Lentiviral Vector Gene Transfer of Endostatin/Angiostatin for Macular Degeneration (GEM) Study

Nanoparticle-Based gene therapy strategies in retinal delivery

Vision loss and blindness are significant issues in both developed and developing countries. There are a wide variety of aetiologies that can cause vision loss, which are outlined in this review. Although treatment has significantly improved over time for some conditions, nearly half of all people with vision impairment are left untreated. Gene delivery is an emerging field that may assist with the treatment of some of these difficult to manage forms of vision loss. Here we review how a component of nanotechnology-based, non-viral gene delivery systems are being applied to help resolve vision impairment. This review focuses on the use of lipid and polymer nanoparticles, and quantum dots as gene delivery vectors to the eye. Finally, we also highlight some emerging technologies that may be useful in this discipline.

Multiple gene therapy as a tool for regulating the expression of molecules involved in neovascular age-related macular degeneration

Anti-vascular endothelial growth factor (VEGF) therapies have revolutionized the treatment of neovascular age-related macular degeneration (nAMD) and other retinal diseases. However, the necessity for repeated intravitreal injections and the observation of variable treatment responses calls for new treatment modalities where fewer and more effective interventions can result in a clinical effect. Gene therapy might be such an alternative, and therefore the development and clinical application of gene therapy aimed at modifying gene expression has received considerable attention. The article reviews current knowledge of the background, pathophysiological mechanisms, technologies, limitations, and future directions for gene therapy aimed at modifying the synthesis of compounds involved in acquired and senescent retinal disease. The authors have contributed to the field by developing gene therapy to reduce the expression of vascular endothelial growth factor (VEGF), as well as multiple gene therapy for simultaneous downregulation of the synthesis of VEGF and upregulation of pigment epithelium-derived factor (PEDF) using adeno-associated virus (AAV) vectors. It is suggested that such multi-target gene therapy might be included in future treatments of retinal diseases where the underlying mechanisms are complex and cannot be attributed to one specific mediator. Such diseases might include dry AMD (dAMD) with geographic atrophy, but also diabetic macular edema (DME) and retinal vein occlusion (RVO). Gene therapy can be expected to be most beneficial for the patients in need of multiple intra-vitreal injections and in whom the therapeutic response is insufficient. It is concluded, that in parallel with basic research, there is a need for clinical studies aimed at identifying factors that can be used to identify patients who will benefit from gene therapy already at the time of diagnosis of the retinal disease.

Endostatin in disease modulation: From cancer to beyond

Angiogenesis plays a pivotal role in various pathological conditions, making it a key target in therapeutic development. Anti-angiogenic therapies are gaining traction for their potential in treating a range of angiogenesis-dependent diseases. Among these, endogenous angiogenesis inhibitors, particularly endostatin, have garnered significant attention for their therapeutic potential. While extensively studied for its anti-angiogenic effects in cancer, endostatin also exhibits anti-atherosclerotic and anti-fibrotic properties, broadening its therapeutic scope. Despite the successful clinical use of recombinant human endostatin in China for nearly two decades, its broader therapeutic potential remains underexplored. Thus, this review delves into the multifaceted applications of endostatin, examining its role in ocular diseases, inflammation, reproductive disorders, and tumor angiogenesis. Furthermore, it provides a comprehensive overview of its emerging roles beyond angiogenesis, particularly in the context of atherosclerosis and fibroproliferative conditions.

Plate centrifugation enhances the efficiency of polyethylenimine-based transfection and lentiviral infection

PURPOSE

To propose an efficient, reproducible, and consistent transgenic technology based on plate centrifugation, which is particularly useful for polyethylenimine (PEI) transfection and lentiviral infection.

METHODS

We optimized multiple factors that could contribute to transfection efficiency, such as the dosage of the PEI or DNA, the working solution buffer used for diluting the PEI or DNA, the incubation time for the PEI/DNA complexes, and the transfection time.

RESULTS

Plate centrifugation led to a 5.46-fold increase in the transfection efficiency of PEI-based transfection while maintaining the cell survival rate. Moreover, the average copy number of viral genes in each genome increased 4.96-fold with plate centrifugation. Plate centrifugation alters the spatial arrangement of the PEI/DNA complexes or lentiviruses, increasing the chances of these complexes or viruses coming into contact with target cells, ultimately resulting in improved transfection or infection efficiency.

CONCLUSIONS

We present a protocol based on plate centrifugation for transfection or lentiviral infection that is suitable for genetic modification of primary cells or stem cells.

Cardiomyopathy: pathogenesis and therapeutic interventions

Cardiomyopathy is a group of disease characterized by structural and functional damage to the myocardium. The etiologies of cardiomyopathies are diverse, spanning from genetic mutations impacting fundamental myocardial functions to systemic disorders that result in widespread cardiac damage. Many specific gene mutations cause primary cardiomyopathy. Environmental factors and metabolic disorders may also lead to the occurrence of cardiomyopathy. This review provides an in-depth analysis of the current understanding of the pathogenesis of various cardiomyopathies, highlighting the molecular and cellular mechanisms that contribute to their development and progression. The current therapeutic interventions for cardiomyopathies range from pharmacological interventions to mechanical support and heart transplantation. Gene therapy and cell therapy, propelled by ongoing advancements in overarching strategies and methodologies, has also emerged as a pivotal clinical intervention for a variety of diseases. The increasing number of causal gene of cardiomyopathies have been identified in recent studies. Therefore, gene therapy targeting causal genes holds promise in offering therapeutic advantages to individuals diagnosed with cardiomyopathies. Acting as a more precise approach to gene therapy, they are gradually emerging as a substitute for traditional gene therapy. This article reviews pathogenesis and therapeutic interventions for different cardiomyopathies.

Advances in ophthalmic therapeutic delivery: A comprehensive overview of present and future directions

Ophthalmic treatment demands precision and consistency in delivering therapeutic agents over extended periods to address many conditions, from common eye disorders to complex diseases. This diversity necessitates a range of delivery strategies, each tailored to specific needs. We delve into various delivery cargos that are pivotal in ophthalmic care. These cargos encompass biodegradable implants that gradually release medication, nonbiodegradable implants for sustained drug delivery, refillable tools allowing flexibility in treatment, hydrogels capable of retaining substances while maintaining ocular comfort, and advanced nanotechnology devices that precisely target eye tissues. Within each cargo category, we explore cutting-edge research-level approaches and FDA-approved methods, providing a thorough overview of the current state of ophthalmic drug delivery. In particular, our focus on nanotechnology reveals the promising potential for gene delivery, cell therapy administration, and the implantation of active devices directly into the retina. These advancements hold the key to more effective, personalized, and minimally- invasive ophthalmic treatments, revolutionizing the field of eye care.

