Antimicrobial peptide-fibrin glue mixture for treatment of methicillin-resistant Staphylococcus aureus-infected wounds.

Aim: This study was conducted to investigate the effect of fibrin glue-CM11 antibacterial peptide mixture (FG-P) on the healing of infected wounds in vivo.Materials & methods: We formulated a mixture of FG-P and evaluated its antimicrobial activity in vitro against multidrug-resistant (MDR) bacteria involved in wound infection as well as its healing effect on wound infected by methicillin-resistant S. aureus (MRSA) in vivo.Results: The peptide had an MIC of 8 µg/ml against all bacteria isolates. Growth inhibition zones were evident for FG-P compared with FG. The in vivo study showed that the FG-P could be significantly effective in healing the MRSA-infected wound.Conclusion: The use of FG-P mixture is a very suitable option for treating infected wounds.

[Box: see text].

Shielding against breast tumor relapse with an autologous chemo-photo-immune active Nano-Micro-Sera based fibrin implant.

Local recurrence post-surgery in early-stage triple-negative breast cancer is a major challenge. To control the regrowth of a residual tumor, we have developed an autologous therapeutic hybrid fibrin glue for intra-operative implantation. Using autologous serum proteins as stabilizers, we have optimized high drug-loaded lapatinib-NanoSera (Lap-NS; ∼66% L.C.) and imiquimod-MicroSera (IMQ-MS; ∼92% L.C). Additionally, plasmonic nanosera (PNS) with an ∼67% photothermal conversion efficiency under 980 nm laser irradiation was also developed. While localized monotherapy with either Lap-NS or PNS reduced the tumor regrowth rate, their combination with IMQ-MS amplified the effect of immunogenic cell death with a high level of tumor infiltration by immune cells at the surgical site. The localized combination immunotherapy with a Nano-MicroSera based hybrid fibrin implant showed superior tumor inhibition and survival with significant promise for clinical translation.

Comparison of nylon, vicryl, and fibrin glue for nerve grafting in rats.

OBJECTIVES: For nerve injuries, not amendable to tensionless epineural coaptation of the nerve, autografts are the preferred treatment. Although absorbable sutures are not recommended for nerve repair, there is no evidence that non-absorbable sutures are superior to absorbable sutures. This study aims to assess the effectiveness of non-absorbable monofilament nylon sutures, absorbable monofilament vicryl sutures, and fibrin glue when used for nerve grafting. METHODS: Lewis rats (N = 32) were subjected to a sciatic nerve transection and randomly assigned to a group: graft with Nylon, graft with Vicryl, graft with Fibrin Glue, or no graft. Motor function, sensory function, and thermal pain were assessed during a 12-week recovery period, and immunohistochemistry was used to assess macrophage response. RESULTS: At 12 weeks, the Vicryl and Nylon groups had significantly larger ankle angles at to lift off, which is a measure of motor function, compared to injured controls (p < 0.05). Grafted rats displayed no difference in thermal response but hypersensitivity to mechanical stimuli compared to the uninjured hindlimb. The Nylon, Vicryl, and Fibrin Glue groups all had significantly less atrophy of the gastrocnemius muscle compared to injured controls (p < 0.0001). In the Fibrin Glue group, 3/9 grafts did not incorporate. The Nylon group had significantly less (p = 0.0004) axon growth surrounding the suture holes compared to the Vicryl group. There were no differences in the axon counts, motor neurons, or sensory neurons between all grafted rats. CONCLUSIONS: These results demonstrate that vicryl sutures work just as well as nylon for nerve recovery after injury and grafting.

Tensile strength of adhesives in peripheral nerve anastomoses: an in vitro biomechanical evaluation of four different neurorrhaphies.

