In Vivo Efficacy of a New Autologous Fibrin Sealant

Neurotrophic keratopathy: General features and new therapies

Neurotrophic keratopathy is an uncommon degenerative corneal disorder characterized by compromised corneal sensory innervation resulting in the formation of epithelial defects and nonhealing corneal ulcers. Various treatment modalities are available to stabilize disease progression, improve patient well-being, and prevent vision loss. For eligible patients, medical and surgical reinnervation have emerged as pioneering therapies, holding promise for better management. We present a comprehensive review of the disorder, providing an update relevant to ophthalmologists on pathogenesis, diagnosis, treatment options, and novel therapies targeting pathophysiological pathways.

A thermo-sensitive hydrogel with prominent hemostatic effect prevents tumor recurrence via anti-anoikis-resistance

Tumor cells can survive when detached from the extracellular matrix (ECM) or lose cell-cell connections, a phenomenon known as anoikis-resistance (AR). AR is closely associated with tumor cell metastasis and recurrence, enabling tumor cells to disseminate, migrate, and invade after detachment. To address this issue, a novel intervention method combining intraoperative hemostasis with multifunctional nanozyme driven-enhanced chemodynamic therapy (ECDT) has been proposed, which holds the potential to weaken the AR capability of tumor cells and suppress tumor recurrence. Here, a nanocomposite containing a dendritic mesoporous nanoframework with Cu2+ was developed using an anion-assisted approach after surface PEG grafting and glucose oxidase (GOx) anchoring (DMSN-Cu@GOx/PEG). DMSN-Cu@GOx/PEG was further encapsulated in a thermal-sensitive hydrogel (H@DMSN-Cu@GOx/PEG). DMSN-Cu@GOx/PEG utilizes its high peroxidase (POD) activity to elevate intracellular ROS levels, thereby weakening the AR capability of bladder cancer cells. Additionally, through its excellent catalase (CAT) activity, DMSN-Cu@GOx/PEG converts the high level of hydrogen peroxide (H2O2) catalyzed by intracellular GOx into oxygen (O2), effectively alleviating tumor hypoxia, downregulating hypoxia-inducible factor-1α (HIF-1α) expression, inhibiting epithelial-mesenchymal transition (EMT) processes, and ultimately suppressing the migration and invasion of bladder cancer cells. Interestingly, in vivo results showed that the thermosensitive hydrogel H@DMSN-Cu@GOx/PEG could rapidly gel at body temperature, forming a gel film on wounds to eliminate residual tumor tissue after tumor resection surgery. Importantly, H@DMSN-Cu@GOx/PEG exhibited excellent hemostatic capabilities, effectively enhancing tissue coagulation during post-tumor resection surgery and mitigating the risk of cancer cell dissemination and recurrence due to surgical bleeding. Such hydrogels undoubtedly possess strong surgical application. Our developed novel nanosystem and hydrogel can inhibit the AR capability of tumor cells and prevent recurrence post-surgery. This study represents the first report of using dendritic mesoporous silica-based nanoreactors for inhibiting the AR capability of bladder cancer cells and suppressing tumor recurrence post-surgery, providing a new avenue for developing strategies to impede tumor recurrence after surgery.

Evaluation and comparison of the efficacy of autologous fibrin glue with 4-0 silk sutures in periodontal flap closure and wound healing - A split mouth randomized controlled trial

BACKGROUND

Fibrin glue has shown to be a pioneering remedy to overcome the inconvenience of suturing. Autologous products reduce the risk of contamination and immunological responses compared to commercial fibrin glue. Hence using autologous fibrin glue (AFG) as a tissue sealant in periodontal flap closure would be of added value for a predictable outcome.

OBJECTIVE

To evaluate and compare the efficacy of AFG with 4-0 silk sutures in periodontal flap closure and healing.

