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PubMed1988

Platelet deposition onto fibrin-coated surfaces under flow conditions.

Platelet deposition on fibrin-coated surfaces and release from these adherent platelets were studied in an in vitro flow system. When a mixed suspension of washed platelets and red cells flowed through a fibrin-coated glass tube, only platelets were deposited onto the fibrin-coated surfaces. The density of adhered platelets increased with flow time and decreased with distance from the tube inlet. The adhesion rate increased with increasing shear rates from 45 s-1 to 180 s-1. This adhesion process appears to fit a diffusion-limited mathematical model. Comparing with glass and other protein-coated surfaces such as collagen, fibrinogen, or albumin coated surfaces, the number of adhered platelet per unit area decreased in the following descending order: collagen, fibrin, fibrinogen, glass, albumin. On the other hand, the degree of release reaction from these platelets decreased by another order: collagen, glass, fibrinogen, fibrin. We observed little release from platelets that were in contact with a fibrin-coated surface. Our results suggest that platelets specifically adhere to fibrin-coated surface and that this interaction does not induce platelet release.

Cells, Cultured↗
PubMed1987

New enzyme immunoassay of fibrin-fibrinogen degradation products in plasma using a monoclonal antibody.

In several diseases, such as disseminated intravascular coagulation, fibrin-fibrinogen degradation products (FDP) can be detected when serum is used. To avoid the use of serum with the risk of falsely positive and negative results, and to quantitatively measure routinely low levels of FDP in plasma, we developed a solid-phase enzyme immunoassay (EIA), using a monoclonal antibody (No. FDP-14). It reacts specifically with FDP, but not with the parent fibrinogen-fibrin molecule. To raise the monoclonal antibodies we injected into mice a whole mixture of fibrin degradation products isolated after complete lysis of a human blood clot by tissue-type plasminogen activator, because there is a chance that such products resemble FDP in patients' blood more closely than antigens derived from purified fibrinogen. The EIA developed is a two-step assay ("cap-tag procedure"), in which the monoclonal antibody is attached to the wells of microtiter plates. The monoclonal antibody is specific for a neoantigenic determinant in the fragment E moiety, exposed after degradation of fibrinogen-fibrin by plasmin. The assay discriminates neither between degradation products of fibrinogen and fibrin nor between fibrin degradation products that are or are not cross-linked. It is not disturbed by the presence of fibrinogen or fibrin monomer in plasma. The assay is accurate above 60 ng FDP per milliliter and has a detection limit down to approximately 10 ng FDP per milliliter when the supernatant of a lysed blood clot is used as calibration material. In frozen, then thawed plasma specimens from normal individuals, FDP values varied between 30 and 110 ng/ml. Plasma of patients with disseminated intravascular coagulation and of patients receiving thrombolytic therapy had increased FDP values. In patients with ovarian carcinoma, FDP concentrations in plasma varied with the clinical course of the disease. Results indicate that the EIA for FDP in plasma is promising as a diagnostic tool in different clinical situations.

Antibodies, Monoclonal↗
PubMed1987

Dermal pericapillary fibrin in venous disease and venous ulceration.

Pericapillary fibrin deposition is thought to contribute to the pathogenesis of venous ulceration. To our knowledge, however, there is no previous evidence that pericapillary fibrin is deposited in the tissue adjacent to venous ulcers. We prospectively studied patients with ulcers of the lower extremities for the presence of dermal pericapillary fibrin in the skin adjacent tot he ulcers. On direct immunofluorescence, pericapillary fibrin was found in 14 (93%) of the 15 patients with venous ulceration but in only one (7%) of the 14 subjects with ulcers due to other causes. We also confirmed the presence of dermal pericapillary fibrin in legs with venous disease without ulcerations. We conclude that the pericapillary fibrin is easily demonstrable in the dermis adjacent to venous ulcers. In the evaluation of ulcers due to uncertain causes, the presence of dermal pericapillary fibrin may provide additional diagnostic help.

