Fibrin sealant in wound repair: a systematic survey of the literature

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.

Physiological fibrin hydrogel modulates immune cells and molecules and accelerates mouse skin wound healing

Introduction

Wound healing is a complex process to restore homeostasis after injury and insufficient skin wound healing is a considerable problem in medicine. Whereas many attempts of regenerative medicine have been made for wound healing with growth factors and cell therapies, simple pharmacological and immunological studies are lagging behind. We investigated how fibrin hydrogels modulate immune cells and molecules in skin wound healing in mice.

Methods

Physiological fibrin hydrogels (3.5 mg/mL fibrinogen) were generated, biophysically analyzed for stiffness and protein contents and were structurally studied by scanning electron microscopy. Physiological fibrin hydrogels were applied to full thickness skin wounds and, after 3 days, cells and molecules in wound tissues were analyzed. Leukocytes, endothelial cells, fibroblasts and keratinocytes were explored with the use of Flow Cytometry, whereas cytokines and matrix metalloproteinases were analyzed with the use of qPCR, ELISAs and zymography. Skin wound healing was analyzed microscopically at day 3, macroscopically followed daily during repair in mice and compared with commercially available fibrin sealant Tisseel.

Results

Exogenous fibrin at physiological concentrations decreased neutrophil and increased non-classical Ly6Clow monocyte and resolutive macrophage (CD206⁺ and CX3CR1⁺) populations, at day 3 after injury. Fibrin hydrogel reduced the expression of pro-inflammatory cytokines and increased IL-10 levels. In line with these findings, gelatinase B/MMP-9 was decreased, whereas gelatinase A/MMP-2 levels remained unaltered. Frequencies of dermal endothelial cells, fibroblasts and keratinocytes were increased and keratinocyte migration was enhanced by fibrin hydrogel. Importantly, physiological fibrin accelerated the healing of skin wounds in contrast to the highly concentrated fibrin sealant Tisseel, which delayed wound repair and possessed a higher fiber density.

Conclusion

Collectively, we show that adding a tailored fibrin hydrogel scaffold to a wound bed positively influences the healing process, modulating leukocyte populations and inflammatory responses towards a faster wound repair.

Fibrin sealant versus sutures in periodontal surgery: A systematic review

Background

The aim of this systematic review was to assess the effectiveness of fibrin sealant compared to sutures in periodontal surgery.

Methods

Five electronic databases (PubMed, Scopus, EBSCO, Cochrane and Web of Science) were screened from initiation to January 2021 for randomized controlled trials (RCTs) comparing fibrin sealant to sutures in periodontal surgery using this search equation: (Periodont* OR Periodontitis) AND ("fibrin tissue adhesive" OR "fibrin glue" OR "fibrin sealant" OR "fibrin sealant system" OR "fibrin adhesive system" OR "fibrin fibronectin sealant system"). Quality assessment of the included studies was performed using the revised tool to assess risk of bias in randomized trials (RoB 2). The level of evidence was evaluated using the GRADE tool.

Results

A total of 240 publications were found as search results in the screened databases. Four RCTs were included in this systematic review based on predetermined inclusion criteria. The trials were published between 1987 and 2014. All the RCTs compared fibrin sealant to sutures in periodontal surgery. The sample size included 101 patients. The overall risk of bias in this systematic review was at high risk in 75% of the studies, while 25% of the studies raised some concerns. The level of evidence evaluated using GRADE tool was very low.

Discussion

The current systematic review indicates a low level of evidence of the use of fibrin sealant as an alternative to sutures in periodontal practice. More interventional and multicentric studies should be conducted to support and confirm the results of the included studies.

