Hyaluronic acid hydrogels crosslinked via blue light-induced thiol-ene reaction for the treatment of rat corneal alkali burn

Artificial Cornea Substitute Based on Hydrogel Skeletons with Natural Stromal Hierarchical Structure and Extracellular Matrix for Sutureless Transplantation

Corneal substitutes with structural and compositional characteristics resembling those of natural corneas have attracted considerable attention. However, biomimicking the complex hierarchical organization of corneal stroma is challenging. In this study, humanized corneal stroma-like adhesive patches (HCSPs) are prepared through a multi-step process. First, polyethylene glycol diacrylate is cast and cured within decellularized porcine cornea (DPC) templates. The DPCs are then enzymatically digested to obtain hydrogel skeletons, which are finally integrated with human corneal extracellular matrix and methacrylate gelatin. HCSPs replicate the ultrastructure, protein components, and optical properties of human corneas and exhibit improved anti-swelling and anti-degradation capabilities compared with conventional DPCs and recombinant human collagen patches. HCSPs can deliver methacrylate gelatin at the ocular surface temperature (37 °C) and achieve stable adhesion to the corneal stroma upon 405 nm light irradiation. Furthermore, HCSPs promote the survival and migration of corneal epithelial and stromal cells while preserving their phenotypes. In rabbit models of lamellar keratoplasty and microperforation repair, HCSPs accelerate epithelial healing, minimize suture-associated complications, and maintain structural stability. These findings suggest that HCSPs are promising donor corneal substitutes for clinical applications.

Green propolis extract for the treatment of alkali-induced superficial corneal ulcers: local and systemic analyses

Green propolis, produced by honeybees from the resin of certain plants, has garnered attention for its potential health benefits. Green propolis contains compounds like artepillin C, which exhibits antioxidant, anti-inflammatory, and antimicrobial properties. This study's objective was to examine the effects of green propolis extract containing 21.05% artepillin C, topically administered (5, 10 and 15 mg/mL) in rats with induced superficial corneal ulcers with alkali, applied four times daily, for 96 hours. Rats treated with the green propolis extract exhibited of ulcer reduction more significant reduction after 24 hours of treatment than untreated animals, suggesting a similar healing activity of the commercial drug. After 96 hours of treatment, the rats were euthanized, and the corneas were submitted for histopathological analysis; no statistical difference was detected between rats treated with green propolis and those not treated in terms of polymorphonuclear and neovessel counts in the corneal stroma. In the toxicogenetic analysis, by the micronucleus test, no significant differences were observed in the frequencies of chromosomal damage and the ratio of polychromatic erythrocytes to the total number of erythrocytes between treated and untreated animals, revealing the absence of genotoxicity and cytotoxicity, respectively. The biochemical results did not indicate a hepatotoxic or nephrotoxic effect of the formulations containing green propolis. Like this, the standardized green propolis extract induced corneal epithelialization without toxic effects, rendering it a promising option for treating superficial keratitis.

Human embryonic stem cell-derived immunity-and-matrix-regulatory cells on collagen scaffold effectively treat rat corneal alkali burn

Corneal alkali burns (CAB) are a severe form of ocular injury that often leads to significant vision loss, with limited effective treatment options available beyond corneal transplantation. Immunity and matrix-regulatory cells (IMRCs) have emerged as a promising alternative due to their ability to modulate immune responses and support tissue repair. This study investigates the efficacy of IMRCs on collagen scaffolds (IMRCs-col) for treating CAB in a rat model. We developed a novel treatment combining IMRCs with a collagen scaffold to align with the ocular surface structure. In vitro analyses showed that IMRCs-col significantly upregulated the expression of immune regulatory molecules, including IL-1RA and SCF. Additionally, IMRCs-col effectively inhibited the production of pro-inflammatory cytokines (IL-8 and Gro-a/CXCL1) while promoting pro-regenerative cytokines (bFGF, HGF, and PDGF). In an animal model of CAB, IMRCs-col transplantation demonstrated substantial efficacy in restoring corneal opacity and reducing neovascularization. Histological examination revealed reduced inflammation and improved corneal tissue regeneration compared to untreated CAB. Enhanced activation of pathways associated with anti-inflammatory responses and tissue repair was observed at days 3, 7, and 21 post-treatment.