Biopsy↗
PubMed1987

125I-fibrin deposition in IgE-dependent immediate hypersensitivity reactions in mouse skin. Demonstration of the role of mast cells using genetically mast cell-deficient mice locally reconstituted with cultured mast cells.

We investigated the clotting associated with IgE-dependent immediate hypersensitivity reactions in the mouse by injecting monoclonal mouse anti-dintrophenyl IgE antibodies i.d. and, the next day, administering 125I-guinea pig fibrinogen i.v. 10 to 30 min before i.v. antigen (2,4-dinitrophenylated human serum albumin) challenge. In normal mice, 2-hr passive cutaneous anaphylaxis (PCA) reactions were associated with substantial leakage of 125I-fibrinogen and deposition of 125I-fibrin. Thus, ears injected with IgE contained up to six times the total cpm of 125I and up to 30 times the cross-linked 125I-fibrin-associated cpm of 125I than did control ears. Several lines of evidence indicated that the 125I-fibrin deposition associated with the PCA reactions was dependent on the activity of mast cells: 1) Mast cell degranulation occurred at sites of PCA reactions. 2) Antigen-induced influx of 125I-fibrinogen and deposition of 125I-fibrin were virtually abolished by heating the IgE (56 degrees C, 1 hr) before i.d. injection. 3) Little or no IgE-dependent 125I-fibrinogen influx or 125I-fibrin deposition occurred in mast cell-deficient WBB6F1-W/Wv or WCB6F1-S1/S1d mice X 4) Adoptive transfer of cutaneous mast cell populations into WBB6F1-W/Wv mice (by each of three approaches: i.v. transplantation of normal bone marrow cells or local i.d. injection of cultured, growth factor-dependent mast cells 2 days or 9 to 10 wk before antigen challenge) conferred on the recipients the ability to express the 125I-fibrinogen influx and 125I-fibrin deposition associated with PCA reactions. These data demonstrate that 125I-fibrinogen influx and 125I-fibrin deposition occurs in association with PCA reactions in the mouse, and that the reaction is largely or entirely dependent on the function of cutaneous mast cells. The experiments also demonstrate the utility of a novel model system for the analysis of mast cell function in vivo: WBB6F1-W/Wv mice locally reconstituted with mast cells by the injection of mast cell populations generated in vitro.

Animals↗
PubMed1979

Comparison of serum and urine fibrin split products and urinary beta-glucuronidase in the diagnosis of renal transplant rejection.

This study compares the usefulness of serum and urine fibrin split products and the urinary enzyme, beta-glucuronidase, in the diagnosis and management of renal transplant rejection. Fibrin split products, determined by a tanned human red cell agglutination inhibition immunoassay, were measured as a reflection of the secondary fibrinolysis from fibrin deposited in the renal microvasculature as a result of rejection. Urinary beta-glucuronidase, expressed as the ratio of enzyme activity to creatinine concentration, was determined by a colorimetric technique following dialysis of urine to remove endogenous activators and inhibitors. Activity of this lysosomal enzyme is thought to reflect tubular injury. Twenty-nine renal transplant recipients (15 from living donors and 14 from cadaver donors) were evaluated. Both serum and urinary fibrin split products and urinary beta-glucuronidase were markedly elevated in the immediate postoperative period, probably reflecting ischemic trauma. Acute rejection occurring within the first three months was associated with elevations of fibrin split products (particularly urine) and beta-glucuronidase. Elevated values returned to normal following successful treatment with steroids and/or heparin, but remained high in the presence of continued rejection. After the first 48 hours post-transplant, in the absence of rejection, values for fibrin split products were within the normal range. Urinary beta-glucuronidase remained elevated if the transplanted kidney was recovering from acute tubular necrosis. Fibrin split products and urinary beta-glucuronidase were usually normal in chronic rejection.