Life-Cycle Analysis and Evaluation of Mechanical Properties of a Bio-Based Structural Adhesive

For this present paper, we performed a life-cycle analysis and an evaluation of the mechanical properties of an epichlorohydrin/cardanol adhesive in a neat and a nano-filled form. Six different potentials and the cost of the adhesives were derived and compared with those of a commercial epoxy resin. Overall, the neat adhesive was found to be more environmentally friendly and to have a lower production cost. However, the addition of carbon nanotubes increased both the environmental footprint and the cost. The evaluation with regards to the mechanical properties was performed through a comparison of bulk properties and joint properties with the respective average values of commonly used structural and nonstructural adhesives from the literature. It was found that for all properties except for the Young’s modulus the novel adhesive had values greater than the average values of the cosmetic adhesives and for most properties it had values close to the average values of the structural adhesives. Moreover, the presence of the carbon nanotubes enhanced the mechanical properties of the adhesive except for the tensile strength.

Treatment of Chronic Venous Ulcers With Heterologous Fibrin Sealant: A Phase I/II Clinical Trial

Background

Heterologous fibrin sealant (HFS) consists of a fibrinogen-rich cryoprecipitate extracted from Bubalus bubalis buffalo blood and a thrombin-like enzyme purified from Crotalus durissus terrificus snake venom. This study evaluated the safety and immunogenicity of HFS, estimated the best dose, and assessed its preliminary efficacy in the treatment of chronic venous ulcers (CVU).

Methods

A phase I/II non-randomized, single-arm clinical trial was performed on 31 participants, accounting for a total of 69 active CVUs. All ulcers were treated with HFS, essential fatty acid, and Unna boot for 12 weeks. The outcomes assessed were: (1) primary safety, immunogenicity analyses, and confirmation of the lowest safe dose; (2) secondary promising efficacy by analyzing the healing process. Immunogenicity was evaluated using the serum-neutralizing (IgM and IgG) and non-neutralizing (IgA and IgE) antibody techniques against the product. The immuno-detection of IgE class antibodies was assessed using dot-blot assay before and at the end of treatment. Positive samples on dot-blot assays were subsequently analyzed by western blotting to verify the results.

Results

No severe systemic adverse events related to the use of HFS were observed. Local adverse events potentially related to treatment include ulcer pain (52%), peri-ulcer maceration (16%), peri-ulcer pruritus (12%), critical colonization (8%), peri-ulcer eczema (4%), the opening of new ulcers (4%), and increased ulcerated area 4%). Neutralizing and non-neutralizing antibodies did not show significant deviations at any of the evaluated time points. Blot assays showed that all patients presented negative immunological reactions, either before or after treatment, with the thrombin-like enzyme component. In addition, two participants showed a positive immunological reaction to the cryoprecipitate component, while another two were positive before and during treatment. Regarding the secondary outcomes of preliminary efficacy, a total healing and significant reduction of the area was observed in 47.5 and 22%, respectively. A qualitative improvement was observed in the wound beds of unhealed ulcers.

Conclusions

The investigational HFS bioproduct proved to be safe and non-immunogenic with a good preliminary efficacy for the treatment of CVU, according to the protocol and doses proposed. A multicentric phase III clinical trial will be necessary to verify these findings.

Chronic venous ulcers: a review on treatment with fibrin sealant and prognostic advances using proteomic strategies

Venous ulcers are the main causes of chronic lower-limb ulcers. The healing difficulties encourage the research and development of new products in order to achieve better therapeutic results. Fibrin sealant is one of these alternatives. Besides being a validated scaffold and drug delivery system, it possesses excellent healing properties. This review covered the last 25 years of the literature and showed that the fibrin sealant is used in various clinical situations to promote the healing of different types of ulcers, especially chronic ones. These are mostly venous in origin and usually does not respond to conventional treatment. Commercially, only the homologous fibrin sealants obtained from human blood are available, which are highly efficient but very expensive. The heterologous fibrin sealant is a non-commercial experimental low-cost product and easily produced due to the abundance of raw material. The phase I/II clinical trial is already completed and showed that the product is safe and promisingly efficacious for the treatment of chronic venous ulcers. In addition, clinical proteomic strategies to assess disease prognosis have been increasingly used. By analyzing liquid samples from the wounds through proteomic strategies, it is possible to predict before treatment which ulcers will evolve favorably and which ones will be difficult to heal. This prognosis is only possible by evaluating the expression of isolated proteins in exudates and analysis using label-free strategies for shotgun. Multicentric clinical trials will be required to evaluate the efficacy of fibrin sealant to treat chronic ulcers, as well as to validate the proteomic strategies to assess prognosis.

