Treatment of alkali-injured cornea by cyclosporine A-loaded electrospun nanofibers – An alternative mode of therapy

Potential of Chitosan/Gelatin-Based Nanofibers in Delivering Drugs for the Management of Varied Complications: A Review

Drug delivery systems have revolutionized traditional drug administration methods by addressing various challenges, such as enhancing drug solubility, prolonging effectiveness, minimizing adverse effects, and preserving potency. Nanotechnology-based drug delivery systems, particularly nanoparticles (NPs) and nanofibers (NFs), have emerged as promising solutions for biomedicine delivery. NFs, with their ability to mimic the porous and fibrous structures of biological tissues, have garnered significant interest in drug-delivering applications. Biopolymers such as gelatin (Ge) and chitosan (CH) have gained much more attention due to their biocompatibility, biodegradability, and versatility in biomedical applications. CH exhibits exceptional biocompatibility, anti-bacterial activity, and wound healing capabilities, whereas Ge provides good biocompatibility and cell adhesion properties. Ge/CH-based NFs stimulate cellular connections and facilitate tissue regeneration owing to their structural resemblance to the extracellular matrix. This review explores the additive methods of preparation, including electrospinning, force pinning, and template synthesis, focusing on electrospinning and the factors influencing the fiber structure. The properties of Ge and CH, their role in drug release, formulation strategies, and characterization techniques for electrospun fibers are discussed. Furthermore, this review addresses applications in delivering active moieties in the management of orthopedics and wound healing with regulatory considerations, along with challenges related to them. Thus, the review aims to provide a comprehensive overview of the potential of Ge/CH-based NFs for drug delivery and biomedical applications.

Progress in Nanotechnology for Treating Ocular Surface Chemical Injuries: Reflecting on Advances in Ophthalmology

Ocular surface chemical injuries often result in permanent visual impairment and necessitate complex, long-term treatments. Immediate and extensive irrigation serves as the first-line intervention, followed by various therapeutic protocols applied throughout different stages of the condition. To optimize outcomes, conventional regimens increasingly incorporate biological agents and surgical techniques. In recent years, nanotechnology has made significant strides, revolutionizing the management of ocular surface chemical injuries by enabling sustained drug release, enhancing treatment efficacy, and minimizing side effects. This review provides a comprehensive analysis of the etiology, epidemiology, classification, and conventional therapies for ocular chemical burns, with a special focus on nanotechnology-based drug delivery systems in managing ocular surface chemical injuries. Twelve categories of nanocarrier platforms are examined, including liposomes, nanoemulsions, nanomicelles, nanowafers, nanostructured lipid carriers, nanoparticles, hydrogels, dendrimers, nanocomplexes, nanofibers, nanozymes, and nanocomposite materials, highlighting their advantages in targeted delivery, biocompatibility, and improved healing efficacy. Additionally, current challenges and limitations in the field are discussed and the future potential of nanotechnology in treating ocular diseases is explored. This review presents the most extensive examination of this topic to date, aiming to link recent advancements with broader therapeutic strategies.

Drug delivery strategies to improve the treatment of corneal disorders

Anterior eye disorders including dry eye syndrome, keratitis, chemical burns, and trauma have varying prevalence rates in the world. Classical dosage forms based-topical ophthalmic drugs are popular treatments for managing corneal diseases. However, current dosage forms of ocular drugs can be associated with major challenges such as the short retention time in the presence of ocular barriers. Developing alternative therapeutic methods is required to overcome drug bioavailability from ocular barriers. Nanocarriers are major platforms and promising candidates for the administration of ophthalmic drugs in an adjustable manner. This paper briefly introduces the advantages, disadvantages, and characteristics of delivery systems for the treatment of corneal diseases. Additionally, advanced technologies such as 3D printing are being considered to fabricate ocular drug carriers and determine drug dosages for personalized treatment. This comprehensive review is gathered through multiple databases such as Google Scholar, PubMed, and Web of Science. It explores information around "ocular drug delivery systems'', "nano-based drug delivery systems'', "engineered nanocarriers'', and "advanced technologies to fabricate personalized drug delivery systems''.