Clinical Laboratory Techniques↗
PubMed1985

Incorporation of thrombospondin into fibrin clots.

Thrombospondin is a major platelet glycoprotein which is released from platelets during blood coagulation. We examined the interaction of thrombospondin with polymerizing fibrin. Thrombospondin, purified from human platelets and labeled with 125I, became incorporated into clots formed from both plasma and purified fibrinogen. Plasma clots contained somewhat less thrombospondin than clots formed from equivalent concentrations of fibrinogen. In plasma clots and fibrin clots formed in the presence of factor XIII, thrombospondin was cross-linked in the clot; thrombospondin in the supernatant remained largely monomeric. Cross-linking of thrombospondin by factor XIII, however, only slightly increased the amount of thrombospondin which was incorporated into the clot. In contrast, incorporation of 125I-fibronectin into clots was dependent upon cross-linking. Most of the incorporation of 125I-thrombospondin occurred during fibrin polymerization as judged by parallel studies of the incorporation of 125I-fibrinogen. The amount of thrombospondin incorporated into a clot was directly related to thrombospondin concentration and was only weakly dependent on fibrinogen concentration. Incorporation was not saturated at thrombospondin:fibrin (mol/mol) ratios as high as 2/1. Thrombospondin, however, modified the final structure of fibrin clots in a concentration-dependent manner as monitored by opacity. When tryptic digests of 125I-thrombospondin were studied, the 270-kilodalton core became incorporated into fibrin whereas the 30-kilodalton heparin binding fragment was excluded. These results indicate that thrombospondin specifically co-polymerizes with fibrin during blood coagulation and may be an important modulator of clot structure.

Blood Coagulation↗
PubMed1985

[Analysis of plasminogen activator in human plasma using the method of fibrin/celite column chromatography--with special reference to the determination of fibrin adsorbable tissue-plasminogen activator by ELISA].

To clarify the clinical importance of tissue-plasminogen activator (t-PA) on the thrombosis, it is essential to be measured t-PA level in human plasma. Taking advantage of strong affinity of t-PA to fibrin, t-PA was isolated with Fibrin/Celite column chromatography. Immunological activities of t-PA of plasma samples determined by ELISA and the elution pattern of it on Fibrin/Celite column chromatography were studied. The results are as follows: The t-PA in human plasma was consisted of fibrin adsorbable t-PA and fibrin nonadsorbable t-PA. Both types of t-PA could be measured separately by using of Fibrin/Celite column chromatography. The fibrin adsorbable t-PA fraction showed two types of molecular size (major peak was Mr congruent to 70,000, minor peak was Mr congruent to 100,000) on Sephadex G-200 chromatography. The level of t-PA in plasma samples taken from 20 healthy subjects at rest was 2.4 +/- 1. 9 ng/ml, and concentration of t-PA increased to 10.4 +/- 3.2 ng/ml after venous stasis. But the t-PA level of plasma samples from patients with cerebral thrombosis did not increase after venous stasis. The changes of immunologically determined t-PA in plasma samples induced by venous stasis were not reflected in the fibrinolytic activities of the euglobulin fractions, but well reflected in the fibrinolytic activities of the elution fractions on Fibrin/Celite column chromatography. The level of fibrin nonadsorbable t-PA did not change by venous stasis, but the level of fibrin adsorbable t-PA increased from 5.1 +/- 1.9 ng/ml to 9.7 +/- 2.7 ng/ml in the case of 6 healthy subjects. It is concluded that, the plasma t-PA increased by venous stasis was the fibrin adsorbable t-PA, and it may play a very important role in physiological fibrinolysis.

Adsorption↗
PubMed1982

Effect of dextran on platelet activation by polymerizing fibrin.