Brief Overview on Bio-Based Adhesives and Sealants

Adhesives and sealants (AS) are materials with excellent properties, versatility, and simple curing mechanisms, being widely used in different areas ranging from the construction to the medical sectors. Due to the fast-growing demand for petroleum-based products and the consequent negative environmental impact, there is an increasing need to develop novel and more sustainable sources to obtain raw materials (monomers). This reality is particularly relevant for AS industries, which are generally dependent on non-sustainable fossil raw materials. In this respect, biopolymers, such as cellulose, starch, lignin, or proteins, emerge as important alternatives. Nevertheless, substantial improvements and developments are still required in order to simplify the synthetic routes, as well as to improve the biopolymer stability and performance of these new bio-based AS formulations. This environmentally friendly strategy will hopefully lead to the future partial or even total replacement of non-renewable petroleum-based feedstock. In this brief overview, the general features of typical AS are reviewed and critically discussed regarding their drawbacks and advantages. Moreover, the challenges faced by novel and more ecological alternatives, in particular lignocellulose-based solutions, are highlighted.

Hybrid Biomaterial with Conjugated Growth Factors and Mesenchymal Stem Cells for Ectopic Bone Formation

Bone is a highly vascularized tissue and efficient bone regeneration requires neovascularization, especially for critical-sized bone defects. We developed a novel hybrid biomaterial comprising nanocalcium sulfate (nCS) and fibrin hydrogel to deliver mesenchymal stem cells (MSCs) and angiogenic factors, vascular endothelial growth factor (VEGF) and fibroblast growth factor 9 (FGF9), to promote neovascularization and bone formation. MSC and growth factor(s)-loaded scaffolds were implanted subcutaneously into mice to examine their angiogenic and osteogenic potential. Micro CT, alkaline phosphatase activity assay, and histological analysis were used to evaluate bone formation, while immunohistochemistry was employed to assess neovessel formation. The presence of fibrin preserved the nCS scaffold structure and promoted de novo bone formation. In addition, the presence of bone morphogenic protein 2-expressing MSC in nCS and fibrin hydrogels improved bone regeneration significantly. While FGF9 alone had no significant effect, the combination FGF9 and VEGF conjugated in fibrin enhanced neovascularization and bone formation more than 4-fold compared to nCS with MSC. Overall, our results suggested that the combination of nCS (to support bone formation) with a fibrin-based VEGF/FGF9 release system (support vascular formation) is an innovative and effective strategy that significantly enhanced ectopic bone formation in vivo.

Generation of a Fibrin Based Three-Layered Skin Substitute

A variety of skin substitutes that restore epidermal and dermal structures are currently available on the market. However, the main focus in research and clinical application lies on dermal and epidermal substitutes whereas the development of a subcutaneous replacement (hypodermis) is often disregarded. In this study we used fibrin sealant as hydrogel scaffold to generate a three-layered skin substitute. For the hypodermal layer adipose-derived stem cells (ASCs) and mature adipocytes were embedded in the fibrin hydrogel and were combined with another fibrin clot with fibroblasts for the construction of the dermal layer. Keratinocytes were added on top of the two-layered construct to form the epidermal layer. The three-layered construct was cultivated for up to 3 weeks. Our results show that ASCs and fibroblasts were viable, proliferated normally, and showed physiological morphology in the skin substitute. ASCs were able to differentiate into mature adipocytes during the course of four weeks and showed morphological resemblance to native adipose tissue. On the surface keratinocytes formed an epithelial-like layer. For the first time we were able to generate a three-layered skin substitute based on a fibrin hydrogel not only serving as a dermal and epidermal substitute but also including the hypodermis.

