Bevacizumab in High-Risk Corneal Transplantation: A Pilot Multicenter Prospective Randomized Control Trial

VEGFR3 pathway in corneal transplantation

PURPOSE

Corneal transplantation, a common procedure in ophthalmology, faces challenges in high-risk (HR) cases due to inflammation and vascularization of the host bed, leading to graft rejection. Despite advancements in surgical techniques and therapeutics, preventing rejection in HR cases remains elusive. This study investigates the role of the vascular endothelial-derived growth factor (VEGF)-C/D-VEGFR3 pathway in corneal transplantation, focusing on its impact on inflammation and immune response.

METHODS

In this study, 42 eyes of 42 patients were evaluated, 24 of whom underwent corneal transplantation, with follow-up visits at 90, 180 and 360 days post-transplantation. Clinical assessments included visual acuity, corneal oedema, endothelial cell count and vascularization. Molecular analyses were performed to measure VEGFR3, VEGF-C, VEGF-D, VEGF-A and inflammatory markers.

RESULTS

Results revealed a distinct pattern of VEGF-C/D and VEGFR3 expression in HR versus low-risk (LR) transplants, correlating with inflammatory markers and clinical outcomes. In HR cases, elevated VEGFR3 expression was associated with increased inflammatory markers (Intercellular Adhesion Molecule 1 (ICAM-1) and Human Leukocyte Antigen - DR isotype (HLA-DR)) and graft rejection risk.

CONCLUSION

These findings underscore the importance of understanding the VEGF-C/D-VEGFR3 pathway in modulating immune responses and inflammation in corneal transplantation, particularly in HR cases. Targeting this pathway could offer novel therapeutic avenues to mitigate inflammation and improve graft survival. Further research is warranted to elucidate the underlying mechanisms and validate these findings, potentially enhancing transplant outcomes, especially in HR patients.

Self-Cascade API Nanozyme for Synergistic Anti-Inflammatory, Antioxidant, and Ferroptosis Modulation in the Treatment of Corneal Neovascularization

Corneal neovascularization is a common pathological ocular change that can severely impairs vision, potentially leading to blindness. Although steroids and non-steroidal anti-inflammatory drugs are the primary treatments, their side effects, such as ocular hypertension, eye irritation, and corneal lysis, limit their widespread use. In the present study, an active pharmaceutical ingredient (API) nanozyme (PC-DS NE) is developed through the metal-organic coordination of ferrous sulfate with the anti-inflammatory agent diclofenac sodium and the natural antioxidant proanthocyanidin. PC-DS NE exhibited a spheroid morphology with a particle size of 39.7 ± 5.2 nm, and could achieve the short-term release of diclofenac sodium and sustained release of proanthocyanidin. Notably, the PC-DS NE possessed favorable biocompatibility, self-cascade redox regulation capacity, and significant anti-inflammatory activity. In corneal alkali burn experiments, PC-DS NE effectively inhibited corneal neovascularization by scavenging reactive oxygen species, inhibiting the expression of inflammatory cytokines and pro-angiogenic factors, and down-regulating ferroptosis. These synergistic effects highlighted the potential of PC-DS NE as a promising treatment for ocular inflammatory diseases.

Analysis of the relevant factors for corneal graft rejection in the southern Liaoning region from 2019 to 2023

Background

The study aimed to review the etiology of corneal blindness and investigate the relative risk of corneal graft rejection (CGR) in the southern Liaoning region.

Methods

The clinical records of 359 patients (394 eyes) who underwent corneal transplantation at the Department of Keratoconus of the Third People's Hospital of Dalian from January 2019 to December 2023 were retrospectively analyzed. The data included patients' age, gender, occupation, diagnosis, surgical procedure, postoperative immune rejection, and neovascularization. The data were collected and descriptively analyzed to characterize the etiology of corneal blindness and to analyze the risk factors for postoperative immune rejection after corneal transplantation using logistic regression.