Dextran has been shown to alter the mechanical properties and lysability of fibrin. The present study was undertaken to determine whether it would also influence the ability of polymerizing fibrin to activate platelets. Human fibrinogen, with or without the presence of dextran, was incubated with either human thrombin or reptilase at 37 C. Macroscopically evident fibrils first appeared at 7 1/2 to 8 minutes in fibrinogen solution not containing dextran and at 2 1/2 to 3 minutes in solution containing dextran. Both solutions caused aggregation of washed human platelets, but the one containing dextran was less potent (P less than 0.005). Similarly, polymerizing fibrin, under the influence of dextran, was a less potent stimulator of platelet release of labeled serotonin. Scanning electron microscopy showed decreased platelet adhesion to fibrin polymerized in the presence of dextran. Inclusion of dextran in plasminogen-rich bovine fibrin clots facilitated their lysis by urokinase. Apparently, dextran not only increases the lysability of fibrin but also alters the platelet-activating activity of polymerizing fibrin.

Animals↗
PubMed1980

Quantitative determination of fibrin and fibrinogen in biological material.

In order to measure quantitatively fibrin and fibrinogen in biological material such as thrombi, exudates, or tissues, the following method was developed and tested on model thrombi of different composition. Any fibrin and fibrinogen present is proteolytically degraded by endogenous and/or exogenous plasmin to their common late, soluble fragments D and E. Fragment E is determined by electroimmunoassay using a specific antiserum. From the amounts of fragment E the original fibrin(fibrinogen) antigen and thus of fibrin plus fibrinogen can be calculated on the basis of a molecular weight ratio of 340,000 for fibrinogen to 48,500 for fragment E. Purified fibrinogen degraded to fragments by plasmin resulted in a yield of 89.9% +/- 1.5 of the expected amount of fragment E. Fibrin under identical conditions resulted in a yield of 84.0% +/- 2.4, whereas crosslinked fibrin gave yields of 78.2% +/- 9.2 only after prolonged incubation. Control studies demonstrated that the presence of plasma proteins did not change the yield of fragment E. Measurement of the fibrin(fibrinogen) content of thrombotic material contained in surgically removed human aortic aneurysms demonstrated the validity and applicability of this method to biological material.

Antigens↗
PubMed1983

The physiological significance of the endoendothelial fibrin lining (EEFL) as the critical interface in the 'vessel-blood organ' and the importance of in vivo 'fibrinogenin formation' in health and disease.

The author's theory of the endoendothelial fibrin lining (EEFL), first advanced in 1953 and developed by him ever since, localizes the homeostasis between steady fibrin formation and deposition, or 'fibrination', and continuous fibrinolysis in the more or less immobile portion of the plasmatic zone next to the vessel wall. In 1971, the author advanced, in relation to the EEFL, the theory of fibrinogen gel clotting without thrombin action or 'fibrinogenin' formation in vivo. Considerable direct and indirect experimental evidence, secured by the author and by several other investigators, advanced markedly the knowledge of the normal physiology and the pathophysiology of various disease processes involving the vessel wall and blood circulation. The information presented is an extension to that given in the author's recent overview (Clin. Hemorheology 1, 9-72, 1981). It deals both with new data by several investigators including those by the author, as well as with older data from the literature. The author maintained already in 1960 that the blood together with the blood vessels, in which it circulates, constitute 'an entity'. In 1981 he postulated this entity to be a very special organ, named conveniently 'vessel-blood organ', which is ubiquitous and penetrates all other organs and adjacent tissues. The EEFL of the vessel-blood organ is considered by the author as the crucial critical interface between the blood and the vessel wall. It is the primary barrier, followed by the endothelium (comprising the endothelial cells and the interendothelial cement substance which contains or is identical with 'cement fibrin') and the basement membrane for the exchanges between the blood, the vessel wall and its surrounding tissues and spaces. The EEFL acts as anticoagulant, is antithrombogenic, maintains vascular patency and aids cardiac action by decreasing significantly the apparent viscosity of blood, referred to in the literature as the 'Copley-Scott Blair phenomenon'. A new concept of leukocyte emigration traversing the capillary wall is presented, affecting focal fibrinolysis of the EEFL and of fibrin contained in the interendothelial cement substance and in the basement membrane. The physical property of capillary (or vascular) permeability is related to the existence of the EEFL, since, as found by Copley et al, both fibrinopeptides, liberated in the transition of fibrinogen to fibrin, and plasminopeptides, freed in the conversion of plasminogen to plasmin, enhance capillary permeability. Capillary fragility, which is antagonistic to capillary permeability, is in great part due to fibrinolytic action on fibrin as a constituent of the basement membrane.(ABSTRACT TRUNCATED AT 400 WORDS)

