Wound Integrity of Clear Corneal Incisions Closed with Fibrin and N-Butyl-2-Cyanoacrylate Adhesives

Porcine Fibrin Sealant Promotes Skin Wound Healing in Rats

Objective

Fibrin sealant (FS) is widely used for skin wound healing, but data on porcine FS (PFS), a new type of FS, are limited. This study investigated the effects and potential mechanisms of porcine fibrin sealant (PFS) on skin wound healing in rats. Methods. Traumatic rats were randomly divided into three groups: control, PFS, and medical Vaseline. The wound area and wound index of the rats were measured within 14 days after surgery. Hematoxylin-eosin (H&E) staining and Masson staining were used to observe the pathological images and collagen formation on the wounded skin, respectively. To investigate the healing mechanisms, the enzyme-linked immunosorbent assay (ELISA) was used to detect platelet endothelial cell adhesion molecule-1 (CD31) and cluster of differentiation 34 (CD34) expression in the wounded skin. Additionally, quantitative real-time PCR (qRT-PCR) was used to evaluate the mRNA levels of the vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), and epidermal growth factor (EGF), and transforming growth factor-β1 (TGF-β1). Meanwhile, TGF-β1 protein expression was assessed by Western blot analysis.

Results

Compared with the control group, both PFS and medical Vaseline treatment significantly reduced the wounded area and increased the wound closure rate. H&E staining showed that the cells in the PFS group proliferated rapidly, and the epidermis and dermis were thickened to some extent with a clear epidermal cell structure. Moreover, PFS promoted the formation of collagen and significantly increased the levels of CD31 and CD34 and the growth factors in the skin tissues of the traumatic rats.

Conclusion

PFS effectively promoted skin wound healing, especially in tissue formation, reepithelialization, angiogenesis, and collagen deposition, in traumatic rat models. This study provides a new strategy and scientific foundation for PFS application in skin wound healing.

A Light-Curable and Tunable Extracellular Matrix Hydrogel for In Situ Suture-Free Corneal Repair

Corneal injuries are a major cause of blindness worldwide. To restore corneal integrity and clarity, there is a need for regenerative bio-integrating materials for in-situ repair and replacement of corneal tissue. Here, we introduce Light-curable COrnea Matrix (LC-COMatrix), a tunable material derived from decellularized porcine cornea extracellular matrix containing un-denatured collagen and sulfated glycosaminoglycans. It is a functionalized hydrogel with proper swelling behavior, biodegradation, and viscosity that can be cross-linked in situ with visible light, providing significantly enhanced biomechanical strength, stability, and adhesiveness. Cross-linked LC-COMatrix strongly adheres to human corneas ex vivo and effectively closes full-thickness corneal perforations with tissue loss. Likewise, in vivo, LC-COMatrix seals large corneal perforations, replaces partial-corneal stromal defects and bio-integrates into the tissue in rabbit models. LC-COMatrix is a natural ready-to-apply bio-integrating adhesive that is representative of native corneal matrix with potential applications in corneal and ocular surgeries.

Ciprofloxacin-loaded bioadhesive hydrogels for ocular applications

The management of corneal infections often requires complex therapeutic regimens involving the prolonged and high-frequency application of antibiotics that provide many challenges to patients and impact compliance with the therapeutic regimens. In the context of severe injuries that lead to tissue defects (e.g. corneal lacerations) topical drug regimens are inadequate and suturing is often indicated. There is thus an unmet need for interventions that can provide tissue closure while concurrently preventing or treating infection. In this study, we describe the development of an antibacterial bioadhesive hydrogel loaded with micelles containing ciprofloxacin (CPX) for the management of corneal injuries at risk of infection. The in vitro release profile showed that the hydrogel system can release CPX, a broad-spectrum antibacterial drug, for up to 24 h. Moreover, the developed CPX-loaded hydrogels exhibited excellent antibacterial properties against Staphylococcus aureus and Pseudomonas aeruginosa, two bacterial strains responsible for the most ocular infections. Physical characterization, as well as adhesion and cytocompatibility tests, were performed to assess the effect of CPX loading in the developed hydrogel. Results showed that CPX loading did not affect stiffness, adhesive properties, or cytocompatibility of hydrogels. The efficiency of the antibacterial hydrogel was assessed using an ex vivo model of infectious pig corneal injury. Corneal tissues treated with the antibacterial hydrogel showed a significant decrease in bacterial colony-forming units (CFU) and a higher corneal epithelial viability after 24 h as compared to non-treated corneas and corneas treated with hydrogel without CPX. These results suggest that the developed adhesive hydrogel system presents a promising suture-free solution to seal corneal wounds while preventing infection.