Current developments of gene therapy in human diseases

Gene therapy has witnessed substantial advancements in recent years, becoming a constructive tactic for treating various human diseases. This review presents a comprehensive overview of these developments, with a focus on their diverse applications in different disease contexts. It explores the evolution of gene delivery systems, encompassing viral (like adeno-associated virus; AAV) and nonviral approaches, and evaluates their inherent strengths and limitations. Moreover, the review delves into the progress made in targeting specific tissues and cell types, spanning the eye, liver, muscles, and central nervous system, among others, using these gene technologies. This targeted approach is crucial in addressing a broad spectrum of genetic disorders, such as inherited lysosomal storage diseases, neurodegenerative disorders, and cardiovascular diseases. Recent clinical trials and successful outcomes in gene therapy, particularly those involving AAV and the clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated proteins, are highlighted, illuminating the transformative potentials of this approach in disease treatment. The review summarizes the current status of gene therapy, its prospects, and its capacity to significantly ameliorate patient outcomes and quality of life. By offering comprehensive analysis, this review provides invaluable insights for researchers, clinicians, and stakeholders, enriching the ongoing discourse on the trajectory of disease treatment.

Gene and cell therapy for age-related macular degeneration: A review

Age-related macular degeneration (AMD) is the most common cause of irreversible vision loss among the elderly in Western communities, with an estimated global prevalence of 10 - 20% in people older than 65 years. AMD leads to central vision loss due to degeneration of the photoreceptors, retinal pigment epithelium and the choriocapillaris. Beckman's classification for AMD, based upon color fundus photographs, divides the disease into early, intermediate, and late forms. The late, vision-threatening stage includes both neovascular AMD and geographic atrophy. Despite its high prevalence and impact on patients' quality of life, treatment options for AMD are limited. While neovascular AMD can be medically managed with anti-VEGF intravitreal injections, until very recently there has been no approved treatment options for atrophic AMD; however, in February 2023 the first treatment for geographic atrophy - pegcetacoplan - was approved by the US FDA. We describe the current landscape of potential gene and cell therapeutic strategies for late-stage AMD, with an emphasis on the therapeutic options that might become available in the next few years.

Recent advancements and applications of ophthalmic gene therapy strategies: A breakthrough in ocular therapeutics

Over the past twenty years, ocular gene therapy has primarily focused on addressing diseases linked to various genetic factors. The eye is an ideal candidate for gene therapy due to its unique characteristics, such as easy accessibility and the ability to target both corneal and retinal conditions, including retinitis pigmentosa (RP), Leber congenital amaurosis (LCA), age-related macular degeneration (AMD), and Stargardt disease. Currently, literature documents 33 clinical trials in this field, with the most promising results emerging from trials focused on LCA. These successes have catalyzed further research into other ocular conditions such as glaucoma, AMD, RP, and choroideremia. The effectiveness of gene therapy relies on the efficient delivery of genetic material to specific cells, ensuring sustained and optimal gene expression over time. Viral vectors have been widely used for this purpose, although concerns about potential risks such as immune reactions and genetic mutations have led to the development of non-viral vector systems. Preliminary laboratory research and clinical investigations have shown a connection between vector dosage and the intensity of immune response and inflammation in the eye. The method of administration significantly influences these reactions, with subretinal delivery resulting in a milder humoral response compared to the intravitreal route. This review discusses various ophthalmic diseases, including both corneal and retinal conditions, and their underlying mechanisms, highlighting recent advances and applications in ocular gene therapies.

PHLDA1-PRDM1 mediates the effect of lentiviral vectors on fate-determination of human retinal progenitor cells

Lentiviral vectors have markedly enhanced gene therapy efficiency in treating congenital diseases, but their long-term safety remains controversial. Most gene therapies for congenital eye diseases need to be carried out at early ages, yet the assessment of related risks to ocular development posed by lentiviral vectors is challenging. Utilizing single-cell transcriptomic profiling on human retinal organoids, this study explored the impact of lentiviral vectors on the retinal development and found that lentiviral vectors can cause retinal precursor cells to shift toward photoreceptor fate through the up-regulation of key fate-determining genes such as PRDM1. Further investigation demonstrated that the intron and intergenic region of PRDM1 was bound by PHLDA1, which was also up-regulated by lentiviral vectors exposure. Importantly, knockdown of PHLDA1 successfully suppressed the lentivirus-induced differentiation bias of photoreceptor cells. The findings also suggest that while lentiviral vectors may disrupt the fate determination of retinal precursor cells, posing risks in early-stage retinal gene therapy, these risks could potentially be reduced by inhibiting the PHLDA1-PRDM1 axis.

The Role of Reactive Oxygen Species in Age-Related Macular Degeneration: A Comprehensive Review of Antioxidant Therapies

This review article delves into the intricate roles of reactive oxygen species (ROS) in the pathogenesis of age-related macular degeneration (AMD). It presents a detailed analysis of the oxidative stress mechanisms that contribute to the development and progression of these diseases. The review systematically explores the dual nature of ROS in ocular physiology and pathology, underscoring their essential roles in cellular signaling and detrimental effects when in excess. In the context of AMD, the focus is on the oxidative impairment in the retinal pigment epithelium and Bruch's membrane, culminating in the deterioration of macular health. Central to this review is the evaluation of various antioxidant strategies in the prevention and management of AMD. It encompasses a wide spectrum of antioxidants, ranging from dietary nutrients like vitamins C and E, lutein, and zeaxanthin to pharmacological agents with antioxidative properties. The review also addresses novel therapeutic approaches, including gene therapy and nanotechnology-based delivery systems, aiming to enhance antioxidant defense mechanisms in ocular tissues. The article concludes by synthesizing current research findings, clinical trial data, and meta-analyses to provide evidence-based recommendations. It underscores the need for further research to optimize antioxidant therapies, considering individual patient factors and disease stages. This comprehensive review thus serves as a valuable resource for clinicians, researchers, and healthcare professionals in ophthalmology, offering insights into the potential of antioxidants in mitigating the burden of AMD.

Gene therapy for neovascular age-related macular degeneration by subretinal delivery of RGX-314: a phase 1/2a dose-escalation study

BACKGROUND

Frequent anti-vascular endothelial growth factor A (VEGF-A) injections reduce the risk of rapid and severe vision loss in patients with neovascular age-related macular degeneration (nAMD); however, due to undertreatment, many patients lose vision over time. New treatments that provide sustained suppression of VEGF-A are needed. RGX-314 (currently known as ABBV-RGX-314) is an adeno-associated virus serotype 8 vector that expresses an anti-VEGF-A antigen-binding fragment, which provides potential for continuous VEGF-A suppression after a single subretinal injection. We report results on the safety and efficacy of subretinal injection of RGX-314 in patients with nAMD.

