Clinical Translation of Long-Acting Drug Delivery Systems for Posterior Capsule Opacification Prophylaxis

Correlation of precisely fabricated geometric characteristics of DNA-origami nanostructures with their cellular entry in human lens epithelial cells

Human lens epithelial cells (hLECs) are critical for lens transparency, and their aberrant metabolic activity and gene expression can lead to cataract. Intracellular delivery to hLECs, especially to sub-cellular organelles (e.g., mitochondrion and nucleus), is a key step in engineering cells for cell- and gene- based therapies. Despite a broad variety of nano- and microparticles can enter cells, their spatial characteristics relevant to cellular uptake and localization remains elusive. To investigate cellular internalization of nanostructures in hLECs, herein, DNA nanotechnology was exploited to precisely fabricate four distinct, mass-controlled DNA-origami nanostructures (DONs) through computer-aided design. Ensembled DONs included the rods, ring, triangle, and octahedron with defined geometric parameters of accessible surface area, effective volume, compactness, aspect ratio, size and vertex number. Atomic force microscopy and agarose gel electrophoresis showed that four DONs self-assembled within 3.5h with up to 59% yield and exhibited structural intactness in cell culture medium for 4 h. Flow cytometry analysis of four Cy5-labelled DONs in hLECs HLE-B3 found time-dependent cellular uptake over 2 h, among which the octahedron and triangle had higher cellular accumulation than the rod and ring. More importantly, the vertex number among other geometric parameters was positively correlated with cellular entry. Confocal images further revealed that four DONs had preferential localization at mitochondria to nucleus at 2 h in HLE-B3 cells, and the degree of their biodistribution varied among DONs as evidenced by Manders' correlation coefficient. This study demonstrates the DONs dependent cellular uptake and intracellular compartment localization in hLECs, heralding the future design of structure-modulating delivery of nanomedicine for ocular therapy.

Promising Pharmacological Interventions for Posterior Capsule Opacification: A Review

Phacoemulsification combined with intraocular lens implantation is the primary treatment for cataract. Although this treatment strategy benefits patients with cataracts, posterior capsule opacification (PCO) remains a common complication that impairs vision and affects treatment outcomes. The pathogenesis of PCO is associated with the proliferation, migration, and fibrogenesis activity of residual lens epithelial cells, with epithelial-mesenchymal transition (EMT) serving as a key mechanism underlying the condition. Transforming growth factor-beta 2 (TGF-β2) is a major promotor of EMT, thereby driving PCO development. Most studies have shown that drugs and miRNAs mitigate EMT by inhibiting, clearing, or eliminating LECs. In addition, targeting EMT-related signaling pathways in TGF-β2-stimulated LECs has garnered attention as a research focus. This review highlights potential treatments for PCO and details the mechanisms by which drugs and miRNAs counter EMT.

Comment on Ma et al.'s "The Preventive Effect of Gentamicin in the Irrigating Solution on Endophthalmitis Caused by Methicillin-Resistant Staphylococcus epidermidis After Phacoemulsification with Intraocular Lens Implantation in Rabbits"

In their recent publication, the authors explored the preventive effect of gentamicin in the irrigating solution on endophthalmitis caused by methicillin-resistant Staphylococcus epidermidis (MRSE) after phacoemulsification with intraocular lens (IOL) implantation in rabbits. This letter commends the authors for their innovative approach and discusses the potential of chitosan-based intraocular lenses as a future solution for reducing the incidence of endophthalmitis. Chitosan's natural antibacterial properties, coupled with its capacity for sustained drug release and surface modification, make it a promising material for IOLs. This letter highlights recent advancements and suggests areas for further research to fully realize the potential of chitosan-based IOLs in ocular surgery.

Microtubular and high porosity design of electrospun PEGylated poly (lactic-co-glycolic acid) fibrous implant for ocular multi-route administration and medication

