on corneal nerves

To investigate the potential effect of repeated intravitreal injection of anti-vascular endothelial growth factor (anti-VEGF) drugs on corneal nerves. A total of 64 patients were treated with intravitreal injection of anti-VEGF drugs. There were 19 cases of neovascular age-related macular degeneration (AMD), 20 cases of diabetic macular edema (DME) and 25 cases of retinal vein occlusion (RVO). Twenty-nine cases were treated with aflibercept (2 mg/0.05 mL) whereas 35 cases were managed with ranibizumab (0.5 mg/0.05 mL). A corneal confocal microscope was used to collect images of corneal subbasal nerve plexus, and Image J was used for image analysis. The changes in corneal nerve were compared between 1 month after each injection and before injection. There were no significant differences in the density and length of corneal nerve at specific time after the surgery in comparison with baseline in patients who were given 3 intravitreal injections. There was no significant correlation between the numbers of injections and the changes of the corneal nerves. After 3rd injection, the nerve length of the DME group was markedly lower than that of AMD and RVO groups, the difference was statistically significant (P < .05). The nerve density of the DME group was not significantly different from that of AMD and RVO groups, whereas the nerve length and nerve density of the AMD and RVO groups were not statistically significant between each other also. The corneal nerve length after the 2nd and 3rd injections of Aflibercept were lower than that before surgery, the difference was statistically significant. There were no significant differences in nerve density and nerve length at each time point after Ranibizumab injection. The length and density of the corneal nerve after multiple injections in contralateral eye displayed no significant changes compared with the baseline. Repeated intravitreal anti-VEGF drug can reduce the length of corneal nerves. For patients who need repeated intravitreal injections of anti-VEGF drugs, especially in DM, attention should be paid on the changes affecting the corneal nerves. It is also needed to strengthen the local anti-inflammatory therapy to avoid infection and to use artificial tears to protect the microenvironment of the ocular surface after the surgery.

Predictors of visual outcome after pars plana vitrectomy secondary to proliferative diabetic retinopathy

Objective: Advanced proliferative diabetic retinopathy can lead to serious ophthalmological complications, including blindness. This research aimed to determine visual outcomes after pars plana vitrectomy secondary to proliferative diabetic retinopathy, as well as to identify its predictors. Methods: This prospective clinical study was performed in the Ophthalmology Clinic of the Clinical Centre University of Sarajevo. 60 subjects (eyes) with performed pars plana vitrectomy secondary to proliferative diabetic retinopathy were included in the study. Results: After univariate linear regression analysis, glucose, HbA1c, vascular endothelial growth factor, previous pan-retinal laser photocoagulation, baseline best corrected visual acuity, gas injection, vitreous haemorrhage, iris rubeosis, and glaucoma were found to be statistically significant parameters associated with postoperative visual outcome (p<0.05). Multivariate linear regression analysis was performed to evaluate the association between factors and postoperative best corrected visual acuity. Only intravitreal vascular endothelial growth factor concentration, previous pan-retinal photocoagulation, and gas injection remained statistically significant associated with postoperative best corrected visual acuity (p<0.05). Conclusion: Vitrectomy is an effective treatment for advanced proliferative diabetic retinopathy. Factors correlated with the better visual outcome are good systemic control, previous pan-retinal photocoagulation, low intravitreal vascular endothelial growth factor concentration, younger age, intraoperative internal gas tamponade, combined phacoemulsification and pars plana vitrectomy surgery, and the absence of postoperative complications. Abbreviations: PDR = proliferative diabetic retinopathy, VEGF = vascular endothelial growth factor, TDR = tractional retinal detachment, BCVA = best corrected visual acuity, DR = diabetic retinopathy, RDD = rhegmatogenous retinal detachment, NVG = neovascular glaucoma, BRVO = branch retinal vein occlusion, CBC = complete blood count, DBT = differential blood count, ESR = erythrocyte sedimentation rate, HbA1c = glycosylated hemoglobin, PHACO = phacoemulsification, ILM = internal limiting membrane, PPV = pars plana vitrectomy, IOP = intraocular pressure, PRP = pan-retinal photocoagulation, ETDRS = Early treatment diabetic retinopathy study.

A Systematic Review and Meta-Analysis of Clinical Outcomes of Small Gauge Vitrectomy with or without Intravitreal Anti-Vascular Endothelial Growth Factor Agents Pretreatment for Proliferative Diabetic Retinopathy

BACKGROUND

Proliferative diabetic retinopathy (PDR) is a common visual threatening ocular disease, patients with nonclearing vitreous hemorrhage (VH), tractional retinal detachment (RD), or extensive fibrovascular proliferation are always in need for surgical treatment. Although several studies reported better surgical outcome in patients underwent surgery after anti-VEGF injection, the effect of anti-VEGF pretreatment for small gauge vitrectomy in PDR patients remains to be elucidated.

OBJECTIVES

The objective of the study was to evaluate the benefits of preoperative anti-VEGF treatment in small gauge vitrectomy for PDR patients.

METHODS

A comprehensive literature search in PubMed, Embase, and the Cochrane Central Register of Controlled Trials was performed to identify relevant studies. Meta-analyses were performed for intraoperative (including intraoperative bleeding, endodiathermy, iatrogenic retinal breaks, surgical time, etc.) and postoperative outcome parameters (including best-corrected visual acuity (BCVA), postoperative VH, postoperative RD, etc.).

RESULTS

Ten randomized controlled trials were identified and used for comparing small gauge vitrectomy alone (344 eyes, control group) and small gauge vitrectomy with preoperative anti-VEGF injection (355 eyes). The intraoperative findings showed that the surgical time, the incidence of clinically significant intraoperative bleeding, iatrogenic retinal breaks, silicone oil tamponade, and the frequency of endodiathermy were significantly less in the anti-VEGF pre-treated group than in the vitrectomy alone group (p < 0.01). The postoperative findings showed that the incidences of early postoperative VH, postoperative RD were significantly less in the anti-VEGF pre-treated group than in the control group (p < 0.05). The pooled result of postoperative rubeosis iridis/neovascular glaucoma was borderline (p = 0.072) between cases and controls, while no statistically significant differences in BCVA at last follow-up and incidences of late postoperative VH were found between these two groups (p > 0.05).

CONCLUSIONS

Anti-VEGF injection prior to small gauge vitrectomy in PDR patients might facilitate easier surgical procedure and reduce intra- and postoperative complications. Further studies are needed to verify our findings and evaluate the optimal interval and dosage for preoperative anti-VEGF injection.