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.

Gelatin nanofibers coated with hyaluronic acid as a mesenchymal stromal cell scaffold for corneal regeneration

Electrospun gelatin nanofibers coated with hyaluronic acid (GelNF-HA) were synthesized as a scaffold for delivering human corneal mesenchymal stromal cells (C-MSCs) directly to deep corneal injuries. Aligned GelNFs were produced by electrospinning, crosslinked using vapor of glutaraldehyde, coated with HA, and crosslinked with EDC/NHS. The GelNF-HA was characterized by SEM, mechanical, and optical properties. It was then investigated as a substrate for C-MSC proliferation and migration in vitro and in a rabbit cornea culture model. The expression of α-smooth muscle actin (α-SMA) was determined in the ex vivo model. SEM showed that the GelNF-HA scaffold was composed of aligned GelNFs with 75 % of the fibers oriented against the same angle. It exhibited a Young's modulus of 1.66 ± 0.59 MPa and approximately 93 % transmittance of visible light. The GelNF-HA membranes supported C-MSC proliferation in vitro. In a scratch migration assay, it facilitated complete wound closure after 48 h in culture. C-MSC-laden GelNF-HA scaffolds supported corneal wound healing in an ex vivo model as well, expressing a lower percentage of stromal α-SMA compared to both the no-treatment keratectomy-only and C-MSC groups (p < 0.05). The C-MSC-supportive GelNF-HA scaffolds hold therapeutic potential for stromal regeneration in the treatment of deep corneal defects.

Enhanced Corneal Repair with Hyaluronic Acid/Proanthocyanidins Nanoparticles

This study investigates the therapeutic potential of hyaluronic acid/proanthocyanidin (HA/PAC) nanoparticles in treating alkali-induced corneal burns. Alkali burns are common ocular emergencies that can lead to severe vision impairment if not promptly and properly treated. The low water solubility of proanthocyanidins (PACs), which are potent antioxidant and anti-inflammatory agents, limits their bioavailability and therapeutic efficacy. To overcome this, hyaluronic acid (HA) was utilized as a carrier to form HA/PAC nanoparticles, enhancing PAC's solubility and bioavailability. The HA/PAC nanoparticles were characterized for morphology, granulometric distribution, hemolysis, and cytotoxicity, demonstrating high blood compatibility and noncytotoxicity. The in vitro antioxidant and anti-inflammatory capacities of HA/PAC were evaluated, showing enhanced activity compared to PAC alone. In vivo studies on C57 mice confirmed the accelerated healing of corneal injuries and reduced corneal opacity with HA/PAC treatment. Histopathological analysis and cytokine quantification further supported the anti-inflammatory and proregenerative effects of HA/PAC, suggesting its potential as an effective treatment for corneal alkali burns.

Novel ophthalmic hyaluronic acid-hydrogel with curcumin nanoparticles for enhanced healing of ulcerative keratitis in rabbit model

Corneal ulcers, whether melting or indolent, are common in humans and companion animals. Treatment involves local administration of antibiotic eye drops and corneal healing drugs. Compared to traditional treatments for ulcerative keratitis, herbal medicines offer unique advantages, such as potent anti-inflammatory effects and inhibition of proinflammatory cytokines. Curcumin, extracted from the Curcuma Longa plant, possesses extensive pharmacological properties, such as anti-inflammatory, anti-cancer, and antioxidant properties, and is used in various medicines. In this study, we developed a novel ophthalmic drop hydrogel using a formulation of Curcumin NPs encapsulated with β-cyclodextrin and hyaluronic acid, to accelerate corneal healing and improve the quality of healed structures. The formation of Curcumin NPs into Hyaluronic acid-based hydrogels was characterized by zeta, FTIR, and scanning electron microscope (SEM) analyses. A total of 25 healthy male New Zealand Albino rabbits were experimentally induced with ulcerative keratitis and treated individually with topical medication. Rabbits were divided into five groups. Fluorescein dye staining, corneal clarity score, Schirmer tear test, proinflammatory cytokine measurement, and pathologic factors assessments were used to evaluate the optimised Curcumin NPs with β-cyclodextrin in Hyaluronic acid hydrogel. Our results demonstrated that the optimized Curcumin NPs with β-cyclodextrin in hyaluronic acid hydrogel significantly reduced the frequency of medication administration compared to conventional therapies, enhancing the quality of healed structures and effectively treating ulcerative keratitis. All findings in this study provide new insight into designing and fabricating novel ophthalmic medicine for ulcerative keratitis for topical usage.