METHODS

For this open-label, multiple-cohort, multicentre, phase 1/2a, dose-escalation study conducted at eight sites in the USA, we enrolled participants with nAMD aged 50-89 years who had previously been treated with anti-VEGF injections into five cohorts (with five different doses of RGX-314). To be eligible, participants had to have macular neovascularisation secondary to nAMD with subretinal or intraretinal fluid in the centre subfield, be pseudophakic (after cataract removal), and have a best-corrected visual acuity (BCVA) in the study eye between 20/63 and 20/400 for the first participant in each cohort and between 20/40 and 20/400 for others. Subretinal injection of RGX-314 was done without a pre-bleb by a wet-laboratory-trained vitreoretinal surgeon. Cohort 1 received 3 × 109 genome copies per eye, cohort 2 received 1 × 1010, and cohort 3 received 6 × 1010. Two additional dose cohorts (cohort 4: 1·6 × 1011; cohort 5: 2·5 × 1011) were added. Participants were seen 1 day and 1 week after administration of RGX-314, and then monthly for 2 years (up to week 106). The primary outcome was safety of RGX-314 delivered by subretinal injection up to week 26. This analysis includes all 42 patients enrolled in the study. This study is registered with ClinicalTrials.gov, NCT03066258.

FINDINGS

Between May 12, 2017, and May 21, 2019, we screened 110 patients for eligibility and enrolled 68. 42 participants demonstrated the required anatomic response to intravitreal ranibizumab and then received a single RGX-314 injection (dose range 3 × 109 to 2·5 × 1011 genome copies per eye) and were followed up for 2 years. There were 20 serious adverse events in 13 participants, of which one was possibly related to RGX-314: pigmentary changes in the macula with severe vision reduction 12 months after injection of RGX-314 at a dose of 2·5 × 1011 genome copies per eye. Asymptomatic pigmentary changes were seen in the inferior retinal periphery several months after subretinal injection of RGX-314 most commonly at doses of 6 × 1010 genome copies per eye or higher. There were no clinically determined immune responses or inflammation beyond that expected following routine vitrectomy. Doses of 6 × 1010 genome copies or higher resulted in sustained concentrations of RGX-314 protein in aqueous humour and stable or improved BCVA and central retinal thickness with few or no supplemental anti-VEGF-A injections in most participants.

INTERPRETATION

Subretinal delivery of RGX-314 was generally well tolerated with no clinically recognised immune responses. RGX-314 gene therapy provides a novel approach for sustained VEGF-A suppression in patients with nAMD that has potential to control exudation, maintain vision, and reduce treatment burden after a single administration. Results from this study informed the pivotal programme to evaluate RGX-314 in patients with nAMD.

FUNDING

RegenxBio.

Engineering lentivirus envelope VSV-G for liver targeted delivery of IDOL-shRNA to ameliorate hypercholesterolemia and atherosclerosis

Lentiviral vectors (LVs) have been widely used as a tool for gene therapies. However, tissue-selective transduction after systemic delivery remains a challenge. Inducible degrader of low-density lipoprotein receptor is an attractive target for treating hypercholesterolemia. Here, a liver-targeted LV, CS8-LV-shIDOL, is developed by incorporating a hepatocyte-targeted peptide derived from circumsporozoite protein (CSP) into the lentivirus envelope for liver-targeted delivery of IDOL-shRNA (short hairpin RNA) to alleviate hypercholesterolemia. Tail-vein injection of CS8-LV-shIDOL results in extremely high accumulation in liver and nearly undetectable levels in other organs in mice. In addition, it shows superior therapeutic efficacy in lowering serum low-density lipoprotein cholesterol (LDL-C) and reducing atherosclerotic lesions over unmodified LV-shIDOL in hyperlipidemic mice. Mechanically, the envelope-engineered CS8-LV-shIDOL can enter liver cells via low-density lipoprotein receptor-related protein (LRP). Thus, this study provides a novel approach for liver-targeted delivery of IDOL-shRNA to treat hypercholesterolemia by using an envelope-engineered LV, and this delivery system has great potential for liver-targeted transgene therapy.

Tumor-specific polycistronic miRNA delivered by engineered exosomes for the treatment of glioblastoma

BACKGROUND

Glioblastoma (GBM) has poor prognosis due to ineffective agents and poor delivery methods. MicroRNAs (miRs) have been explored as novel therapeutics for GBM, but the optimal miRs and the ideal delivery strategy remain unresolved. In this study, we sought to identify the most effective pan-subtype anti-GBM miRs and to develop an improved delivery system for these miRs.

METHODS

We conducted an unbiased screen of over 600 miRs against 7 glioma stem cell (GSC) lines representing all GBM subtypes to identify a set of pan-subtype-specific anti-GBM miRs and then used available TCGA GBM patient outcomes and miR expression data to hone in on miRs that were most likely to be clinically effective. To enhance delivery and expression of the miRs, we generated a polycistronic plasmid encoding 3 miRs (pPolymiR) and used HEK293T cells as biofactories to package pPolymiR into engineered exosomes (eExos) that incorporate viral proteins (Gag/VSVg) in their structure (eExos+pPolymiR) to enhance function.

RESULTS

Our stepwise screen identified miR-124-2, miR-135a-2, and let-7i as the most effective miRs across all GBM subtypes with clinical relevance. Delivery of eExos+pPolymiR resulted in high expression of all 3 miRs in GSCs, and significantly decreased GSC proliferation in vitro. eExos+pPolymiR prolonged survival of GSC-bearing mice in vivo when compared with eExos carrying each of the miRs individually or as a cocktail.

CONCLUSION

eExos+pPolymiR, which includes a pan-subtype anti-glioma-specific miR combination encoded in a polycistronic plasmid and a novel exosome delivery platform, represents a new and potentially powerful anti-GBM therapeutic.

Beyond Vision: An Overview of Regenerative Medicine and Its Current Applications in Ophthalmological Care

Regenerative medicine (RM) has emerged as a promising and revolutionary solution to address a range of unmet needs in healthcare, including ophthalmology. Moreover, RM takes advantage of the body's innate ability to repair and replace pathologically affected tissues. On the other hand, despite its immense promise, RM faces challenges such as ethical concerns, host-related immune responses, and the need for additional scientific validation, among others. The primary aim of this review is to present a high-level overview of current strategies in the domain of RM (cell therapy, exosomes, scaffolds, in vivo reprogramming, organoids, and interspecies chimerism), centering around the field of ophthalmology. A search conducted on clinicaltrials.gov unveiled a total of at least 209 interventional trials related to RM within the ophthalmological field. Among these trials, there were numerous early-phase studies, including phase I, I/II, II, II/III, and III trials. Many of these studies demonstrate potential in addressing previously challenging and degenerative eye conditions, spanning from posterior segment pathologies like Age-related Macular Degeneration and Retinitis Pigmentosa to anterior structure diseases such as Dry Eye Disease and Limbal Stem Cell Deficiency. Notably, these therapeutic approaches offer tailored solutions specific to the underlying causes of each pathology, thus allowing for the hopeful possibility of bringing forth a treatment for ocular diseases that previously seemed incurable and significantly enhancing patients' quality of life. As advancements in research and technology continue to unfold, future objectives should focus on ensuring the safety and prolonged viability of transplanted cells, devising efficient delivery techniques, etc.