Advances in nanomedicine for retinal drug delivery: overcoming barriers and enhancing therapeutic outcomes

Nanomedicine offers a promising avenue for improving retinal drug delivery, effectively addressing challenges associated with ocular diseases like age-related macular degeneration and diabetic retinopathy. Nanoparticles, with their submicron size and customisable surface properties, enable enhanced permeability and retention within retinal tissues, supporting sustained drug release and minimising systemic side effects. Nanostructured scaffolds further provide a supportive environment for retinal cell growth and tissue regeneration, crucial for treating degenerative conditions. Additionally, advanced nanodevices facilitate real-time monitoring and controlled drug release, marking significant progress in retinal therapy. This study reviews recent advancements in nanomedicine for retinal drug delivery, critically analysing design innovations, therapeutic benefits, and limitations of these systems. By advancing nanotechnology integration in ocular therapies, this field holds strong potential for overcoming current barriers, ultimately improving patient outcomes and quality of life.

Dexamethasone acetate loaded poly(ε-caprolactone) nanofibers for rat corneal chemical burn treatment

Topical eye drop approaches to treat ocular inflammation in dry eyes often face limitations such as low efficiency and short duration of drug delivery. Nanofibers serve to overcome the limitation of the short duration of action of topical eye drops used against ocular inflammation in dry eyes. Several attempts to develop suitable nanofibers have been made; however, there is no ideal solution. Here, we developed polycaprolactone (PCL) nanofibers loaded with dexamethasone acetate (DEX), prepared by electrospinning, as a potential ocular drug delivery platform for corneal injury treatment. Thirty-nine Sprague Dawley rats (7 weeks old males) were divided into four treatment groups after alkaline burns of the cornea; negative control (no treatment group); dexamethasone eyedrops (DEX group); PCL fiber (PCL group); dexamethasone loaded PCL (PCL + DEX group). We evaluated therapeutic efficacy of PCL + DEX by examining the epithelial wound healing effect, the extent of corneal opacity and neovascularization. Additionally, various inflammatory factors, including IL-1β, were investigated through immunochemistry, western blot analysis, and quantitative real-time RT-PCR (qRT-PCR). PCL + DEX group showed histologically alleviated signs of corneal inflammation compared with DEX group, which showed a decrease in IL-1β and MMP9 in the corneal stroma. The quantitative expression on day 1 after alkaline burn of pro-inflammatory markers, including IL-1β and IL-6, in the PCL + DEX group was significantly lower than that in the DEX group. Notably, PCL + DEX treatment significantly suppressed neovascularization, and enhanced the anti-inflammatory function of DEX during the acute phase of ocular inflammation. Collectively, these findings suggest that PCL + DEX may be a promising approach to effective drug delivery in corneal burn injuries.

Available Therapeutic Options for Corneal Neovascularization: A Review

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

Transmucosal Delivery of Peptides and Proteins Through Nanofibers: Current Status and Emerging Developments

Advancements in recombinant DNA technology have made proteins and peptides available for diagnostic and therapeutic applications, but their effectiveness when taken orally leads to poor patient compliance, requiring clinical administration. Among the alternative routes, transmucosal delivery has the advantage of being noninvasive and bypassing hepato-gastrointestinal clearance. Various mucosal routes-buccal, nasal, pulmonary, rectal, and vaginal-have been explored for delivering these macromolecules. Nanofibers, due to their unique properties like high surface-area-to-volume ratio, mechanical strength, and improved encapsulation efficiency, serve as promising carriers for proteins and peptides. These nanofibers can be tailored for quick dissolution, controlled release, enhanced encapsulation, targeted delivery, and improved bioavailability, offering superior pharmaceutical and pharmacokinetic performance compared to conventional methods. This leads to reduced dosages, fewer side effects, and enhanced patient compliance. Hence, nanofibers hold tremendous potential for protein/peptide delivery, especially through mucosal routes. This review focuses on the therapeutic application of proteins and peptides, challenges faced in their conventional delivery, techniques for fabricating different types of nanofibers and, various nanofiber-based dosage forms, and factors influencing nanofiber generation. Insights pertaining to the precise selection of materials used for fabricating nanofibers and regulatory aspects have been covered. Case studies wherein the use of specific protein/peptide-loaded nanofibers and delivered via oral/vaginal/nasal mucosa for diagnostic/therapeutic use and related preclinical and clinical studies conducted have been included in this review.