Efficacy and Toxicity of Combined Inhibition of EGFR and VEGF in Patients With Advanced Non-small Cell Lung Cancer Harboring Activating EGFR Mutations: A Systematic Review and Meta-analysis

Dual inhibition of epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) pathways have demonstrated promising results for treatment of advanced non-small cell lung cancer. We conducted a systematic review and meta-analysis to assess the efficacy and toxicity of the combined treatment with EGFR tyrosine kinase inhibitors (TKIs) and VEGF blockade for patients with advanced non-small cell lung cancer harboring activating EGFR mutations, in comparison to EGFR TKIs alone. The electronic databases were searched for relevant randomized trials between 2000 and 2022. The primary endpoints were overall survival (OS) and progression-free survival. Secondary endpoints included objective response rate (ORR), disease control rate, and grade ≥3 adverse events (AEs). The pooled hazard ratios (HR) and odds ratios were meta-analyzed using the generic inverse variance and the Mantel-Haenszel methods. A total of 1528 patients from 8 trials were evaluated for analyses. The combination treatment decreased the risk of disease progression by 37% (HR=0.63; 95% CI, 0.56 to 0.72) but had no added benefit on OS compared with EGFR inhibition alone (HR=0.90; 95% CI, 0.76 to 1.05). There was no significant difference in objective response rate or disease control rate between treatments. There was a significantly increased number of AEs reported in the dual treatment arm (odds ratio=3.02; 95% CI, 1.71 to 5.31), with proteinuria and hypertension being the most significantly increased AEs. This meta-analysis suggests combined inhibition of EGFR and VEGF pathways significantly improves progression-free survival, with no OS benefit, and increases AEs. Mature OS data are needed along with results from more trials exploring this strategy with third-generation EGFR TKIs to strengthen these results.

Effects of acute aerobic exercise on cytokines, klotho, irisin, and vascular endothelial growth factor responses in rheumatoid arthritis patients

BACKGROUND

Rheumatoid arthritis (RA) is a chronic inflammatory joint disease that causes cartilage and bone damage as well as disability.  AIMS : The aim of this study was to examine the effects of acute aerobic exercise on cytokines such as serum interleukin-6 (IL-6), interleukin-1β (IL-1β), Tumor Necrosis Factor-α (TNF-α) and irisin, vascular endothelial growth factor(VEGF) and klotho in RA patients.  METHODS: Forty RA patient and 40 healthy volunteers of the same age participated in this study. All participants walked on the treadmill for 30 minutes at 60-80% of maximal heart rate. Blood samples were taken before and immediately after the exercise. Serum levels of IL-6, IL1β, TNF-α and irisin, VEGF and klotho were measured by enzyme-linked immunosorbent analysis.  RESULTS: Baseline levels of inflammatory cytokines, irisin, VEGF and klotho were found to be higher in RA patients compared to the control group. In both groups, there was an increase in serum klotho levels after exercise compared to baseline (p<0.05), while a decrease in IL1β, TNF-α levels were observed. While serum VEGF level decreased in RA group, it increased in the control group(p<0.05). Irisin levels decreased in both groups. IL-6 level did not change in the control group, while it increased in RA group. A single exercise session had an acute anti-inflammatory effect in RA patients.

CONCLUSION

It can be concluded that acute aerobic exercise can be beneficial for patients with RA through cytokine, irisin, klotho and VEGF levels, and also it can be safely implemented to the RA rehabilitation program for additional anti-inflammatory effects. Trial registration ClinicalTrials.gov: NCT04439682.

Factors That Can Prolong Ocular Treatment Duration in Age-Related Macular Degeneration

Intravitreal injections of anti-vascular endothelial growth factor (VEGF) agents are used to treat wet age-related macular degeneration (wAMD); however, they are associated with a considerable treatment burden and poor real-world outcomes. The molecular size and charge of anti-VEGF agents influence drug pharmacokinetics in the vitreous and peak drug efficacy. This article reviews the established and novel strategies to prolong drug action, in the vitreal cavity, and thus reduce dosing frequency. Increased ocular residency can be attained by increasing drug size as with large molecules, such as KSI-301; adding polyethylene glycol to pegcetacoplan (APL-2) or avacincaptad pegol to increase molecular size; or binding to other targets that increase molecular size, such as vitreal albumin in the case of BI-X. Faricimab is a bispecific antibody in which the fragment crystallizable portion is engineered to prolong ocular residency and reduce systemic exposure. Conversely, small VEGF-binding molecules, such as brolucizumab, can be administered at higher clinical doses, with the potential for prolonged clinical activity versus larger molecules. Other important considerations include sustained drug delivery routes, such as the ranibizumab port delivery system or subconjunctival or suprachoroidal injection. More effective and longer-lasting treatments are needed for wAMD to prolong drug action and reduce dosing frequency. Several strategies are under investigation and the prevention of vision loss in patients with AMD or other retinal diseases may be attainable in the near future.

Two-year clinical outcomes of triple therapy with photodynamic therapy, anti-vascular endothelial growth factor agent, and triamcinolone acetonide for neovascular age-related macular degeneration

PURPOSE

To analyze the 2-year treatment outcomes of triple therapy with standard-fluence photodynamic therapy (PDT), intravitreal injection of ranibizumab (IVR)/aflibercept (IVA), and sub-tenon injection of triamcinolone acetonide (STTA) for neovascular age-related macular degeneration (nAMD) in Japanese patients.

STUDY DESIGN

A retrospective, clinical case-series study.

METHODS

Forty-four eyes of 44 patients with treatment-naïve nAMD followed for more than 24 months were evaluated. Initial treatment was given with triple therapy and retreatment with IVR/IVA as a pro re nata regimen. Best-corrected visual acuity (BCVA), central retinal thickness (CRT), the number of treatments, and intraocular pressure elevation were analyzed.

RESULTS

The mean age was 73.3 ± 10.0 years. The mean BCVA significantly improved from 0.61 ± 0.30 at baseline to 0.50 ± 0.46 at 24 months (p = 0.034). CRT significantly improved from 373 ± 162 μm at baseline to 200 ± 107 μm at 24 months (p < 0.001). The number of treatments given during the 2-year treatment period was 2.7 ± 1.8. No retreatments were necessary in 18 of 44 eyes (40.9%), with no significant difference between IVR (46.4%) or IVA (31.3%) used during the 2-year follow-up of triple therapy (p = 0.51). Four eyes (9.1%) temporarily required glaucoma eye drop treatments.

CONCLUSION

In nAMD patients, induction treatment with triple therapy resulted in approximately 40% of the patients requiring no retreatment for 2 years. The type of anti-VEGF agents used made no difference in the results.

Received anti-VEGF therapy in a patient with CRAO sparing the CLRA with subretinal fluid: A case report

RATIONALE

Central retinal artery occlusion (CRAO) sparing the cilioretinal artery (CLRA) with severe subretinal fluid and non-characteristic cherry-red spot is uncommon. In the present case, the patient received an intravitreal injection of anti- vascular endothelial growth factor, which is very rare.