Results

The mean age of the patients who underwent corneal transplantation was 55.90 ± 0.80 years, and there were more male patients than female patients with corneal blindness. Infectious keratitis (41.1%) was reported as the leading cause of corneal blindness, and penetrating corneal transplantation was the main surgical procedure for the recovery of sight. Preoperative corneal vascularization and penetrating corneal graft rejection were identified as risk factors for immune rejection of corneal grafts. The preoperative corneal vascularization was performed (p = 0.044, OR = 2.607). Penetrating keratoplasty (PKP) was performed (p = 0.024, OR = 1.953), and deep anterior lamellar keratoplasty was also performed (p = 0.801, OR = 1.088). Viral infections (p < 0.001, OR = 16.871) were the major risk factor for preoperative corneal neovascularization (CNV) compared to other etiologies, such as fungal infections (p < 0.001, OR = 0.018), mechanical ocular trauma (p < 0.001, OR = 0.034), immune keratitis (p = 0.023, OR = 0.152), and endothelial dysfunction (p < 0.001, OR = 0.054).

Conclusion

Infectious keratitis was identified as the major cause of corneal blindness in the southern Liaoning region over the past 5 years. Penetrating keratoplasty and preoperative corneal vascularization were the risk factors for corneal graft rejection. In addition, virus-derived keratitis was considered to be the main risk factor for corneal neovascularization, and deep anterior lamellar keratoplasty was not found to have an effect on corneal graft rejection in this study.

In silico evaluation of corneal patch eluting anti-VEGF agents concept

This study introduces a novel approach utilizing a temporary drug-eluting hydrogel corneal patch to prevent neovascularization, alongside a numerical predictive tool for assessing the release and transport kinetics of bevacizumab (BVZ) after the keratoplasty. A key focus was investigating the impact of tear film clearance on the release kinetics and drug transport from the designed corneal patch. The proposed tear drug clearance model incorporates the physiological mechanism of lacrimal flow (tear turnover), distinguishing itself from previous models. Validation against experimental data confirms the model's robustness, despite limitations such as a 2D axisymmetrical framework and omission of blink frequency and saccadic eye movements potential effects. Analysis highlights the significant influence of lacrimal flow on ocular drug transport, with the corneal patch extending BVZ residence time compared to topical administration. This research sets the stage for exploring multi-layer drug-eluting corneal patches as a promising therapeutic strategy in ocular health.

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

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

Cannabidiol alleviates suture-induced corneal pathological angiogenesis and inflammation by inducing myeloid-derived suppressor cells

BACKGROUND

Currently, no perfect treatment for neovascularization and lymphangiogenesis exist, and each treatment method has its complications and side effects. This study aimed to investigate the anti-angiogenic and anti-inflammatory effects of cannabidiol and its mechanism of action.

METHOD

An in vivo corneal neovascularization (CNV) model was established using the suture method to investigate the inhibitory effects of CBD on suture-induced corneal inflammation, pathological blood vessel formation, and lymphangiogenesis. Additionally, the impact of CBD on immune cells was studied. In vitro methodologies, including cell sorting and co-culture, were employed to elucidate its mechanism of action.

RESULTS

Compared with the CNV group, CBD can inhibit CNV, lymphangiogenesis, and inflammation induced via the suture method. In addition, CBD specifically induced CD45+CD11b+Gr-1+ cell upregulation, which significantly inhibited the proliferation of CD4+ T lymphocytes in vitro and exhibited a CD31+ phenotype, proving that they were myeloid-derived suppressor cells (MDSCs). We administered anti-Gr-1 to mice to eliminate MDSCs in vivo and found that anti-Gr-1 partially reversed the anti-inflammatory and angiogenic effects of CBD. Furthermore, we found that compared with MDSCs in the normal group, CBD-induced MDSCs overexpress peroxisome proliferator-activated receptor-gamma (PPAR-γ). Administering PPAR-γ inhibitor in mice almost reversed the induction of MDSCs by CBD, demonstrating the role of PPAR-γ in the function of CBD.