Basement Membrane↗
PubMed1978

Fibrin formation: effect of calcium ions.

Using laser fluctuation spectroscopy, a technique that measures particle size change in solution, the kinetics of fibrin clot formation from fibrinogen can be studied. With this technique the effect of calcium on the three distinguishable phases of clot formation, (1) proteolysis of fibrinogen, (2) fibrinogen-fibrin monomer complex formation, and (3) fibrin monomer polymerization, were investigated. Only a small change in the length of the induction period that results from the fibrinogen-fibrin monomer interactions was observed. However, there was a marked increase in the rate of fibrin monomer polymerization in the presence of calcium ions. These data show that calcium decreases the time required for fibrin formation from fibrinogen by markedly accelerating the phase of fibrin monomer polymerization.

Blood Coagulation↗
PubMed1982

Fibrin deposits in Hodgkin's disease.

Fibrin deposits were observed in the involved lymph nodes and/or spleens of 15 patients with Hodgkin's disease by specific immunofluorescence and by electron microscopy. Two basic patterns of fibrin deposition were observed: 1) intercellular deposits, chiefly associated with nonneoplastic-appearing lymphoid cells and 2) deposits associated with the collagen fibers of young connective tissue. In addition, coarse fibrin deposits were observed in areas of necrosis, presumably a non-specific finding. Fibronectin was also observed in intercellular areas, but staining was less intense than for fibrin. Fibrin deposits were also observed in 3 of 6 cases of non-Hodgkin's lymphoma, indicating that the finding is not an exclusive feature of Hodgkin's disease. The pathogenesis and possible significance of fibrin deposition in Hodgkin's disease are related to earlier observations of activation of the coagulation system on neoplasia and cell-mediated immunity and to the possible role of fibrin, fibronectin, and their breakdown products in angiogenesis and fibroplasia.

Collagen↗
PubMed1982

Kinetics of the activation of plasminogen by human tissue plasminogen activator. Role of fibrin.

The kinetics of the activation of Glu-plasminogen and Lys-plasminogen (P) by a two-chain form of human tissue plasminogen activator (A) were studied in purified systems, and in the presence of fibrinogen (f) and of fibrin films (F) of increasing size and surface density. The activation in the purified systems followed Michaelis-Menten kinetics with a Michaelis constant of 65 microM and a catalytic rate constant of 0.06 s-1 for Glu-plasminogen as compared to 19 microM 0.2 s-1 for Lys-plasminogen. In the presence of fibrinogen plots of 1/v versus 1/[P] or 1/v versus 1/[f] yielded straight lines with an apparent Michaelis constant at infinite [f] of 28 microM and a catalytic rate constant of 0.3 s-1 for Glu-plasminogen as compared to 1.8 microM and 0.3 s-1 for Lys-plasminogen. In the systems with fibrin, plasmin was estimated from the rate of release of 125I from 125I-labeled fibrin films. The initial rate of activation (v) was calculated and Lineweaver-Burk plots of 1/v versus 1/[P] or 1/v versus 1/[F] yielded straight lines. Activation occurred with an intrinsic Michaelis constant of 0.16 microM and a catalytic rate constant of 0.1 s-1 for Glu-plasminogen as compared to 0.02 microM and 0.2 s-1 for Lys-plasminogen. The kinetic analysis suggested that the activation in the presence of fibrin occurs through binding of an activator molecule to the clot surface and subsequent addition of plasminogen (sequential ordered mechanism) to form a cyclic ternary complex. The Low Michaelis constant in the presence of fibrin allows efficient plasminogen activation on a fibrin clot, while its high value in the absence of fibrin prevents efficient activation in plasma.