Development of dual-functional core-shell electrospun mats with controlled release of anti-inflammatory and anti-bacterial agents for the treatment of corneal alkali burn injuries

In this study, a novel dual-drug carrier for the co-administration of an anti-inflammatory and antibiotic agent consisting of core-shell nanofibers for the treatment of cornea alkali burns was designed. The core-shell nanofibers were prepared via coaxial electrospinning of curcumin-loaded silk fibroin as the core and vancomycin-loaded chitosan/polyvinyl alcohol (PVA) as the shell. Electron microscopy (SEM and TEM) images confirmed the preparation of smooth, bead-free, and continuous fibers that formed clear core-shell structures. For further studies, nanofiber mats were cross-linked by heat treatment to avoid rapid disintegration in water and improve both mechanical properties and drug release. The release profile of curcumin and vancomycin indicated an initial burst release, continued by the extended release of both drugs within 72 hours. Rabbit corneal cells demonstrated high rates of proliferation when evaluated using a cell metabolism assay. Finally, the therapeutic efficiency of core/shell nanofibers in healing cornea alkali burn was studied by microscopic and macroscopic observation, fluorescence staining, and hematoxylin-eosin assay on rabbit eyes. The anti-inflammatory activity of fabricated fibers was evaluated by enzyme-linked immunosorbent assay and Immunofluorescence analysis. In conclusion, using a robust array of in vitro and in vivo experiments this study demonstrated the ability of the dual-drug carriers to promote corneal re-epithelialization, minimize inflammation, and inhibit corneal neovascularization. Since these parameters are critical to the healing of corneal wounds from alkali burns, we suggest that this discovery represents a promising future therapeutic agent that warrants further study in humans.

Up-to-date molecular medicine strategies for management of ocular surface neovascularization

Ocular surface neovascularization and its resulting pathological changes significantly alter corneal refraction and obstruct the light path to the retina, and hence is a major cause of vision loss. Various factors such as infection, irritation, trauma, dry eye, and ocular surface surgery trigger neovascularization via angiogenesis and lymphangiogenesis dependent on VEGF-related and alternative mechanisms. Recent advances in antiangiogenic drugs, nanotechnology, gene therapy, surgical equipment and techniques, animal models, and drug delivery strategies have provided a range of novel therapeutic options for the treatment of ocular surface neovascularization. In this review article, we comprehensively discuss the etiology and mechanisms of corneal neovascularization and other types of ocular surface neovascularization, as well as emerging animal models and drug delivery strategies that facilitate its management.

Ocular application of electrospun materials for drug delivery and cellular therapies

The constraints of delivering conventional drugs, biologics and cell-based therapeutics to target ocular sites necessitate the fabrication of novel drug delivery systems to treat diverse ocular diseases. Conventional ocular drug delivery approaches are prone to low bioavailability, poor penetration and degradation of therapeutics, including cell-based therapies, leading to the need for frequent topical applications or intraocular injections. However, owing to their exceptional structural properties, nanofibrous and microfibrous electrospun materials have gained significant interest in ocular drug delivery and biomaterial applications. This review covers the recent developments of electrospun fibers for the delivery of drugs, biologics, cells, growth factors and tissue regeneration in treating ocular diseases. The insights from this review can provide a thorough understanding of the selection of materials for the fabrication of nano- and/or micro-fibrous systems for ocular applications, with a particular interest in achieving controlled drug release and cell therapy. A detailed modality for fabricating different types of nano- and micro-fibers produced from electrospinning and factors influencing generation are also discussed.