CONCLUSION

This study indicates that CBD may induce MDSCs upregulation by activating the nuclear receptor PPAR-γ, exerting anti-inflammatory, antiangiogenic, and lymphangiogenic effects, and revealing potential therapeutic targets for corneal neovascularization and lymphangiogenesis.

Combination Nanomedicine Strategy for Preventing High-Risk Corneal Transplantation Rejection

High-risk (HR) corneal transplantation presents a formidable challenge, with over 50% of grafts experiencing rejection despite intensive postoperative care involving frequent topical eyedrop administration up to every 2 h, gradually tapering over 6-12 months, and ongoing maintenance dosing. While clinical evidence underscores the potential benefits of inhibiting postoperative angiogenesis, effective antiangiogenesis therapy remains elusive in this context. Here, we engineered controlled-release nanomedicine formulations comprising immunosuppressants (nanoparticles) and antiangiogenesis drugs (nanowafer) and demonstrated that these formulations can prevent HR corneal transplantation rejection for at least 6 months in a clinically relevant rat model. Unlike untreated corneal grafts, which universally faced rejection within 2 weeks postsurgery, a single subconjunctival injection of the long-acting immunosuppressant nanoparticle alone effectively averted graft rejection for 6 months, achieving a graft survival rate of ∼70%. Notably, the combination of an immunosuppressant nanoparticle and an anti-VEGF nanowafer yielded significantly better efficacy with a graft survival rate of >85%. The significantly enhanced efficacy demonstrated that a combination nanomedicine strategy incorporating immunosuppressants and antiangiogenesis drugs can greatly enhance the ocular drug delivery and benefit the outcome of HR corneal transplantation with increased survival rate, ensuring patient compliance and mitigating dosing frequency and toxicity concerns.

Suppression of Neovascularization by Topical and Subconjunctival Bevacizumab After High-Risk Corneal Transplantation

Purpose

To assess the effectiveness of topical and subconjunctival bevacizumab in suppressing vascularization in graft and host bed after high-risk corneal transplantation.

Design

Secondary analysis of prospective, randomized, double-blind, placebo-controlled multicentric clinical trial.

Participants

The study includes patients aged > 18 years who underwent high-risk penetrating keratoplasty, which was defined as corneal vascularization in ≥ 1 quadrants of the corneal graft and host bed, excluding the limbus.

Methods

Patients were randomized to treatment and control groups. The patients in the treatment group received subconjunctival injection of bevacizumab (2.5 mg/0.1 ml) on the day of the procedure, followed by topical bevacizumab (10 mg/ml) 4 times per day for 4 weeks. The patients in control group received injection of vehicle (0.9% sodium chloride) on the day of procedure, followed by topical vehicle (carboxymethylcellulose sodium 1%) 4 times a day for 4 weeks.

Main Outcome Measures

Vessel and invasion area of vessels in the corneal graft and host beds.

Results

This study included 56 eyes of 56 patients who underwent high-risk corneal transplantation, with equal numbers in the bevacizumab and vehicle (control) treatment groups. The mean age of patients who received bevacizumab was 61.2 ± 15.9 years, and the mean age of those treated with vehicle was 60.0 ± 16.1 years. The vessel area at baseline was comparable in the bevacizumab (16.72% ± 3.19%) and control groups (15.48% ± 3.12%; P = 0.72). Similarly, the invasion areas were also similar in the treatment (35.60% ± 2.47%) and control (34.23% ± 2.64%; P = 0.9) groups at baseline. The reduction in vessel area was significantly higher in the bevacizumab-treated group (83.7%) over a period of 52 weeks compared with the control group (61.5%; P < 0.0001). In the bevacizumab-treated group, invasion area was reduced by 75.8% as compared with 46.5% in the control group. The vessel area was similar at 52 weeks postprocedure in cases of first (3.54% ± 1.21%) and repeat (3.80% ± 0.40%) corneal transplantation in patients who received bevacizumab treatment. In the vehicle-treated patients, the vessel area was significantly higher in repeat (9.76% ± 0.32%) compared with first (8.06% ± 1.02%; P < 0.0001) penetrating keratoplasty. In the bevacizumab treatment group, invasion areas at week 52 were comparable in first (11.70% ± 3.38%) and repeat (11.64% ± 1.74%) procedures, whereas invasion area was significantly higher in repeat (27.87% ± 2.57%) as compared with first (24.11% ± 2.17%) penetrating keratoplasty in vehicle-treated patients.