Thrombin as important factor for cutaneous wound healing: comparison of fibrin biomatrices in vitro and in a rat excisional wound healing model

Fibrin biomatrices have been used for many years for hemostasis and sealing and are a well-established surgical tool. The objective of the present study was to compare two commercially available fibrin biomatrices regarding the effect of their thrombin concentration on keratinocytes and wound healing in vitro and in vivo. Keratinocytes showed significant differences in adhesion, viability, and morphology in the presence of the fibrin matrices in vitro. A high thrombin concentration (800-1,200 IU/mL) caused deteriorated cell compatibility. By using a thrombin inhibitor, those differences could be reversed. In a rat excisional wound healing model, we observed more rapid wound closure and less wound severity in wounds treated with a fibrin matrix containing a lower concentration of thrombin (4 IU/mL). Furthermore, fewer new functional vessels and a lower level of vascular endothelial growth factor were measured in wounds after 7 days treated with the matrix with higher thrombin concentration. These in vivo results may be partially explained by the in vitro biocompatibility data. Additionally, results show that low thrombin biomatrices were degraded faster than the high thrombin material. Hence, we conclude that the composition of fibrin biomatrices influences keratinocytes and therefore has an impact on wound healing.

Hepatocellular carcinoma: preclinical data on a dual-lumen catheter kit for fibrin sealant infusion following loco-regional treatments

BACKGROUND

Fibrin sealants are currently used in a variety of surgical and endoscopic settings to improve time to haemostasis, reduce blood loss and complications. However, the application of sealants (composed of two essential components: fibrinogen and thrombin) is not without difficulties. These sealants are normally applied to the resected area using dual-chamber delivery systems. Administration of these substances with different viscosities and diverse flow rates through a long catheter means that a certain amount of force needs to be applied and clot formation and clogging at the distal end of the catheter can occur.

METHODS

We designed a novel dual-lumen catheter to facilitate the optimal application of fibrin sealant after diagnostic and therapeutic percutaneous procedures and assessed the efficacy and tolerability of this dual-lumen kit when used in a model of hepatic fine needle aspiration (FNA) biopsy and radiofrequency ablation (RFA) in an in vivo, preclinical porcine study.

RESULTS

The experimental was performed on nine pigs (mean body weight 85 ± 7 kg) and with the exception of one pig, all animals survived in good conditions until the day of hepatectomy and euthanasia. The premature death of this animal was in the veterinarian's judgment caused by a common, non-infective disease. In all nine pigs, bleeding was stopped within 3 minutes of the application of the fibrin sealant and no cases of recurrent bleeding occurred.

CONCLUSIONS

The new dual aspect catheter increased ease of delivery of the sealant and FNA liver biopsy and RFA procedures were successfully and safely performed.

Influence of sealant fibrin on the wound healing of the pigs vocal folds

Fibrin sealants or fibrin glue are products made from human plasma proteins, which mimic the final pathway of the coagulation cascade. Its application to stimulate the healing process has been a topic of debate in the literature. The use of fibrin sealants in phonosurgery has been empirical; there have been no studies that investigate the action of fibrin sealant in Reinke's space.

Aim

To evaluate the effect of fibrin glue in healing of the vocal folds of pigs after surgical manipulation.

Materials and Methods

This was a prospective and experimental study. Six animals had both vocal folds incised. Sealant was applied in one of them; the other served as a control. After three months, the animals were sacrificed and a collagen count was carried out.

Results

The side on which glue was applied had an average of 27.8% against 20.4% of the side without glue.

Conclusion

The collagen concentration in the samples where the fibrin sealant was applied was significantly higher compared to samples without glue. Thus, the presence of a fibrin sealant stimulates fibrogenesis in this tissue.