Comparison and application of commercially available fibrin sealants in ophthalmology

Fibrin glues carry many advantages over traditional suture as a tissue adhesive and have been increasingly used in a variety of ophthalmic procedures over the past 15 years. Several fibrin sealants are commercially available worldwide, each of which differs slightly in its composition and mechanism of delivery. The focus of our review is to briefly discuss the reported uses of fibrin in ophthalmic surgery and provide a broad overview of the properties associated with each commercially available fibrin sealant.

Sutureless repair of corneal injuries using naturally derived bioadhesive hydrogels

Corneal injuries are common causes of visual impairment worldwide. Accordingly, there is an unmet need for transparent biomaterials that have high adhesion, cohesion, and regenerative properties. Herein, we engineer a highly biocompatible and transparent bioadhesive for corneal reconstruction using a visible light cross-linkable, naturally derived polymer, GelCORE (gel for corneal regeneration). The physical properties of GelCORE could be finely tuned by changing prepolymer concentration and photocrosslinking time. GelCORE revealed higher tissue adhesion compared to commercial adhesives. Furthermore, in situ photopolymerization of GelCORE facilitated easy delivery to the cornea, allowing for bioadhesive curing precisely according to the required geometry of the defect. In vivo experiments, using a rabbit stromal defect model, showed that bioadhesive could effectively seal corneal defects and induce stromal regeneration and re-epithelialization. Overall, GelCORE has many advantages including low cost and ease of production and use. This makes GelCORE a promising bioadhesive for corneal repair.

Surgical adhesives in ophthalmology: history and current trends

Tissue adhesives are gaining popularity in ophthalmology, as they could potentially reduce the complications associated with current surgical methods. An ideal tissue adhesive should have superior tensile strength, be non-toxic and anti-inflammatory, improve efficiency and be cost-effective. Both synthetic and biological glues are available. The primary synthetic glues include cyanoacrylate and the recently introduced polyethylene glycol (PEG) derivatives, while most biological glues are composed of fibrin. Cyanoacrylate has a high tensile strength, but rapidly polymerises upon contact with any fluid and has been associated with histotoxicity. Fibrin induces less toxic and inflammatory reactions, and its polymerisation time can be controlled. Tensile strength studies have shown that fibrin is not as strong as cyanoacrylate. While more research is needed, PEG variants currently appear to have the most promise. These glues are non-toxic, strong and time-effective. Through MEDLINE and internet searches, this paper presents a systematic review of the current applications of surgical adhesives to corneal, glaucoma, retinal, cataract and strabismus surgeries. Our review suggests that surgical adhesives have promise to reduce problems in current ophthalmic surgical procedures.

Characterization of silver nanoparticle-infused tissue adhesive for ophthalmic use

In this work, we demonstrate the successful enhancement of breaking strength, adhesive strength, and antibacterial efficacy of ophthalmic tissue adhesive (2-octyl cyanoacrylate) by doping with silver nanoparticles, and investigate the effects of nanoparticle size and concentration. Recent work has shown that silver nanoparticles are a viable antibacterial additive to many compounds, but their efficacy in tissue adhesives was heretofore untested. Our results indicate that doping the adhesive with silver nanoparticles reduced bacterial growth by an order of magnitude or more; nanoparticle size and concentration had minimal influence in the range tested. Tensile breaking strength of polymerized adhesive samples and adhesive strength between a T-shaped support and excised porcine sclera were measured using a universal testing machine according to ASTM (formerly American Society for Testing and Materials) standard techniques. Both tests showed significant improvement with the addition of silver nanoparticles. The enhanced mechanical strength and antibacterial efficacy of the doped adhesive supports the use of tissue adhesives as a viable supplement or alternative to sutures.