AAV-Based Strategies for Treatment of Retinal and Choroidal Vascular Diseases: Advances in Age-Related Macular Degeneration and Diabetic Retinopathy Therapies

Age-related macular degeneration (AMD) and diabetic retinopathy (DR) are vascular diseases with high prevalence, ranking among the leading causes of blindness and vision loss worldwide. Despite being effective, current treatments for AMD and DR are burdensome for patients and clinicians, resulting in suboptimal compliance and real risk of vision loss. Thus, there is an unmet need for long-lasting alternatives with improved safety and efficacy. Adeno-associated virus (AAV) is the leading vector for ocular gene delivery, given its ability to enable long-term expression while eliciting relatively mild immune responses. Progress has been made in AAV-based gene therapies for not only inherited retinal diseases but also acquired conditions with preclinical and clinical studies of AMD and DR showing promising results. These studies have explored several pathways involved in the disease pathogenesis, as well as different strategies to optimise gene delivery. These include engineered capsids with enhanced tropism to particular cell types, and expression cassettes incorporating elements for a targeted and controlled expression. Multiple-acting constructs have also been investigated, in addition to gene silencing and editing. Here, we provide an overview of strategies employing AAV-mediated gene delivery to treat AMD and DR. We discuss preclinical efficacy studies and present the latest data from clinical trials for both diseases.

Duchenne muscular dystrophy treatment with lentiviral vector containing mini-dystrophin gene in vivo

Duchenne muscular dystrophy (DMD) is an incurable X-linked recessive genetic disease caused by mutations in the dystrophin gene. Many researchers aim to restore truncated dystrophin via viral vectors. However, the low packaging capacity and immunogenicity of vectors have hampered their clinical application. Herein, we constructed four lentiviral vectors with truncated and sequence-optimized dystrophin genes driven by muscle-specific promoters. The four lentiviral vectors stably expressed mini-dystrophin in C2C12 muscle cells in vitro. To estimate the treatment effect in vivo, we transferred the lentiviral vectors into neonatal C57BL/10ScSn-Dmdmdx mice through local injection. The levels of modified dystrophin expression increased, and their distribution was also restored in treated mice. At the same time, they exhibited the restoration of pull force and a decrease in the number of mononuclear cells. The remissions lasted 3-6 months in vivo. Moreover, no integration sites of vectors were distributed into the oncogenes. In summary, this study preliminarily demonstrated the feasibility and safety of lentiviral vectors with mini-dystrophin for DMD gene therapy and provided a new strategy to restore truncated dystrophin.

Recent Developments in Gene Therapy for Neovascular Age-Related Macular Degeneration: A Review

Age-related macular degeneration (AMD) is a complex and multifactorial disease and a leading cause of irreversible blindness in the elderly population. The anti-vascular endothelial growth factor (anti-VEGF) therapy has revolutionized the management and prognosis of neovascular AMD (nAMD) and is currently the standard of care for this disease. However, patients are required to receive repeated injections, imposing substantial social and economic burdens. The implementation of gene therapy methods to achieve sustained delivery of various therapeutic proteins holds the promise of a single treatment that could ameliorate the treatment challenges associated with chronic intravitreal therapy, and potentially improve visual outcomes. Several early-phase trials are currently underway, evaluating the safety and efficacy of gene therapy for nAMD; however, areas of controversy persist, including the therapeutic target, route of administration, and potential safety issues. In this review, we assess the evolution of gene therapy for nAMD and summarize several preclinical and early-stage clinical trials, exploring challenges and future directions.

Lentiviral delivered aflibercept OXB-203 for treatment of neovascular AMD

Neovascular age-related macular degeneration (nAMD) is a leading cause of blindness in the aging population, with vascular endothelial growth factor (VEGF) playing a key role. Treatment with recombinant anti-VEGFs is the current standard of care; however, it is only effective for 1-2 months at a time and requires re-administration. Gene therapy could pave the way for stable, long-term expression of therapeutic anti-VEGF with a single dose, reducing the frequency of treatment and potentially improving clinical outcomes. As such, we have developed OXB-203, a lentiviral-based gene therapy encoding the anti-VEGF protein aflibercept. Aflibercept derived from OXB-203 exhibited comparable in vitro binding characteristics to VEGF as recombinant aflibercept. Furthermore, its biological potency was demonstrated by the equivalent inhibition of VEGF-induced human umbilical vein endothelial cell (HUVEC) proliferation and tubule formation as recombinant aflibercept. In a rat choroidal neovascularization (CNV) model of nAMD, a single subretinal administration of OXB-203 reduced laser-induced CNV lesion areas analogous to an intravitreal bolus of recombinant aflibercept. Finally, in a head-to-head comparative study, aflibercept derived from OXB-203 was shown to be expressed at significantly higher levels in ocular tissues than from an AAV8-aflibercept vector following a single subretinal delivery to rats. These findings support the therapeutic potential of OXB-203 for the management of nAMD.

Subretinal Injection Under Perfluorocarbon Liquids to Avoid Foveal Dehiscence

SUMMARY

We describe a novel technique modification of subretinal injection to reduce the risk of foveal dehiscence during subretinal tissue plasminogen activator delivery for submacular haemorrhage, using a perfluorocarbon liquid filled vitreous cavity and an eccentric injection point, with a viscous fluid injector system controlled injection.

PURPOSE

To describe a novel method of subretinal injection to reduce the risk of foveal dehiscence during subretinal tissue plasminogen activator delivery for submacular hemorrhage.

METHOD

Description of technique with illustrative case description and details of four cases treated. The subretinal injection is delivered under a perfluorocarbon liquid bubble filling 80% of the vitreous cavity. An eccentric injection point is used and the tissue plasminogen activator injected under a pneumatically controlled viscous fluid injection system with a 38-g polyimide cannula and low injection pressure.

RESULTS

Four cases have been treated with controlled subretinal injection extending under the fovea without dehiscence, including one case with apparent preexisting foveal dehiscence and a preretinal clot.

CONCLUSION

The technique allows the creation of a low more diffuse subretinal bleb compared with without perfluorocarbon liquid, minimizing hydraulic stress on the fovea during injection and could be applied to other subretinal injection scenarios where the fovea is at risk of hydraulic blowout. Further experience of the technique is needed to validate this initial report.

Nme2 Cas9-mediated therapeutic editing in inhibiting angiogenesis after wet age-related macular degeneration onset

BACKGROUND

Age-related macular degeneration (AMD), particularly wet AMD characterised by choroidal neovascularization (CNV), is a leading cause of vision loss in the elderly. The hypoxia-inducible factor-1α (HIF-1α)/vascular endothelial growth factor (VEGF)/VEGF receptor 2 (VEGFR2) pathway contributes to CNV pathogenesis. Previous gene editing research indicated that disrupting these genes in retinal pigment epithelial cells could have a preventive effect on CNV progression. However, no studies have yet been conducted using gene editing to disrupt VEGF signalling after CNV induction for therapeutic validation, which is critical to the clinical application of wet AMD gene editing therapies.