High thrombin concentrations in fibrin sealants induce apoptosis in human keratinocytes

Over the last century many studies have been performed to assess the impact of fibrin sealant (FS) components on cells. Because of the noncovalent bonding of thrombin to fibrin during fibrin clot formation, we wanted to further evaluate the impact of fibrin bound thrombin on cell viability. Initially, we quantified the activity of thrombin in three different, commercially available FS. This information was used to prepare fibrin clots covering a range of thrombin concentrations from 4 to 820 IU mL(-1), but which were identical with respect to all other constituents. Although these fibrin clots did not differ in their three-dimensional structure, clots prepared with highly concentrated thrombin (820 IU mL(-1)) failed to support adhesion and spreading of primary human keratinocytes (NHEK). The number of attached cells was also significantly reduced on high thrombin activity clots. We hypothesized that these observations are not only the consequence of decreased proliferation but of apoptotic mechanisms, since the expression of cleaved caspase 3 and 7 was strongly enhanced on fibrin clots with high thrombin activity. This was accompanied by an induction of expression of Trail-R2 which is a receptor known to mediate apoptosis signals. Blocking of thrombin activity by hirudin led to an improvement of cell morphology and to an increase in number of attached cells. In addition, the induction of caspase 3 and 7 was also reduced. Thus, here we report for the first time that fibrin bound thrombin does not only decrease proliferation (as already published by others), it also does induce NHEK apoptosis when present at high concentrations.

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.

Cell Compatibility of Fibrin Sealants: In Vitro Study with Cells Involved in Soft Tissue Repair

Fibrin sealants can be used to support tissue regeneration or as vehicles for delivery of cells in tissue engineering. Differences in the composition of fibrin sealants, however, could determine the success of such applications. The results presented in this article show clear differences between Fibrin sealant A (FS A) clots and Fibrin sealant B (FS B) clots with respect to their compatibility with primary human cells involved in soft tissue repair. FS A clots, which are characterized by a physiological coarse fibrin structure, promoted attachment, spreading, and proliferation of keratinocytes, fibroblasts, and endothelial cells. In contrast, FS B clots displaying a fine to medium clot structure failed to support spreading of all three cell types. Adhesion of keratinocytes was decreased on FS B clots compared to FS A clots after 3 h incubation, whereas number of attached fibroblasts and endothelial cells was initially comparable between the two fibrin sealants. However, all three cell types proliferated on FS A clots but no sustained proliferation was detected on FS B clots. We further demonstrate that the observed differences between FS A and B clots are partly based upon 1 M sodium chloride extractable constituents, like thrombin, and partly on nonextractable constituents or the fibrin structure. In conclusion, our in vitro results demonstrate that FS A clots serve as a provisional matrix that encourages adhesion and growth of keratinocytes, fibroblasts, and endothelial cells. Therefore, FS A seems to be well suited for applications in tissue engineering.

Comparison of the effectiveness of autologous fibrin glue and macroporous biphasic calcium phosphate as carriers in the osteogenesis process with or without mesenchymal stem cells

BACKGROUND

Facial bone reconstruction has been a challenge for oral and maxillofacial surgeons for a long time. Recently, some studies have reported the use of stem cells in facial reconstruction to achieve osteogenesis. However, to ensure that stem cells remain in the recipient site, a biocompatible carrier is needed to transfer the stem cells. Fibrin glue has been shown to promote hemostasis in wound management and accelerate soft tissue healing, but the role of fibrin glue in bone regeneration remains debatable. The purpose of this study was to compare the effectiveness of autologous fibrin glue and macroporous biphasic calcium phosphate (MBCP) as carriers in the osteogenesis process with/without mesenchymal stem cells.