Enzyme Activation↗
PubMed1995

On the role of von Willebrand factor in promoting platelet adhesion to fibrin in flowing blood.

Platelet adhesion to fibrin at high shear rates depends on both the glycoprotein (GP) IIb:IIIa complex and a secondary interaction between GPIb and von Willebrand factor (vWF). This alternative link between platelets and vWF in promoting platelet adhesion to fibrin has been examined in flowing whole blood with a rectangular perfusion chamber. Optimal adhesion required both platelets and vWF, as shown by the following observations. No binding of vWF could be detected when plasma was perfused over a fibrin surface or when coated fibrinogen was incubated with control plasma in an enzyme-linked immunosorbent assay. However, when platelets were present during perfusion, interactions between vWF and fibrin could be visualized with immunoelectron microscopy. Exposure of fibrin surfaces to normal plasma before perfusion with severe von Willebrand's disease blood did not compensate for the presence of plasma vWF necessary for adhesion. vWF mutants in which the GPIIb:IIIa binding site was mutated or the GPIb binding site was deleted showed that vWF only interacts with GPIb on platelets in supporting adhesion to fibrin and not with GPIIb:IIIa. Complementary results were obtained with specific monoclonal antibodies against vWF. Thus, vWF must first bind to platelets before it can interact with fibrin and promote platelet adhesion. Furthermore, only GPIb, but not GPIIb:IIIa is directly involved in this interaction of vWF with platelets.

Bernard-Soulier Syndrome↗
PubMed1995

Role of collagen-adherent platelets in mediating fibrin formation in flowing whole blood.

Activated platelets provide assembly sites for coagulation enzyme complexes and in this way can mediate coagulation during hemostasis and thrombosis. In this study, we examined the procoagulant activity of platelets adhering directly to fibrillar collagen, a main thrombogenic constituent of subendothelium. For this purpose, we used a human ex-vivo thrombosis model in which collagen-coated coverslips were exposed to flowing nonanticoagulated blood (shear rate, 65/s) for 5.5 minutes, which led to the deposition of adherent platelets, platelet thrombi, and fibrin. To examine the procoagulant activity of adherent platelets only, a selective antagonist of the platelet GPIIb-IIIa complex, Ro 44-9883, was infused via a mixing device, resulting in a complete abrogation of platelet thrombus formation but leaving the collagen-adherent platelet layer intact. This platelet layer generated increased postchamber fibrinopeptide A (FPA) levels (203 +/- 33 ng/mL) as compared with control experiments without infusion of inhibitor (95 +/- 13 ng/mL). Concomitantly, fibrin deposition measured by morphometric analysis of cross-sections was also increased, as was the platelet adhesion to collagen. An immunochemical staining of fibrin fibers further showed that the adherent platelets formed the nuclei for fibrin fiber formation. This increase in fibrin deposition was mediated by the intrinsic factor X (F.X) activation complex on adherent single platelets, because almost complete inhibition of FPA generation (9 ng/mL) and fibrin deposition (0.4% +/- 0.2% coverage) was achieved upon coinfusion of the GP IIb-IIIa antagonist and active site-inhibited F.IXa. The large platelet thrombi that were deposited in control experiments contained no significant amounts of immunodetectable fibrin except at the thrombus base, where adherent platelets anchored the thrombi to the collagen surface. These results suggest that the collagen-adherent platelets are important promoters of coagulation during the initial phase of thrombogenesis by providing assembly sites for the F.X activation complex.

Acetates↗
PubMed1995

Evidence that fibrin alpha-chain RGDX sequences are not required for platelet adhesion in flowing whole blood.