Nanofibers in Ocular Drug Targeting and Tissue Engineering: Their Importance, Advantages, Advances, and Future Perspectives

Nanofibers are frequently encountered in daily life as a modern material with a wide range of applications. The important advantages of production techniques, such as being easy, cost effective, and industrially applicable are important factors in the preference for nanofibers. Nanofibers, which have a broad scope of use in the field of health, are preferred both in drug delivery systems and tissue engineering. Due to the biocompatible materials used in their construction, they are also frequently preferred in ocular applications. The fact that they have a long drug release time as a drug delivery system and have been used in corneal tissue studies, which have been successfully developed in tissue engineering, stand out as important advantages of nanofibers. This review examines nanofibers, their production techniques and general information, nanofiber-based ocular drug delivery systems, and tissue engineering concepts in detail.

An electrospun scaffold functionalized with a ROS-scavenging hydrogel stimulates ocular wound healing

Ocular alkali burn is a serious ophthalmic emergency. Highly penetrative alkalis cause strong inflammatory responses leading to persistent epithelial defects, acute corneal perforation and severe scarring, and thereby persistent pain, loss of vision and cicatricial sequelae. Early and effective anti-inflammation management is vital in reducing the severity of injury. In this study, a double network biomaterial was prepared by compounding electrospinning nanofibres of thioketal-containing polyurethane (PUTK) with a reactive oxygen species (ROS)-scavenging hydrogel (RH) fabricated by crosslinking poly(poly(ethylene glycol) methyl ether methacrylate-co-glycidyl methacrylate) with thioketal diamine and 3,3'-dithiobis(propionohydrazide). The developed PUTK/RH patch exhibited good transparency, high tensile strength and increased hydrophilicity. Most importantly, it demonstrated strong antioxidant activity against H₂O₂ and 2,2-di(4-tert-octylphenyl)-1-picryl-hydrazyl (DPPH). Next, a rat corneal alkali burn model was established, and the PUTK/RH patch was transplanted on the injured cornea. Reduced inflammatory cell infiltration was revealed by confocal microscopy, and lower expression levels of genes relative to inflammation, vascularization and scarring were identified by qRT-PCR and western blot. Fluorescein sodium dyeing, hematoxylin and eosin (H&E) staining and immunohistochemical staining confirmed that the PUTK/RH patch could accelerate corneal wound healing by inhibiting inflammation, promoting epithelial regeneration and decreasing scar formation. STATEMENT OF SIGNIFICANCE: Ocular alkali burn is a serious ophthalmic emergency, characterized with persistent inflammation and irreversible vision loss. Oxidative stress is the main pathological process at the acute inflammatory stage, during which combined use of glucocorticoids and amniotic membrane transplantation is the most widely accepted treatment. In this study, we fabricated a polyurethane electrospun nanofiber membrane functionalized with a ROS-scavenging hydrogel. This composite patch could be a promising amniotic membrane substitute, possessing with a transparent appearance, elasticity and anti-inflammation effect. It could be easily transplanted onto the alkali-burned corneas, resulting in a significant inhibition of stromal inflammation and accelerating the recovery of corneal transparency. The conception of ROS-scavenging wound patch may offer a new way for ocular alkali burn.

[Methods of diagnosis and treatment of corneal neovascularization]

Corneal neovascularization is one of the most common causes of decreased visual acuity and disability for vision loss, increase in the risk of corneal graft rejection, and appearance of opacifications on the cornea. This article reviews literature on etiological factors of the development of corneal neovascularization, as well as modern methods of diagnosis, conservative and surgical treatment of this pathology.

