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PubMed1977

Specific binding of soluble fibrin to macrophages.

Guinea pig peritoneal macrophages were demonstrated to bind selectively soluble 125I-fibrin and fibrin/fibrinogen complexes as compared with fibrinogen, fibrinogen degradation products, and fibrin degradation products. Cellular uptake was considered to be surface receptor binding on the basis of removal of bound 125I-fibrin by trypsin and because uptake occurred in the presence of metabolic inhibitors. 125I-fibrin uptake could be blocked by nonradioactive fibrin but not by IgG or immune complexes. Binding was uneffected by prior treatment with plasmin or trypsin but was calcium dependent. Only limited reversibility of binding could be demonstrated after prolonged incubation. Scatchard plots permitted an estimate of the number of bound molecules. At saturation 6.92 X 10(6) 125I-fibrin molecules were bound per cell. Similar binding of fibrin was noted in polymorphonuclear leukocytes, but not lymphocytes or fibroblasts. Soluble fibrin binding may be a host defense mechanism whereby the reticuloendothelial system can remove fibrin from the blood before the development of microthrombi.

Animals↗
PubMed1984

Measurement of cross linked fibrin derivatives in plasma: an immunoassay using monoclonal antibodies.

Fibrinogen degradation, fibrin polymerisation, and the insertion of cross links into fibrin by fibrin stabilising factor lead to the appearance of new antigenic determinants. Antibodies against these antigenic sites may react specifically with the derivatives but not with the parent molecules. We have utilised a monoclonal antibody, which interacts with the cross linked fragment D dimer and related high molecular weight fibrin derivatives, to develop an enzyme immunoassay which measures cross linked fibrin derivatives in plasma and serum using D dimer as standard. Mean concentration in plasma from normal subjects was 75 ng/ml with an upper limit of about 144 ng/ml. Concentrations in patients with pulmonary embolism, deep venous thrombosis, arterial thromboembolism, and disseminated intravascular coagulation were raised in all cases. Confirmation of the specific increase of cross linked fibrin derivatives in patients with disseminated intravascular coagulation was obtained by parallel monitoring of their fibrin degradation products in serum using affinity chromatography and sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis. In many patients the plasma concentrations greatly exceeded the serum values of cross linked fibrin degradation products, suggesting that the procedure can measure fibrin derivatives in plasma which are absent from serum.

Antibodies, Monoclonal↗
PubMed2006

Fibrin derived from patients with chronic thromboembolic pulmonary hypertension is resistant to lysis.

RATIONALE: Although acute pulmonary embolism is epidemiologically associated with chronic thromboembolic pulmonary hypertension, the factors responsible for resistance to thrombolysis and a shift toward vascular remodeling within the pulmonary arteries of patients with chronic thromboembolic pulmonary hypertension are unknown. OBJECTIVE: Determine whether fibrin from patients is more resistant to plasmin-mediated lysis than fibrin from healthy control subjects. METHODS: Fibrinogen purified from patients and control subjects was used to prepare fibrin clots, which were subsequently digested with plasmin for various periods of time. The degradation of the alpha-, beta-, and gamma-chains of fibrin and the appearance of peptide fragments over time were assessed by polyacrylamide gel electrophoresis and Western blotting. MEASUREMENTS AND MAIN RESULTS: Densitometry of Coomassie-stained gels revealed significantly slower cleavage of all three polypeptide chains of fibrin from patients compared with control subjects (p < 0.05). In particular, release of N-terminal fragments from the beta-chain of fibrin, which promote cell signaling, cell migration, and angiogenesis, was retarded in patients compared with control subjects (p < 0.01). CONCLUSIONS: The relative resistance of patient fibrin to plasmin-mediated lysis may be due to alterations in fibrin(ogen) structure affecting accessibility to plasmin cleavage sites. The persistence of structural motifs of fibrin, such as the beta-chain N-terminus, within the pulmonary vasculature could promote the transition from acute thromboemboli into chronic obstructive vascular scars.