The role of the RGDX putative receptor-recognition sites, which are present on the alpha chains of fibrin, in promoting platelet adhesion has been examined in flowing whole blood using the rectangular perfusion chamber at wall shear rates of 340 and 1,600/s. Platelets adhered to a comparable extent to surfaces coated with native fibrin and surfaces coated with fragment X-fibrin, a product of limited fibrinolysis that lacks the RGDS sites normally present at positions 572 to 575 of the alpha chains. The strengths of these adhesive interactions were comparable based on the concentrations of the antiadhesive peptide D-RGDW required to block platelet deposition to native and fragment X-fibrin at both low and high wall shear rate. Blocking either or both RGDX sequences with peptide-specific monoclonal antibodies did not inhibit platelet deposition in perfusion experiments performed with normal blood at 340/s, indicating that neither RGD motif is required for adhesion. However, adhesion was partly inhibited by anti-RGDX antibodies when perfusions were performed with blood from an afibrinogenemic patient, suggesting the RGDX sequences may play a limited role in platelet deposition. Exposure of fibrin surfaces to plasminogen/tissue-type plasminogen activator did cause a time-dependent loss of adhesiveness, but this effect was only weakly correlated with proteolysis of the fibrin alpha chains. These observations provide evidence that neither RGDX sequence is required for platelets to adhere avidly to fibrin in flowing blood. These results further suggest that incomplete fibrinolysis yields a highly thrombogenic surface.

Amino Acid Sequence↗
PubMed1995

Laser-assisted fibrin clot soldering of human menisci.

Fibrin mixtures have been used as a solder in conjunction with argon ion lasers to create strong tissue welds in several organ systems. An analogous method of meniscus repair could obviate the need for partial meniscectomy and its subsequent degenerative effects in a subset of meniscal tears. This study measured the in vitro tensile strength in 4 groups of human menisci (1-mm x 2-mm x 5-mm sections): (1) bisected menisci repaired with fibrin clot mixture, (2) bisected menisci bonded by fibrin clot mixture and exposure to argon laser energy (energy density, 60 W/cm2), (3) bisected menisci repaired with 2 interrupted sutures, and (4) untreated meniscal controls. After irradiation with argon ion laser energy, the tensile strength of the laser-assisted fibrin clot-bonded menisci increased 40-fold over that of nonirradiated fibrin clot-bonded menisci. Suture controls (0.515 +/- 0.221 MPa) had a higher tensile strength than the fibrin clot mixture and irradiated groups; however, the suture controls had only 8.5% the strength of native menisci (6.081 +/- 0.221 MPa). Laser-assisted fibrin clot soldering may allow the opposing edges of a meniscal tear to be held together with a biologic scaffold, possibly inducing reparative cell migration and proliferation.

Combined Modality Therapy↗
PubMed1994

Extravascular coagulation and fibrin deposition in acute lung injury.

Extravascular fibrin deposition is characteristic of the acute inflammatory response and is, for example, prominent in the alveolar compartment of patients with the adult respiratory distress syndrome. Fibrin deposition in the injured lung is regulated by a balance of locally expressed pathways of coagulation and fibrin clearance, called fibrinolysis. These pathways comprise part of the interactive network of responses that influence local inflammatory cell traffic, microvascular permeability, and repair mechanisms. In this sense, fibrin turnover in the lung extends beyond traditional hemostasis and may influence the acute inflammatory response and resolution. Within the injured alveolar compartment, fibrin deposition is initiated by increased activity of the extrinsic coagulation pathway-tissue factor associated with factor VII. Activation of the contact and intrinsic coagulation pathways also occurs. Local fibrinolysis is generally impaired, which may potentiate extravascular fibrin deposition. Fibrin turnover in the adult mammalian lung is similarly disrupted in several forms of injury but differs from the injury that occurs in the lungs of premature infants with respiratory distress.

Animals↗