Surgical Treatment of Age-Related Macular Degeneration

Advancing cell therapy for neurodegenerative diseases

Cell-based therapies are being developed for various neurodegenerative diseases that affect the central nervous system (CNS). Concomitantly, the roles of individual cell types in neurodegenerative pathology are being uncovered by genetic and single-cell studies. With a greater understanding of cellular contributions to health and disease and with the arrival of promising approaches to modulate them, effective therapeutic cell products are now emerging. This review examines how the ability to generate diverse CNS cell types from stem cells, along with a deeper understanding of cell-type-specific functions and pathology, is advancing preclinical development of cell products for the treatment of neurodegenerative diseases.

Therapeutic implications of nanodrug and tissue engineering for retinal pigment epithelium-related diseases

The retinal pigment epithelium (RPE), as a single layer of cells that performs multiple functions posteriorly in the eye, is a promising target site for the prevention and treatment of several clinical diseases, including proliferative diabetic retinopathy, age-related macular degeneration, chorionic neovascularization, and retinitis pigmentosa. In recent decades, several nanodrug delivery platforms and tissue-engineered RPE have been widely developed to treat RPE-related diseases. This work summarizes the recent advances in nanoplatforms and tissue engineering scaffolds developed in these fields. The diseases associated with pathological RPE and their common therapy strategies are first introduced. Then, the recent progress made with a variety of drug delivery systems is presented, with an emphasis on the modification strategies of nanomaterials for targeted delivery. Tissue engineering-mediated RPE transplantation for treating these diseases is subsequently described. Finally, the clinical translation challenges in these fields are discussed in depth. This article will offer readers a better understanding of emerging nanotechnology and tissue engineering related to the treatment of RPE-related diseases and could facilitate their widespread use in experiments in vivo and in clinical applications.

Ten Years of Knowledge of Nano-Carrier Based Drug Delivery Systems in Ophthalmology: Current Evidence, Challenges, and Future Prospective

The complex drug delivery barrier in the eye reduces the bioavailability of many drugs, resulting in poor therapeutic effects. It is necessary to investigate new drugs through appropriate delivery routes and vehicles. Nanotechnology has utilized various nano-carriers to develop potential ocular drug delivery techniques that interact with the ocular mucosa, prolong the retention time of drugs in the eye, and increase permeability. Additionally, nano-carriers such as liposomes, nanoparticles, nano-suspensions, nano-micelles, and nano-emulsions have grown in popularity as an effective theranostic application to combat different microbial superbugs. In this review, we summarize the nano-carrier based drug delivery system developments over the last decade, particularly review the biology, methodology, approaches, and clinical applications of nano-carrier based drug delivery system in the field of ocular therapeutics. Furthermore, this review addresses upcoming challenges, and provides an outlook on potential future trends of nano-carrier-based drug delivery approaches in ophthalmology, and hopes to eventually provide successful applications for treating ocular diseases.

Intravitreal Recombinant Tissue Plasminogen Activator and Sulphur Hexafluoride Gas for Submacular Haemorrhage Displacement in Age-Related Macular Degeneration: Looking behind the Blood

PURPOSE

To evaluate the effectiveness of recombinant tissue plasminogen activator (rtPA) and sulphur hexafluoride gas (SF6) intravitreal injection for the displacement of large submacular haemorrhages (SMH) secondary to neovascular age-related macular degeneration and for guiding the selection of additional treatments or observations for choroidal neovascularization (CNV).

METHODS

The medical records of consecutive patients with recent-onset, large SMH, treated at Sacro Cuore Hospital from January 2004 to May 2016, were retrospectively analysed. All eyes underwent a 0.05-mL intravitreal injection of 50 μg rtPA, 0.3 mL of 100% SF6, and then face-down positioning. Afterwards, the eyes received additional treatments for CNV or observation, based on the severity and extent of the underlying pathology. The multimodal imaging features revealed after blood displacement were analysed and then correlated to the treatment selected as a second therapeutic option.

RESULTS

A total of 96 eyes met the inclusion criteria and was evaluated in this study. SMH was displaced from the fovea in the majority of the eyes (76%), allowing several diagnostic tools to evaluate the underlying macular features. In 19 cases (19.8%) exhibiting severe macular damage, no additional treatment was applied. In the remaining eyes, subsequent treatments included anti-vascular endothelial growth factor injections (44.8%), photodynamic therapy (n = 2), and submacular surgery (35.4%). Statistically significant correlations were found between the macular findings revealed after blood displacement and the additional treatments or observations selected for the underlying disease. The mean follow-up was 35 months. Improvements in visual acuity were statistically significant up to 3 years.