Cataract surgery and methods of wound closure: a review

Clear corneal incisions are routinely used in cataract surgery, but watertight wound closure may not always be achieved, which can increase the risk for anterior chamber fluid egress or ocular surface fluid ingress. A new US Food and Drug Administration-approved ocular sealant appears to have good efficacy in sealing clear corneal incisions; its use may be indicated when wound integrity is in question.

Experimental application of tissue adhesives in corneal traumas

OBJECTIVE

To evaluate intraoperative difficulties of the use of glues for corneal trauma.


METHODS

Partial or full-thickness perpendicular corneal incisions (3-4 mm straight cuts) near the limbus (perpendicular or parallel to it) were made in 8 albino rabbits and were then sealed with fibrin or cyanoacrylate glue. Follow-up examinations were performed under the surgical microscope. Tissue specimens were also taken for light microscopic evaluation. 


RESULTS

The cyanoacrylate glue polymerized almost immediately after application on the tissue, limiting the ability of the surgeon to oppose the corneal incisions appropriately. The fibrin glue polymerized more gradually, giving enough time for manipulations to reconstruct the wound properly and for removal of excessive glue, especially when the 2 components were applied separately. Excessive glue and crust formation on the eye surface induced irritation.


CONCLUSIONS

Fibrin glue for the reconstruction of corneal wounds was easier to use than cyanoacrylate glue and caused less glue crust formation on the corneal surface. The speed of polymerization is an important factor. Excessive glue on the cornea was irritating.

Evaluation of tensile strength of tissue adhesives and sutures for clear corneal incisions using porcine and bovine eyes, with a novel standardized testing platform

BACKGROUND

Tissue adhesives for ophthalmologic applications were proposed almost 50 years ago, yet to date no adequate tissue glues have been identified that combine strong sealing properties with adequate safety and absence of postsurgical side effects. In recent years, cataract surgeries and Descemet's stripping with endothelial keratoplasty procedures have significantly increased the number of clear corneal incisions performed. One of the obstacles to discovery and development of novel tissue adhesives has been the result of nonstandardized testing of potential tissue glues.

METHODS

We developed an instrument capable of controlling intraocular pressure in explanted porcine and bovine eyes in order to evaluate sealants, adhesives, and surgical closure methods used in ophthalmic surgery in a controlled, repeatable, and validated fashion. We herein developed and validated our instrument by testing the adhesive properties of cyanoacrylate glue in both porcine and bovine explant eyes.

RESULTS

The instrument applied and maintained intraocular pressure through a broad range of physiological intraocular pressures. Cyanoacrylate-based glues showed significantly enhanced sealing properties of clear corneal incisions compared with sutured wounds.

CONCLUSION

This study shows the feasibility of our instrument for reliable and standardized testing of tissue adhesive for ophthalmological surgery.

Cut and paste: a novel method of re-attaching rectus muscles with cyanoacrylate during recessions in strabismus

Aim:

Bio-adhesives like cyanoacrylate offer an alternative to sutures to attach tissues, including in ophthalmology. This prospective trial evaluated the suitability and bio-tolerance of iso-amyl cyanoacrylate in rectus muscle recession surgery for strabismus.

Materials and Methods:

We randomized one eye in each of 10 cases of bilateral horizontal rectus recessions to 6/0 polyglactin and the other to iso-amyl-cyanoacrylate. We compared time to reattachment (from disinsertion), complications and inflammatory scores (0 to +3: nil, mild, moderate and severe) on Day One, at two and at four to six weeks post surgery.

Results:

There were no significant group differences in inflammatory scores (Wilcoxon, all values of P>0.05). All attachments held firm. Gluing took significantly longer by 5.24±1.91 min (95% CI for difference: 3.87-6.61). There were no complications.

Conclusion:

We feel that although it takes marginally longer, iso-amyl cyanoacrylate offers an effective and safe alternative to sutures for muscle recession in strabismus surgery. Since it is cheaper (vs. polyglactin) and offers multi-use possibility it may also prove to be cost-effective.