PATIENT CONCERNS

A 59-year-old man underwent vitrectomy of the left eye for diabetic retinopathy and vitreous hemorrhage. Six months after the operation, the patient presented with sudden painless visual-acuity decline in his left eye and was diagnosed with CRAO; his best corrected visual acuity was weak light perception. Whole retinal edema was seen on the fundus, and macular gray retinal opacification was present without a characteristic cherry-red spot. Optical coherence tomography revealed subretinal fluid (SRF) in the papillomacular bundle and inner retinal thickening. Fundus fluorescein angiography confirmed that the central retinal artery was not filled at 40 seconds and that the CLRA supplied a part of the macular area. Eight months after the second intravitreal injection of ranibizumab, Optical coherence tomography showed a significant reduction in inner retinal hyperreflectivity and the thickness of the nasal macular retina. The SRF was clearly absorbed, and the visual acuity improved to 1.1 logMAR units.

DIAGNOSIS

Atypical CRAO.

INTERVENTIONS

The patient was treated with intravitreal injection of anti-VEGF in his left eye. The thickness of the nasal macular retina decreased.

OUTCOMES

The SRF was clearly absorbed, and the patient's visual acuity significantly improved.

LESSONS

When CRAO occurs in patients with diabetic retinopathy sparing the CLRA, the non-characteristic cherry-red spot may be due to macular inner retinal edema, SRF and other factors. According to the patient's condition, anti-vascular endothelial growth factor can be administered as appropriate to inhibit choroidal neovascularization, reduce SRF in the macular retina, and save some vision.

Effect of pan-retinal laser photocoagulation on intravitreal vascular endothelial growth factor concentration in proliferative diabetic retinopathy

Objective: This study aimed to determine the intravitreal concentration of VEGF in eyes with PDR and to evaluate the effects of previous PRP on its level.

Methods: It was a cross-sectional study performed at the Clinical Centre University. It included 90 eyes surgically treated with PPV, divided into three groups, group A - patients with PDR with previous PRP, group B - patients with PDR without previous PRP, and group C - PPV performed due to the indication unrelated to diabetes. A vitreous sample was obtained during PPV, and the VEGF concentration was determined using an Enzyme-linked immunosorbent assay test (ELISA). Shapiro-Wilk, nonparametric tests Kruskal-Wallis, Mann-Whithney U test, ANOVA and Spearman’s correlation test were used.

Results: The highest vitreous VEGF concentration was in group B - 972.96 (743.33-1149.13) and was higher than in group A - 69.22 (37.33-225.15) and in group C - 19.93 (1.15-32.17) (p<0.001). There was a positive correlation between VEGF vitreous concentration and glucose level in group A patients (Rho=0.410; p=0.027).

Conclusion: As a treatment before PPV surgery, PRP showed to be effective in the reduction of VEGF levels, which also highlighted a decrease in complications during and postoperatively.

Abbreviations: DRS = Diabetic Retinopathy Study, PDR = proliferative diabetic retinopathy, VEGF = vascular endothelial growth factor, PRP = pan-retinal photocoagulation, PPV = pars plana vitrectomy, HbA1c = glycosylated hemoglobin, ETDRS = Early treatment diabetic retinopathy study, ESR = erythrocyte sedimentation rate, BCVA = best corrected visual acuity, OCT = optical coherent tomography, ILM = internal limiting membrane, PHACO = phacoemulsification, IOL = intraocular lens, ELISA = Enzyme-linked immunosorbent assay test, AUC = area under the curve, DME = diabetic macular oedema, TDR = tractional retinal detachment, VMT = vitreomacular traction

Reassessing vascular endothelial growth factor (VEGF) in anti-angiogenic cancer therapy

Vascularization is fundamental to the growth and spread of tumor cells to distant sites. As a consequence, angiogenesis, the sprouting of new blood vessels from existing ones, is a characteristic trait of cancer. In 1971, Judah Folkman postulated that tumour growth is angiogenesis dependent and that by cutting off blood supply, a neoplastic lesion could be potentially starved into remission. Decades of research have been devoted to understanding the role that vascular endothelial growth factor (VEGF) plays in tumor angiogenesis, and it has been identified as a significant pro-angiogenic factor that is frequently overexpressed within a tumor mass. Today, anti-VEGF drugs such as Sunitinib, Sorafenib, Axitinib, Tanibirumab, and Ramucirumab have been approved for the treatment of advanced and metastatic cancers. However, anti-angiogenic therapy has turned out to be more complex than originally thought. The failure of this therapeutic option calls for a reevaluation of VEGF as the major target in anti-angiogenic cancer therapy. The call for reassessment is based on two rationales: first, tumour blood vessels are abnormal, disorganized, and leaky; this not only prevents optimal drug delivery but it also promotes hypoxia and metastasis; secondly, tumour growth or regrowth might be blood vessel dependent and not angiogenesis dependent as tumour cells can acquire blood vessels via non-angiogenic mechanisms. Therefore, a critical assessment of VEGF, VEGFRs, and their inhibitors could glean newer options such as repurposing anti-VEGF drugs as vascular normalizing agents to enhance drug delivery of immune checkpoint inhibitors.

Vitrectomy with subretinal tissue plasminogen activator (r-TPA) and intravitreal injection of anti-vascular endothelial growth factor (anti-VEGF) for submacular hemorrhages treatment: Retrospective analysis of 22 cases

BACKGROUND

Macular hemorrhages are a severe complication of other retinal pathologies, such as age-related macular degeneration (AMD) or macroaneurysms. Their therapeutic approach is not standardized, and can vary from observation to surgical treatment.

MATERIAL AND METHODS

Retrospective analysis of 22 cases of macular hemorrhage, treated with vitrectomy associated to subretinal rTPA and intravitreal anti-VEGF over a period of 5 years.

RESULTS

22 eyes of 22 patients were included, of which 12 (52%) were women. The mean age at diagnosis was 84.4 years. 13 patients were pseudophakic (54.1%) and 19 (86.36%) had previous ophthalmological comorbidities. The etiology of the macular hemorrhage was AMD in 19 patients (86.36%). The mean of best VA corrected at diagnosis was 24.55 (Early Treatment Diabetic Retinopathy Study score -ETDRS), with a statistically significant improvement to 36.78 3 months after surgery (p = 0.011). With an average of 23.5 months of follow-up, no differences in prognosis associated with the etiology or size of the hemorrhage were observed.

CONCLUSION

The treatment of macular hemorrhages by vitrectomy, subretinal rTPA and antiVEGF improves the visual prognosis of affected patients.