Recent Advancements in Molecular Therapeutics for Corneal Scar Treatment

The process of corneal wound healing is complex and induces scar formation. Corneal scarring is a leading cause of blindness worldwide. The fibrotic healing of a major ocular wound disrupts the highly organized fibrillar collagen arrangement of the corneal stroma, rendering it opaque. The process of regaining this organized extracellular matrix (ECM) arrangement of the stromal layer to restore corneal transparency is complicated. The surface retention capacity of ocular drugs is poor, and there is a large gap between suitable corneal donors and clinical requirements. Therefore, a more efficient way of treating corneal scarring is needed. The eight major classes of interventions targeted as therapeutic tools for healing scarred corneas include those based on exosomes, targeted gene therapy, microRNAs, recombinant viral vectors, histone deacetylase inhibitors, bioactive molecules, growth factors, and nanotechnology. This review highlights the recent advancements in molecular therapeutics to restore a cornea without scarring. It also provides a scope to overcome the limitations of present studies and perform robust clinical research using these strategies.

Recent advancements in polymeric nanofibers for ophthalmic drug delivery and ophthalmic tissue engineering

Nanofibers due to their unique properties such as high surface-to-volume ratio, porous structure, mechanical strength, flexibility and their resemblance to the extracellular matrix, have been researched extensively in the field of ocular drug delivery and tissue engineering. Further, different modifications considering the formulation and process parameters have been carried out to alter the drug release profile and its interaction with the surrounding biological environment. Electrospinning is the most commonly used technique for preparing nanofibers with industrial scalability. Advanced techniques such as co-axial electrospinning and combined system such as embedding nanoparticles in nanofiber provide an alternative approach to enhance the performance of the scaffold. Electrospun nanofibers offers a matrix like structure for cell regeneration. Nanofibers have been used for ocular delivery of various drugs like antibiotics, anti-inflammatory and various proteins. In addition, lens-coated medical devices provide new insights into the clinical use of nanofibers. Through fabricating the nanofibers researchers have overcome the issues of low bioavailability and compatibility with ocular tissue. Therefore, nanofibers have great potential in ocular drug delivery and tissue engineering and have the capacity to revolutionize these therapeutic areas in the field of ophthalmology. This review is mainly focused on the recent advances in the preparation of nanofibers and their applications in ocular drug delivery and tissue engineering. The authors have attempted to emphasize the processing challenges and future perspectives along with an overview of the safety and toxicity aspects of nanofibers.

In Situ Gelling Electrospun Ocular Films Sustain the Intraocular Pressure-Lowering Effect of Timolol Maleate: In Vitro, Ex Vivo, and Pharmacodynamic Assessment

Most common intraocular pressure (IOP) reduction regimens for the management of glaucoma include the topical use of eye drops, a dosage form that is associated with short residence time at the site of action, increased dosing frequency, and reduced patient compliance. In situ gelling nanofiber films comprising poly(vinyl alcohol) and Poloxamer 407 were fabricated via electrospinning for the ocular delivery of timolol maleate (TM), aiming to sustain the IOP-lowering effect of the β-blocker, compared to conventional eye drops. The electrospinning process was optimized, and the physicochemical properties of the developed formulations were thoroughly investigated. The fiber diameters of the drug-loaded films ranged between 123 and 145 nm and the drug content between 5.85 and 7.83% w/w. Total in vitro drug release from the ocular films was attained within 15 min following first-order kinetics, showing higher apparent permeability (P_app) values across porcine corneas compared to the drug's solution. The fabricated films did not induce any ocular irritation as evidenced by both the hen's egg test on chorioallantoic membrane and the in vivo Draize test. In vivo administration of the ocular films in rabbits induced a faster onset of action and a sustained IOP-lowering effect up to 24 h compared to TM solution, suggesting that the proposed ocular films are promising systems for the sustained topical delivery of TM.