BACKGROUND: The fundamental prerequisite for prognostically favorable postoperative results of peripheral nerve repair is stable neurorrhaphy without interruption and gap formation. METHODS: This study evaluates 60 neurorrhaphies on femoral chicken nerves in terms of the procedure and the biomechanical properties. Sutured neurorrhaphies (n = 15) served as control and three sutureless adhesive-based nerve repair techniques: Fibrin glue (n = 15), Histoacryl glue (n = 15), and the novel polyurethane adhesive VIVO (n = 15). Tensile and elongation tests of neurorrhaphies were performed on a tensile testing machine at a displacement rate of 20 mm/min until failure. The maximum tensile force and elongation were recorded. RESULTS: All adhesive-based neurorrhaphies were significant faster in preparation compared to sutured anastomoses (p < 0.001). Neurorrhaphies by sutured (102.8 [cN]; p < 0.001), Histoacryl (91.5 [cN]; p < 0.001) and VIVO (45.47 [cN]; p < 0.05) withstood significant higher longitudinal tensile forces compared to fibrin glue (10.55 [cN]). VIVO, with △L/L0 of 6.96 [%], showed significantly higher elongation (p < 0.001) compared to neurorrhaphy using fibrin glue. CONCLUSION: Within the limitations of an in vitro study the adhesive-based neurorrhaphy technique with VIVO and Histoacryl have the biomechanical potential to offer alternatives to sutured neuroanastomosis because of their stability, and faster handling. Further in vivo studies are required to evaluate functional outcomes and confirm safety.

Fibrin Glue Coating Limits Scar Tissue Formation around Peripheral Nerves.

Scar tissue formation presents a significant barrier to peripheral nerve recovery in clinical practice. While different experimental methods have been described, there is no clinically available gold standard for its prevention. This study aims to determine the potential of fibrin glue (FG) to limit scarring around peripheral nerves. Thirty rats were divided into three groups: glutaraldehyde-induced sciatic nerve injury treated with FG (GA + FG), sciatic nerve injury with no treatment (GA), and no sciatic nerve injury (Sham). Neural regeneration was assessed with weekly measurements of the visual static sciatic index as a parameter for sciatic nerve function across a 12-week period. After 12 weeks, qualitative and quantitative histological analysis of scar tissue formation was performed. Furthermore, histomorphometric analysis and wet muscle weight analysis were performed after the postoperative observation period. The GA + FG group showed a faster functional recovery (6 versus 9 weeks) compared to the GA group. The FG-treated group showed significantly lower perineural scar tissue formation and significantly higher fiber density, myelin thickness, axon thickness, and myelinated fiber thickness than the GA group. A significantly higher wet muscle weight ratio of the tibialis anterior muscle was found in the GA + FG group compared to the GA group. Our results suggest that applying FG to injured nerves is a promising scar tissue prevention strategy associated with improved regeneration both at the microscopic and at the functional level. Our results can serve as a platform for innovation in the field of perineural regeneration with immense clinical potential.

Investigation of the appropriate viscosity of fibrinogen in repairing pleural defects using ventilation and anchoring in an ex vivo pig model.

OBJECTIVE: Our previous study revealed that the viscosity of fibrinogen could influence the effectiveness of ventilation and anchoring (V/A) methods for controlling air leakages. Here, we examined the association between the viscosity of fibrinogen and effectiveness using an ex vivo pig model. METHODS: The fibrin glue used in this study was BOLHEAL® (KM Biologics Co., Ltd., Kumamoto, Japan). We prepared three types of fibrinogen with different viscosities (higher and lower than normal), including one without additives. Using an ex vivo pig model, a pleural defect was made, and the defect was repaired using three different viscosities of fibrinogen through the V/A method. We measured the rupture pressure at the repair site (N = 10) and histologically evaluated the depth of fibrin infiltration into the lung parenchyma at the repair sites. RESULTS: The median rupture pressure was 51.5 (40-73) cmH2O in Group 1 (lower viscosity), 47.0 (47-88) cmH2O in Group 2 (no change in viscosity), and 35.5 (25-61) cmH2O in Group 3 (higher viscosity). There was no statistically significant difference between Groups 1 and 2 (p = 0.819), but the rupture pressure was significantly higher in Group 2 than in Group 3 (p = 0.0136). Histological evaluation revealed deep infiltration of fibrin into the lung parenchyma in Groups 1 and 2, but no such infiltration was observed in the higher-viscosity group. CONCLUSIONS: The results of this experiment suggested that the V/A method using fibrin glue containing low-viscosity fibrinogen was more effective in controlling air leakage due to pleural defects.

Ultrasound-guided periadventitial administration of rapamycin-fibrin glue attenuates neointimal hyperplasia in the rat carotid artery injury model.