Endothelial Phospholipase Cγ2 Improves Outcomes of Diabetic Ischemic Limb Rescue Following VEGF Therapy

Therapeutic vascular endothelial growth factor (VEGF) replenishment has met with limited success for the management of critical limb-threatening ischemia. To improve outcomes of VEGF therapy, we applied single-cell RNA sequencing (scRNA-seq) technology to study the endothelial cells of the human diabetic skin. Single-cell suspensions were generated from the human skin followed by cDNA preparation using the Chromium Next GEM Single-cell 3' Kit v3.1. Using appropriate quality control measures, 36,487 cells were chosen for downstream analysis. scRNA-seq studies identified that although VEGF signaling was not significantly altered in diabetic versus nondiabetic skin, phospholipase Cγ2 (PLCγ2) was downregulated. The significance of PLCγ2 in VEGF-mediated increase in endothelial cell metabolism and function was assessed in cultured human microvascular endothelial cells. In these cells, VEGF enhanced mitochondrial function, as indicated by elevation in oxygen consumption rate and extracellular acidification rate. The VEGF-dependent increase in cell metabolism was blunted in response to PLCγ2 inhibition. Follow-up rescue studies therefore focused on understanding the significance of VEGF therapy in presence or absence of endothelial PLCγ2 in type 1 (streptozotocin-injected) and type 2 (db/db) diabetic ischemic tissue. Nonviral topical tissue nanotransfection technology (TNT) delivery of CDH5 promoter-driven PLCγ2 open reading frame promoted the rescue of hindlimb ischemia in diabetic mice. Improvement of blood flow was also associated with higher abundance of VWF+/CD31+ and VWF+/SMA+ immunohistochemical staining. TNT-based gene delivery was not associated with tissue edema, a commonly noted complication associated with proangiogenic gene therapies. Taken together, our study demonstrates that TNT-mediated delivery of endothelial PLCγ2, as part of combination gene therapy, is effective in diabetic ischemic limb rescue.

Visual acuity and progression of macular atrophy in patients receiving intravitreal anti-VEGF for age-related macular degeneration

PURPOSE

Whether intravitreal anti-vascular endothelial growth factors (VEGFs) cause retinal atrophy is still a subject of debate. We reported 13 eyes that received several injections of anti-VEGF for wet age-related macular degeneration (AMD) with good visual acuity despite geographic atrophy on imaging.

METHODS

This is a case series study conducted at Byers Eye Institute at Stanford University. Patients of three retina specialists with wet AMD who received six or more intravitreal injection of anti-VEGFs with visual acuity of 20/60 or better and incomplete RPE and outer retina atrophy (iRORA) or complete RPE and outer retinal atrophy (cRORA) were enrolled in this case series. Different imaging modalities were reviewed by three retina specialists comparing the baseline with the most recent exam.

RESULTS

About 13 eyes of 10 patients met the selection criteria. Eleven eyes were classified as iRORA and 2 as cRORA. Despite the development of macular atrophy on imaging after an average of 38.1 injections, eyes maintained stable visual acuity.

CONCLUSION

The discrepancy between structural and functional findings in this cohort suggests that patients treated by anti-VEGF drugs exhibit divergent clinical outcomes for currently unknown reasons. The authors propose anti-VEGF may affect melanosomes within RPE without disrupting RPE and photoreceptors function completely. This requires further investigation.

Effectiveness of microperimetry in evaluating anti-vascular endothelial growth factor therapy for diabetic macular edema patients with relatively good vision: A retrospective observational study

No studies have evaluated the retinal sensitivity (RS) for diabetic macular edema (DME) patients with good vision. Therefore, this study aimed to determine the effectiveness of microperimetry in evaluating the effectiveness of anti-vascular endothelial growth factor (anti-VEGF) treatment for DME patients with relatively good vision.Twenty-seven eyes of 27 patients (mean age, 61.3 ± 11.2 years) with DME and decimal best-corrected visual acuity (BCVA) ≥0.6 were studied. All patients received 3 consecutive monthly injections of intravitreal anti-VEGF agents. The BCVA, central subfield macular thickness (CMT), and RS were evaluated by microperimetry (MAIA) within the 10 degree of the foveal center. To determine significant differences between the values, we used paired t tests.Patients were evaluated at baseline and 4 weeks after the third injection. The BCVA improved significantly from 0.18 ± 0.06 logarithm of the minimum angle of resolution (logMAR) units to 0.13 ± 0.13 logMAR units (P = .002; paired t test). The CMT decreased significantly from 464.3 ± 91.8 μm to 393.4 ± 129.0 μm (P = .005), and the RS also improved significantly from 21.8 ± 3.1 dB to 24.1 ± 2.8 dB at 4 weeks after treatment (P = .006). Among the patients with a decimal BCVA of 0.7 or better at baseline, there was no significant improvement in the BCVA (P = .28). However, the CMT decreased significantly from 479.5 ± 79.1 μm to 394.0 ± 99.8 μm at 4 weeks after treatment (P = .007). The RS also improved significantly from 22.0 ± 2.4 dB to 24.0 ± 3.1 dB at 4 weeks after treatment (P = .004).Measuring RS by microperimetry is a good option for evaluating the effectiveness of anti-VEGF treatment for DME patients with a relatively good BCVA.

A Structural Overview of Vascular Endothelial Growth Factors Pharmacological Ligands: From Macromolecules to Designed Peptidomimetics

The vascular endothelial growth factor (VEGF) family of cytokines plays a key role in vasculogenesis, angiogenesis, and lymphangiogenesis. VEGF-A is the main member of this family, alongside placental growth factor (PlGF), VEGF-B/C/D in mammals, and VEGF-E/F in other organisms. To study the activities of these growth factors under physiological and pathological conditions, resulting in therapeutic applications in cancer and age-related macular degeneration, blocking ligands have been developed. These have mostly been large biomolecules like antibodies. Ligands with high affinities, at least in the nanomolar range, and accurate structural data from X-ray crystallography and NMR spectroscopy have been described. They constitute the main focus of this overview, which evidences similarities and differences in their binding modes. For VEGF-A ligands, and to a limited extent also for PlGF, a transition is now observed towards developing smaller ligands like nanobodies and peptides. These include unnatural amino acids and chemical modifications for designed and improved properties, such as serum stability and greater affinity. However, this review also highlights the scarcity of such small molecular entities and the striking lack of small organic molecule ligands. It also shows the gap between the rather large array of ligands targeting VEGF-A and the general absence of ligands binding other VEGF members, besides some antibodies. Future developments in these directions are expected in the upcoming years, and the study of these growth factors and their promising therapeutic applications will be welcomed.