Electrospun fibers have been gaining popularity in ocular drug delivery and cellular therapies. However, most of electrospun fibers are planar-shape membrane with large dimension relative to intraocular space, making difficult to use as therapeutic implants. Herein, fibrous microtubes with a hollow center were fabricated by electrospinning using linear diblock mPEG2000-PLGA. Uniform microfibers with 0.809 μm diameter was tailored using Box-Behnken Design model for electrospinning process optimization. The microtubes were 1 mm long with a 0.386 mm diameter. Their suitability for intraocular administration was demonstrated by both injection via a 22-gauge needle and implant via integration of intraocular lens into the vitreous or anterior chamber of eyes, respectively. Electrospun mPEG2000-PLGA had higher porosity, smaller specific surface area, and smaller water contact angle, than that of PLGA. Macroscopically, mPEG2000-PLGA microfibers can maintain overall geometry upon exposure to aqueous buffer for 12 h while having high water uptake and exhibited good elasticity. Hydrolysis with 90 % polymeric degradation in 10.5 weeks underlied sustained slow release of anti-inflammatory drug dexamethasone. PEGylation of PLGA imparted preferential cell adhesion with markedly higher growth of human retinal epithelial cells than lens epithelial ones. This study highlights the potential utility of implantable electrospun PLGA-based microtubes for multiple intraocular delivery routes.

Injectable and pH-Responsive Metformin-Loaded Hydrogel for Active Inhibition of Posterior Capsular Opacification

Posterior capsular opacification (PCO) is a common complication following cataract surgery, which can lead to a significant vision loss. This study introduces a facile method for developing a metformin-derived hydrogel (HCM6) stabilized by dynamic covalent bonds among natural polymers. This hydrogel demonstrates antifibrotic properties, on-demand drug release, pH responsiveness, injectability, and self-healing capabilities. Our in vitro experiments confirmed that the HCM6 hydrogel exhibits excellent biocompatibility, inhibiting lens epithelial cell migration, and transforming growth factor-2β (TGFβ2)-induced α-smooth muscle actin (α-SMA) expression in lens epithelial cells. In vivo studies conducted in a rat extracapsular lens extraction (ECLE) model revealed that HCM6 significantly suppressed PCO after 21 days of implantation with no observed pathological effects on surrounding tissues or the optic nerve. According to our experimental results, the inhibitory mechanism of PCO may be attributed to metformin's suppressive effect on lens cell migration, epithelial-mesenchymal transition (EMT), and lens fiber formation. In summary, the long-acting, controllable, and on-demand release characteristics of the HCM6 hydrogel not only provide an effective strategy for preventing PCO but also offer new avenues for treating undesirable proliferative conditions in ophthalmology and beyond.

Oxidative Stress, Glutaredoxins, and Their Therapeutic Potential in Posterior Capsular Opacification

Posterior capsular opacification (PCO) is the most common long-term complication of cataract surgery. Traditionally, the pathogenesis of PCO involves the residual lens epithelial cells (LECs), which undergo transdifferentiation into a myofibroblast phenotype, hyperproliferation, matrix contraction, and matrix deposition. This process is driven by the marked upregulation of inflammatory and growth factors post-surgery. Recently, research on the role of redox environments has gained considerable attention. LECs, which are in direct contact with the aqueous humour after cataract surgery, are subjected to oxidative stress due to decreased levels of reduced glutathione and increased oxygen content compared to contact with the outer fibre layer of the lens before surgery. In this review, we examine the critical role of oxidative stress in PCO formation. We also focus on glutaredoxins (Grxs), which are antioxidative enzymes produced via deglutathionylation, their protective role against PCO formation, and their therapeutic potential. Furthermore, we discuss the latest advancements in PCO therapy, particularly the development of advanced antioxidative pharmacological agents, and emphasise the importance and approaches of anti-inflammatory and antioxidant treatments in PCO management. In conclusion, this review highlights the significant roles of oxidative stress in PCO, the protective effects of Grxs against PCO formation, and the potential of anti-inflammatory and antioxidant therapies in treating PCO.

TiO2-Nanoparticle-Enhanced Sonodynamic Therapy for Prevention of Posterior Capsular Opacification and Ferroptosis Exploration of Its Mechanism

Purpose

To explore the application and potential ferroptosis mechanisms of sonodynamic therapy (SDT) using titanium dioxide nanoparticles (TiO2-NPs) as sonosensitizers for the prevention of posterior capsule opacification (PCO).

Methods

We fabricated TiO2-NP-coated intraocular lenses (TiO2-IOLs) using the spin-coating method, followed by ultrasound activation of the photosensitizer TiO2. In vitro experiments were performed with human lens epithelial cells (HLECs) to explore the appropriate concentration of TiO2 and ultrasonic parameters. Investigations included reactive oxygen species (ROS) generation, glutathione (GSH) depletion, glutathione peroxidase 4 (GPX4) western blot analysis, lipid peroxidation assays, and transcriptomics analysis. Finally, TiO2-IOLs were implanted in rabbit eyes to explore the in vivo performance of SDT.