INTRODUCTION: Arterial restenosis caused by intimal hyperplasia (IH) is a serious complication after vascular interventions. In the rat carotid balloon injury model, we injected phosphate buffer saline (PBS), rapamycin-phosphate buffer saline suspension (RPM-PBS), blank fibrin glue (FG) and rapamycin-fibrin glue (RPM-FG) around the injured carotid artery under ultrasound guidance and observed the inhibitory effect on IH. METHODS: The properties of RPM-FG in vitro were verified by scanning electron microscopy (SEM) and determination of the drug release rate. FG metabolism in vivo was observed by fluorescence imaging. The rat carotid balloon injury models were randomly classified into 4 groups: PBS group (control group), RPM-PBS group, FG group, and RPM-FG group. Periadventitial administration was performed by ultrasound-guided percutaneous puncture on the first day after angioplasty. Carotid artery specimens were analyzed by immunostaining, Evans blue staining and hematoxylin-eosin staining. RESULTS: The RPM particles showed clustered distributions in the FG block. The glue was maintained for a longer time in vivo (> 14 days) than in vitro (approximately 7 days). Two-component liquid FG administered by ultrasound-guided injection completely encapsulated the injured artery before coagulation. The RPM-FG inhibited IH after carotid angioplasty vs. control and other groups. The proliferation of vascular smooth muscle cells (VSMCs) was significantly inhibited during neointima formation, whereas endothelial cell (EC) repair was not affected. CONCLUSION: Periadventitial delivery of RPM-FG contributed to inhibiting IH in the rat carotid artery injury model without compromising re-endothelialization. Additionally, FG provided a promising platform for the future development of a safe, effective, and minimally invasive perivascular drug delivery method to treat vascular disease.

Conjunctiva in strabismus surgery - to stitch or to stick? - A randomized clinical trial.

PURPOSE: To evaluate the clinical outcomes with fibrin glue in comparison with vicryl sutures for limbal conjunctival wound closure in strabismus surgery. METHODS: In this prospective interventional study, patients undergoing horizontal muscle strabismus surgery were randomized into two groups: the vicryl suture group and the fibrin glue group. The limbal conjunctival incisions were closed with 8-0 vicryl in the suture group and with fibrin glue in the other group. The outcomes measured were post-operative conjunctival inflammation and wound apposition, patient comfort with the help of a questionnaire, and conjunctival thickness using anterior segment optical coherence tomography (AS-OCT) for both groups at 6 weeks. RESULTS: The study included 64 eyes of 64 patients (32 eyes in each group). The fibrin glue group performed better than the vicryl suture group for most of the symptoms like redness, irritation, watering, and foreign body sensation till 2 weeks post-operatively ( P < 0.001), after which both the groups performed similarly. As for clinical signs, no significant difference was noted between the two groups, except for conjunctival hyperemia, which was significantly lesser in the fibrin glue group at 2 weeks post-operatively ( P < 0.001). The conjunctival thickness measured at 6 weeks using AS-OCT revealed that the thickness increased significantly in the suture group compared to that in the glue group ( P < 0.001 medial site, P = 0.004 lateral site). CONCLUSION: Because of greater patient comfort and reduced inflammation associated with fibrin glue, it may be considered as a procedure of choice for conjunctival wound closure in strabismus surgery in the absence of the cost constraints.

Topical Fibrin Sealant (Tisseel@) Does Not Provide a Synergic Blood-Conservation Effect with Tranexamic Acid in Total Knee Arthroplasty-A Prospective Randomized Controlled Trial.

Background and Objectives: The efficacy of tranexamic acid (TXA) in reducing perioperative blood loss during total knee arthroplasty (TKA) is well established. However, the potential synergistic blood-conservation effect of topical fibrin sealant (Tisseel@) remains unclear. This study aims to assess the effectiveness of the combination of Tisseel and TXA during TKA. Materials and Methods: A single-blinded, prospective, randomized controlled trial was conducted with 100 patients (100 knees) undergoing primary TKA. Participants were randomly assigned to either the TXA group (n = 50), receiving intravenous (IV) TXA, or the Tisseel@ + TXA group (n = 50), receiving intra-articular Tisseel@ combined with IV TXA. The primary outcomes included blood transfusion rate, decrease in Hb level, calculated blood loss, and estimated total postoperative blood loss. Secondary outcomes involved assessing clinical differences between the groups. Results: The transfusion rate was zero in both groups. The average estimated blood loss in the Tisseel@ + TXA group was 0.463 ± 0.2422 L, which was similar to that of the TXA group at 0.455 ± 0.2522 L. The total calculated blood loss in the Tisseel@ + TXA group was 0.259 ± 0.1 L, compared with the TXA group's 0.268 ± 0.108 L. The mean hemoglobin reduction in the first 24 h postoperatively was 1.57 ± 0.83 g/dL for the Tisseel@ + TXA group and 1.46 ± 0.82 g/dL for the TXA-only group. The reduction in blood loss in the topical Tisseel@ + TXA group was not significantly different from that achieved in the TXA-only group. The clinical results of TKA up to the 6-week follow-up were comparable between the groups. Conclusions: The combination of the topical fibrin sealant Tisseel@ and perioperative IV TXA administration, following the described protocol, demonstrated no significant synergistic blood-conservation effect in patients undergoing TKR.