MATERIAL AND METHODS

Total of 17 patients diagnosed with generalized periodontitis in the age group of 18 to 60 years with probing pocket depth of ≥ 6 mm and clinical attachment level of ≥5 mm in at least two quadrants were categorized into test group (AFG) and control group (4-0 silk sutures). Primary outcome measures [modified gingival index (MGI), early wound index (EHI) and interleukin 1 beta (IL-1ß) and secondary outcome measures (oral hygiene index, plaque index and visual analog scale (VAS) were recorded at baseline, 1, 2, 3 and 4 weeks.

RESULTS

A statistically significant reduction of IL-1ß value (p =.005); MGI (p = .02); EHI (p = .004), VAS scores (p < .001) and a positive Spearman's correlation (rho = 0.15) was seen between EHI scores & IL-1ß levels in test group at 1week period in comparison to control group.

CONCLUSION

AFG showed promising results as an alternative to sutures. The use of AFG significantly improved clinical parameters and reduced the levels of pro-inflammatory cytokines making it an effective adhesive with healing properties in the era of suture-less periodontal flap surgery.

Application of fibrin glue for hematoma prophylaxis in selective aponeurectomy in Dupuytren's disease

INTRODUCTION

Fibrin glue (FG) can be applied in several surgical procedures at wound closure to reduce postoperative complications such as hematoma formation and wound impairment. The purpose of this study is to assess these preventive surgical benefits in Dupuytren's disease of the hand.

PATIENTS AND METHODS

We performed a monocentric retrospective cohort study. All patients who underwent selective aponeurectomy for Dupuytren's disease between 2010 and 2020 were included. Patients were divided into two groups: either receiving or not receiving FG. The primary outcome variables were postoperative bleeding, wound healing impairment, and further pooled postoperative complications.

RESULTS

One hundred and thirty-three patients were included in the analysis of which 108 patients were treated with FG, while 24 did not. There was no statistically significant difference in outcomes regarding postoperative bleeding, infections, or revision surgery. However, in the group receiving FG, there was a tendency toward higher wound healing impairment (13%, p = 0.07). The FG group showed a significantly higher pooled complication rate (18.5%, p < 0.02). Complication in general increased with higher Tubiana classification and number of resected cords. Smoking tripled the risk of impaired wound, while cardiovascular comorbidities increased postoperative bleeding by the factor of 11.

CONCLUSION

FG did not show a preventive outcome regarding bleeding. The FG group had a tendency for a higher wound healing incidence. Smoking and arterial hypertension correlated with a higher postoperative complication rate. The overall incidence of complications was higher in the FG group. The quality of the surgical intervention as well as accurate hemostasis cannot be corrected by the application of FG.

An Integrated Strategy for Rapid Hemostasis during Tumor Resection and Prevention of Postoperative Tumor Recurrence of Hepatocellular Carcinoma by Antibacterial Shape Memory Cryogel

The inevitable bleeding during tumor resection greatly increases the risk of tumor recurrence caused by metastasis of cancer cells with blood, and hemostasis and prevention of post-operation tumor recurrence is still a challenge. However, a biomaterials approach for rapid hemostasis during tumor resection and simultaneous prevention of tumor recurrence is rarely reported. Here, zeolitic imidazolate framework (ZIF-8) nanoparticle-enhanced multinetwork cryogels are proposed which provide an integrated treatment regimen for rapid hemostasis through intraoperative blood trigger shape recovery and enhanced coagulation, and prevention of postoperative cancer recurrence via sonodynamic anticancer in a hepatocellular carcinoma model. A series of antibacterial shape memory multifunctional cryogels are synthesized based on glycidyl methacrylate-functionalized quaternized chitosan (QCSG), dopamine-modified hyaluronic acid (HA-DA), and hematoporphyrin monomethyl ether (HMME)-loaded dopamine-modified ZIF-8 (ZDH). Blood loss in different bleeding models confirms good hemostasis of ZIF-8 loading cryogels. Besides, in vitro tests confirm that QCSG/HA-DA/ZDH (QH/ZDH) cryogels significantly killed cancer cells by generating reactive oxygen species under ultrasound. Finally, significantly reduced tumor recurrence after the resection of ectopic hepatocellular carcinoma further confirms the good effect of QH/ZDH cryogels in preventing recurrence by a coordinated strategy of intraoperative hemostasis and postoperative sonodynamic therapy by pH-responsive HMME release, showing great potential in clinical application.