METHODS

Fifteen New Zealand white rabbits were used in this study. Mesenchymal stem cells were harvested from the iliac bone, and autologous fibrin glue was made from peripheral blood. Three cranial defects with a diameter of 6 mm were created over the cranial bone in each rabbit. The 15 animals were separated into 2 groups. The first group contained 12 rabbits. The grafted substances placed over the regions of defect were: (1) stem cells plus autologous fibrin glue; (2) stem cells plus MBCP; (3) defect alone as control. In the second group of 3 rabbits, the cranial defects were grafted with: (1) autologous fibrin glue alone; (2) MBCP alone; (3) defect alone as control. Rabbits were sacrificed at 1, 2 and 3 months post operation. Radiography and histology were used to detect bone formation.

RESULTS

Stem cells plus autologous fibrin glue induced more bone formation 2 months post operation and more mature bone was found 3 months post operation compared with the other groups. MBCP with or without stem cells showed moderate tissue reaction, including giant cell, histiocyte and eosinophil cell accumulation.

CONCLUSION

Using stem cells plus autologous fibrin glue as the carrier may accelerate new bone regeneration.

Discrete crosslinked fibrin microthread scaffolds for tissue regeneration

In this study, we report on the development of discrete fibrin microthreads as well as novel scaffolds composed of arrays of fibrin threads. These scaffolds exhibit mechanical properties that are significantly greater than fibrin gels and cellular responses suggesting that the materials are conducive to the development of organized, aligned tissues. Fibrin microthreads were produced by coextruding solutions of 70 mg/mL fibrinogen and 6 U/mL thrombin through small diameter polyethylene tubing. Uncrosslinked fibrin microthreads averaged 55-65 microm in hydrated diameter and achieved ultimate tensile strengths approaching 4.5 MPa. The strengths and stiffnesses of the microthreads were approximately twofold greater when the materials were treated with exposure to ultraviolet (UV) light. Although UV crosslinking attenuated fibroblast proliferation, uncrosslinked fibrin microthreads supported fibroblast attachment, proliferation, and alignment, suggesting that they represent a viable biomaterial for the aligned regeneration of tissues. Because of the physiologic roles of fibrin matrices in the early phase of wound healing, we anticipate that these fibrin-based microthreads will direct the spatially and temporally complex processes of cell-mediated tissue ingrowth and regeneration.

Treatment of rupture of the Achilles tendon with fibrin sealant

BACKGROUND

The optimal management strategy for acute Achilles tendon ruptures is controversial. These injuries historically were treated by nonoperative methods (cast immobilization, bandaging); however, operative repair of the ruptured tendon has become popular.

METHODS

Thirty-two patients who had rupture of the Achilles tendon were treated operatively with use of fibrin sealant, and clinical and functional performance measures were assessed after a mean followup of at least 6 months between November, 1998, and July, 2003. All of the patients were male. Average age was 38.18 (30 to 45) years. All of the patients were followed for at least 18 months after surgery. Average followup time was 22.4 (18 to 56) months. We evaluated all patients according to the scoring system of Thermann et al.

RESULTS

Our results were excellent in 24 patients and good in eight patients. One patient had rerupture 3 weeks after surgery.

CONCLUSION

Fibrin sealants are biologically compatible, hemostatic agents derived from human plasma that can be used instead of suture or suture support. We think that the treatment of rupture of the Achilles tendon with fibrin sealant is a useful treatment, and there is less risk of complications, such as deep infection, than in other operative procedures. We had no wound closure problems, the incision size was small, and the operating time was short. However, it must be remembered that the risk of disease transfer by fibrin sealant application is still present.