Injectable kaempferol-loaded fibrin glue regulates the metabolic balance and inhibits inflammation in intervertebral disc degeneration.

To construct an injectable fibrin glue system loaded with kaempferol (FG@F) to improve the bioavailability of kaempferol and observe its efficacy in the treatment of intervertebral disc degeneration (IVDD). Kaempferol-loaded fibrin glue was first synthesized in advance. Subsequently, the materials were characterized by various experimental methods. Then, nucleus pulposus cells (NPCs) were stimulated with lipopolysaccharide (LPS) to establish a degenerative cell model, and the corresponding intervention treatment was conducted to observe the effect in vitro. Finally, the tail disc of rats was punctured to establish a model of IVDD, and the therapeutic effect of the material in vivo was observed after intervertebral disc injection. The FG@F system has good injectability, sustained release and biocompatibility. This treatment reduced the inflammatory response associated with IVDD and regulated matrix synthesis and degradation. Animal experimental results showed that the FG@F system can effectively improve needle puncture-induced IVDD in rats. The FG@F system has better efficacy than kaempferol or FG alone due to its slow release and mechanical properties. The drug delivery and biotherapy platform based on this functional system might also serve as an alternative therapy for IVDD.

Developing the supraparticle technology for round window-mediated drug administration into the cochlea.

The semi-permeable round window membrane (RWM) is the gateway to the cochlea. Although the RWM is considered a minimally invasive and clinically accepted route for localised drug delivery to the cochlea, overcoming this barrier is challenging, hindering development of effective therapies for hearing loss. Neurotrophin 3 (NT3) is an emerging treatment option for hearing loss, but its therapeutic effect relies on sustained delivery across the RWM into the cochlea. Silica supraparticles (SPs) are drug delivery carriers capable of providing long-term NT3 delivery, when injected directly into the guinea pig cochlea. However, for clinical translation, a RWM delivery approach is desirable. Here, we aimed to test approaches to improve the longevity and biodistribution of NT3 inside the cochlea after RWM implantation of SPs in guinea pigs and cats. Three approaches were tested (i) coating the SPs to slow drug release (ii) improving the retention of SPs on the RWM using a clinically approved gel formulation and (iii) permeabilising the RWM with hyaluronic acid. A radioactive tracer (iodine 125: 125I) tagged to NT3 (125I NT3) was loaded into the SPs to characterise drug pharmacokinetics in vitro and in vivo. The neurotrophin-loaded SPs were coated using a chitosan and alginate layer-by-layer coating strategy, named as '(Chi/Alg)SPs', to promote long term drug release. The guinea pigs were implanted with 5× 125I NT3 loaded (Chi/Alg) SPs on the RWM, while cats were implanted with 30× (Chi/Alg) SPs. A cohort of animals were also implanted with SPs (controls). We found that the NT3 loaded (Chi/Alg)SPs exhibited a more linear release profile compared to NT3 loaded SPs alone. The 125I NT3 loaded (Chi/Alg)SPs in fibrin sealant had efficient drug loading (~5 µg of NT3 loaded per SP that weights ~50 µg) and elution capacities (~49% over one month) in vitro. Compared to the SPs in fibrin sealant, the (Chi/Alg)SPs in fibrin sealant had a significantly slower 125I NT3 drug release profile over the first 7 days in vitro (~12% for (Chi/Alg) SPs in fibrin sealant vs ~43% for SPs in fibrin sealant). One-month post-implantation of (Chi/Alg) SPs, gamma count measurements revealed an average of 0.3 µg NT3 remained in the guinea pig cochlea, while for the cat, 1.3 µg remained. Histological analysis of cochlear tissue revealed presence of a 125I NT3 signal localised in the basilar membrane of the lower basal turn in some cochleae after 4 weeks in guinea pigs and 8 weeks in cats. Comparatively, and in contrast to the in vitro release data, implantation of the SPs presented better NT3 retention and distribution inside the cochlea in both the guinea pigs and cats. No significant difference in drug entry was observed upon acute treatment of the RWM with hyaluronic acid. Collectively, our findings indicate that SPs and (Chi/Alg)SPs can facilitate drug transfer across the RWM, with detectable levels inside the cat cochlea even after 8 weeks with the intracochlear approach. This is the first study to examine neurotrophin pharmacokinetics in the cochlea for such an extended period of times in these two animal species. Whilst promising, we note that outcomes between animals were variable, and opposing results were found between in vitro and in vivo release studies. These findings have important clinical ramifications, emphasising the need to understand the physical properties and mechanics of this complex barrier in parallel with the development of therapies for hearing loss.