The combined effect of epidermal growth factor and keratinocyte growth factor delivered by hyaluronic acid hydrogel on corneal wound healing

This study strategically incorporates epidermal growth factor (EGF) and keratinocyte growth factor (KGF) within a hyaluronic acid (HA) hydrogel to enhance corneal wound healing. The controlled release of EGF and KGF from the HA hydrogel is engineered to promote the regeneration of both the epithelial and stromal layers. Specifically, EGF plays a pivotal role in the regeneration of the epithelial layer, while KGF exhibits efficacy in the regeneration of the stromal layer. The combination of these growth factors facilitates efficient regeneration of each layer and demonstrates the capability to modulate each other's regenerative effects. The interplay between EGF and KGF provides an understanding of their cooperative influence on the dynamics of corneal wound healing. The results of this study contribute to the development of advanced strategies for corneal wound management and offer insights into the complex process of corneal regeneration.

Research progress of photo-crosslink hydrogels in ophthalmology: A comprehensive review focus on the applications

Hydrogel presents a three-dimensional polymer network with high water content. Over the past decade, hydrogel has developed from static material to intelligent material with controllable response. Various stimuli are involved in the formation of hydrogel network, among which photo-stimulation has attracted wide attention due to the advantages of controllable conditions, which has a good application prospect in the treatment of ophthalmic diseases. This paper reviews the application of photo-crosslink hydrogels in ophthalmology, focusing on the types of photo-crosslink hydrogels and their applications in ophthalmology, including drug delivery, tissue engineering and 3D printing. In addition, the limitations and future prospects of photo-crosslink hydrogels are also provided.

Kuragel: A biomimetic hydrogel scaffold designed to promote corneal regeneration

Cornea-related injuries are the most common cause of blindness worldwide. Transplantation remains the primary approach for addressing corneal blindness, though the demand for donor corneas outmatches the supply by millions. Tissue adhesives employed to seal corneal wounds have shown inefficient healing and incomplete vision restoration. We have developed a biodegradable hydrogel - Kuragel, with the ability to promote corneal regeneration. Functionalized gelatin and hyaluronic acid form photo-crosslinkable hydrogel with transparency and compressive modulus similar to healthy human cornea. Kuragel composition was tuned to achieve sufficient adhesive strength for sutureless integration to host tissue, with minimal swelling post-administration. Studies in the New Zealand rabbit mechanical injury model affecting corneal epithelium and stroma demonstrate that Kuragel efficiently promotes re-epithelialization within 1 month of administration, while stroma and sub-basal nerve plexus regenerate within 3 months. We propose Kuragel as a regenerative treatment for patients suffering from corneal defects including thinning, by restoration of transparency and thickness.

Hyaluronic acid-based hydrogels: As an exosome delivery system in bone regeneration

Exosomes are extracellular vesicles (EVs) containing various ingredients such as DNA, RNA, lipids and proteins, which play a significant role in intercellular communication. Numerous studies have demonstrated the important role of exosomes in bone regeneration through promoting the expression of osteogenic-related genes and proteins in mesenchymal stem cells. However, the low targeting ability and short circulating half-life of exosomes limited their clinical application. In order to solve those problems, different delivery systems and biological scaffolds have been developed. Hydrogel is a kind of absorbable biological scaffold composed of three-dimensional hydrophilic polymers. It not only has excellent biocompatibility and superior mechanical strength but can also provide a suitable nutrient environment for the growth of the endogenous cells. Thus, the combination between exosomes and hydrogels can improve the stability and maintain the biological activity of exosomes while achieving the sustained release of exosomes in the bone defect sites. As an important component of the extracellular matrix (ECM), hyaluronic acid (HA) plays a critical role in various physiological and pathological processes such as cell differentiation, proliferation, migration, inflammation, angiogenesis, tissue regeneration, wound healing and cancer. In recent years, hyaluronic acid-based hydrogels have been used as an exosome delivery system for bone regeneration and have displayed positive effects. This review mainly summarized the potential mechanism of HA and exosomes in promoting bone regeneration and the application prospects and challenges of hyaluronic acid-based hydrogels as exosome delivery devices in bone regeneration.