The Development of Macular Atrophy in Patients with Wet Age-Related Macular Degeneration Receiving Anti-VEGF Treatment

Age-related macular degeneration (AMD) is a leading cause of blindness. Late AMD can be classified into exudative (commonly known as wet AMD [wAMD]) or dry AMD, both of which may progress to macular atrophy (MA). MA causes irreversible vision loss and currently has no approved pharmacological treatment. The standard of care for wAMD is treatment with anti-vascular endothelial growth factors (VEGF). However, recent evidence suggests that anti-VEGF treatment may play a role in the development of MA. Therefore, it is important to identify risk factors for the development of MA in patients with wAMD. For example, excessive blockade of VEGF through intense use of anti-VEGF agents may accelerate the development of MA. Patients with type III macular neovascularisation (retinal angiomatous proliferation) have a particularly high risk of MA. These patients are characterised as having a pre-existing thin choroid (age-related choroidopathy), suggesting that the choroidal circulation is unable to respond to increased VEGF expression. Evidence suggests that subretinal fluid (possibly indicative of residual VEGF activity) may play a protective role. Patients receiving anti-VEGF agents must be assessed for overall risk of MA and there is an unmet medical need to prevent the development of MA without undertreating wAMD.

Controlled release of anti-VEGF by redox-responsive polydopamine nanoparticles

Reactive oxidative species (ROS) are the primary mediator of angiogenesis by upregulating the expression of vascular endothelial growth factor (VEGF) in the development of wet age-related macular degeneration (AMD). However, the current treatment of AMD currently relies on monthly intravitreal injection of anti-angiogenic therapeutics to inhibit new choroidal angiogenesis. However, repeated injections have been associated with side-effects, are costly, and may lower patient compliance. Moreover, the intraocular oxidative stress-dependent angiogenesis is not alleviated by current treatments, which limits the overall efficacy of the treatment strategy. Recently, nanoparticle-based devices present potential in sustained delivery of angiogenesis inhibitors and excellent capability of scavenging reactive oxygen species (ROS). Nevertheless, limited efforts have been dedicated to the treatment of oxidative stress-related diseases via a combined anti-angiogenesis and anti-oxidization pathway. For this purpose, we developed anti-angiogenetic protein-loaded polydopamine (PDA) nanoparticles for the enhanced treatment of AMD. Remarkably, the PDA nanoparticles could efficiently scavenge ROS to reduce the expression of angiogenic agents. In parallel, the particles were able to controllably release loaded anti-angiogenic drugs in response to oxidative stress.

Changes in inner retinal layer thickness in patients with exudative age-related macular degeneration during treatment with anti-vascular endothelial growth factor

The aim of this study was to identify any changes that occur in the retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GC-IPL) in patients with exudative age-related macular degeneration (AMD) during treatment with anti-vascular endothelial growth factor (VEGF) injections.Patients were enrolled in this retrospective study if they had exudative AMD, had received at least 3 injections of ranibizumab or aflibercept, and had a minimum of 12 months of follow-up. We analyzed the changes in the RNFL and GC-IPL using spectral-domain optical coherence tomography in rescan mode.Fifty-two eyes of 52 patients who had been treated with repeated anti-VEGF injections for exudative AMD were included. At the final visit, there was no significant between-group difference in best-corrected visual acuity or intraocular pressure. There was a significant decrease in central macular thickness in all groups (P < .05). There was a decrease in RNFL thickness that was only statistically significant in the ranibizumab group and when the ranibizumab or aflibercept groups were combined (P = .036 and .044, respectively). The thickness of the GC-IPL layer was significantly decreased in the aflibercept and total group (P = .035 and P = .048, respectively).The thicknesses of the RNFL and GC-IPL decreased in patients with exudative AMD who underwent repeated anti-VEGF injections.

Angiogenesis: Bench to Bedside, Have We Learned Anything?

End-stage ischemic cardiomyopathy patients are an ever-increasing group of coronary artery disease patients, often with no options in our current treatment armamentarium. Angiogenesis therapy pre-clinical and phase I clinical trials showed great promise, however, the benefits of single growth factor treatments have not been borne out in the larger phase II randomized trials. The complexity of angiogenesis process and the challenges in creating animal models to replicate and study this process in ischemic adult human myocardium have been major limitations to progress in this field. In addition failure to control for the powerful placebo effect in the clinical trials and inadequate methods of outcomes measures assessment have created difficult to overcome road blocks in establishing the efficacy of angiogenic strategies. Herein we review the challenges of angiogenesis research and development of treatment strategies. We also propose a structured model for further investigations of angiogenic therapies. The adherence to such a regimented approach as proposed here is, in our opinion, the only way to achieve success in angiogenesis approach development to treatment of patients with end-stage cardiac ischemia refractory to other established therapies.

Therapeutic angiogenesis by vascular endothelial growth factor supplementation for treatment of renal disease

PURPOSE OF REVIEW

Vascular endothelial growth factors (VEGFs) influence renal function through angiogenesis, with VEGF-A being the most potent inducer of vascular formation. In the normal glomerulus, tight homeostatic balance is maintained between the levels of VEGF-A isoforms produced by podocyte cells, and the VEGF receptors (VEGFRs) expressed by glomerular endothelial, mesangial, and podocyte cells. Renal disease occurs when this homeostatic balance is lost, manifesting in the abnormal autocrine and paracrine VEGF-A/VEGFR signaling, ultrastructural glomerular and tubular damage, and impaired filtration.

RECENT FINDINGS

Preclinical disease models of ischemic renal injury, including acute ischemia/reperfusion, thrombotic microangiopathy, and chronic renovascular disease, treated with exogenous VEGF supplementation demonstrated therapeutic efficacy. These results suggest a therapeutic VEGF-A paracrine effect on endothelial cells in the context of acute or chronic obstructive ischemia. Conversely, renal dysfunction in diabetic nephropathy appears to occur through an upregulated VEGF autocrine effect on podocyte cells, which is exacerbated by hyperglycemia. Therefore, VEGF supplementation therapy may be contraindicated for treatment of diabetic nephropathy, but specific results will depend on dose and on the specific site of VEGF delivery. A drug delivery system that demonstrates cell specificity for glomerular or peritubular capillaries could be employed to restore balance to VEGF-A/VEGFR2 signaling, and by doing so, prevent the progression to end-stage renal disease.

SUMMARY

The review discusses the preclinical data available for VEGF supplementation therapy in models of renal disease.

Therapeutic Angiogenesis Using Vascular Endothelial Growth Factor

Therapeutic angiogenesis using vascular endothelial growth factor can reduce tissue ischemia by simulating the natural process of angiogenesis. Vascular endothelial growth factor not only stimulates endothelial cells to proliferate and migrate, but also mobilizes endothelial progenitor cells and achieves vascular protection. Besides direct administration of angiogenic proteins, plasmids and viral vectors carrying angiogenic genes have been used. Animal experiments have shown promise with evidence of neovascularization and improved perfusion in the target myocardium. Initial phase I and II clinical trials results are encouraging and reflect the potential success of therapeutic angiogenesis as a clinical modality for the treatment of ischemic heart disease. This review discusses the role of vascular endothelial growth factor in therapeutic angiogenesis, along with the problems and considerations of this approach as a treatment strategy.