Kaempferol Incorporated Bovine Serum Albumin Fibrous Films for Ocular Drug Delivery

The possibility of using drug loaded bovine serum albumin (BSA) porous films as therapeutic contact lenses is investigated. Kaempferol (KAE), a hydrophobic antioxidant and anti-inflammatory agent, is incorporated into BSA porous films to form BSA/KAE films. The BSA/KAE films are transparent in the visible wavelength range of the human eye, possessing high water content and good cytocompatibility. A prolonged and sustained drug release is observed, and the in vivo efficacy of BSA/KAE films is better than the individual KAE. BSA/KAE films promoted the corneal re-epithelialization, inhibited neovascularization, and reduced the inflammation of an alkali burn induced corneal injury model. The study demonstrates the promising potential of BSA/KAE films as therapeutic contact lenses for the treatment of corneal injury, builds an available ocular drug delivery platform for ocular diseases.

Preparation and Characterization of Electrospun Polylactic Acid (PLA) Fiber Loaded with Birch Bark Triterpene Extract for Wound Dressing

Drug-loaded electrospun fibers have attracted increasing attention as a promising wound dressing material due to their capability of preventing from infections and inflammation and maintaining an appropriate environment for wound healing. In this study, polylactic acid (PLA), which is widely used in wound management, was chosen as electrospinnable polymer. A triterpene extract (TE) from the outer bark of birch known for its anti-inflammatory, antiviral, antibacterial, and wound healing effects was chosen to produce TE-loaded PLA electrospun fibers for wound dressing. A binary solvent system of dichloromethane (DCM) and dimethyl sulfoxide (DMSO) was employed, and the ratio of the solvents was optimized for preparing smooth and uniform fibers. The morphology of TE-loaded PLA electrospun fibers was investigated by scanning electron microscopy (SEM). The entrapment of TE in PLA fibers was confirmed by confocal laser scanning microscopy (CLSM). Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were used to analyze the solid state of TE in PLA fibers. The release behavior of TE was assayed by a shaking flask method for a period of 96 h. The results revealed that TE-loaded electrospun PLA microfibers could be reliably prepared and are promising future candidates in wound therapy.

In vitro and in vivo biological assessment of dual drug-loaded coaxial nanofibers for the treatment of corneal abrasion

The treatment of corneal abrasion currently involves the topical administration of antibiotics, with moxifloxacin HCl (0.5% w/v) eye drops being one of the most widely used treatments. Our previous work (Tawfik et al., 2020) involved the development of coaxial poly-lactic-co-glycolic acid (PLGA) and polyvinylpyrrolidone (PVP) nanofibers loaded with the antibiotic moxifloxacin HCl and the anti-scarring agent pirfenidone in the core (PVP) and shell (PLGA) respectively, with a view to the system comprising an ocular insert for the combination therapy of corneal abrasion. In this study, we examine the antimicrobial, anti-scarring and pharmacokinetic properties of the fibers alongside consideration of their toxicity and propensity for irritation. Minimum inhibitory concentration and zone of inhibition studies against S. aureus and P. aeruginosa were performed, while fibroblast cell viability and α-smooth muscle actin (α-SMA, a biomarker for scar formation) were measured using MTT and Western Blot assays, respectively. Pharmacokinetic studies and efficacy against infection were performed using a rabbit model, while ocular irritancy was assessed using the Draize test. The studies demonstrated that the antimicrobial activity of the moxifloxacin HCl was preserved following encapsulation into the nanofibers, while the downregulation of α-SMA was demonstrated using concentrations below the IC₂₀ values (concentration required to decrease corneal fibroblast viability by no more than 20%). The pharmacokinetic study showed retention and sustained release of the moxifloxacin HCl over a 24-hour period, in contrast to equivalent eye drops which required four times daily dosing. Evidence of low level (according to the MMTS scale) irritation was detected for the nanofiber systems. Overall, the study has demonstrated that the dual drug-loaded nanofiber system shows potential for once daily dosing as an ocular insert for the treatment of corneal abrasion.

Anti-VEGF Treatment in Corneal Diseases

BACKGROUND

Corneal neovascularization (CN) is a clue feature of different ocular pathological conditions and can lead to corneal edema and opacification with subsequent vision loss. Vascular endothelial growth factor (VEGF), which plays a key role in new vessels formation, proliferation and migration, was found to be up-regulated in these conditions. Nowadays, it is possible to downregulate the angiogenic process by using anti-VEGF agents administered by different routes.