Adult↗
PubMed1989

Immunohistochemical characterization of fibrin(ogen)-related antigens in human tissues using monoclonal antibodies.

A new approach to study the distribution of fibrin(ogen)-related antigens was investigated using three different monoclonal antibodies (MAbs) and the avidin-biotin complex immunoperoxidase technique. MAb I8C6 recognizes B beta 1-42 peptide and can react with either fibrinogen or fibrin I; MAb T2G1 recognizes B beta 15-42 peptide and detects fibrin II but does not cross-react with fibrinogen; MAb GC4 reacts with Fragments D/DD derived from plasmin degradation of fibrinogen or fibrin but not with intact fibrinogen. The method can be applied to frozen or Bouin's fixed paraffin-embedded tissues obtained at biopsy, surgery, and autopsy. The distribution of the three antigens observed with the three MAbs was compared with that obtained with a polyclonal antiserum to fibrinogen and with the more conventional histochemical stains used in pathology to demonstrate fibrin deposits in tissues (Lendrum and PTAH). The staining observed with the three monoclonals clearly detected three different populations of fibrin(ogen)-related antigen in the tissues examined. The staining with MAb T2G1 specifically detected fibrin II with greater sensitivity than did conventional stains. The results of this study suggest that this method allows the molecular form of fibrin(ogen)-related deposits in tissues to be determined and this information may help to elucidate the role of fibrin in various disease states, such as atherosclerosis and renal disease, and in tumor growth and metastasis.

Antibodies, Monoclonal↗
PubMed1993

The stimulatory capacity of soluble fibrin prepared from high and low molecular weight fibrinogen on plasminogen activation.

High molecular weight, low molecular weight and very low molecular weight fibrinogen were purified from human plasma, and converted partially or completely to fibrin by the action of thrombin or batroxobin. The stimulatory effects of these fibrin(ogen) preparations on plasminogen activation by tissue plasminogen activator were studied. When only 3-30% of the fibrinogen molecules were converted to fibrin, the high molecular weight fibrin had a greater stimulatory effect on plasminogen activation than equal amounts of low and very low molecular weight fibrin. In completely converted fibrin preparations, the plasminogen activating capacity of high molecular weight fibrin was either equal to (thrombin treated preparations) or greater than (batroxobin-treated preparations) that of very low molecular weight fibrin. These findings suggest that degradation of the A alpha-chain of fibrin does not per se increase its plasminogen activating capacity.

Batroxobin↗
PubMed2000

Repair of chronic anorectal fistulae using commercial fibrin sealant.

HYPOTHESIS: Commercially produced fibrin sealant can be used to completely close both simple and complex fistulae in ano. METHODS: A 29-patient prospective nonrandomized clinical trial was performed. In the operating room, the patient underwent an examination with anesthesia and the primary and secondary fistula tract openings were attempted to be identified. The fistula tract was curetted and fibrin sealant was injected into the secondary fistula tract opening until fibrin sealant was seen coming from the primary opening. A petroleum jelly gauze was then applied over the secondary opening and the patient was sent home. Follow-up visits were scheduled for 1 week, 1 month, 3 months, and 1 year later. RESULTS: Twenty-nine consecutive patients received fibrin sealant injections for their fistulae in ano, with a mean follow-up of 6 months. Two patients had a history of Crohn disease (regional enteritis) and 2 patients had human immunodeficiency virus infection. Overall, 17 (68%) of 25 patients have had successful closure of their fistula with 4 patients lost to follow-up. Two patients required reinjection with fibrin sealant, and neither of these subsequently had closure. One of the 2 patients with Crohn disease had closure, as well as 1 human immunodeficiency virus-positive patient. In addition, there has been no evidence of incontinence or complications related to the use of fibrin sealant in this procedure. CONCLUSIONS: Initial results in the treatment of chronic anorectal fistulae using commercial fibrin sealant are optimistic, but require further support through longer follow-up data. Fibrin sealant treatment of anorectal fistulae offers a unique mode of management which is safe, simple, and easy for the surgeon to perform. By using fibrin sealant, the patient avoids the risk of fecal incontinence and the discomfort of prolonged wound healing that may be associated with fistulotomy.