Conclusions

In patients undergoing vascularized high-risk corneal transplantation, bevacizumab is efficacious in reducing vascularization of corneal graft and host bed, thereby reducing the risk of corneal graft rejection in vascularized host beds.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Current trends in the management of corneal neovascularization

PURPOSE OF REVIEW

The aim of this study was to highlight recent developments in the medical and surgical management of corneal neovascularization (NV).

RECENT FINDINGS

Improved understanding and diagnostic criteria among clinicians have led to advancements in the characterization of corneal NV and objective assessment of treatment response through ancillary imaging devices. Developments in corneal NV treatments, such as antivascular endothelial growth factor, fine needle diathermy, and photodynamic therapy, have improved treatment success rates and visual outcomes. More recent surgical treatment advancements include corneal cross-linking, endothelial keratoplasty, and mitomycin intravascular chemoembolization. Finally, a greater appreciation of the molecular pathogenesis and angiogenic factors involved in corneal NV has identified numerous potential targeted therapies in the future.

SUMMARY

The management of corneal NV has evolved to include several standalone and combination medical and surgical options. Additionally, improvements in quantifying corneal NV and understanding its molecular basis have contributed to new management strategies with improved outcomes.

Available Therapeutic Options for Corneal Neovascularization: A Review

Corneal neovascularization can impair vision and result in a poor quality of life. The pathogenesis involves a complex interplay of angiogenic factors, notably vascular endothelial growth factor (VEGF). This review provides a comprehensive overview of potential therapies for corneal neovascularization, covering tissue inhibitors of metalloproteinases (TIMPs), transforming growth factor beta (TGF-β) inhibitors, interleukin-1L receptor antagonist (IL-1 Ra), nitric oxide synthase (NOS) isoforms, galectin-3 inhibitors, retinal pigment epithelium-derived factor (PEDF), platelet-derived growth factor (PDGF) receptor inhibitors, and surgical treatments. Conventional treatments include anti-VEGF therapy and laser interventions, while emerging therapies such as immunosuppressive drugs (cyclosporine and rapamycin) have been explored. Losartan and decorin are potential antifibrotic agents that mitigate TGF-β-induced fibrosis. Ocular nanosystems are innovative drug-delivery platforms that facilitate the targeted release of therapeutic agents. Gene therapies, such as small interfering RNA and antisense oligonucleotides, are promising approaches for selectively inhibiting angiogenesis-related gene expression. Aganirsen is efficacious in reducing the corneal neovascularization area without significant adverse effects. These multifaceted approaches underscore the corneal neovascularization management complexity and highlight ideas for enhancing therapeutic outcomes. Furthermore, the importance of combination therapies and the need for further research to develop specific inhibitors while considering their therapeutic efficacy and potential adverse effects are discussed.