METHOD

Here, we employed the single-adeno-associated virus-mediated Nme2 Cas9 to disrupt key molecules in VEGF signalling, Hif1α, Vegfa and Vegfr2 after inducing CNV and estimated their therapeutic effects.

RESULTS

We found that Nme2 Cas9 made efficient editing in target genes up to 71.8% post 11 days in vivo. And only Nme2 Cas9-Vegfa treatment during the early stage of CNV development reduced the CNV lesion area by 49.5%, compared to the negative control, while Nme2 Cas9-Hif1α or Nme2 Cas9-Vegfr2 treatment did not show therapeutic effect. Besides, no off-target effects were observed in Nme2 Cas9-mediated gene editing in vivo.

CONCLUSIONS

This study provides proof-of-concept possibility of employing Nme2 Cas9 for potential anti-angiogenesis therapy in wet AMD.

Enhanced Biosafety of the Sleeping Beauty Transposon System by Using mRNA as Source of Transposase to Efficiently and Stably Transfect Retinal Pigment Epithelial Cells

Neovascular age-related macular degeneration (nvAMD) is characterized by choroidal neovascularization (CNV), which leads to retinal pigment epithelial (RPE) cell and photoreceptor degeneration and blindness if untreated. Since blood vessel growth is mediated by endothelial cell growth factors, including vascular endothelial growth factor (VEGF), treatment consists of repeated, often monthly, intravitreal injections of anti-angiogenic biopharmaceuticals. Frequent injections are costly and present logistic difficulties; therefore, our laboratories are developing a cell-based gene therapy based on autologous RPE cells transfected ex vivo with the pigment epithelium derived factor (PEDF), which is the most potent natural antagonist of VEGF. Gene delivery and long-term expression of the transgene are enabled by the use of the non-viral Sleeping Beauty (SB100X) transposon system that is introduced into the cells by electroporation. The transposase may have a cytotoxic effect and a low risk of remobilization of the transposon if supplied in the form of DNA. Here, we investigated the use of the SB100X transposase delivered as mRNA and showed that ARPE-19 cells as well as primary human RPE cells were successfully transfected with the Venus or the PEDF gene, followed by stable transgene expression. In human RPE cells, secretion of recombinant PEDF could be detected in cell culture up to one year. Non-viral ex vivo transfection using SB100X-mRNA in combination with electroporation increases the biosafety of our gene therapeutic approach to treat nvAMD while ensuring high transfection efficiency and long-term transgene expression in RPE cells.

Novel Approaches in the Drug Development and Delivery Systems for Age-Related Macular Degeneration

The number of patients with ocular disorders has increased due to contributing factors such as aging populations, environmental changes, smoking, genetic abnormalities, etc. Age-related macular degeneration (AMD) is one of the common ocular disorders which may advance to loss of vision in severe cases. The advanced form of AMD is classified into two types, dry (non-exudative) and wet (exudative) AMD. Although several therapeutic approaches are explored for the management of AMD, no approved therapy can substantially slow down the progression of dry AMD into the later stages. The focus of researchers in recent times has been engaged in developing targeted therapeutic products to halt the progression and maintain or improve vision in individuals diagnosed with AMD. The delivery of anti-VEGF agents using intravitreal therapy has found some success in managing AMD, and novel formulation approaches have been introduced in various studies to potentiate the efficacy. Some of the novel approaches, such as hydrogel, microspheres, polymeric nanoparticles, liposomes, implants, etc. have been discussed. Apart from this, subretinal, suprachoroidal, and port delivery systems have also been investigated for biologics and gene therapies. The unmet potential of approved therapeutic products has contributed to several patent applications in recent years. This review outlines the current treatment options, outcomes of recent research studies, and patent details around the novel drug delivery approach for the treatment of AMD.

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.

Stem Cell-based and Advanced Therapeutic Modalities for Parkinson's Disease: A Risk-effectiveness Patient-centered Analysis

Treatment of Parkinson's disease (PD), the second most prevalent neurodegenerative disorder, is currently considered a challenging issue since it causes substantial disability, poor quality of life, and mortality. Despite remarkable progress in advanced conventional therapeutic interventions, the global burden of the disease has nearly doubled, prompting us to assess the riskeffectiveness of different treatment modalities. Each protocol could be considered as the best alternative treatment depending on the patient's situation. Prescription of levodopa, the most effective available medicine for this disorder, has been associated with many complications, i.e., multiple episodes of "off-time" and treatment resistance. Other medications, which are typically used in combination with levodopa, may have several adverse effects as well. As a result, the therapies that are more in line with human physiology and make the least interference with other pathways are worth investigating. On the other hand, remaining and persistent symptoms after therapy and the lack of effective response to the conventional approaches have raised expectations towards innovative alternative approaches, such as stem cell-based therapy. It is critical to not overlook the unexplored side effects of innovative approaches due to the limited number of research. In this review, we aimed to compare the efficacy and risk of advanced therapies with innovative cell-based and stemcell- based modalities in PD patients. This paper recapitulated the underlying factors/conditions, which could lead us to more practical and established therapeutic outcomes with more advantages and few complications. It could be an initial step to reconsider the therapeutic blueprint for patients with Parkinson's disease.

Genetic Aspects of Age-Related Macular Degeneration and Their Therapeutic Potential

Age-related macular degeneration (AMD) is a complex and multifactorial disease, resulting from the interaction of environmental and genetic factors. The continuous discovery of associations between genetic polymorphisms and AMD gives reason for the pivotal role attributed to the genetic component to its development. In that light, genetic tests and polygenic scores have been created to predict the risk of development and response to therapy. Still, none of them have yet been validated. Furthermore, there is no evidence from a clinical trial that the determination of the individual genetic structure can improve treatment outcomes. In this comprehensive review, we summarize the polymorphisms of the main pathogenetic ways involved in AMD development to identify which of them constitutes a potential therapeutic target. As complement overactivation plays a major role, the modulation of targeted complement proteins seems to be a promising therapeutic approach. Herein, we summarize the complement-modulating molecules now undergoing clinical trials, enlightening those in an advanced phase of trial. Gene therapy is a potential innovative one-time treatment, and its relevance is quickly evolving in the field of retinal diseases. We describe the state of the art of gene therapies now undergoing clinical trials both in the field of complement-suppressors and that of anti-VEGF.