Adult↗
PubMed2003

Fibrin sealant use for minimising peri-operative allogeneic blood transfusion.

BACKGROUND: Fibrin sealants have gained increasing popularity as interventions to improve peri-operative (intra/post-operative) haemostasis and diminish the need for allogeneic red cell transfusion (blood from an unrelated donor). OBJECTIVES: To examine the efficacy of fibrin sealants in reducing peri-operative blood loss and allogeneic red blood cell (RBC) transfusion. SEARCH STRATEGY: Studies were identified by: searches of MEDLINE, EMBASE, Current Contents, the Cochrane Library (July 2002), manufacturer web sites (to July 2002), and bibliographies of published articles. SELECTION CRITERIA: Controlled trials in which adult patients, scheduled for elective surgery, were randomised to fibrin sealant treatment or to a control group who did not receive fibrin sealant treatment. Trials were eligible if they reported data on the number of patients exposed to allogeneic red cell transfusion, the volume of blood transfused, or blood loss (assessed objectively). DATA COLLECTION AND ANALYSIS: Primary outcomes measured were: the number of patients exposed to allogeneic red cells, the amount of blood transfused, and blood loss. Other outcomes measured were: re-operation due to bleeding, infection, mortality, and length of hospital stay. Treatment effects were pooled using a random effects model. MAIN RESULTS: Seven trials, including a total of 388 patients, reported data on peri-operative exposure to allogeneic RBC transfusion. Fibrin sealant treatment, on average, reduced the rate of exposure to allogeneic red cell transfusion by a relative 54% (relative risk [RR] = 0.46: 95%CI = 0.32 to 0.68). Eight trials, including a total of 442 patients, provided data for post-operative blood loss. Fibrin sealant treatment reduced blood loss on average by around 134 per patient (95%CI = 51 to 217 ). However the trials reviewed were small and of poor methodological quality (91% unblinded). REVIEWER'S CONCLUSIONS: Overall the results suggest that fibrin sealants are efficacious in reducing both post-operative blood loss and peri-operative exposure to allogeneic RBC transfusion. However, due to the lack of blinding, transfusion practices may have been influenced by knowledge of the patient's treatment status. This raises concerns about the use of blood transfusion practice as an outcome variable in trials of fibrin sealant. In the case of blood loss, the results must be interpreted with caution, in view of the statistically significant heterogeneity in treatment effect observed. Large, methodologically rigorous, randomised controlled trials of fibrin sealants are needed.

Adult↗
PubMed2002

Effect of fibrin sealant composition on human neutrophil chemotaxis.

The use of fibrin sealants offers one of the most physiologically compatible approaches to preventing postoperative adhesions. Although a number of fibrin sealant formulations have been developed, little is known about how the various components of these preparations affect the wound-healing process. Because one of the key steps in wound healing is the migration of phagocytic leukocytes, such as neutrophils, into the site of injury, we performed studies to characterize systematically the effects of various fibrin sealant components on neutrophil chemotaxis. Using a transwell chemotaxis assay, we found that increasing fibrin concentration resulted in an inhibition of the ability of the cells to migrate through the clots in a dose-dependent manner, and at fibrin clot concentrations >2.0 mg/mL chemotaxis was completely blocked. Factor XIII crosslinking of the clots also had a significant impact on neutrophil chemotaxis, and sealant preparations deficient in Factor XIII allowed neutrophil migration at much higher fibrin concentrations. The presence of various other fibrin sealant components such as plasminogen and fibrinolysis inhibitors (aprotinin and tranexamic acid) did not have any significant effects on the ability of neutrophils to migrate through fibrin clots as compared to control clots without these components. Overall, these studies show that the composition of fibrin sealant preparations can significantly affect neutrophil migration into the site of injury, which could possibly influence the wound healing process.