Strategies to use fibrinogen as bioink for 3D bioprinting fibrin-based soft and hard tissues

Fibrin gel has been widely used for engineering various types of tissues due to its biocompatible nature, biodegradability, and tunable mechanical and nanofibrous structural properties. Despite their promising regenerative capacity and extensive biocompatibility with various tissue types, fibrin-based biomaterials are often notoriously known as burdensome candidates for 3D biofabrication and bioprinting. The high viscosity of fibrin (crosslinked form) hinders proper ink extrusion, and its pre-polymer form, fibrinogen, is not capable of maintaining shape fidelity. To overcome these limitations and empower fibrinogen-based bioinks for fibrin biomimetics and regenerative applications, different strategies can be practiced. The aim of this review is to report the strategies that bring fabrication compatibility to these bioinks through mixing fibrinogen with printable biomaterials, using supporting bath supplemented with crosslinking agents, and crosslinking fibrin in situ. Moreover, the review discusses some of the recent advances in 3D bioprinting of biomimetic soft and hard tissues using fibrinogen-based bioinks, and highlights the impacts of these strategies on fibrin properties, its bioactivity, and the functionality of the consequent biomimetic tissue. Statement of Significance Due to its biocompatible nature, biodegradability, and tunable mechanical and nanofibrous structural properties, fibrin gel has been widely employed in tissue engineering and more recently, used as in 3D bioprinting. The fibrinogen's poor printable properties make it difficult to maintain the 3D shape of bioprinted constructs. Our work describes the strategies employed in tissue engineering to allow the 3D bioprinting of fibrinogen-based bioinks, such as the combination of fibrinogen with printable biomaterials, the in situ fibrin crosslinking, and the use of supporting bath supplemented with crosslinking agents. Further, this review discuss the application of 3D bioprinting technology to biofabricate fibrin-based soft and hard tissues for biomedical applications, and discuss current limitations and future of such in vitro models.

Recent Advances in Hemostasis at the Nanoscale

Rapid and effective hemostatic materials have received wide attention not only in the battlefield but also in hospitals and clinics. Traditional hemostasis relies on materials with little designability which has many limitations. Nanohemostasis has been proposed since the use of peptides in hemostasis. Nanomaterials exhibit excellent adhesion, versatility, and designability compared to traditional materials, laying a good foundation for future hemostatic materials. This review first summarizes current hemostatic methods and materials, and then introduces several cutting-edge designs and applications of nanohemostatic materials such as polypeptide assembly, electrospinning of cyanoacrylate, and nanochitosan. Particularly, their advantages and working mechanisms are introduced. Finally, the challenges and prospects of nanohemostasis are discussed.

Cauterisation versus fibrin glue for conjunctival autografting in primary pterygium surgery (CAGE CUP): study protocol of a randomised controlled trial

INTRODUCTION

Pterygium is a non-cancerous growth of the conjunctival tissue over the cornea that may lead to visual impairment in advanced stages, restriction of ocular motility, chronic inflammation and cosmetic concerns. Surgical removal is the treatment of choice, but recurrence of pterygium is a frequent problem. It has been previously shown that fibrin glue may result in less recurrence and may take less time than sutures for fixing the conjunctival graft in place during pterygium surgery. However, fibrin glue is a biological material and it carries the risk of transmitting infectious agents from pooled and single-donor blood donors and anaphylaxis in susceptible individuals. Cauterisation is another surgical option, and it would be advantageous to know whether cauterisation may be superior surgical option compared with fibrin glue. This protocol describes the rationale and design of the randomised controlled trial (RCT) in which we will compare cauterisation versus fibrin glue for conjunctival autografting in primary pterygium surgery.