The healing capacity and osteogenesis pattern of demineralized dentin matrix (DDM)-fibrin glue (FG) compound.

Demineralized dentin matrix (DDM) is an osteoconductive and osteoinductive material that has been successfully used in sinus floor augmentation and alveolar ridge augmentation in clinical applications. It releases bone morphogenetic proteins (BMPs) and other growth factors, making DDM a suitable grafting material. However, the granular particle of DDM makes it difficult to anchor into the bone defect area. The aim of this study was to investigate the biological effects and osteoinductivity of the combination of DDM and Fibrin Glue (FG) at an optimal ratio on bone healing from a critical bone defect in an animal model. The mouse osteoblastic cell line (MC3T3-E1) was co-cultured with various ratios of DDM and FG to examine their effects on osteoblast proliferation and differentiation, as indicated by alkaline phosphatase (ALP) activity, osteocalcin (OC) production and mineralized nodules formation. The optimal ratio was then chosen for further study with a rabbit calvarial defective model, in which they were implanted with DDM or DDM-FG1 (1 g: 0.1 ml) and DDM-FG2 (1 g: 0.5 ml) compounds, or left blank for 2, 4, 8 and 12 weeks to investigate soft tissue and new bone regeneration. Micro-CT and histology analysis were used to evaluate the total grafting properties according to the different healing periods. The result from in vitro studies demonstrated that the ratio of 1:0.1 induced more ALP activity and mineralized nodules, while the ratio of 1: 0.5 (DDM-FG combined) induced more osteocalcin (OC) at specific time points. In the animal model, the 3D new bone volume in all DDM-FG treatment groups was significantly greater than that in the blank group at 2, 4, 8 and 12 weeks. Furthermore, the new bone volume was greater in DDM-FG2 when compared to the other groups during the early weeks of the healing period. In histological analysis, clusters of osteoblasts were formed adjacent to the DDM particles, and newly formed bone was observed in all groups, suggesting an osteoinductive property of DDM. Moreover, the greater new collagen synthesis observed at 4 weeks suggested that early bone healing was induced in the DDM-FG2 group. This study demonstrated that at an optimal ratio, the DDM-FG compound enhances osteogenic activities and bone regeneration.

The use of commercial fibrin glue in dermal replacement material reduces angiogenic and lymphangiogenic gene and protein expression in vitro.

BACKGROUND: Commercial fibrin glue is increasingly finding its way into clinical practice in surgeries to seal anastomosis, and initiate hemostasis or tissue repair. Human biological glue is also being discussed as a possible cell carrier. To date, there are only a few studies addressing the effects of fibrin glue on the cell-molecular level. This study examines the effects of fibrin glue on angiogenesis and lymphangiogenesis, as well as adipose-derived stem cells (ASCs) with a focus on gene and protein expression in scaffolds regularly used for tissue engineering approaches. METHODS: Collagen-based dermal regeneration matrices (DRM) were seeded with human umbilical vein endothelial cells (HUVEC), human dermal lymphatic endothelial cells (LECs), or adipose-derived stem cells (ASC) and fixed with or without fibrin glue according to the experimental group. Cultures were maintained for 1 and 7 days. Finally, angiogenic and lymphangiogenic gene and protein expression were measured with special regard to subtypes of vascular endothelial growth factor (VEGF) and corresponding receptors using Multiplex-qPCR and ELISA assays. In addition, the hypoxia-induced factor 1-alpha (HIF1a) mediated intracellular signaling pathways were included in assessments to analyze a hypoxic encapsulating effect of fibrin polymers. RESULTS: All cell types reacted to fibrin glue application with an alteration of gene and protein expression. In particular, vascular endothelial growth factor A (VEGFA), vascular endothelial growth factor B (VEGFB), vascular endothelial growth factor C (VEGFC), vascular endothelial growth receptor 1 (VEGFR1/FLT1), vascular endothelial growth receptor 2 (VEGFR2/KDR), vascular endothelial growth receptor 3 (VEGFR3/FLT4) and Prospero Homeobox 1 (PROX1) were depressed significantly depending on fibrin glue. Especially short-term fibrin effect led to a continuous downregulation of respective gene and protein expression in HUVECs, LECs, and ASCs. CONCLUSION: Our findings demonstrate the impact of fibrin glue application in dermal regeneration with special regard to angiogenesis and lymphangiogenesis. In particular, a short fibrin treatment of 24 hours led to a decrease in gene and protein levels of LECS, HUVECs, and ASCs. In contrast, the long-term application showed less effect on gene and protein expressions. Therefore, this work demonstrated the negative effects of fibrin-treated cells in tissue engineering approaches and could affect wound healing during dermal regeneration.