Chemotaxis, Leukocyte↗
PubMed2007

Controlled release of nerve growth factor from fibrin gel.

Nerve growth factor (NGF) is known to promote the axonal regeneration in injured nerve system. Delivery of NGF for a long period in a controlled manner may enhance the regeneration efficacy. In this study, we investigated whether NGF can be released from fibrin gel for a long period in a controlled manner. We also investigated whether sustained delivery of NGF using fibrin gel can enhance the efficacy of NGF in vitro. The addition of heparin to fibrin gel decreased the rate of NGF release from the fibrin gel. As the concentrations of thrombin and fibrinogen in fibrin gel increased, the NGF release rate decreased significantly, and the initial release burst decreased. NGF was released for up to 14 days in vitro. The bioactivity of NGF released from fibrin gel was assessed by morphological changes of pheochromocytoma (PC12) cells cultured in the presence of NGF-containing fibrin gel. NGF released from fibrin gel exhibited significantly higher degrees of PC12 cell viability and differentiation than NGF added in a free form daily into the culture medium. This study demonstrates that fibrin gel can release NGF in a sustained, controlled manner and in a bioactive form.

Animals↗
PubMed1996

In vitro fibroplasia: matrix contraction, cell growth, and collagen production of fibroblasts cultured in fibrin gels.

Extracellular matrix (ECM) reorganization, cell growth, and collagen synthesis/deposition are key features of fibroplasia during tissue repair. An in vitro fibrin gel culture model system simulating fibroplasia of wound repair was characterized. In the model system, fibrin gels were stabilized on plastic culture plates as hemispheres. In this way, fibroblasts were able to reorganize fibrin fibrils, resulting in a measurable decrease in gel thickness with no change in gel diameter, thereby producing a matrix with tension relevant to that of a repairing tissue. Within the study period, human dermal fibroblasts exhibited dynamic activities in cell growth and in reorganization and remodeling of the fibrin matrix. In the first 2 days of culture, fibroblasts quickly reorganized the fibrin matrix to 10% of its original thickness. Fibroblast proliferation occurred at a much slower rate compared to monolayer cultures. Proliferation continued at the same rate throughout the study in contrast to monolayer cultures, which ceased proliferation at confluence. Collagen synthesis was detected as early as the second day in culture. Type I collagen was the major collagen synthesized by fibroblasts with small amounts of type V and type III collagen. Collagen from either monolayer or fibrin gel cultures appeared identical when analyzed by two-dimensional peptide mapping of their CNBr fragments. Although collagen was detected biochemically from Day 2, organized collagen fibrils were apparently only in the later stage of cultures in transmission electron micrographs. Also, at this time, fibrin fibrils were largely removed and the matrix was filled with collagen fibrils and other filamentous ECM. The growth factor TGF-beta stimulated both fibrin gel contraction and collagen synthesis by fibroblasts. Therefore, using the model system, we have demonstrated that fibroblasts can actively reorganize the fibrin matrix and subsequently remodel it into a collagen-containing scar-like tissue. The unique features of this model system allow for creative designs in studying the complex mechanisms underlying tissue repair.

Cell Culture Techniques↗
PubMed1994

Interactions of plasminogen with polymerizing fibrin and its derivatives, monitored with a photoaffinity cross-linker and electron microscopy.