Therapeutic angiogenesis for myocardial ischemia

Therapeutic angiogenesis offers promise as a novel treatment for ischemic heart disease, particularly for patients who are not candidates for current methods of revascularization. The goal of treatment is both relief of symptoms of coronary artery disease and improvement of cardiac function by increasing perfusion to the ischemic region. Protein-based therapy with cytokines including vascular endothelial growth factor and fibroblast growth factor demonstrated functionally significant angiogenesis in several animal models. However, clinical trials have yielded largely disappointing results. The attenuated angiogenic response seen in clinical trials of patients with coronary artery disease may be due to multiple factors including endothelial dysfunction, particularly in the context of advanced atherosclerotic disease and associated comorbid conditions, regimens of single agents, as well as inefficiencies of current delivery methods. Gene therapy has several advantages over protein therapy and recent advances in gene transfer techniques have improved the feasibility of this approach. The safety and tolerability of therapeutic angiogenesis by gene transfer has been demonstrated in phase I clinical trials. The utility of therapeutic angiogenesis by gene transfer as a treatment option for ischemic cardiovascular disease will be determined by adequately powered, randomized, placebo-controlled Phase II and III clinical trials. Cell-based therapies offer yet another approach to therapeutic angiogenesis. Although it is a promising therapeutic strategy, additional preclinical studies are warranted to determine the optimal cell type to be administered, as well as the optimal delivery method. It is likely the optimal treatment will involve multiple agents as angiogenesis is a complex process involving a large cascade of cytokines, as well as cells and extracellular matrix, and administration of a single factor may be insufficient. The promise of therapeutic angiogenesis as a novel treatment for no-option patients should be approached with cautious optimism as the field progresses.

The forgotten player of in-stent restenosis: Endothelial dysfunction

Reduced coronary endothelium-dependent vasodilation may play a role in the pathophysiology of in-stent restenosis. Moreover, endothelial dysfunction may cause to progression of athetrosclerosis in coronary arteries in patients undergoing percutaneous coronary intervention, especially stent deployment. We believe that the agents improving endothelial dysfunction and healing-enhanced stents, namely vascular endothelial growth factor (VEGF)-eluting stents, estradiol-eluting stents and stents attracting endothelial cells, might take an important role in the prevention of stent restenosis strategies in the near future.

Growth factor-induced therapeutic neovascularization for ischaemic vascular disease: time for a re-evaluation?

PURPOSE OF REVIEW

Therapeutic angiogenesis and arteriogenesis represent an alternative treatment modality for patients with advanced ischaemic coronary or peripheral artery occlusive disease, who are unsuitable for standard revascularization procedures.

RECENT DEVELOPMENTS

Proof-of-concept evidence for therapeutic growth factor, both gene and protein-mediated neovascularization was provided in animal models of chronic myocardial and hindlimb ischaemia. Early human, phase I, trials utilizing the prototypical growth factor families, vascular endothelial growth factor and fibroblast growth factor, documented safety and suggested improvements in anginal symptoms and functional status. Large, randomized, placebo-controlled phase II/III clinical trials have, however, yielded variable results as such studies have suffered from significant limitations in therapeutic approach or design, which limits the ability to draw firm conclusions.

SUMMARY

Future trials must incorporate robust delivery strategies and address issues of study design including proper patient selection. Laboratory-based refinements in therapy, including a focus on the promotion of arteriogenesis and the modification of patient 'endotheliopathy', will all further enhance the potential of therapeutic neovascularization strategies.

Growth factors for therapeutic angiogenesis in peripheral arterial disease

PURPOSE OF REVIEW

Peripheral arterial disease is a common disease that has few treatment options. Angiogenesis is defined as the growth of new blood vessels from preexisting vasculature. Therapeutic angiogenesis is an investigational method that uses vascular growth to alleviate disorders of tissue ischemia, such as coronary artery disease and peripheral arterial disease. There have been tremendous changes in the field of therapeutic angiogenesis over the past decade, and there is much promise for the future.

RECENT FINDINGS

Initial preclinical work with cytokine growth factor delivery resulted in a great deal of enthusiasm, but larger clinical studies have failed to achieve similar success. With an increased understanding of the complex mechanisms involved in angiogenesis, gene therapy and cell therapy have moved to the forefront of therapeutic angiogenesis. Novel therapies which target multiple different angiogenic pathways are also being developed and tested.

SUMMARY

Therapeutic angiogenesis is an exciting field that continues to evolve. This review will focus on the different growth factors being used, their routes of delivery, the results of clinical trials, and some of the novel therapies being developed.

Adeno-associated Viral Vector–Encoding Vascular Endothelial Growth Factor Gene: Effect on Cardiovascular MR Perfusion and Infarct Resorption Measurements in Swine

PURPOSE

To prospectively determine in swine the effects of cardiac-specific and hypoxia-inducible vascular endothelial growth factor (VEGF) expression gene on angiogenesis and arteriogenesis by using cardiovascular magnetic resonance (MR) imaging for evaluation of infarct resorption and left ventricular (LV) function.

MATERIALS AND METHODS

The investigation conformed to U.S. National Institutes of Health guidelines. Twelve pigs with reperfused infarcts were studied with cardiovascular MR 3 days and 8 weeks after surgery. In six pigs, adeno-associated viral (AAV) vector-encoding VEGF (AAV-VEGF) gene was injected at eight sites 1 hour after reperfusion. Six pigs served as controls. Cardiovascular MR measurements of perfusion, area at risk, infarct size, and LV function were used in evaluation of the therapy. Hematoxylin-eosin, Masson trichrome, and biotinylated isolectin B4 stains were used to assess regional vascular density. Two-way Student t test was used to determine significant differences between means.

RESULTS

AAV-VEGF had no effect on cardiovascular MR perfusion or infarct size measurements 3 days after infarction. At 8 weeks, the therapy increased infarct resorption, perfusion, and vascular density and prevented deterioration of ejection fraction in treated animals. These changes were associated with a significantly greater reduction in extent of enhanced region in treated (18.6% of LV surface area +/- 1.5 [standard error of mean] to 9.8% +/- 1.1) than in control animals (17.7% +/- 1.8 to 14.5% +/- 1.5, P = .028). Histopathologic findings in treated animals showed increased capillary and arterial density in infarct and periinfarct regions. These new vessels were active and thin-walled compared with thick-walled vessels of control animals.

CONCLUSION

AAV-VEGF improves cardiovascular MR measurement of regional myocardial perfusion and LV function.