OBJECTIVE

To evaluate the efficacy, safety and possible future directions of anti-VEGF agents used for the treatment of CNV owing to different aetiologies.

METHODS

A computerized search of articles dealing with the topic of anti-VEGF therapy in CN was conducted in PubMed, Scopus and Medline electronic databases. The following key phrases were used: anti-VEGF agents, corneal neovascularization, bevacizumab, ranibizumab, vascular endothelial growth factor, angiogenesis.

RESULTS

The use of anti-VEGF therapy in the treatment of CN reduced pathological vessel density without causing significant side effects. Various administration routes such as topical, subconjunctival and intrastromal ones are available, and the choice depends on patient and disease characteristics. Much more effectiveness is achieved in case of early administration before mature and wellestablished vessels take place. A combined approach between various drugs including anti-VEGF agents should be adopted in those cases at higher risk of neovascularization recurrence such as chronic long-standing diseases where ischemic and inflammatory stimuli are not definitively reversed.

CONCLUSION

The efficacy and safety of anti-VEGF agents support their adoption into the daily clinical practice for the management of CN.

Pharmacological Potential of Small Molecules for Treating Corneal Neovascularization

Under healthy conditions, the cornea is an avascular structure which allows for transparency and optimal visual acuity. Its avascular nature is maintained by a balance of proangiogenic and antiangiogenic factors. An imbalance of these factors can result in abnormal blood vessel proliferation into the cornea. This corneal neovascularization (CoNV) can stem from a variety of insults including hypoxia and ocular surface inflammation caused by trauma, infection, chemical burns, and immunological diseases. CoNV threatens corneal transparency, resulting in permanent vision loss. Mainstay treatments of CoNV have partial efficacy and associated side effects, revealing the need for novel treatments. Numerous natural products and synthetic small molecules have shown potential in preclinical studies in vivo as antiangiogenic therapies for CoNV. Such small molecules include synthetic inhibitors of the vascular endothelial growth factor (VEGF) receptor and other tyrosine kinases, plus repurposed antimicrobials, as well as natural source-derived flavonoid and non-flavonoid phytochemicals, immunosuppressants, vitamins, and histone deacetylase inhibitors. They induce antiangiogenic and anti-inflammatory effects through inhibition of VEGF, NF-κB, and other growth factor receptor pathways. Here, we review the potential of small molecules, both synthetics and natural products, targeting these and other molecular mechanisms, as antiangiogenic agents in the treatment of CoNV.

Crosslinked Hyaluronan Electrospun Nanofibers for Ferulic Acid Ocular Delivery

Electrospun nanofibers are gaining interest as ocular drug delivery platforms that may adapt to the eye surface and provide sustained release. The aim of this work was to design an innovative ophthalmic insert composed of hyaluronan (HA) nanofibers for the dual delivery of an antioxidant (ferulic acid, FA) and an antimicrobial peptide (ε-polylysine, ε-PL). Polyvinylpyrrolidone (PVP) was added to facilitate the electrospinning process. Fibers with diameters of approx. 100 nm were obtained with PVP 5%-HA 0.8% w/v and PVP 10%-HA 0.5% w/v mixtures in ethanol:water 4:6 v/v. An increase in PVP concentration to 20% w/v in both presence and absence of HA rendered fibers of approx. 1 µm. PVP 5%-HA 0.8% w/v fibers were loaded with 83.3 ± 14.0 µg FA per mg. After nanofibers crosslinking with ε-PL, blank and FA-loaded inserts showed a mean thickness of 270 ± 21 µm and 273 ± 41 µm, respectively. Blank and FA-loaded inserts completely released ε-PL within 30 min under sink conditions, whereas FA-loaded inserts released the antioxidant within 20 min. Both blank and FA-loaded inserts were challenged against Pseudomonas aeruginosa and Staphylococcus aureus, demonstrating their efficacy against relevant microbial species.