Results

Through both in vitro and in vivo experiments, the study determined that the ultrasound parameters of 5-minute duration, 1-MHz frequency, 50% duty cycle, and 1.2-W/cm2 intensity were reliable and valid for killing HLECs without damaging other ocular structures. In vitro experiments demonstrated that SDT generated excess ROS, which disrupted the mitochondrial membrane potential and significantly reduced the GSH content. Additionally, the downregulation of GPX4, accumulation of lipid peroxides, and alteration of mitochondrial morphology were observed, suggesting that ferroptosis may be the underlying mechanism. The RNA-sequencing analysis results also showed an increase in the expression of multiple pro-ferroptosis genes and the ferroptosis marker gene PTGS2. Animal experiments preliminarily demonstrated the safety and effectiveness of SDT in treating PCO in vivo.

Conclusions

TiO2-IOLs combined with SDT effectively prevented PCO by generating ROS and intracellular ferroptosis.

Advances in Extracellular-Vesicles-Based Diagnostic and Therapeutic Approaches for Ocular Diseases

Extracellular vesicles (EVs) are nanoscale membrane vesicles of various sizes that can be secreted by most cells. EVs contain a diverse array of cargo, including RNAs, lipids, proteins, and other molecules with functions of intercellular communication, immune modulation, and regulation of physiological and pathological processes. The biofluids in the eye, including tears, aqueous humor, and vitreous humor, are important sources for EV-based diagnosis of ocular disease. Because the molecular cargos may reflect the biology of their parental cells, EVs in these biofluids, as well as in the blood, have been recognized as promising candidates as biomarkers for early diagnosis of ocular disease. Moreover, EVs have also been used as therapeutics and targeted drug delivery nanocarriers in many ocular disorders because of their low immunogenicity and superior biocompatibility in nature. In this review, we provide an overview of the recent advances in the field of EV-based studies on the diagnosis and therapeutics of ocular disease. We summarized the origins of EVs applied in ocular disease, assessed different methods for EV isolation from ocular biofluid samples, highlighted bioengineering strategies of EVs as drug delivery systems, introduced the latest applications in the diagnosis and treatment of ocular disease, and presented their potential in the current clinical trials. Finally, we briefly discussed the challenges of EV-based studies in ocular disease and some issues of concern for better focusing on clinical translational studies of EVs in the future.

Injectable hydrogels based on biopolymers for the treatment of ocular diseases

Injectable hydrogels based on biopolymers, fabricated utilizing diverse chemical and physical methodologies, exhibit exceptional physical, chemical, and biological properties. They have multifaceted applications encompassing wound healing, tissue regeneration, and across diverse scientific realms. This review critically evaluates their largely uncharted potential in ophthalmology, elucidating their diverse applications across an array of ocular diseases. These conditions include glaucoma, cataracts, corneal disorders (spanning from age-related degeneration to trauma, infections, and underlying chronic illnesses), retina-associated ailments (such as diabetic retinopathy, retinitis pigmentosa, and age-related macular degeneration (AMD)), eyelid abnormalities, and uveal melanoma (UM). This study provides a thorough analysis of applications of injectable hydrogels based on biopolymers across these ocular disorders. Injectable hydrogels based on biopolymers can be customized to have specific physical, chemical, and biological properties that make them suitable as drug delivery vehicles, tissue scaffolds, and sealants in the eye. For example, they can be engineered to have optimum viscosity to be injected intravitreally and sustain drug release to treat retinal diseases. Their porous structure and biocompatibility promote cellular infiltration to regenerate diseased corneal tissue. By accentuating their indispensable role in ocular disease treatment, this review strives to present innovative and targeted approaches in this domain, thereby advancing ocular therapeutics.

Gastrodin improves osteoblast function and adhesion to titanium surface in a high glucose environment

Objective

To investigate the effects of gastrodin on the biological behavior of osteoblasts and osseointegration on the surface of the titanium plate in a high glucose environment, and to explore the possible regulatory mechanisms involved.

Methods

A high glucose-induced oxidative damage model of MC3T3-E1 cells was established in vitro to observe the effects of gastrodin on cellular oxidative stress, cell viability, osteogenic differentiation, mineralization, migration, and adhesion ability on the titanium surface.