Novel artemisinin derivative P31 inhibits VEGF-induced corneal neovascularization through AKT and ERK1/2 pathways

Corneal neovascularization (CoNV)is a major cause of blindness in many ocular diseases. Substantial evidence indicates that vascular endothelial growth factor (VEGF) plays an important role in the pathogenesis of corneal neovascularization. Previous evidence showed that artemisinin may inhibit angiogenesis through down regulation of the VEGF receptors. We designed and synthesized artemisinin derivatives, and validated their inhibitory effect on neovascularization in cell and animal models, and explored the mechanisms by which they exert an inhibitory effect on CoNV. Among these derivatives, P31 demonstrated significant anti-angiogenic effects in vivo and in vitro. Besides, P31 inhibited VEGF-induced HUVECs angiogenesis and neovascularization in rabbit model via AKT and ERK pathways. Moreover, P31 alleviated angiogenic and inflammatory responses in suture rabbit cornea. In conclusion, as a novel artemisinin derivative, P31 attenuates corneal neovascularization and has a promising application in ocular diseases.

Efficacy and safety of anti-vascular endothelial growth factor agents on corneal neovascularization: A meta-analysis

BACKGROUND

Corneal neovascularization (CoNV) is the second major cause of blindness. Vascular endothelial growth factor (VEGF) inhibitors, e.g., bevacizumab, have been used to prevent CoNV.

AIM

We conducted an updated systematic review and meta-analysis of clinical trials to examine the efficacy and safety of anti-VEGF in CoNV.

METHODS

A literature search was conducted using three electronic databases. Mean difference (MD), standard mean difference (SMD), and relative risk (RR) are used to estimate the effect size.

RESULTS

Nine randomized controlled and three non-randomized trials were obtained. The pooled results demonstrated a significant reduction of CoNV area/Length (SMD = -1.17, 95%CI: -1.58 to -0.75), best corrected visual acuity (MD = -0.54, 95%CI: -0.91 to -0.17), and graft rejection (RR = 0.44, 95%CI: 0.24 to 0.8) and failure (RR = 0.39, 95%CI: 0.19 to 0.78) rates in the anti-VEGF group than the placebo group. A non-significant reduction of the epithelial defect was also observed in the bevacizumab group compared with the placebo (RR = 0.56, 95%CI: 0.30 to 1.06). Compared with a placebo, the unsynthesizable trials also support that bevacizumab improves visual acuity, CoNV, graft rejection, and failure rates. Trials reporting other comparisons revealed the superiority of combined remedy with bevacizumab compared to other treatments in reducing CoNV.

CONCLUSION

Anti-VEGF agents, mainly bevacizumab, are an effective and safe treatment for CoNV of all causes and prevent corneal graft rejection and failure in corneal transplantation.

The novel role of lymphatic vessels in the pathogenesis of ocular diseases

Historically, the eye has been considered as an organ free of lymphatic vessels. In recent years, however, it became evident, that lymphatic vessels or lymphatic-like vessels contribute to several ocular pathologies at various peri- and intraocular locations. The aim of this review is to outline the pathogenetic role of ocular lymphatics, the respective molecular mechanisms and to discuss current and future therapeutic options based thereon. We will give an overview on the vascular anatomy of the healthy ocular surface and the molecular mechanisms contributing to corneal (lymph)angiogenic privilege. In addition, we present (i) current insights into the cellular and molecular mechanisms occurring during pathological neovascularization of the cornea triggered e.g. by inflammation or trauma, (ii) the role of lymphatic vessels in different ocular surface pathologies such as dry eye disease, corneal graft rejection, ocular graft versus host disease, allergy, and pterygium, (iii) the involvement of lymphatic vessels in ocular tumors and metastasis, and (iv) the novel role of the lymphatic-like structure of Schlemm's canal in glaucoma. Identification of the underlying molecular mechanisms and of novel modulators of lymphangiogenesis will contribute to the development of new therapeutic targets for the treatment of ocular diseases associated with pathological lymphangiogenesis in the future. The preclinical data presented here outline novel therapeutic concepts for promoting transplant survival, inhibiting metastasis of ocular tumors, reducing inflammation of the ocular surface, and treating glaucoma. Initial data from clinical trials suggest first success of novel treatment strategies to promote transplant survival based on pretransplant corneal lymphangioregression.