Utility of nanomedicine targeting scar-forming myofibroblasts to attenuate corneal scarring and haze

Corneal scarring refers to the loss of normal corneal tissue, replaced by fibrotic tissue (during wound repair) thereby affecting corneal transparency and vision quality. The corneal wound healing process involves a complex series of physiological events resulting in the transformation of transparent keratocytes into opaque myofibroblasts; the prominent cause of irregular extracellular matrix synthesis leading to the development of corneal opacity/hazy vision. Globally, corneal scarring/haze is one of the most prevalent causes of blindness. Ocular trauma (physical and chemical) and microbial infections induce corneal tissue damage. Although great progress has been made in the clinical management of ocular diseases, the global rates of corneal blindness remain high, nonetheless. The topical conventional modalities treating corneal wounds/injuries have inherent limitations/side effects such as low bioavailability of a therapeutic agent, upregulation of the intraocular pressure and the toxicity/allergy of the drug. These limitations/side effects rather than treating the wound, often negatively affect the healing process, especially, when applied frequently for longer periods. Recently, there has been an increasing evidence provided by the preclinical studies that nanotechnology-based drug-delivery systems can improve drug bioavailability, through controlled drug release and targeted delivery. After reviewing the epidemiology, risk factors of corneal scarring/haze and the conventional ocular medicines, we review here the different nanodrug-delivery systems and potential drug candidates including nanoherbal formulations investigated for their efficacy to heal the damaged cornea. Finally, we discuss the challenges of using these nanomedicinal platforms.

Therapeutic approaches for corneal neovascularization

Angiogenesis refers to new blood vessels that originate from pre-existing vascular structures. Corneal neovascularization which can lead to compromised visual acuity occurs in a wide variety of corneal pathologies. A large subset of measures has been advocated to prevent and/or treat corneal neovascularization with varying degrees of success. These approaches include topical corticosteroid administration, laser treatment, cautery, and fine needle diathermy. Since the imbalance between proangiogenic agents and antiangiogenic agents primarily mediate the process of corneal neovascularization, recent therapies are intended to disrupt the different steps in the synthesis and actions of proangiogenic factors. These approaches, however, are only partially effective and may lead to several side effects. The aim of this article is to review the most relevant treatments for corneal neovascularization available so far.

Cyclosporine A Loaded Electrospun Poly(D,L-Lactic Acid)/Poly(Ethylene Glycol) Nanofibers: Drug Carriers Utilizable in Local Immunosuppression

PURPOSE

The present study aims to prepare poly(D,L-lactic acid) (PLA) nanofibers loaded by the immunosuppressant cyclosporine A (CsA, 10 wt%). Amphiphilic poly(ethylene glycol)s (PEG) additives were used to modify the hydrophobic drug release kinetics.

METHODS

Four types of CsA-loaded PLA nanofibrous carriers varying in the presence and molecular weight (MW) of PEG (6, 20 and 35 kDa) were prepared by needleless electrospinning. The samples were extracted for 144 h in phosphate buffer saline or tissue culture medium. A newly developed and validated LC-MS/MS method was utilized to quantify the amount of released CsA from the carriers. In vitro cell experiments were used to evaluate biological activity.

RESULTS

Nanofibers containing 15 wt% of PEG showed improved drug release characteristics; significantly higher release rates were achieved in initial part of experiment (24 h). The highest released doses of CsA were obtained from the nanofibers with PEG of the lowest MW (6 kDa). In vitro experiments on ConA-stimulated spleen cells revealed the biological activity of the released CsA for the whole study period of 144 h and nanofibers containing PEG with the lowest MW exhibited the highest impact (inhibition).

CONCLUSIONS

The addition of PEG of a particular MW enables to control CsA release from PLA nanofibrous carriers. The biological activity of CsA-loaded PLA nanofibers with PEG persists even after 144 h of previous extraction. Prepared materials are promising for local immunosuppression in various medical applications.