Molecular and Functional Characterization of BDNF-Overexpressing Human Retinal Pigment Epithelial Cells Established by Sleeping Beauty Transposon-Mediated Gene Transfer

More and more patients suffer from multifactorial neurodegenerative diseases, such as age-related macular degeneration (AMD). However, their pathological mechanisms are still poorly understood, which complicates the development of effective therapies. To improve treatment of multifactorial diseases, cell-based gene therapy can be used to increase the expression of therapeutic factors. To date, there is no approved therapy for dry AMD, including late-stage geographic atrophy. We present a treatment option for dry AMD that transfers the brain-derived neurotrophic factor (BDNF) gene into retinal pigment epithelial (RPE) cells by electroporation using the plasmid-based Sleeping Beauty (SB) transposon system. ARPE-19 cells and primary human RPE cells were co-transfected with two plasmids encoding the SB100X transposase and the transposon carrying a BDNF transcription cassette. We demonstrated efficient expression and secretion of BDNF in both RPE cell types, which were further increased in ARPE-19 cell cultures exposed to hydrogen peroxide. BDNF-transfected cells exhibited lower apoptosis rates and stimulated neurite outgrowth in human SH-SY5Y cells. This study is an important step in the development of a cell-based BDNF gene therapy that could be applied as an advanced therapy medicinal product to treat dry AMD or other degenerative retinal diseases.

Design, construction and in vivo functional assessment of a hinge truncated sFLT01

Gene therapy for the treatment of ocular neovascularization has reached clinical trial phases. The AAV2-sFLT01 construct was already evaluated in a phase 1 open-label trial administered intravitreally to patients with advanced neovascular age-related macular degeneration. SFLT01 protein functions by binding to VEGF and PlGF molecules and inhibiting their activities simultaneously. It consists of human VEGFR1/Flt-1 (hVEGFR1), a polyglycine linker, and the Fc region of human IgG1. The IgG1 upper hinge region of the sFLT01 molecule makes it vulnerable to radical attacks and prone to causing immune reactions. This study pursued two goals: (i) minimizing the immunogenicity and vulnerability of the molecule by designing a truncated molecule called htsFLT01 (hinge truncated sFLT01) that lacked the IgG1 upper hinge and lacked 2 amino acids from the core hinge region; and (ii) investigating the structural and functional properties of the aforesaid chimeric molecule at different levels (in silico, in vitro, and in vivo). Molecular dynamics simulations and molecular mechanics energies combined with Poisson-Boltzmann and surface area continuum solvation calculations revealed comparable free energy of binding and binding affinity for sFLT01 and htsFLT01 to their cognate ligands. Conditioned media from human retinal pigment epithelial (hRPE) cells that expressed htsFLT01 significantly reduced tube formation in HUVECs. The AAV2-htsFLT01 virus suppressed vascular development in the eyes of newborn mice. The htsFLT01 gene construct is a novel anti-angiogenic tool with promising improvements compared to existing treatments.

Update on Viral Gene Therapy Clinical Trials for Retinal Diseases

In 2001, the first large animal was successfully treated with a gene therapy that restored its vision. Lancelot, the Briard dog that was treated, suffered from a human childhood blindness called Leber's congenital amaurosis type 2. Sixteen years later, the gene therapy was approved by the U.S. Food and Drug Administration. The success of this gene therapy in dogs led to a fast expansion of the ocular gene therapy field. By now every class of inherited retinal dystrophy has been treated in at least one animal model and many clinical trials have been initiated in humans. In this study, we review the status of viral gene therapies for the retina, with a focus on ongoing human clinical trials. It is likely that in the next decade we will see several new viral gene therapies approved.

Recent Advances in Age-Related Macular Degeneration Therapies

Age-related macular degeneration (AMD) was described for the first time in the 1840s and is currently the leading cause of blindness for patients over 65 years in Western Countries. This disease impacts the eye’s posterior segment and damages the macula, a retina section with high levels of photoreceptor cells and responsible for the central vision. Advanced AMD stages are divided into the atrophic (dry) form and the exudative (wet) form. Atrophic AMD consists in the progressive atrophy of the retinal pigment epithelium (RPE) and the outer retinal layers, while the exudative form results in the anarchic invasion by choroidal neo-vessels of RPE and the retina. This invasion is responsible for fluid accumulation in the intra/sub-retinal spaces and for a progressive dysfunction of the photoreceptor cells. To date, the few existing anti-AMD therapies may only delay or suspend its progression, without providing cure to patients. However, in the last decade, an outstanding number of research programs targeting its different aspects have been initiated by academics and industrials. This review aims to bring together the most recent advances and insights into the mechanisms underlying AMD pathogenicity and disease evolution, and to highlight the current hypotheses towards the development of new treatments, i.e., symptomatic vs. curative. The therapeutic options and drugs proposed to tackle these mechanisms are analyzed and critically compared. A particular emphasis has been given to the therapeutic agents currently tested in clinical trials, whose results have been carefully collected and discussed whenever possible.

Lentiviral Vectors for Ocular Gene Therapy

This review offers the basics of lentiviral vector technologies, their advantages and pitfalls, and an overview of their use in the field of ophthalmology. First, the description of the global challenges encountered to develop safe and efficient lentiviral recombinant vectors for clinical application is provided. The risks and the measures taken to minimize secondary effects as well as new strategies using these vectors are also discussed. This review then focuses on lentiviral vectors specifically designed for ocular therapy and goes over preclinical and clinical studies describing their safety and efficacy. A therapeutic approach using lentiviral vector-mediated gene therapy is currently being developed for many ocular diseases, e.g., aged-related macular degeneration, retinopathy of prematurity, inherited retinal dystrophies (Leber congenital amaurosis type 2, Stargardt disease, Usher syndrome), glaucoma, and corneal fibrosis or engraftment rejection. In summary, this review shows how lentiviral vectors offer an interesting alternative for gene therapy in all ocular compartments.

Novel Treatments for Age-Related Macular Degeneration: A Review of Clinical Advances in Sustained Drug Delivery Systems

In recent years, the number of patients with ocular diseases is increasing as a consequence of population aging. Among them, one of the most common is the age-related macular degeneration (AMD), a condition that leads to vision loss if it is not treated. AMD is a multifactorial disorder with two advanced forms, dry and neovascular AMD. Currently, although there is no approved therapy that significantly impacts dry AMD progression, several pharmacologic therapies exist for neovascular AMD. Notwithstanding, evidence suggests a suboptimal result in a high number of patients receiving these therapeutic options. Consequently, finding effective strategies is not only a still unmet medical need in dry AMD but also in neovascular AMD. This underlines the need for new drug delivery technologies that can improve the pharmacological action and drug concentration at the target sites. In this regard, sustained drug delivery systems are presented as the most promising therapeutic options in AMD patients. This review summarized the pathogenesis and the current treatment options for AMD, focusing on the emerging ocular sustained drug delivery approaches undergoing clinical trials.