Design Considerations, Formulation Approaches, and Strategic Advances of Hydrogel Dressings for Chronic Wound Management

Wound healing is a complex and dynamic physiological process consisting of a series of cellular and molecular events that initiate immediately after a tissue lesion, to reconstruct the skin layer. It is indubitable that patients with chronic wounds, severely infected wounds, or any metabolic disorder of the wound microenvironment always endure severe pain and discomfort that affect their quality of life. It is essential to treat chronic wounds for conserving the physical as well as mental well-being of affected patients and for convalescing to improve their quality of life. For supporting and augmenting the healing process, the selection of pertinent wound dressing is essential. A substantial reduction in healing duration, disability, associated cost, and risk of recurrent infections can be achieved via engineering wound dressings. Hydrogels play a leading role in the path of engineering ideal wound dressings. Hydrogels, comprising water to a large extent, providing a moist environment, being comfortable to patients, and having biocompatible and biodegradable properties, have found their success as suitable wound dressings in the market. The exploitation of hydrogels is increasing perpetually after substantiation of their broader therapeutic actions owing to their resemblance to dermal tissues, their capability to stimulate partial skin regeneration, and their ability to incorporate therapeutic moieties promoting wound healing. This review entails properties of hydrogel supporting wound healing, types of hydrogels, cross-linking mechanisms, design considerations, and formulation strategies of hydrogel engineering. Various categories of hydrogel wound dressing fabricated recently are discussed based on their gel network composition, degradability, and physical and chemical cross-linking mechanisms, which provide an outlook regarding the importance of tailoring the physicochemical properties of hydrogels. The examples of marketed hydrogel wound dressings are also incorporated along with the future perspectives and challenges associated with them.

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.

Using Convolutional Neural Network as a Statistical Algorithm to Explore the Therapeutic Effect of Insulin Liposomes on Corneal Inflammation

Aiming at the disadvantages of easy recurrence of keratitis, difficult eradication by surgery, and easy bacterial resistance, insulin-loaded liposomes were prepared, and convolutional neural network was used as a statistical algorithm to build SD rat corneal inflammation model and study insulin-loaded liposomes, alleviating effect on corneal inflammatory structure in SD rats. The INS/PFOB@LIP was developed by means of thin-film dispersive phacoemulsification, its structure was monitored using a transmission electron microscope, particle size and appearance potential were monitored using a Malvern particle sizer, and ultraviolet consumption spectrum was monitored using a UV spectrophotometer. The encapsulation rate, drug loading, and distribution of insulin liposomes in rat corneal inflammatory model were measured and calculated. The cytotoxicity of liposome materials was evaluated by CCK-8 assay, and the toxic effects of insulin and insulin liposomes on cells were detected. The cornea of SD rats was burned with NaOH solution (1 mol/L), and the SD rat corneal inflammation model was created. The insulin liposome was applied to the corneal inflammation model, and the therapeutic effect of insulin liposome on corneal inflammation was evaluated by slit lamp, corneal immunohistochemistry, corneal HE staining, and corneal Sirius red staining. Insulin-loaded liposomes were successfully constructed with an average particle size of (130.69 ± 3.87) nm and a surface potential of (−38.24 ± 2.57) mV. The encapsulation rate of insulin liposomes was (48.89 ± 1.24)%, and the drug loading rate was (24.45 ± 1.24)%. The SD rat corneal inflammation model was successfully established. After insulin liposome treatment, the staining area of corneal fluorescein sodium was significantly reduced, the corneal epithelium was significantly thickened, the content of corneal collagen was increased, the expression of inflammatory factors was significantly reduced, and new blood vessels (corneal neovascularization, CNV) growth was inhibited.