Does perivascular fibrin glue application have a preventive effect for the endothelial damage on saphenous vein graft? An experimental model.

BACKGROUND: The effect of tissue adhesives on coronary grafts in cardiac surgery is a controversial issue. OBJECTIVE: The aim of this study is to investigate the effect of fibrin glue (FG) applied around the saphenous vein grafts (SVG) in preventing cellular damage resulting from intraluminal pressure increase. METHODS: Twenty volunteer patients were included in this ex vivo study. The SVGs remained after coronary artery bypass grafting were connected to the arterial line of the cardiopulmonary bypass circuit. The grafts were divided into two segments and one segment received perivascular FG applied whereas the other part was used plain. SVGs were kept in circulation at 120 mmHg pressure 250 mL/min flow rate for 60 min. The tissues were sent for histopathological examination to determine the endothelial damage. RESULTS: Endothelial damage was more pronounced in the control group when compared with the FG group. In the FG group, no damage was seen in 13 samples and no Type 3 endothelial damage was observe whereas Type 1 injury was detected in seven specimens, Type 2 injury was observed in seven specimens, and Type 3 injury was detected in two specimens in the control group. CONCLUSION: Perivascular application of FG on the SVG showed a protective effect against endothelial damage resulting from increased intraluminal pressure.

ANTECEDENTES: El efecto de los adhesivos tisulares sobre los injertos coronarios en cirugía cardíaca es un tema controvertido. OBJETIVO: Investigar el efecto del pegamento de fibrina aplicado alrededor de los injertos de vena safena para prevenir el daño celular resultante del aumento de la presión intraluminal. MÉTODO: En este estudio ex vivo fueron incluidos 20 pacientes voluntarios. Los injertos de vena safena que quedaron después del injerto de derivación de la arteria coronaria se conectaron a la línea arterial del circuito de derivación cardiopulmonar. Los injertos se dividieron en dos segmentos y a uno de ellos se le aplicó pegamento de fibrina perivascular, mientras que la otra parte se usó sola. Los injertos de vena safena se mantuvieron en circulación a una presión de 120 mmHg y una velocidad de flujo de 250 ml/min durante 60 minutos. Los tejidos se enviaron para examen histopatológico para determinar el daño endotelial. RESULTADOS: El daño endotelial fue más pronunciado en el grupo de control que en el grupo de pegamento de fibrina. Se observó lesión de tipo 2 en siete muestras del grupo de pegamento de fibrina y lesión de tipo 3 en dos muestras del grupo de control. CONCLUSIONES: La aplicación perivascular de pegamento de fibrina en los injertos de vena safena mostró un efecto protector contra el daño endotelial resultante del aumento de la presión intraluminal.

Neuroregeneration and immune response after neurorrhaphy are improved with the use of heterologous fibrin biopolymer in addition to suture repair alone.

