Recent advances and future prospects: current status and challenges of the intraocular injection of drugs for vitreoretinal diseases

In Situ Crystallized Ceria-Vesicle Nanohybrid Therapeutic for Effective Treatment of Inflammatory Intraocular Disease

Posterior uveitis is a leading cause of vision impairment and blindness globally due to its detrimental effects on the choroid and retina. The condition is worsened by oxidative stress, which heightens inflammation and perpetuates a cycle of damage that current treatments only temporarily relieve. To address this, a novel treatment involving the in situ crystallization of ultrasmall cerium oxide nanoparticles (≈3 nm) on mesenchymal stem cell (MSC) extracellular vesicles (EVs) for the management of primed mycobacterial uveitis (PMU) is developed. This nanohybrid leverages the individual and synergistic effects of its components for a comprehensive therapeutic approach. The cerium oxide nanoparticles act as a nanozyme to reduce inflammation and scavenge excessive reactive oxygen species (ROS), while the MSC EVs, with their biocompatibility, modulate inflammatory cell infiltration and alleviate tissue damage. This synergistic system offers a promising new treatment strategy for ocular diseases characterized by oxidative stress and inflammation.

Current Treatment Options for Diabetic Retinal Disease

The global incidence of diabetes is rising steadily and with it the number of people living with diabetic retinal disease (DRD) is increasing. Like diabetes, DRD can be treated but not cured. In response, therapies to address DRD include targeted ocular and systemic medications. This review discusses diabetes and DRD in terms of current screening recommendations, treatments, and considerations related to those therapies and future drug targets and trials on the horizon. This discourse is targeted at all members of the diabetes care team, including primary care providers, optometrists, and ophthalmologists. The dynamic landscape of diabetic retinopathy treatment is promising for the prevention and improvement of visually significant disease.

Nanotechnological approaches to improve corticosteroids ocular therapy

The administration of corticosteroids is the first-line treatment of the clinical conditions with ocular inflammation. Nonetheless, ocular physiological mechanisms, anatomical barriers and corticosteroid properties prevent it from reaching the target site. Thus, frequent topical administered doses or ocular injections are required, leading to a higher risk of adverse events and poor patient compliance. Designing novel drug delivery systems based on nanotechnological tools is a useful approach to overcome disadvantages associated with the ocular delivery of corticosteroids. Nanoparticle-based drug delivery systems represent an alternative to the current dosage forms for the ocular administration of corticosteroids, since due to their particle size and the properties of their materials, they can increase their solubility, improve ocular permeability, control their release and increase bioavailability after their ocular administration. In this way, lipid and polymer-based nanoparticles have been the main strategies developed, giving rise to novel patent applications to protect these innovative drug delivery systems as a product, its preparation or administration method. Additionally, it should be noted that at least 10 clinical trials are being carried out to evaluate the ocular application of different pharmaceutical formulations based on corticosteroid-loaded nanoparticles. Through a comprehensive and extensive analysis, this review highlights the impact of nanotechnology applications in ocular inflammation therapy with corticosteroids.

Development of puerarin-loaded poly(lactic acid) microspheres for sustained ocular delivery: In vitro/vivo evaluation

Diabetic retinopathy, an ocular complication of diabetes, is an important cause of blindness in adults. Puerarin is considered to have promising potential for clinical use in treating diabetic retinopathy. In this study, we designed a novel puerarin-loaded poly(lactic acid) sustained-release microspheres suitable for ocular administration, and we assessed itsin vitro and in vivo properties. The preparation of puerarin-loaded microspheres was optimized by Box-Behnken response surface design. The encapsulation efficiency and drug loading of microspheres were 35.71% and 3.85%, respectively. The microspheres exhibited good dispersion and high safety, making it suitable for ocular drug delivery. In vitro release demonstrated that microspheres had a well-sustained release effectiveness, and its release behavior complied with the zero-order kinetic characteristics. The results of ocular tissue distribution revealed that the CmaxandAUC0-∞ of the microspheres group in the retina and choroid were considerably higher than those of the solution group and the intravenous injection group. This research revealed that intravitreal injection of microspheres can significantly prolong the half-life of puerarin in eye tissues and achieve sustained drug release. Therefore, intravitreal injection of microspheres has positive implications for the treatment of diabetic retinopathy.