Localization of the plasminogen binding sites on fibrin has been difficult since these interactions occur on polymerizing fibrin, and studies with fragments can be misleading because of multiple carboxyl-terminal lysines that may bind to plasminogen. A hetero-functional photoaffinity cross-linker was used to study these interactions. Following attachment of the cross-linker to plasminogen in the dark, a clot was formed by addition of fibrinogen or fragment X and thrombin, and then the plasminogen was cross-linked to adjacent parts of fibrin by exposure to light. There was more Glu1-plasminogen bound to fibrin than to fibrinogen and more to fragment X polymer than to fibrin. Electron microscopy of rotary shadowed individual molecules reveals that Glu1-plasminogen appears to be more compact than Lys78-plasminogen or Glu1-plasminogen with 6-aminohexanoic acid. Cross-linked complexes from the dissolved clot observed by electron microscopy reveal plasminogen bound to the end of fibrin or bridging the ends of two fibrin molecules; larger complexes were also observed. Analysis of changes in the appearance of negatively contrasted fibers with plasminogen bound also indicates the probable locations of binding sites, yielding results consistent with the cross-linking studies. The photoaffinity probe was also used to study interactions between plasminogen and fibrin or its derivatives in the course of tissue plasminogen activator-mediated fibrinolysis. Samples cross-linked at various times indicate that complexes with fragment X are particularly dominant during the rapid phase of plasminogen activation. In conclusion, these studies indicate that plasminogen binds to the pocket at the end-to-end junction between two fibrin or fragment X molecules in the protofibril; from this position, it can reach all of the sites that are cleaved during fibrinolysis.

Affinity Labels↗
PubMed1993

Transient protection of incomplete colonic anastomoses with fibrin sealant: an experimental study in the rat.

Fibrin glue has been used as a protective seal in normal and high-risk anastomoses to prevent leakage. The influence of fibrin adhesive on the healing colonic anastomosis in a control and high-risk model was tested. Resection and anastomosis of the left colon was performed in rats. In group Ia an end-to-end anastomosis was constructed with 12 7-O polypropylene sutures; in group Ib the anastomosis was sealed with fibrin adhesive. In group II an incomplete anastomosis was constructed with only 4 sutures at 90 degrees, therefore potentially leaking. In group IIb additional sealing with fibrin glue was performed. On Days 2, 4, and 7 body weight, adhesion formation, anastomotic bursting pressure, and collagen concentration were measured. The results showed increased adhesion formation after fibrin sealing. The anastomotic bursting pressure of incomplete anastomoses showed a significant increase after sealing on Day 2 only; on Day 4 and 7 no differences were found. Sealing of control anastomoses caused lower bursting pressures on Day 4. Collagen concentration is significantly reduced after fibrin sealing of normal anastomoses. We conclude that fibrin sealing of control anastomoses inhibits wound healing. Incomplete anastomoses are temporarily protected by fibrin glue sealing. Finally, fibrin sealing of the colon wound does not prevent adhesion formation.

Anastomosis, Surgical↗
PubMed2000

Repair of fistulas-in-ano using fibrin adhesive: long-term follow-up.

PURPOSE: Fibrin adhesive has been successfully used to treat fistulas-in-ano, but long-term data have been lacking. We report the results of our 18-month study examining the repair of fistulas-in-ano using autologous and commercial fibrin adhesive. METHODS: A 79-patient, prospective, non-randomized clinical trial was performed in which fibrin adhesive was used to repair fistulas-in-ano. Twenty-six patients were treated with autologous fibrin tissue adhesive made from their own blood, and 53 patients were treated with commercial fibrin sealant. In the operating room the patient underwent an examination under anesthesia, with an attempt to identify the primary and secondary fistula tract openings. The fistula tract was then curetted. Fibrin adhesive was injected into the secondary fistula tract opening until adhesive was seen coming from the primary opening. A petroleum jelly gauze was then applied over both the primary and secondary openings, and the patient was sent home. Follow-up visits occurred one week, one month, three months, and one year later. RESULTS: Fourteen of 26 (54 percent) patients treated with autologous fibrin tissue adhesive made from their own blood had complete closure of their fistulas after a one-year follow-up, whereas 34 of 53 (64 percent) patients treated with commercial fibrin sealant had closure of their fistulas. Most treatment failures occurred within the first 3 months, but late failures were seen as far as 11 months postoperative. CONCLUSIONS: Fibrin tissue adhesive offers a unique mode of managing fistulas-in-ano, which is surgically less invasive, but recurrences up to one year later are being seen. Longer follow-up and further research is recommended for improvement.