CRISPR-based VEGF suppression using paired guide RNAs for treatment of choroidal neovascularization

Clustered regularly interspaced short palindromic repeats (CRISPR)-based genomic disruption of vascular endothelial growth factor A (Vegfa) with a single gRNA suppresses choroidal neovascularization (CNV) in preclinical studies, offering the prospect of long-term anti-angiogenesis therapy for neovascular age-related macular degeneration (AMD). Genome editing using CRISPR-CRISPR-associated endonucleases (Cas9) with multiple guide RNAs (gRNAs) can enhance gene-ablation efficacy by augmenting insertion-deletion (indel) mutations with gene truncations but may also increase the risk of off-target effects. In this study, we compare the effectiveness of adeno-associated virus (AAV)-mediated CRISPR-Cas9 systems using single versus paired gRNAs to target two different loci in the Vegfa gene that are conserved in human, rhesus macaque, and mouse. Paired gRNAs increased Vegfa gene-ablation rates in human cells in vitro but did not enhance VEGF suppression in mouse eyes in vivo. Genome editing using paired gRNAs also showed a similar degree of CNV suppression compared with single-gRNA systems. Unbiased genome-wide analysis using genome-wide unbiased identification of double-stranded breaks (DSBs) enabled by sequencing (GUIDE-seq) revealed weak off-target activity arising from the second gRNA. These findings suggest that in vivo CRISPR-Cas9 genome editing using two gRNAs may increase gene ablation but also the potential risk of off-target mutations, while the functional benefit of targeting an additional locus in the Vegfa gene as treatment for neovascular retinal conditions is unclear.

Viruses as tools in gene therapy, vaccine development, and cancer treatment

Using viruses to our advantage has been a huge leap for humanity. Their ability to mediate horizontal gene transfer has made them useful tools for gene therapy, vaccine development, and cancer treatment. Adenoviruses, adeno-associated viruses, retroviruses, lentiviruses, alphaviruses, and herpesviruses are a few of the most common candidates for use as therapeutic agents or efficient gene delivery systems. Efforts are being made to improve and perfect viral-vector-based therapies to overcome potential or reported drawbacks. Some preclinical trials of viral vector vaccines have yielded positive results, indicating their potential as prophylactic or therapeutic vaccine candidates. Utilization of the oncolytic activity of viruses is the future of cancer therapy, as patients will then be free from the harmful effects of chemo- or radiotherapy. This review discusses in vitro and in vivo studies showing the brilliant therapeutic potential of viruses.

Delivery of nVEGFi using AAV8 for the treatment of neovascular age-related macular degeneration

Inhibition of vascular endothelial growth factor (VEGF) is the standard therapy for neovascular age-related macular degeneration (nAMD). However, anti-VEGF agents used in the clinic require repeated injections, causing adverse effects. Gene therapy could provide sustained anti-VEGF levels after a single injection, thereby drastically decreasing the treatment burden and improving visual outcomes. In this study, we developed a novel VEGF Trap, nVEGFi, containing domains 1 and 2 of VEGFR1 and domain 3 of VEGFR2 fused to the Fc portion of human IgG. The nVEGFi had a higher expression level than aflibercept under the same expression cassettes of adeno-associated virus (AAV)8 in vitro and in vivo. nVEGFi was found to be noninferior to aflibercept in binding and blocking VEGF in vitro. AAV8-mediated expression of nVEGFi was maintained for at least 12 weeks by subretinal delivery in C57BL/6J mice. In a mouse laser-induced choroidal neovascularization (CNV) model, 4 × 10⁸ genome copies of AAV8-nVEGFi exhibited a significantly increased reduction in the CNV area compared with AAV8-aflibercept (78.1% vs. 63.9%, p < 0.05), while causing no structural or functional changes to the retina. In conclusion, this preclinical study showed that subretinal injection of AAV8-nVEGFi was long lasting, well tolerated, and effective for nAMD treatment, supporting future translation to the clinic.

Exudative versus Nonexudative Age-Related Macular Degeneration: Physiopathology and Treatment Options

Age-related macular degeneration (AMD) is an eye disease typically associated with the aging and can be classified into two types—namely, the exudative and the nonexudative AMD. Currently available treatments for exudative AMD use intravitreal injections, which are associated with high risk of infection that can lead to endophthalmitis, while no successful treatments yet exist for the nonexudative form of AMD. In addition to the pharmacologic therapies administered by intravitreal injection already approved by the Food and Drug Administration (FDA) in exudative AMD, there are some laser treatments approved that can be used in combination with the pharmacological therapies. In this review, we discuss the latest developments of treatment options for AMD. Relevant literature available from 1993 was used, which included original articles and reviews available in PubMed database and also information collected from Clinical Trials Gov website using “age-related macular degeneration” and “antiangiogenic therapies” as keywords. The clinical trials search was limited to ongoing trials from 2015 to date.

Developing Non-Human Primate Models of Inherited Retinal Diseases

Inherited retinal diseases (IRDs) represent a genetically and clinically heterogenous group of diseases that can eventually lead to blindness. Advances in sequencing technologies have resulted in better molecular characterization and genotype-phenotype correlation of IRDs. This has fueled research into therapeutic development over the recent years. Animal models are required for pre-clinical efficacy assessment. Non-human primates (NHP) are ideal due to the anatomical and genetic similarities shared with humans. However, developing NHP disease to recapitulate the disease phenotype for specific IRDs may be challenging from both technical and cost perspectives. This review discusses the currently available NHP IRD models and the methods used for development, with a particular focus on gene-editing technologies.

Novel approach to antiangiogenic factors in age-related macular degeneration therapy

Age-related macular degeneration (AMD) is a leading cause of irreversible vision loss among the population above 85 worldwide. There are two main types of AMD: neovascular and dry AMD. Neovascular AMD leads to macular changes resulting from abnormal choroidal neovascularization. Untreated neovascular AMD leads to scar formation and irreversible sight deterioration. Dry AMD in consequence leads to atrophic changes of the macula. The last decades brought a breakthrough in the therapy of neovascular age-related macular degeneration by introduction of, firstly, photodynamic therapy and, later, anti-VEGF agents administered intravitreally in order to stop neoangiogenesis. However, the treatment of dry AMD is still challenging. Among the directions in dry AMD treatment, the most promising are complement cascade inhibitors and complement cascade targeted gene therapy. In the article we outline the main directions in up-to-date experimental and practical approaches to wet and dry AMD therapy with the emphasis on antiangiogenic factors and gene therapy focused on the inhibition of pathological angiogenesis.

Emerging Treatment Modalities for Neovascular Age-Related Macular Degeneration: A Systematic Overview

INTRODUCTION

Neovascular age-related macular degeneration (nAMD) represents a leading cause of irreversible visual loss affecting the quality of life of millions of elderly patients worldwide. Although the introduction of intravitreal injections with anti-vascular endothelial growth factors (anti-VEGF) agents has revolutionized the management of nAMD, their effectiveness and ultimate success are limited by several therapeutic challenges. Consequently, real-world efficacy appears significantly inferior to that reported by randomized controlled trials. Therefore, further innovative, long-term treatment options are essential to improve the prognosis and outcome of nAMD therapy.

METHODS

Emerging pharmacological therapies for nAMD and those currently in clinical trials are reviewed and their mechanism of action, safety, and efficacy are discussed. The evidence presented herein has been collected from online databases PubMed, Cochrane library, and the ClinicalTrials.gov site.