Vascular endothelial growth factors: biology and current status of clinical applications in cardiovascular medicine

Members of the vascular endothelial growth factor (VEGF) family are among the most powerful modulators of vascular biology. They regulate vasculogenesis, angiogenesis, and vascular maintenance during embryogenesis and in adults. Because of their profound effects on blood vessels, VEGFs have received much attention regarding their potential therapeutic use in cardiovascular medicine, especially for therapeutic vascular growth in myocardial and peripheral ischemia. However, completed randomized controlled VEGF trials have not provided convincing evidence of clinical efficacy. On the other hand, recent preclinical proangiogenic VEGF studies have given insight, and anti-VEGF studies have shown that the disturbance of vascular homeostasis by blocking VEGF-A may lead to endothelial dysfunction and adverse vascular effects. Excess VEGF-A may contribute to neovascularization of atherosclerotic lesions but, currently, there is no evidence that transient overexpression by gene transfer could lead to plaque destabilization. Here, we review the biology and effects of VEGFs as well as the current status of clinical applications and future perspectives of the therapeutic use of VEGFs in cardiovascular medicine.

Delayed release particles from vascular endothelial growth factor for repairing spinal cord ischemic injury of rats

OBJECTIVE

To study the effect of delayed release particles from vascular endothelial growth factor (VEGF) on the reparation of ischemic injury of spinal cord in rats.

METHODS

The spinal cord ischemia model of rats was established. The delayed release particles from VEGF were injected via the intubation of spinal subarachnoid space. The rehabilitation was observed by the assessment of unfold claw reflection, space between toes, spinal evoked potential (SEP) and motor evoked potential (MEP).

RESULTS

VEGF prompted SEP and MEP appearance, improved the motor function of hind limbs.

CONCLUSIONS

VEGF can promote the rehabilitation of spinal cord ischemic injury of rats.

Molecular aspects of ischemic heart disease: ischemia/reperfusion-induced genetic changes and potential applications of gene and RNA interference therapy

Molecular biologic techniques have a variety of applications in the study of ischemic heart disease, including roles in elucidating cardiac genetic changes resulting from ischemia as well as in developing therapeutic interventions to treat ischemic heart disease. This review describes recent studies documenting genetic changes associated with myocardial ischemia and infarction as well as those investigating the safety and effectiveness of gene therapy for stimulating angiogenesis, protecting the heart against reperfusion injury, and treating heart failure. Also discussed are future research directions, including the potential use of RNA interference and combined stem cell therapy and gene therapy for the treatment of cardiovascular disease.

Angiogenesis--a new target for future therapy

Development of blood vessels from in situ differentiating endothelial cells (EC) is called vasculogenesis, whereas sprouting of new blood vessels from the pre-existing ones is termed angiogenesis or neovascularisation. Angiogenesis, the growth of new blood vessels, is essential during tissue repair, foetal development, and female reproductive cycle. In contrast, uncontrolled angiogenesis promotes tumor and retinopathies, while inadequate angiogenesis can lead to coronary artery disease. A balance between pro-angiogenic and anti-angiogenic growth factors and cytokines tightly controls angiogenesis. With the identification of several proangiogenic molecules such as the vascular endothelial cell growth factor (VEGF), the fibroblast growth factors (FGFs), and the angiopoietins, and the recent description of specific inhibitors of angiogenesis such as platelet factor-4, angiostatin, endostatin, and vasostatin, it is recognized that therapeutic interference with vasculature formation offers a tool for clinical applications in various pathologies. Inhibition of angiogenesis can prevent diseases such as cancer, diabetic nephropathy, arthritis, psoriasis, whereas stimulation of angiogenesis is beneficial in the treatment of coronary artery disease (CAD), cardiac failure, tissue injury, etc. One of the most specific and critical regulators of angiogenesis is vascular endothelial growth factor (VEGF), which regulates endothelial proliferation, permeability, and survival. Substantial evidence also implicates VEGF as an angiogenic mediator in tumors and intraocular neovascular syndromes, and numerous clinical trials are presently testing the hypothesis that inhibition of VEGF may have therapeutic value.

Emerging new drugs for wound repair

Every year, millions of people experience burns, suffer from nonhealing wounds, or have acute wounds that become complicated by infection, dehiscence or problematic scarring. Effective wound treatment requires carefully considered interventions often requiring multiple clinic or hospital visits. The resulting costs of wound care are staggering, and more efficacious and cost-effective therapies are needed to decrease this burden. Unfortunately, the expenses and difficulties encountered in performing clinical trials have led to a relatively slow growth of new treatment options for the wound management. Research efforts attempting to examine wound pathophysiology have been hampered by the lack of an adequate chronic wound healing model, and the complexity of the wound healing cascade has limited attempts at pharmacological modification. As such, currently available wound healing therapies are only partially effective. Therefore, many new therapies are emerging that target various aspects of wound repair and the promise of new therapeutic interventions is on the immediate horizon.

Therapeutic angiogenesis

Still a long way off

Vascular-targeting agents and radiation therapy in lung cancer: where do we stand in 2005?

With recent Food and Drug Administration approval of the anti-vascular endothelial growth factor (VEGF) antibody for the treatment of colon cancer, it may be possible to achieve similar progress in the treatment of locally advanced lung cancer. Antiangiogenic therapies in the clinic are a reality, and it is important to demonstrate that they can be used safely with conventional modalities, including radiation therapy (RT). Strategies under scrutiny in preclinical and clinical studies include the use of endogenous inhibitors of angiogenesis, use of agents that target VEGF and VEGF receptor signaling, targeting endothelial-related integrins during angiogenesis, and targeting the preexisting immature vessels growing within tumors (ie, vascular targeting). Regardless of the approach, it is necessary to address whether angiogenesis is a consistent phenomenon within the lung parenchyma around a cancer and a relevant target and whether inhibiting angiogenesis will improve current lung cancer therapies without increasing toxicity. Vascular-targeting agents (VTAs) are an interesting class of agents that have the potential to enhance RT, but their clinical promise has yet to be realized. In preclinical models, these agents selectively destroy the tumor vasculature, initiating a rapid centralized necrosis within established tumors. Characteristically, after treatment with VTAs, a rim of viable tumor cells remains at the periphery of the tumor, which remains well perfused and should therefore be relatively sensitive to radiation-induced cytotoxicity. This review will focus on VTAs in the treatment of lung cancer and includes a discussion of combination studies with RT in the laboratory and some of the hurdles in the clinical application of these agents.

Gene Therapy for Ischemic Cardiovascular Diseases: Some Lessons Learned from the First Clinical Trials

Stimulation of angiogenesis, arteriogenesis, and lymphangiogenesis (i.e., therapeutic vascular growth) is a new concept for the treatment of ischemic cardiovascular diseases. A wealth of information is already available about the mechanisms and mediators of angiogenesis and arteriogenesis, which has led to the first randomized, controlled, phase II/III trials with recombinant growth factors or their genes. Even though end points predefined in the study protocols have been positive in several trials, it is still evident that the trials have not produced any clearly meaningful clinical benefits for the patients. This review addresses same questions and concepts related to the gene therapy-based applications of therapeutic vascular growth.