Adult↗
PubMedDate not supplied

In vitro angiogenesis is modulated by the mechanical properties of fibrin gels and is related to alpha(v)beta3 integrin localization.

This study deals with the role of the mechanical properties of matrices in in vitro angiogenesis. The ability of rigid fibrinogen matrices with fibrin gels to promote capillarylike structures was compared. The role of the mechanical properties of the fibrin gels was assessed by varying concentration of the fibrin gels. When the concentration of fibrin gels was decreased from 2 mg/ml to 0.5 mg/ml, the capillarylike network increased. On rigid fibrinogen matrices, capillarylike structures were not formed. The extent of the capillarylike network formed on fibrin gels having the lowest concentration depended on the number of cells seeded. The dynamic analysis of capillarylike network formation permitted a direct visualization of a progressive stretching of the 0.5 mg/ml fibrin gels. This stretching was not observed when fibrin concentration increases. This analysis shows that 10 h after seeding, a prearrangement of cells into ringlike structures was observed. These ringlike structures grew in size. Between 16 and 24 h after seeding, the capillarylike structures were formed at the junction of two ringlike structures. Analysis of the alpha(v)beta3 integrin localization demonstrates that cell adhesion to fibrinogen is mediated through the alpha(v)beta3 integrin localized into adhesion plaques. Conversely, cell adhesion to fibrin shows a diffuse and dot-contact distribution. We suggest that the balance of the stresses between the tractions exerted by the cells and the resistance of the fibrin gels triggers an angiogenic signal into the intracellular compartment. This signal could be associated with modification in the alpha(v)beta3 integrin distribution.

Biomechanical Phenomena↗
PubMed2004

New application method of fibrin glue for more effective hemostasis in cardiovascular surgery: rub-and-spray method.

OBJECTIVE: This study was performed to determine the most effective application method of fibrin glue as a hemostatic sealant in cardiovascular surgery. METHODS: The effectiveness of fibrin glue as a hemostatic sealant was compared between 4 methods of application; dripping, spray, spray-and-rub, and rub-and-spray methods. I. In vitro 'burst pressure' was measured in fibrin glue-sealed needle holes of polytetrafluoroethylene (PTFE) graft in each method. II. Fibrin glue-sealed needle holes of PTFE grafts implanted between an abdominal aorta and iliac arteries of a pig was microscopically examined to determine the effectiveness of fibrin glue sealing in each method. RESULTS: I. Burst pressures were 24.1 +/- 7.9 mmHg in dripping, 98.1 +/- 35.4 mmHg in spray, 140.8 +/- 34.8 mmHg in spray-and-rub and 206.7 +/- 26.1 mmHg in rub-and-spray method (statistically significant, p<0.01, between each method). II. Microscopically, no fibrin glue remained on the external surface of the PTFE graft in the dripping method. Fibrin glue plugged 1/3 or 2/3 of the depth of the needle hole in the spray method and spray-and-rub methods respectively. In the rub-and-spray method, fibrin glue covered the needle hole over the external surface of the graft, completely plugged the needle hole to its whole depth, leaving no spaces where blood came into the needle hole. CONCLUSION: The rub-and-spray method of fibrin glue application revealed the strongest sealing and hemostatic effects, and can be safely and effectively used for hemostasis in cardiovascular surgery that requires systemic heparinization or prolonged extracorporeal circulation.

Administration, Topical↗
PubMed1990

A turbidimetric method for measuring fibrin formation and fibrinolysis at solid-liquid interfaces.