CONCLUSION

Intravitreal rtPA and gas injection was found to be effective for the displacement of large SMH, allowing postoperative diagnostic testing, and thus guiding the opportunity to apply further treatments. The addition of subsequent individualized treatments may allow long-term visual gain in selected cases.

Magnetic nanoparticles conjugated with "RPE cell -MCP-1 antibody -VEGF antibody" compounds for the targeted therapy of age-related macular degeneration: a hypothesis

Age-related macular degeneration (AMD) is the leading cause of vision loss in the elderly throughout the world. Treatment of AMD utilizing retinal pigment epithelium (RPE) transplantation represents a promising therapy. However, simplex RPE transplantation can only replace the diseased RPE cells, but has no abilities to stop the development of AMD. It has been indicated that oxidization triggers the development of AMD by inducing the dysfunction and degeneration of RPE cells, which results in the upregulation of local monocyte chemotactic protein-1 (MCP-1) expression. MCP-1 induces macrophage recruiment which triggers local inflammation. As a result, the expression of vascular endothelial growth factor (VEGF) is upregulated by MCP-1 mediated inflammation and results in the formation of choroidal neovascularization (CNV). We accordingly propose a targeted therapy of AMD by subretinal transplanting the compound of RPE cell, MCP-1 antibody, and VEGF antibody and using a magnetic system to guide RPE cell compounds conjugated with superparamagnetic iron oxide nanoparticles (SPIONs). Furthermore, SPION-labelled RPE cells can be tracked and detected in vivo by non-invasive magnetic resonance imaging (MRI). This novel RPE cell transplantation methodology seems very promising to provide a new therapeutic approach for the treatment of AMD.

Outcomes of eyes with lesions composed of >50% blood in the Comparison of Age-related Macular Degeneration Treatments Trials (CATT)

OBJECTIVE

To compare baseline characteristics, treatment frequency, visual acuity (VA), and morphologic outcomes of eyes with >50% of the lesion composed of blood (B50 group) versus all other eyes (Other group) enrolled in the Comparison of Age-Related Macular Degeneration Treatments Trials (CATT).

DESIGN

Prospective cohort study within a multicenter randomized clinical trial.

PARTICIPANTS

CATT patients with neovascular age-related macular degeneration (AMD).

METHODS

Treatment for the study eye was assigned randomly to either ranibizumab or bevacizumab and to 3 different dosing regimens over a 2-year period. Reading center graders evaluated baseline and follow-up morphology in color fundus photographs, fluorescein angiography (FA), and optical coherence tomography (OCT). Masked examiners tested VA.

MAIN OUTCOME MEASURES

Morphologic features and VA at 1 and 2 years.

RESULTS

The B50 group consisted of 84 of 1185 (7.1%) patients enrolled in CATT. Baseline lesion characteristics differed between groups. In the B50 group, choroidal neovascularization size was smaller (0.73 vs 1.83 disc areas [DA]; P < 0.001), total lesion size was greater (4.55 vs 2.31 DA; P <0.001), total retinal thickness was greater (524 vs 455 μm; P = 0.02), and mean VA was worse (56.0 vs 60.9 letters; P = 0.002). Increases in mean VA were similar in the B50 and Other groups at 1 year (+9.3 vs +7.2 letters; P = 0.22) and at 2 years (9.0 vs 6.1 letters; P = 0.17). Eyes treated PRN received a similar number of injections in the 2 groups (12.2 vs 13.4; P = 0.27). Mean lesion size in the B50 group decreased by 1.2 DA at both 1 and 2 years (primarily owing to resolution of hemorrhage) and increased in the Other group by 0.33 DA at 1 year and 0.91 DA at 2 years (P < 0.001). Leakage on FA and fluid on OCT were similar between groups at 1 and 2 years.

CONCLUSIONS

In CATT, the B50 group had a visual prognosis similar to the Other group. Lesion size decreased markedly through 2 years. Eyes like those enrolled in CATT with neovascular AMD lesions composed of >50% blood can be managed similarly to those with less or no blood.

FPR1 interacts with CFH, HTRA1 and smoking in exudative age-related macular degeneration and polypoidal choroidal vasculopathy

PURPOSE

To determine the genetic association of an inflammation-related gene, formyl peptide receptor 1 (FPR1), in exudative age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV).