Multifunctional Nanotherapeutics with Long-Acting Release against Macular Degeneration by Minimally Invasive Administration

Neovascular age-related macular degeneration (AMD), a leading cause of blindness, requires frequent intravitreal injection of antivascular endothelial growth factor (anti-VEGF), which could generate a succession of complications with poor patient compliance. The current VEGF-targeting therapies often fail in half of patients due to the complex pathologic microenvironment of excessive reactive oxygen species (ROS) production, and increased levels of inflammation are accompanied by choroidal neovascularization (CNV). We herein reported multifunctional nanotherapeutics featuring superior antioxidant and anti-inflammation properties that aim to reverse the pathological condition, alongside its strong targeted antiangiogenesis to CNV and its ability to provide long-term sustained bioactive delivery via the minimally invasive subconjunctival injection, so as to achieve satisfactory wet AMD treatment effects. Concretely, the nanomedicine was designed by coencapsulation of astaxanthin (AST), a red pigmented carotenoid known for its antioxidative, anti-inflammatory and antiapoptotic properties, and axitinib (AXI), a small molecule tyrosine kinase inhibitor that selectively targets the vascular epidermal growth factor receptor for antiangiogenesis, into the Food and Drug Administration (FDA) approved poly(lactic-co-glycolic acid) (PLGA), which forms the nanodrug of PLGA@AST/AXI. Our results demonstrated that a single-dose subconjunctival administration of PLGA@AST/AXI showed a rational synergistic effect by targeting various prevailing risk factors associated with wet AMD, ensuring persistent drug release profiles, maintaining good ocular biocompatibility, and causing no obvious mechanical damage. Such attributes are vital and hold significant potential in treating ocular posterior segment diseases. Moreover, this nanotherapeutic strategy represents a versatile and broad-spectrum nanoplatform, offering a promising alternative for the complex pathological progression of other neovascular diseases.

Iron Oxide Nanoparticles Engineered Macrophage-Derived Exosomes for Targeted Pathological Angiogenesis Therapy

Engineering exosomes with nanomaterials usually leads to the damage of exosomal membrane and bioactive molecules. Here, pathological angiogenesis targeting exosomes with magnetic imaging, ferroptosis inducing, and immunotherapeutic properties is fabricated using a simple coincubation method with macrophages being the bioreactor. Extremely small iron oxide nanoparticle (ESIONPs) incorporated exosomes (ESIONPs@EXO) are acquired by sorting the secreted exosomes from M1-polarized macrophages induced by ESIONPs. ESIONPs@EXO suppress pathological angiogenesis in vitro and in vivo without toxicity. Furthermore, ESIONPs@EXO target pathological angiogenesis and exhibit an excellent T1-weighted contrast property for magnetic resonance imaging. Mechanistically, ESIONPs@EXO induce ferroptosis and exhibit immunotherapeutic ability toward pathological angiogenesis. These findings demonstrate that a pure biological method engineered ESIONPs@EXO using macrophages shows potential for targeted pathological angiogenesis therapy.

Topical Application of Cell-Penetrating Peptide Modified Anti-VEGF Drug Alleviated Choroidal Neovascularization in Mice

Background

Age-related macular degeneration (AMD) stands as the foremost cause of irreversible central vision impairment, marked by choroidal neovascularization (CNV). The prevailing clinical approach to AMD treatment relies on intravitreal injections of anti-vascular endothelial growth factor (VEGF) drugs. However, this method is encumbered by diverse complications, prompting exploration of non-invasive alternatives such as ocular administration via eye drops for anti-VEGF therapy.

Methods

Two complexes, 5-FITC-CPP-Ranibizumab (5-FCR) and 5-FITC-CPP-Conbercept (5-FCC), were synthesized by incorporating the anti-VEGF drugs Ranibizumab (RBZ) or Conbercept (CBC) with cell-penetrating peptide (CPP). Circular dichroism spectrum (CD) facilitated complexes characterization. Eye drops was utilized to address laser-induced CNV in mice. Fluorescein fundus angiography (FFA) observe the CNV lesion, while FITC-dextran and IB4 dual fluorescent staining, along with hematoxylin-eosin (HE) staining, assessed in lesion size. Tissue immunofluorescence examined CD31 and VEGF expression in choroidal/retinal pigment epithelial (RPE) tissues. Biocompatibility and biosafety of 5-FCR and 5-FCC was evaluated through histological examination of various organs or cell experiments.