We have developed a rapid and sensitive method by which to quantitate proteolysis of fibrin(ogen) at interfaces. Microscopic polystyrene-divinylbenzene beads coated with a mixed monomolecular film of lecithin and fibrinogen aggregate in aqueous media following exposure to thrombin or enzymes of thrombin-like activity. This aggregation is a consequence of interbead association of fibrin. As an indirect measure of the rate of fibrin formation, the rate of aggregation of beads can be used advantageously to assay enzymes and enzyme regulators pertinent to coagulation. Since the apparent absorbance of monodisperse beads is greater than that of bead aggregates, determination of the rate of change of apparent absorbance of a stirred dispersion of beads following addition of enzyme or enzyme-regulator mixture is a convenient and simple means by which to quantitate the rate of bead aggregation. Using a simple spectrophotometer or aggregometer, the method can be used to quantitate as little as 0.0005 NIH unit of thrombin. Aggregates of fibrin-coated beads can be disaggregated by several proteinases, most notably plasmin. Thus, just as bead aggregation can be used to quantitate effectors of fibrin formation, dissociation of aggregates of fibrin-coated beads can be used to quantitate effectors of fibrinolysis. Using disaggregation as a measure of fibrinolysis, the method is sensitive to as little as 0.005 unit of plasmin. Fibrin(ogen)-coated beads should prove a useful tool for studying proteolysis of fibrin(ogen) in general, and adsorbed fibrin(ogen) in particular.

Endopeptidases↗
PubMed1976

Analysis of soluble fibrin complexes by agarose gel chromatography and protamine sulfate gelation.

The molecular makeup of soluble fibrin complexes was studied by gel exclusion chromatography using radio-labelling to characterize individual components in protein mixtures. Products of limited plasmin degradation of fibrinogen and mixtures of fibrinogen and "early" fibrinogen digests formed high molecular weight soluble fibrin complexes upon incubation with thrombin. Purified, nonclottable fragment Y did not incorporate into soluble fibrin complexes, nor could we demonstrate incorporation of fragments D and E as previously described from our laboratory. Thus, under the conditions of these experiments, soluble fibrin complexes have two identifiable components, fibrin monomer and clottable fragment X monomer, although incorporation of native fibrinogen or fragment X unreacted by thrombin into soluble fibrin complexes cannot be excluded. Individual fractions of thrombin-treated early fibrinogen digests isolated by agarose gel chromatography were treated with protamine sulfate at 37 degrees C resulting in precipitation-gelation of greater than 90 per cent of high molecular weight soluble fibrin complexes; whereas, less than 10 per cent of lower molecular weight fibrinogen degradation products precipitated by protamine sulfate. These findings do not support the widely held concept that soluble fibrin complexes incorporate nonclottable degradation products of fibrinogen proteolysis, nor do they support the notion that the so-called paracoagulation reaction induced by protamine sulfate results from the splitting of complexes between fibrin monomer and nonclottable fibrinogen degradation products.

Binding Sites↗
PubMed1982

The effect of fibrin on endothelial cell migration in vitro.

Endothelial cells are known to migrate and come into contact with fibrin during numerous physiological processes, such as in wound healing and in tumor growth. The present study was initiated to investigate the effect of fibrin on endothelial cell migration in vitro. Endothelial cell migration was assayed by wounding confluent monolayers of bovine aortic endothelial cells with a razor blade and counting the number of cells crossing the wound per unit time. Wound-induced proliferation of endothelial cells was inhibited by mitomycin C-treatment without affecting endothelial cell migration, indicating that in this assay migration could be measured independent of proliferation. Migration of endothelial cells in vitro was inhibited by fibrin in a concentration dependent manner. Endothelial cell migration under fibrin was further reduced by plasminogen depletion of the serum, and fibrin still inhibited the migration of mitomycin C-treated endothelial cells. Kadish et al. (Tissue and Cell, 11, 99, 1979) previously reported that fibrin did not affect EC migration in vitro. The inability to inhibit EC migration with fibrin appears to be due to their assay system which employed agarose, since pre-treating the wounded monolayer with agarose eliminated the inhibition of EC migration by fibrin. The present results indicate that EC migration in vitro can be used as a model system for studying the interaction of fibrin with EC.

Animals↗