Angiogenic growth factors and/or cellular therapy for myocardial regeneration: A comparative study

BACKGROUND

Locally delivered angiogenic growth factors and cell implantation have been proposed for patients with myocardial infarcts without a possibility of percutaneous or surgical revascularization. The goal of this study was to compare the effects of these techniques in an experimental model of myocardial infarct.

METHODS

Left ventricular myocardial infarction was created in 27 sheep by ligation of 2 coronary arteries. Three weeks after creation of the infarct, animals were randomized into 4 groups. In group 1, sheep received a culture medium injection to the infarct area (control group); group 2 underwent autologous myoblast implantation; group 3 received vascular endothelial growth factor; and group 4 received injection of both vascular endothelial growth factor and myoblasts. Evaluation included serum troponin IC levels, echocardiography (2-dimensional and color kinesis), and immunohistologic studies for quantitative analysis of capillaries (3 months after surgery).

RESULTS

Four animals died of refractory ventricular fibrillation during myocardial infarction; 2 died after surgery because of stroke and 2 because of infections. Serum troponin increased to 45.6 +/- 4.7 ng/mL at postinfarction day 2. Echocardiography at 3 months showed a significant limitation of left ventricular dilation in the cell group (57 +/- 11.1 mL) and in the cell plus vascular endothelial growth factor group (58.6 +/- 6.6 mL: control group, 74.4 +/- 11.2 mL; vascular endothelial growth factor group, 68.1 +/- 3.4 mL). Color kinesis echography showed important improvements of regional fractional area change in the cell group (from 13.6% +/- 0.8% to 21.1% +/- 1.5%) and in the cell plus vascular endothelial growth factor group (from 12.8% +/- 0.9% to 18.7% +/- 2.3%). The number of capillaries increased in the peri-infarct region of the vascular endothelial growth factor group (1036 +/- 75: control group, 785 +/- 31; cell group, 830 +/- 75; cell plus vascular endothelial growth factor group, 831 +/- 83).

CONCLUSIONS

In the cell therapy groups, regional ventricular contractility improved and heart dilatation was limited compared with either vascular endothelial growth factor or control; thus, postischemic remodeling was reduced. Angiogenesis was demonstrated in the vascular endothelial growth factor group, without improvement of ventricular function and remodeling. To improve local conditions for cell survival, further studies are warranted on prevascularization of myocardial scars with angiogenic therapy.

The Potential Role of Vascular Endothelial Growth Factor in the Central Nervous System

During the past decade, vascular endothelial growth factor (VEGF) has been widely investigated, and reported to have pleiotropic functions in the central nervous system (CNS) and its supporting physiological environment. VEGF is involved in not only such well-known functions as angiogenesis, accentuation of vessel permeability, and glial proliferation, but also more recently acknowledged functions such as neuroprotection and even neurogenesis itself. Most recently, the neurogenesis function has attracted much attention, and a number of research groups have taken up the challenge of elucidating this activity. In keeping with this trend, our knowledge of VEGF receptors has increased, and certain suggestions concerning the mechanisms of neuroprotection have come to light in the course of the ongoing work, though at times what the researchers had to work with was only a tiny percent of the signal transduction of VEGF. Together with flt-1 (VEGF receptor 1) and flk-1 (VEGF receptor 2), neuropilin (NP) is frequently described as being involved in the neuroprotective effects of VEGF. In this review, both the direct and indirect neuroprotective effects of VEGF, including various signaling pathways as well as the neurogenesis induced by this factor, are discussed in the context of the newly emerging insights into the biological mechanisms of VEGF and closely related, interacting molecules.

Vascular endothelial growth factor stimulates angiogenesis without improving collateral blood flow following hindlimb ischemia in rabbits

This study was designed to test the ability of adenovirus-delivered vascular endothelial growth factor (Ad-VEGF) to stimulate angiogenesis and arteriogenesis in the rabbit hindlimb following the induction of ischemia and to evaluate the functional changes in the collateral circulation. Ten days after the surgical induction of hindlimb ischemia, either a control virus (1 x 10(9) pfu) or an adenovirus containing the gene for VEGF(165) (1 x 10(6), 1 x 10(7), 1 x 10(8), or 1 x 10(9) pfu) was administered intramuscularly into the ischemic limb. Thirty days after administration of the adenoviral vectors, skeletal muscle capillary density was assessed and angiography was performed as markers of angiogenesis and arteriogenesis, respectively. Hindlimb blood flow was directly measured and hyperemic tests were performed to evaluate the functional improvements in collateral blood flow. Animals treated with Ad-VEGF at 1 x 10(8) and 1 x 10(9) pfu showed elevated levels of circulating VEGF and dose-dependent hindlimb edema. These doses also led to a robust angiogenic response (i.e., increase in capillary density), but failed to improve collateral blood flow. Consistent with the lack of a functional response, there was no angiographic evidence of enhanced arteriogenesis with any dose of Ad-VEGF. Following the induction of hindlimb ischemia, administration of Ad-VEGF stimulated capillary sprouting (i.e., angiogenesis), but did not increase the growth and development of larger conduit vessels (i.e., arteriogenesis) or improve collateral blood flow. These results support the concept that VEGF may not be expected to have therapeutic utility for the treatment of peripheral or myocardial ischemia.

Therapeutic angiogenesis in ischemic heart disease: gene or recombinant vascular growth factor protein therapy?

In the last decennium the challenge to research has been to find methods of inducing new vascular growth in ischemic myocardium due to atherosclerotic coronary artery disease, which could not be treated with balloon angioplasty or coronary artery by-pass grafting. Therapeutic angiogenesis with recombinant vascular endothelial growth factor proteins or gene encoding for the proteins is a new potential treatment for cardiovascular disease. The greatest interest and research has been concentrated on basic Fibroblast Growth Factor (FGF1 and FGF2) and Vascular Endothelial Growth Factor A (VEGF-A165 and VEGF-A121). Several small clinical phase I-II safety and efficacy trials with recombinant vascular endothelial growth factor proteins or gene encoding for the proteins have demonstrated that these treatment regimes seem to be safe and the results have been encouraging. However, two large doubleblind randomized placebo-controlled studies with intracoronary infusions of the recombinant proteins FGF2 and VEGF-A165 could not detect any clinical effect. Large scaled phase II studies with gene therapy are in progress. Therapeutic angiogenesis is still a promising new treatment in patients with coronary artery disease. However, more research including large scaled clinical trials is needed before deciding whether the vascular endothelial growth factor therapy either as a gene or a recombinant slow-release protein formulation therapy can be offered to patients with severe coronary artery disease, which cannot be treated with conventional revascularization.

[The research and application of vascular endothelial factor]

Vascular endothelial growth factor (VEGF) is a mult-effective catokines on the endothelial cells specificly. It promotes the endothelial cells to split multiply proliferate and metastasis. It increases vascular permeability and accelerates new vascular generation. VEGF participates many physiological and pathological processes. It has achieved more clinical application and will have extensive applicative prospect.