INTRODUCTION/AIMS: Peripheral nerve injuries result in impaired neuromuscular interactions, leading to morphological and functional alterations. Adjuvant suture repair methods have been used to improve nerve regeneration and modulate the immune response. Heterologous fibrin biopolymer (HFB), a scaffold with adhesive properties, plays a critical role in tissue repair. The aim of this study is to evaluate neuroregeneration and immune response focusing on neuromuscular recovery, using suture-associated HFB for sciatic nerve repair. METHODS: Forty adult male Wistar rats were distributed into four groups (n = 10): C (control), only sciatic nerve location; D (denervated), neurotmesis and 6-mm gap removal and fixation stumps in subcutaneous tissue; S (suture), neurotmesis followed by suture; and SB (suture + HFB), neurotmesis followed by suture and HFB. Analysis of M2 macrophages (CD206+ ), as well as the morphology and morphometry of nerves, soleus muscle, and neuromuscular junctions (NMJs), were performed at 7 and 30 days after surgery. RESULTS: The SB group had the highest M2 macrophage area in both periods. After 7 days, SB was the only group similar to the C group regarding the number of axons; furthermore, after 30 days, the SB group was closer to the C group concerning blood vessel and central myonuclear numbers, NMJ angle, and connective tissue volume. After 7 days, increases in nerve area, as well as the number and area of blood vessels, were also observed in SB. DISCUSSION: HFB potentiates the immune response, increases axonal regeneration, induces angiogenesis, prevents severe muscle degeneration, and assists in NMJ recovery. In conclusion, suture-associated HFB has major implications for improved peripheral nerve repair.

Snake venom-defined fibrin architecture dictates fibroblast survival and differentiation.

Fibrin is the provisional matrix formed after injury, setting the trajectory for the subsequent stages of wound healing. It is commonly used as a wound sealant and a natural hydrogel for three-dimensional (3D) biophysical studies. However, the traditional thrombin-driven fibrin systems are poorly controlled. Therefore, the precise roles of fibrin's biophysical properties on fibroblast functions, which underlie healing outcomes, are unknown. Here, we establish a snake venom-controlled fibrin system with precisely and independently tuned architectural and mechanical properties. Employing this defined system, we show that fibrin architecture influences fibroblast survival, spreading phenotype, and differentiation. A fine fibrin architecture is a key prerequisite for fibroblast differentiation, while a coarse architecture induces cell loss and disengages fibroblast's sensitivity towards TGF-ß1. Our results demonstrate that snake venom-controlled fibrin can precisely control fibroblast differentiation. Applying these biophysical principles to fibrin sealants has translational significance in regenerative medicine and tissue engineering.

A mathematical model of fibrinogen-mediated erythrocyte-erythrocyte adhesion.

Erythrocytes are deformable cells that undergo progressive biophysical and biochemical changes affecting the normal blood flow. Fibrinogen, one of the most abundant plasma proteins, is a primary determinant for changes in haemorheological properties, and a major independent risk factor for cardiovascular diseases. In this study, the adhesion between human erythrocytes is measured by atomic force microscopy (AFM) and its effect observed by micropipette aspiration technique, in the absence and presence of fibrinogen. These experimental data are then used in the development of a mathematical model to examine the biomedical relevant interaction between two erythrocytes. Our designed mathematical model is able to explore the erythrocyte-erythrocyte adhesion forces and changes in erythrocyte morphology. AFM erythrocyte-erythrocyte adhesion data show that the work and detachment force necessary to overcome the adhesion between two erythrocytes increase in the presence of fibrinogen. The changes in erythrocyte morphology, the strong cell-cell adhesion and the slow separation of the two cells are successfully followed in the mathematical simulation. Erythrocyte-erythrocyte adhesion forces and energies are quantified and matched with experimental data. The changes observed on erythrocyte-erythrocyte interactions may give important insights about the pathophysiological relevance of fibrinogen and erythrocyte aggregation in hindering microcirculatory blood flow.

In vitro and Ex vivo Assessments of the Compatibility of Fibrin Sealant with Antimicrobial Compounds.