METHODS AND ANALYSES

This will be a parallel group RCT comparing cauterisation versus fibrin glue for conjunctival autografting in primary pterygium surgery. Computer-generated randomisation will be used, and allocation concealment will be conducted using sequentially numbered opaque sealed envelopes. Surgeons will not be blinded to the procedures, but participants, other investigators and outcome assessors will be blinded. Adult participants with primary pterygium operated in a tertiary hospital in Split, Croatia, will be included. Primary outcome will be recurrence of pterygium, defined as any regrowth of tissue from the area of excision across the limbus onto the cornea after 180 days.

ETHICS AND DISSEMINATION

The trial was approved by the ethics review board of the University Hospital Split (500-03/17-01/68). Results will be disseminated at conferences and through peer-reviewed publications.

TRIAL REGISTRATION NUMBER

NCT03321201; Pre-results.

Fibrin hydrogels as a xenofree and rapidly degradable support for transplantation of retinal pigment epithelium monolayers

Recent phase 1 trials of embryonic stem cell and induced pluripotent stem cell (iPSCs) derived RPE transplants for the treatment of macular degeneration have demonstrated the relative safety of this process. However, there is concern over clumping, thickening, folding, and wrinkling of the transplanted RPE. To deliver a flat RPE monolayer, current phase 1 trials are testing synthetic substrates for RPE transplantation. These substrates, however, cause localized inflammation and fibrosis in animal models due to long degradation times. Here we describe the use of thin fibrin hydrogels as a support material for the transplantation of RPE. Fibrin was formed into a mechanically rigid support that allow for easy manipulation with standard surgical instruments. Using fibrinolytic enzymes, fibrin hydrogels were degraded on the scale of hours. The rate of degradation could be controlled by varying the fibrinolytic enzyme concentration used. RPE cells degraded fibrin spontaneously. To preserve the fibrin support during differentiation of iPSCs to RPE, media was supplemented with the protease inhibitor aprotinin. iPSC-RPE on fibrin gels remained viable, generated monolayers with characteristic cobblestone appearance and dark pigmentation, and expressed mRNA and protein markers characteristic of RPE in the eye. Following differentiation of the cells, addition of fibrinolytic enzymes fully and rapidly degraded the fibrin support leaving behind an intact, viable iPSC-RPE monolayer. In conclusion, human fibrin hydrogels provide a xeno-free support on which iPSCs can be differentiated to RPE cells for transplant which can be rapidly degraded under controlled conditions using fibrinolytic enzymes without adverse effects to the cells.

STATEMENT OF SIGNIFICANCE

Stem cell-derived retinal pigment epithelial (RPE) cell transplantation is currently in phase 1 clinical trials for macular degeneration (MD). A major obstacle in these studies is delivering the RPE as a living, flat sheets without leaving behind foreign materials in the retina. Here we investigate the suitability of using hydrogels made from human blood-derived proteins for RPE transplant. Our data shows that these fibrin hydrogels are rigid enough for use in surgery, support growth of stem cell-derived RPE, and are easily degraded within hours without damage to the RPE sheet. These fibrin hydrogels offer a promising solution to transplant RPE for patients with MD.

Photochemical Cross-Linking for Penetrating Corneal Wound Closure in Enucleated Porcine Eyes

PURPOSE

To compare the efficacy of photochemical-induced tissue cross-linking (PCL), utilizing Rose Bengal (RB) and 532 nm green light irradiation (RB-PCL), with standard sutures for closure of penetrating corneal incision in porcine cadaver eyes.

METHODS

A full-thickness penetrating incision, 3 mm in length parallel to the limbus and perpendicular to the corneal surface, was made in the enucleated porcine cornea. Photochemical cross-linking was performed with tropical RB application and irradiation of 532 nm green light (0.6 W/cm²) for 200, 250, and 300 seconds at laser fluences of 120, 150, and 180 J/cm², respectively, which was compared with the standard 10-0 nylon suture group. Following treatment, intraocular pressure to the point where wound leakage occurred (IOP_L) was measured. Corneal central thickness and surface temperature before and after PCL treatment were recorded. Optical coherence tomography (OCT) and scanning electron microscopy (SEM) were utilized to evaluate wound closure.