RESULTS

A number of promising technologies and novel anti-VEGF therapies are currently being tested and some have already reached phase III trials. Anti-VEGF agents with enhanced durability and possibly efficacy, gene therapy, angiogenic targets, alternative drug delivery routes such as sustained delivery implants, drug carriers, and encapsulated cell technology are currently being explored. We briefly discuss the potential value of these options.

CONCLUSION

Several options may optimize future nAMD management. On the basis of current, albeit limited evidence, the most promising technology to reach clinical practice soon appears to be the sustained drug delivery options, which may improve visual outcome and reduce the socioeconomic burden of nAMD.

Novel therapies for proliferative retinopathies

Proliferative retinopathies, such as neovascular age–related macular degeneration and proliferative diabetic retinopathy, are a special health issue due to their contribution to irreversible blindness. Although the promoting conditions and physiopathology of proliferative retinopathies are different, these feature a highly detrimental angiogenesis driven by the overproduction of vascular endothelial growth factor (VEGF). This article describes the mechanism of action of ocular antiangiogenic therapies currently found in clinical development. Systems classify accordingly as (a) novel anti-VEGF systems, (b) molecules targeting non-VEGF pathways, and (c) gene therapies. Whereas most therapies are designed to neutralize VEGF, there is a significant set of products with diverse complexity and mechanism of action. Anti-VEGF therapies are still the most studied approach to tackle angiogenesis. Therapies targeting non-VEGF pathways, however, are highlighted because they could be an option for patients nonresponsive to anti-VEGF therapies. Finally, gene therapy is a promissory technology platform but still is subject to demonstrate safety and efficacy.

Gene-Based Therapeutics for Acquired Retinal Disease: Opportunities and Progress

Acquired retinal diseases such as age-related macular degeneration and diabetic retinopathy rank among the leading causes of blindness and visual loss worldwide. Effective treatments for these conditions are available, but often have a high treatment burden, and poor compliance can lead to disappointing real-world outcomes. Development of new treatment strategies that provide more durable treatment effects could help to address some of these unmet needs. Gene-based therapeutics, pioneered for the treatment of monogenic inherited retinal disease, are being actively investigated as new treatments for acquired retinal disease. There are significant advantages to the application of gene-based therapeutics in acquired retinal disease, including the presence of established therapeutic targets and common pathophysiologic pathways between diseases, the lack of genotype-specificity required, and the larger potential treatment population per therapy. Different gene-based therapeutic strategies have been attempted, including gene augmentation therapy to induce in vivo expression of therapeutic molecules, and gene editing to knock down genes encoding specific mediators in disease pathways. We highlight the opportunities and unmet clinical needs in acquired retinal disease, review the progress made thus far with current therapeutic strategies and surgical delivery techniques, and discuss limitations and future directions in the field.

Synergistic effect of baculovirus-mediated endostatin and angiostatin combined with gemcitabine in hepatocellular carcinoma

Anti-angiogenic gene therapy is a promising strategy in treating cancer. Endostatin and angiostatin are widely used in tumor anti-angiogenesis therapy. Our previous studies have shown that the BDS-hEA, a baculovirus long-term expressing the fusion protein of human endostatin and angiostatin, has a favorable effect in inhibiting the growth and angiogenesis of hepatocellular carcinoma. The purpose of this study was to further investigate its synergistic antitumor efficiency in combination with low-dose chemotherapeutic gemcitabine (GEM) on the subcutaneous hepatocellular carcinoma xenograft model in nude mice. The results showed that the combined group significantly inhibited (P<0.05 or P<0.01 or P<0.001) the growth of tumor weight and volume, reduced the expression of ki67 (cell proliferation marker), CD31 (angiogenic marker) and Matrix metalloproteinase 9 (MMP-9, tumor invasion and metastasis marker) and increased the apoptosis of tumor cells compared with the monotherapy and control groups, respectively. Synergistic index results showed that BDS-hEA combined with GEM had a synergistic effect in inhibiting tumor volume, proliferation, microvessel density, metastasis and promoting tumor apoptosis. Furthermore, there were no metastatic nodules and obvious pathological changes in liver tissue of the combined group, and the serum liver function indicators aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin (T-BIL), alkaline phosphatase (ALP) and glutamyl transpeptidase (GGT) were significantly reduced (P<0.05 or P<0.01 or P<0.001) in the BDS-hEA or GEM groups compared with the control group. Notably, the combined therapy showed lower levels of liver function indicators than the GEM group. These data support the view that the combination of BDS-hEA and GEM has a synergistic anti-tumor properties and can reduce the damage of liver to certain extent.

Cellular Proteo-Transcriptomic Changes in the Immediate Early-Phase of Lentiviral Transduction

Lentivirus-based vectors derived from human immunodeficiency viruses type 1 and 2 (HIV-1 and 2) are widely used tools in research and may also be utilized in clinical settings. Like their parental virions, they are known to depend on the cellular machinery for successful gene delivery and integration. While most of the studies on cellular proteomic and transcriptomic changes have focused on the late phase of the transduction, studies of those changes in early time-points, especially in the case of HIV-2 based vectors, are widely lacking. Using second generation HIV-1 and 2 vesicular stomatitis virus G protein (VSV-G) pseudotyped lentiviral vectors, we transduced HEK-293T human embryonic kidney cells and carried out transcriptomic profiling at 0 and 2 h time points, with accompanying proteomic analysis at 2 h following transduction. Significant variations were observed in gene expression profile between HIV-1 and HIV-2 transduced samples. Thrombospondin 1 (THBS1), collagens (COL1A2, COL3A1), and eukaryotic translation factors (EIF3CL) in addition to various genes coding for long non-coding RNA (lncRNA) were significantly upregulated 2 h after HIV-2 transduction compared to HIV-1. Label-free quantification mass spectrometry (MS) indicated that seven proteins involved in RNA binding, mRNA transport, and chaperoning were significantly downregulated. The identification of cellular protein targets of lentiviral vectors and their effect on the cellular transcriptome will undoubtedly shed more light on their complex life cycle and may be utilized against infection by their parental lentiviruses. Furthermore, characterizing the early phase of HIV-2 infection may aid in the understanding of its pathomechanism and long incubation period.

A robust method for protein depletion based on gene editing

The technology of clustered regularly interspaced short palindromic repeats (CRISPR)-associated nuclease Cas9 (CRISPR-Cas9) is a powerful system for protein depletion resulting from insertions and deletions following Cas9 cleavage of genome at specific site in vitro and in vivo. We herein present a relatively standard protocol for protein depletion in a step-by-step procedure, including guide RNA designation and vector construction, lentivirus production, cell selection, and experimentally validate the function of targeted protein. We exemplified this approach by editing PDGFRβ in human epithelial cells, and expected that this simplified and detailed protocol will be more broadly applied on specific genes to aid understanding gene functions.