Background: Fibrin sealants are used as antimicrobial-releasing carriers for preventing surgical site infections; however, it is important to determine the release kinetics and antimicrobial effects of drugs added to fibrin sealants and the effects of drugs on clot/clotting properties. Materials and Methods: The antimicrobial and antibiofilm activity of cefazolin, colistin, gentamicin, oxacillin, tobramycin, and silver nitrate released from fibrin sealant were characterized using in vitro and ex vivo assays against bacteria commonly found on the skin. The effects of antimicrobial agents on the physical structure of the fibrin sealant were assessed with scanning electron microscopy (SEM) and on the clotting rate and strength of fibrin clots using run-off tests and rheology. Results: Generally, antibiotic agents were released gradually from fibrin sealant and were stable after release, with antimicrobial effects evident up to three days. Cefazolin, gentamicin, and oxacillin prevented biofilm formation of Staphylococcus aureus in porcine skin explants; gentamicin and colistin prevented biofilm formation of Pseudomonas aeruginosa. Gentamicin, cefazolin, colistin, and tobramycin did not affect the structural integrity or viscoelastic properties of fibrin sealant; changes were observed with oxacillin (SEM) and particularly silver nitrate (SEM and rheology). No antimicrobial agents caused deterioration of clotting time (run-off tests). Conclusions: From the antimicrobial agents tested, gentamicin and cefazolin showed prolonged release from fibrin sealant, sustained antimicrobial activity, and biofilm prevention properties against Staphylococcus aureus; similar results were observed for gentamicin and colistin against Pseudomonas aeruginosa. For each of these findings, the physical structure of the fibrin sealant, clotting rate, and strength of fibrin clots were unaffected.

A comparative high-resolution physicochemical analysis of commercially available fibrin sealants: Impact of sealant osmolality on biological performance.

Fibrin sealants are well-established components of the surgical toolbox, especially in procedures that harbor a high risk of perioperative bleeding. Their widespread use as hemostats, sealants or tissue-adhesives in various surgical settings has shown that the choice of the appropriate sealant system affects the clinical outcome. While many studies have compared the hemostatic efficiency of fibrin sealants to that of other natural or synthetic sealants, there is still limited data on how subtle differences in fibrin sealant formulations relate to their biological performance. Here, we performed an in-depth physicochemical and biological characterization of the two most commonly used fibrin sealants in the US and Europe: TISSEEL™ ("FS") and VISTASEAL™/VERASEAL™ ("FS+Osm"). Our chemical analyses demonstrated differences between the two sealants, with lower fibrinogen concentrations and supraphysiological osmolality in the FS+Osm formulation. Rheological testing revealed FS clots have greater clot stiffness, which strongly correlated with network density. Ultrastructural analysis by scanning electron microscopy revealed differences between FS and FS+Osm fibrin networks, the latter characterized by a largely amorphous hydrogel structure in contrast to the physiological fibrillar network of FS. Cytocompatibility experiments with human fibroblasts seeded on FS and FS+Osm fibrin networks, or cultured in presence of sealant extracts, revealed that FS+Osm induced apoptosis, which was not observed with FS. Although differential sealant osmolality and amounts of fibrinogen, as well as the presence of Factor XIII or additives such as antifibrinolytics, may explain the mechanical and structural differences observed between the two fibrin sealants, none of these substances are known to cause apoptosis at the respective concentrations in the sealant formulation. We thus conclude that hyper osmolality in the FS+Osm formulation is the primary trigger of apoptosis-a mechanism that should be evaluated in more detail, as it may affect the cellular wound healing response in situ.

Histopathological Study of the Effects of Dura Adhesive Agents Used in Spinal Surgery Practice on Spinal Epidural Fibrosis in Experimental Animal Model.

Objective: Histopathological examination of the effects of Tisseel, Cova, Glubran and Coseal, which are used for sealing purposes in spinal surgery practice, on epidural fibrosis is aimed. Methods: Forty Sprague Dawley rats were randomly divided into five groups in our study as Group 1 (n=8) control group (Laminectomy); Group 2 (n=8) Cova group (Laminectomy + Cova); Group 3 (n=8) Tissel group (Laminectomy + Tisseel); Group 4 (n=8) Coseal group (Laminectomy + Coseal); and Group 5 Glubrane group (Laminectomy + Glubrane). Control group was only applied laminectomy. After laminectomy to other groups, Cova was applied to the 2nd group, Tissel to the 3rd group, Coseal to the 4th group and Glubran to the 5th group in surgical fields. After the rats were monitored in separate cages for 6 weeks after the operation, the relevant spinal level was extracted and the samples were examined histopathologically and the results were evaluated statistically. Results: It was found that there was a statistically significant difference in Tisseel and Glubran groups in terms of fibrosis grading compared to the control group, and this had a positive effect on fibrosis. Compared to the control group, there was no statistically significant difference on fibrosis in Cova and Coseal groups. Conclusion: As dura adhesive agents used in spinal surgery practice did not increase spinal epidural fibrosis statistically significantly, we concluded that these products can be used safely during spinal surgery if necessary.