RESULTS

The mean corneal central thickness was increased from 812.0 ± 47.0 to 838.0 ± 45.6 µm after the incision as a result of cornea aqueous humor infiltration. RB penetrated approximately 140 μm into the porcine corneal stroma. The mean IOP_L for untreated blank group after incision was 4.27 ± 0.36 mmHg. Increased laser fluences produced increased IOP_L of 27.02 ± 3.01 (PCL₁₂₀), 31.60 ± 3.67 (PCL₁₅₀) and 36.73 ± 3.25 mmHg (PCL₁₈₀), which were statistically different from the control intact group. The mean IOP_L in the sutured cornea was 57.30 ± 4.59 mmHg. The average surface temperature difference before and after PCL treatment was 2.03 ± 0.45-2.47 ± 0.79°C. OCT demonstrated not only complete but also improved closure in comparison with disorganized collagen fibers after conventional suturing, which is further confirmed by SEM.

CONCLUSIONS

Complete and clinically relevant seal of full-thickness porcine corneal incision was achieved using PCL method ex vivo, which provides potential application of this technique in ocular wound closure.

Comparative evaluation of the biological properties of fibrin for bone regeneration

Fibrin is a natural provisional matrix found in wound healing, while type I collagen is a major organic component of bone matrix. Despite the frequent use of fibrin and type I collagen in bone regenerative approaches, their comparative efficacies have not yet been evaluated. In the present study, we compared the effects of fibrin and collagen on the proliferation and differentiation of osteoblasts and protein adsorption. Compared to collagen, fibrin adsorbed approximately 6.7 times more serum fibronectin. Moreover, fibrin allowed the proliferation of larger MC3T3-E1 pre-osteoblasts, especially at a low cell density. Fibrin promoted osteoblast differentiation at higher levels than collagen, as confirmed by Runx2 expression and transcriptional activity, alkaline phosphatase activity, and calcium deposition. The results of the present study suggest that fibrin is superior to collagen in the support of bone regeneration. [BMB Reports 2014; 47(2): 110-114]

Hemostatic strategies for traumatic and surgical bleeding

Wide interest in new hemostatic approaches has stemmed from unmet needs in the hospital and on the battlefield. Many current commercial hemostatic agents fail to fulfill the design requirements of safety, efficacy, cost, and storage. Academic focus has led to the improvement of existing strategies as well as new developments. This review will identify and discuss the three major classes of hemostatic approaches: biologically derived materials, synthetically derived materials, and intravenously administered hemostatic agents. The general class is first discussed, then specific approaches discussed in detail, including the hemostatic mechanisms and the advancement of the method. As hemostatic strategies evolve and synthetic-biologic interactions are more fully understood, current clinical methodologies will be replaced.

Rapid production of autologous fibrin hydrogels for cellular encapsulation in organ regeneration

Autologous hydrogel manufacture is an exciting technique within the field of regenerative medicine. Fibrin is a protein with many biocompatible and regenerative features. The ability to generate fibrin scaffolds with the necessary matrix topography for cell integration, from a patient's autologous tissue, could improve the translation of many tissue engineering efforts from bench to clinical application. Here we describe the rapid extraction and production of fibrin hydrogels for development of organs, using a simple low-cost series of centrifugations and ethanol precipitation, which produces hydrogels of a more predictable amount and morphology.

Management of haemostasis in surgery: sealant and glue applications

Blood loss has always been a sensitive issue in surgery. Traditional techniques, such as suturing and electrocautery, have drastically reduced operatory bleeding. Unfortunately, wound edges and point application devices are frequently characterized by bleeding and infections. Over the past 20 years, haemostatic agents and tissue sealants have been developed and now are currently used, along with classic suture in various surgical specialties. Their fluid nature allows management of blood loss along any point of the wound and tissue repair. This review presents an overview of the most diffused haemostatic sealants, focusing on their main use in surgery and their adverse effects.

The use of novel hemostatic sealant (Tisseel) in laparoscopic myomectomy: a case-control study

BACKGROUND

This is the first case-control study on the use of a fibrin sealant (Tisseel) on uterine suture during laparoscopic myomectomy (LM), with the primary endpoint to evaluate the intraoperative bleeding and postoperative blood loss. In addition, we evaluated the time required to achieve hemostasis using Tisseel and how much it can influence operative time.