Cloned transgenic farm animals produce a bispecific antibody for T cell-mediated tumor cell killing

Complex recombinant antibody fragments for modulation of immune function such as tumor cell destruction have emerged at a rapid pace and diverse anticancer strategies are being developed to benefit patients. Despite improvements in molecule design and expression systems, the quantity and stability, e.g., of single-chain antibodies produced in cell culture, is often insufficient for treatment of human disease, and the costs of scale-up, labor, and fermentation facilities are prohibitive. The ability to yield mg/ml levels of recombinant antibodies and the scale-up flexibility make transgenic production in plants and livestock an attractive alternative to mammalian cell culture as a source of large quantities of biotherapeutics. Here, we report on the efficient production of a bispecific single-chain antibody in the serum of transgenic rabbits and a herd of nine cloned, transgenic cattle. The bispecific protein, designated r28M, is directed to a melanoma-associated proteoglycan and the human CD28 molecule on T cells. Purified from the serum of transgenic animals, the protein is stable and fully active in mediating target cell-restricted T cell stimulation and tumor cell killing.

Fibrin sealant improves hemostasis in peripheral vascular surgery: a randomized prospective trial

OBJECTIVE

To evaluate the efficacy and safety of an investigational fibrin sealant (FS) in a randomized prospective, partially blinded, controlled, multicenter trial.

SUMMARY BACKGROUND DATA

Upper extremity vascular access surgery using polytetrafluorethylene (PTFE) graft placement for dialysis was chosen as a reproducible, clinically relevant model for evaluating the usefulness of FS. The FS consisted of pooled human fibrinogen (60 mg/mL) and thrombin (500 NIH U/mL). Time to hemostasis was measured, and adverse events were monitored.

METHODS

Consenting adult patients (n = 48) undergoing placement of a standard PTFE graft were randomized in a 2:1:1 ratio to the treatment group using FS (ZLB Bioplasma AG, Bern, Switzerland), oxidized regenerated cellulose (Surgicel, Johnson & Johnson, New Brunswick, NJ), or pressure. Patients received heparin (3,000 IU IVP) before placement of vascular clamps. If the treatment was FS, clamps were left in place for 120 seconds after the application of study material to permit polymerization. If treatment was Surgicel, clamps were left in place until the agent had been applied according to manufacturer's instructions. If the treatment was pressure, clamps were released as soon as the investigator was ready to apply compression. Immediately after release of the last clamp, the arterial and venous suture lines were evaluated for bleeding. The time to hemostasis at both the venous and arterial sites was recorded.

RESULTS

Significant (P < or =.005) reduction in time to hemostasis was achieved in the FS group. Thirteen (54.2%) patients randomized to FS experienced immediate hemostasis at both suture lines following clamp removal compared to no patients using Surgicel or pressure. Only one patient (7.1%) in the Surgicel group and no patients in the pressure group experienced hemostasis at 120 seconds from clamp removal, compared to 13 (54.2%) patients for FS. Adverse events were comparable in all groups. There were no seroconversions.

CONCLUSIONS

FS achieved more rapid hemostasis than traditional techniques in this peripheral vascular procedure. FS use appeared to be safe for this procedure.

Fibrin sealants and platelet preparations in bone and periodontal healing

Fibrin sealants and platelet concentrates have been used alone or in association with bone substitutes to promote bone healing in orthopedic and oral surgery. Commercial fibrin sealants are homologous plasma-derived products that mimic the last step of a coagulation cascade, leading to a fibrin clot. They are used for topical hemostasis and tissue sealing and as melting agents for particulate bone substitutes. Infectious risk led to the development of autologous fibrin sealants from the patient's own plasma. However, their fabrication results in less reproducible or less satisfactory rheologic properties. The use of autologous products with high platelet concentrations, such as platelet-rich plasma, platelet concentrate, and platelet gels, has recently been suggested for combining the fibrin sealant properties with the growth factor effects of platelets. We describe the characteristics and limitations of fibrin sealants (commercial/autologous) and platelet preparations and review their effects on bone and periodontal healing as reported in experimental studies and clinical trials.