Results

High glucose environment can cause oxidative stress damage to MC3T3-E1 cells, leading to a decrease in cell viability, osteogenesis, migration, adhesion and other functions. Gastrodin can upregulate the expression of antioxidant enzymes (Nrf2 and HO-1) and osteogenic differentiation related proteins (RUNX2 and BMP2) in MC3T3-E1 cells in high glucose environment, thereby inhibiting the excessive production of intracellular reactive oxygen species (ROS), reversing the decrease in cell viability, and improving the osteogenic differentiation and mineralization ability of osteoblasts. And gastrodin alleviated the decline in cell migration ability, improved the morphology of the cytoskeleton and increased the adhesion ability of osteoblasts on the surface of titanium plates in high glucose environment. However, gastrodin itself did not affect the cell viability, osteogenic differentiation and mineralization ability of osteoblasts in normal environment.

Conclusions

Gastrodin may protect MC3T3-E1 cells osteogenesis and osseointegration on the surface of the titanium plate in vitro by upregulating antioxidant enzymes expression, and attenuating high glucose-induced oxidative stress. Therefore, gastrodin may be a potential drug to address the problem of poor implant osseointegration in patients with diabetes.

Physicochemical Properties and Release Study of Antimetabolite-Incorporated Stearoyl Chitosan

Stearoyl chitosan (SC), derived from the acylation of chitosan, contributes to the efficiency of drug delivery systems because of its structure, which accommodates the drug in a particle. Nonetheless, its role in chemotherapy has been largely unexplored. The present study involves the synthesis of stearoyl chitosan through the reaction of depolymerized chitosan with stearoyl chloride under mild reaction conditions. The resulting compound was subjected to structural analysis utilizing Fourier-transform infrared (FTIR) spectroscopy, 1H NMR, and X-ray diffraction (XRD) spectroscopy. The dispersion of SC molecules in phosphate-buffered saline (PBS) forms SC nanoparticles. The best dispersion of SC in the solution was achieved at a 1:60 chitosan-to-stearoyl chloride weight ratio. Three antimetabolite drugs, methotrexate, pemetrexed, and raltitrexed, were selected to examine the loading efficacy of SC. Pemetrexed had the highest drug-loading value of 36.8% among the three antimetabolites incorporated into SC, along with an encapsulation efficiency of 85.1%. The size of SC loaded with antimetabolites ranged from 225 to 369 nm, and their spherical form was verified via a transmission electron microscope. The in vitro release study showed that SC demonstrated controlled drug release, suggesting that SC nanoparticles have significant promise as a delivery strategy for chemotherapy.

Microfluidics-based PLGA nanoparticles of ratiometric multidrug: From encapsulation and release rates to cytotoxicity in human lens epithelial cells

Multidrug nanomedicine is an effective therapeutic approach for the treatment of chronic diseases and cancers. However, co-encapsulation and release of drug combination at a fixed ratio by nanoparticles, particularly for long acting ocular formulations, remains challenging. Herein, poly (lactic-co-glycolic acid) nanoparticles ratiometrically co-encapsulating hydrophilic dual drugs, mitomycin C and doxorubicin, was obtained (D/M PLGANPs) by combining microfluidics and the Design of Experiments approaches. The formulation variable of lactide-to-glycolide ratios (L/G 50:50, 75:15 and 85:15) was used to achieve fast, medium and slow drug release rates of D/M PLGANPs. The dissolution of D/M PLGANPs in simulated intraocular fluid exhibited sustained release of dual drugs at the fixed ratio over 7 days, and analysis using the Korsmeyer-Peppas model showed mechanism of drug release to be governed by diffusion. More importantly, in human lens epithelial cells, the drug release rate was negatively correlated with drug potency. The slower drug release from D/M PLGANPs led to lower efficacy of drug combination against pathogenesis of cellular migration and proliferation, the key pathogenic processes of capsular opacification after cataract surgery. Compared to fast (L/G 50:50) and medium (L/G 75:15) drug release rate of D/M PLGANPs, the slow release formulation (L/G 85:15) exhibited the least cellular uptake of the dual drugs and the ratio of drug combination was not maintained intracellularly. The present study implicates the potential of using microfluidics for synthesizing polymeric nanoparticles of ratiometric drug combination and highlights the drug release rate as the critical determinant of efficacy for the long-acting nanomedicine design.