METHODS

The coding region of FPR1 gene was sequenced in 554 unrelated Chinese individuals: 155 exudative AMD patients, 179 PCV patients, and 220 controls. Interactions and combined effects of FPR1 with complement factor H (CFH), high temperature requirement factor A1 (HTRA1), and smoking were also investigated.

RESULTS

A total of 28 polymorphisms in FPR1 were identified. Single nucleotide polymorphisms (SNP) rs78488639 increased the risk to exudative AMD (P=0.043) and PCV (P=0.016), whereas SNP rs867229 decreased the risk to exudative AMD (P=0.0026), but not PCV. Homozygous G allele of rs1042229 was associated with exudative AMD (P=0.0394, odds ratio (OR)=2.27, 95% confident interval: 1.08-4.74), but not with PCV. Exudative AMD, but not PCV, was associated with the heterozygous genotypes of rs2070746 (P=0.019, OR=0.57) and rs867229 (P=0.0082, OR=0.54). Significantly, interactions were identified among FPR1 rs78488639, CFH rs800292, and HTRA1 rs11200638 in both exudative AMD and PCV. Combined heterozygous risk alleles of CFH rs800292 GA and FPR1 rs78488639 CA were posed to PCV (P=2.22 × 10(-4), OR=10.47), but not exudative AMD. Furthermore, FPR1 rs78488639 CA combining with HTRA1 rs11200638 and smoking was also predisposed risks to exudative AMD and PCV.

CONCLUSION

FPR1 is associated with exudative AMD and PCV in a Hong Kong Chinese cohort. FPR1 rs78488639 interacted with CFH rs800292, HTRA1 rs11200638, and smoking, enhancing risk to exudative AMD and PCV.

Stem cells as source for retinal pigment epithelium transplantation

Inherited maculopathies, age related macular degeneration and some forms of retinitis pigmentosa are associated with impaired function or loss of the retinal pigment epithelium (RPE). Among potential treatments, transplantation approaches are particularly promising. The arrangement of RPE cells in a well-defined tissue layer makes the RPE amenable to cell or tissue sheet transplantation. Different cell sources have been suggested for RPE transplantation but the development of a clinical protocol faces several obstacles. The source should provide a sufficient number of cells to at least recover the macula area. Secondly, cells should be plastic enough to be able to integrate in the host tissue. Tissue sheets should be considered as well, but the substrate on which RPE cells are cultured needs to be carefully evaluated. Immunogenicity can also be an obstacle for effective transplantation as well as tumorigenicity of not fully differentiated cells. Finally, ethical concerns may represent drawbacks when embryo-derived cells are proposed for RPE transplantation. Here we discuss different cell sources that became available in recent years and their different properties. We also present data on a new source of human RPE. We provide a protocol for RPE differentiation of retinal stem cells derived from adult ciliary bodies of post-mortem donors. We show molecular characterization of the in vitro differentiated RPE tissue and demonstrate its functionality based on a phagocytosis assay. This new source may provide tissue for allogenic transplantation based on best matches through histocompatibility testing.

Aflibercept: a Potent Vascular Endothelial Growth Factor Antagonist for Neovascular Age-Related Macular Degeneration and Other Retinal Vascular Diseases

Introduction

In the western hemisphere, age-related macular degeneration (AMD) is the leading cause of visual loss in the elderly. Currently approved therapies for AMD include argon laser, photodynamic therapy, and antivascular endothelial growth factor (VEGF) therapy. The index review discusses aflibercept (VEGF Trap-Eye) in the context of current anti-VEGF therapies for neovascular AMD and other retinal vascular diseases. It highlights important differences between VEGF Trap-Eye and currently used anti-VEGF therapies for neovascular AMD; and discusses the efficacy of these treatments utilizing information from landmark clinical trials.

Methods

A systematic search of literature was conducted on PubMed, Science Direct, and Scopus with no limitations of language or years of publication.

Results

Preclinical studies have shown that VEGF Trap-Eye binds to VEGF-A with a higher affinity than other anti-VEGF molecules; and that it also binds to placental growth factor (PlGF). In clinical trials, VEGF Trap-Eye has been shown to be as effective in the treatment of neovascular AMD as other anti-VEGF therapies and possibly to have a longer duration of drug activity.

Conclusion

VEGF Trap-Eye has enhanced the treatment options currently available for the management of neovascular AMD. The comparable efficacy of VEGF Trap-Eye (to other anti-VEGF agents) coupled with its longer dosing interval may decrease the number of annual office visits for patients with AMD and their caregivers.