Fibrinogen inhibits fibroblast-mediated contraction of collagen

Extracellular matrix changes in composition and organization as it transitions from the provisional matrix of the fibrin/platelet plug to collagen scar in healed wounds. The manner in which individual matrix proteins affect these activities is not well established. In this article we describe the interactions of two important extracellular matrix components, fibrin and collagen, using an in vitro model of wound contraction, the fibroblast-populated collagen lattice. We utilized different fibrinogen sources and measured tissue reorganization in floating and tensioned collagen lattices. Our results showed that both fibrin and fibrinogen decreased the contraction of fibroblast populated collagen lattices in a dose-dependent manner. Polymerization of fibrinogen to fibrin using thrombin had no effect on this inhibition. Further, there was no effect due to changes in protein concentration, alternate components of the fibrin sealant, or the enzymatic action of thrombin. These results suggest that the initial stability of the fibrin provisional matrix is due to the fibrin, because this protein appears to inhibit contraction of the matrix. This may be important in the early phases of wound healing when clot stability is vital for hemostasis. Later, as fibrin is replaced by collagen, wound contraction can occur.

Fibrin Sealant Facilitates Hemostasis in Arteriovenous Polytetrafluoroethylene Grafts for Renal Dialysis Access

A prospective randomized study was performed to evaluate the efficacy of fibrin sealant (FS) in patients undergoing upper-extremity polytetrafluoroethylene (PTFE) graft placement for dialysis. This procedure appears to be a reproducible and clinically relevant model for evaluating FS in vascular surgery. Consenting adult patients (n = 28) undergoing placement of a PTFE graft (6 mm) were randomized to either the treatment group using FS (Hemaseel APR, Haemacure Corp., Sarasota, FL) or control comparator groups (four) of bovine thrombin (T) (Thrombogen, GenTrac Inc., Middleton, WI), pressure (P), bovine thrombin (Thrombogen, GenTrac Inc.) -soaked cellulose sponges (TG) (Gelfoam, Upjohn Co., Kalamazoo, MI), or oxidized regenerated cellulose (S) (Surgicel, Johnson & Johnson, New Brunswick, NJ). All patients received heparin (3000 IU intravenous push) before placement of vascular clamps. The mean time to hemostasis was 29.3 seconds for FS, 147.4 seconds for T, 872.2 seconds for P, 346 seconds for TG, and 1044.5 seconds for S. There were no significant adverse events. FS appeared to be a superior hemostatic agent in these vascular procedures. No complications from FS were noted.

Transforming growth factor-beta2 (TGF-beta2) reverses the inhibitory effects of fibrin sealant on cutaneous wound repair in the pig

Tensile strength of 2-cm, full-thickness, surgically incised porcine skin wounds sealed with fibrin sealant was enhanced compared to conventionally sutured wounds at 6 hours postwounding, but was significantly reduced after 3 days. Supplementation of fibrin sealant with transforming growth factor-beta2 (TGF-beta2) reversed the inhibitory effects of fibrin sealant on tensile strength at 3 days, and enhanced tensile strength at 7 days compared to suture or fibrin sealant alone. By 14 days, the tensile strengths of all wounds were similar, although wounds treated with fibrin sealant supplemented with TGF-beta2 showed a small, but statistically significant, improvement in wound strength compared to wounds treated with fibrin sealant alone. Histological assessment at day 7 revealed significant remnants of fibrin sealant at the wound site following fibrin sealant treatment alone, while wounds treated with fibrin sealant supplemented with TGF-beta2 or suture exhibited fibroblast infiltration and extracellular matrix deposition. At day 7, TGF-beta was immunolocalized in the base and margins of only wounds treated with fibrin sealant supplemented with TGF-beta2. A significant increase in matrix metalloproteinase-9 activity was found in fibrin sealant-treated wounds at day 7 as compared to sutured wounds. Addition of TGF-beta to the fibrin sealant suppressed the up-regulation of matrix metalloproteinase-9 in these wounds. These results suggest that fibrin sealant supplemented with TGF-beta may provide superior wound healing as compared to fibrin sealant alone.