METHODS

From December 2009 to January 2011, consecutive patients older than 18 years with symptomatic isolate intramural myoma with maximal diameter B6 cm and ≥ 4 cm and with a sonographically diagnosed free myometrium margin ≥ 0.5 cm were included in the study. We selected from our institute's database a group of consecutive patients with homogeneous features of the study group, who underwent laparoscopic myomectomy without Tisseel application.

RESULTS

Fifteen women with symptomatic myoma were enrolled in the study (group A). Regarding the control group (group B), we selected a homogenous group of 15 patients with the same preoperative characteristics of the study group. Mean operative time was 47.7 min and 62.1 min, for groups A and B respectively (p < 0.05). Mean time required to achieve complete haemostasis was 195.5 s in group A and 361.8 in control group B (p < 0.0001). Mean estimated blood loss was 111.3 mL and 230 mL in groups A and B, respectively (p < 0.05). Mean hemoglobin decrease was 1.36 g/dL and 2.04 g/dL in groups A and B, respectively (p < 0.05).

CONCLUSIONS

The use of Tisseel during LM may represent a valid alternative solution for obtaining hemostasis, reducing intra- and postoperative bleeding. Furthermore, it may help the surgeon to obtain a rapid healing of the injured surfaces, probably reducing the use of electrocoagulationand traumatisms.

In vivo and in vitro study of suprachoroidal fibrin glue

PURPOSE

The suprachoroidal space is preferred for many reasons for implantation of retinal prostheses or drug delivery systems. This study aimed to investigate the safety and feasibility of suprachoroidal fibrin glue (FG), one of the adhesives used to fix the implanted material.

METHODS

Human retinal pigment epithelium cells (hRPE) were cultured with FG, assayed with 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay, and studied by transmission electron microscopy. A total of 48 rabbits were randomly divided into three groups to undergo surgery: group 1, 0.1 ml suprachoroidal FG; group 2, 0.1 ml suprachoroidal normal saline (control); group 3, 0.1 ml intravitreal FG. Slit-lamp examination, indirect ophthalmoscopy, fundus photography, fundus fluorescein angiography (FFA), indocyanine green angiography (IA), electroretinography (ERG), and histopathological examination were performed at various time points till 90 days after injection.

RESULTS

No apoptosis changes of electron microscopy were observed in the hRPE cultured with FG, and the difference in the MTT test results was not statistically significant when compared with the control group (P>0.2). One day after suprachoroidal injection, slight choroidal hemorrhage occurred. No severe intraocular reactions were observed in any of the three groups, and FFA and IA showed no edema or leakage around blood vessels. There was no significant difference in latency or amplitude of the ERG wave among the three groups (P>0.1). Histopathological examinations showed the suprachoroidal FG induced localized inflammation (from acute inflammation to chronic phagocytosis) at the early stage and finally turned into fibrosis tissue.

CONCLUSIONS

FG is feasible for suprachoroidal use, and no obvious toxic reaction was observed in either in vitro or in vivo studies.

Fibrin glue in ophthalmology

Suturing is a time consuming task in ophthalmology and suture induced irritation and redness are frequent problems. Postoperative wound infection and corneal graft rejection are examples of possible suture related complications. To prevent these complications, ophthalmic surgeons are switching to sutureless surgery. A number of recent developments have established tissue adhesives like cyanoacrylate glue and fibrin glue as attractive alternatives to sutures. A possible and promising new application for tissue adhesives is to provide a platform for tissue engineering. Currently, tissue glue is being used for conjunctival closure following pterygium and strabismus surgery, forniceal reconstruction surgery, amniotic membrane transplantation, lamellar corneal grafting, closure of corneal perforations and descematoceles, management of conjunctival wound leaks after trabeculectomy, lid surgery, adnexal surgery and as a hemostat to minimise bleeding. The purpose of this review is to discuss the currently available information on fibrin glue.