Results

Both 5-FCR and 5-FCC exhibited favorable biocompatibility and safety profiles. VEGF-induced migration of Human umbilical vein endothelial cells (HUVECs) significantly decreased post-5-FCR/5-FCC treatment. Additionally, both complexes suppressed VEGF-induced tube formation in HUVECs. FFA results revealed a significant improvement in retinal exudation in mice. Histological examination unveiled the lesion areas in the 5-FCR and 5-FCC groups showed a significant reduction compared to the control group. Similar outcomes were observed in histological sections of the RPE-choroid-sclera flat mounts.

Conclusion

In this study, utilizing the properties of CPP and two anti-VEGF drugs, we successfully synthesized two complexes, 5-FCR and 5-FCC, through a straightforward approach. Effectively delivering the anti-VEGF drugs to the target area in a non-invasive manner, suppressing the progression of laser-induced CNV. This offers a novel approach for the treatment of wet AMD.

Regression of Neovascularization after Panretinal Photocoagulation Combined with Anti-VEGF Injection for Proliferative Diabetic Retinopathy-A Review

Proliferative diabetic retinopathy (PDR) poses a significant therapeutic problem that often results in severe visual loss. Panretinal photocoagulation (PRP) has long been a mainstay treatment for this condition. Conversely, intravitreal anti-VEGF therapy has served as an alternative treatment for PDR. This review aimed to evaluate the effects of PRP combined with anti-VEGF therapy on the regression of neovascularization (NV), including functional outcomes and incidence of complications. The MEDLINE database was searched for articles evaluating regression of NV using a combination of the following terms: "proliferative diabetic retinopathy", "anti-VEGF", "panretinal photocoagulation", and "combined treatment". The search yielded a total of 22 articles. The analysis of their results indicated PRP combined with ant-VEGF therapy as superior over PRP alone in the management of PDR. Combination treatment yields better and faster regression of NV and a lower incidence of serious complications, such as vitreous hemorrhage and the need for pars plana vitrectomy. Nevertheless, complete regression of NV is not achieved in a significant proportion of patients. Further research is needed to establish the most effective schedule for intravitreal injections as an adjunct to PRP. The current literature shows that in some cases, cessation of anti-VEGF injection in combination treatment for PDR can lead to relapse of NV.

Method to Regulate Monocyte Function by Silencing HIF-1α mRNA in a Model of Retinal Neovascularization

Circulating monocytes migrate into the retina in response to inflammation and neovascularization. Furthermore, under inflammatory conditions such as diabetes, healthy monocytes become activated in the circulation. However, the contribution of activated monocytes to neovascularization is largely unknown. HIF-1α has been shown to contribute to the pathogenesis of neovascularization. We describe here the synthesis of a hybrid nanomaterial for targeted delivery and gene silencing in activated monocytes that are associated with pathological neovascularization. To test the gene silencing ability of AS-shRNA-lipids in vitro, we used the probe to inhibit HIF-1α mRNA induced in mouse monocytes by exposing them to hypoxia. In addition, we tested AS-shRNA-lipids for inhibition of neovascularization in vivo using the mouse model of oxygen-induced retinopathy (OIR). Significant reduction of neovascularization was achieved in mouse OIR by targeting activated monocytes using intraperitoneal injections of AS-shRNA-lipids. Expression of HIF-1α and CD14 mRNA were both inhibited in circulating cells, suggesting normalization of the activated monocytes in P17 OIR animals treated with AS-shRNA-lipids. We hypothesized that inhibition of HIF-1α mRNA in activated monocytes may have a direct impact on VEGF expression in the retinal tissues in vivo. We observed that VEGF mRNA expression was inhibited in P17 retinal tissues after systemic treatment with HIF-1α-targeted AS-shRNA-lipids. These findings may provide a framework for a strategy to inhibit retinal neovascularization by targeting circulating activated monocytes.