Fibrin elasticity and coagulation

Sudden increase of viscosity in former times indicated the start of coagulation. Yet its measurement destroyed the structure of coagulum. By the precursor method of thrombelastography the author 1944 found elasticity to be the essential physiological property of coagulum. In the production of elastic fibrin structure its early phase is the most efficient in this respect. The speed of prime structure formation is extremely fast in presence of enough phospholipid as well as of plasma factor XIII. Even high amounts of thrombin cannot replace one or both of these substances indispensable to grow rapidly a perfect fibrin web. This phase yet does not become effective if it is not accompanied by the orbital micro-flow of the new orbitometry method. Its shear is comparable to that in a coronary artery. The special resonance effect of the method in combination with the early phase of fibrin production is generating some kind of a physiological feed back: increasing fibrin will strengthen shear stress as long as less platelets are entangled which will reduce the elastic flexibility of fibrin web. Some kind of a "coagulation spin effect" in optimal combination of shear stress, phospholipid and factorXIII, will extremely fast originate a firm fibrin structure, a mechanism which may be of significance for a fast occlusion of arterial stenoses.     

Fibrin Degradation Products and Ovarian Tumours

Fibrin degradation products (F.D.P.) were determined in the serum of 163 women in whom ovarian tumours had been suspected on palpation at gynaecological examination and who were afterwards examined by laparoscopy or subjected to laparotomy. F.D.P. were found in the serum (0·5-30 mg/100 ml) of 23 (72%) out of 32 patients with malignant tumours. Of 131 patients with benign findings F.D.P. (traces to 2 mg/100 ml) were found in six (4·5%), and in most of these the occurrence of F.D.P. could be explained on other clinical grounds. The findings suggest that the examination of F.D.P. in suspected malignant ovarian tumour may be of diagnostic value.Determination of F.D.P. in malignant ascitic fluid showed very high values, ranging between 40 and 350 mg/ 100 ml. This argues for the occurrence of F.D.P. in the blood being due to an extravascular breakdown of fibrin caused by tumour cells, but they may also be due to thromboplastic and fibrinolytic agents from the tumour entering the blood stream.     

Observing and Quantifying Fibroblast-mediated Fibrin Gel Compaction

Cells embedded in collagen and fibrin gels attach and exert traction forces on the fibers of the gel. These forces can lead to local and global reorganization and realignment of the gel microstructure. This process proceeds in a complex manner that is dependent in part on the interplay between the location of the cells, the geometry of the gel, and the mechanical constraints on the gel. To better understand how these variables produce global fiber alignment patterns, we use time-lapse differential interference contrast (DIC) microscopy coupled with an environmentally controlled bioreactor to observe the compaction process between geometrically spaced explants (clusters of fibroblasts). The images are then analyzed with a custom image processing algorithm to obtain maps of the strain. The information obtained from this technique can be used to probe the mechanobiology of various cell-matrix interactions, which has important implications for understanding processes in wound healing, disease development, and tissue engineering applications.     

Aggregates Dramatically Alter Fibrin Ultrastructure

Among the many factors influencing fibrin formation and structure (concentration, temperature, composition, pH, etc.), it has been suggested that the polydispersity of fibrinogen may play an important role. We propose here a detailed investigation of the influence of this parameter on fibrin multiscale structure. Two commercial fibrinogen preparations were used, a monodisperse and a polydisperse one. First, the respective compositions of both fibrinogen preparations were thoroughly determined by measuring the fibrin-stabilizing factor; fibronectin; α, β, and γ intact chain contents; the γ/γ′ chains ratio; the N-glycosylation; and the post-translational modifications. Slight variations between the composition of the two fibrinogen preparations were found that are much smaller than the compositional variations necessary to alter significantly fibrin multiscale structure as observed in the literature. Conversely, multiangle laser light scattering-coupled size exclusion chromatography and dynamic light scattering measurements showed that the polydisperse preparation contains significant amounts of aggregates, whereas the other preparation is essentially monodisperse. The multiscale structure of the fibrins produced from those two fibrinogen preparations was determined by using x-ray scattering, spectrophotometry, and confocal microscopy. Results show that fibers made from the aggregate-free fibrinogen present a crystalline longitudinal and lateral structure and form a mikado-like network. The network produced from the aggregates containing fibrinogen looks to be partly built around bright spots that are attributed to the aggregate. The multiscale structure of mixtures between the two preparations shows a smooth evolution, demonstrating that the quantity of aggregates is a major determining factor for fibrin multiscale structure. Indeed, the effect of a few percent in the mass of aggregates is larger than any other effect because of compositional differences under the same reaction conditions. Finally, we propose a mechanistic interpretation of our results, which points at a direct role of the aggregates during polymerization, which disrupts the ideal ordering of monomers inside fibrin protofibrils and fibers.     

Menstrual Blood Loss and Fibrin Degradation Products

As part of a large-scale study of menstrual blood loss in the community serum fibrin degradation products were measured soon after menstruation in 331 women. No significant correlation was found between the amount of blood lost and the serum level of fibrin degradation products. These findings conflict with reports suggesting that excessive intrauterine fibrinolysis, which may play a part in menorrhagia, is associated with raised serum F.D.P. concentrations.     

Fibrin gels as biological filters and interfaces

We present data which show that fibrin gels are ordered network structures, the porosity of which is determined by the amount of thrombin being present during the activation step preceding gelation. On activation of fibrinogen, fibrinopeptides are released and simultaneously polymers are formed, obeying apparent first order kinetics. The pore size of the network is inversely related to the rate of polymer formation. It is proposed that at the time of gelation the polymers form an ordered lattice structure, which in the organism may serve as a biological interface.     

Leukocyte Inclusion within a Platelet Rich Plasma-Derived Fibrin Scaffold Stimulates a More Pro-Inflammatory Environment and Alters Fibrin Properties

One of the main differences among platelet-rich plasma (PRP) products is the inclusion of leukocytes that may affect the biological efficacy of these autologous preparations. The purpose of this study was to evaluate whether the addition of leukocytes modified the morphological, biomechanical and biological properties of PRP under normal and inflammatory conditions. The release of pro-inflammatory cytokines from plasma rich in growth factors (PRGF) and leukocyte-platelet rich plasma (L-PRP) scaffolds was determined by enzyme-linked immunosorbent assay (ELISA) and was significantly increased under an inflammatory condition when leukocytes were included in the PRP. Fibroblasts and osteoblasts treated with L-PRP, under an inflammatory situation, underwent a greater activation of NFĸB pathway, proliferated significantly less and secreted a higher concentration of pro-inflammatory cytokines. These cellular events were assessed through Western blot and fluorimetric and ELISA methods, respectively. Therefore, the inclusion of leukocytes induced significantly higher pro-inflammatory conditions.     

Fibrin Degradation Products in Pre-eclamptic Toxaemia and Eclampsia

Serum levels of fibrinogen/fibrin degradation products, measured in African women, were significantly higher in pre-eclamptic toxaemia than in normal pregnancy, and were significantly higher with eclampsia than with toxaemia. These findings are in accord with the hypothesis that eclampsia and toxaemia are associated with disseminated intravascular coagulation, which may be responsible for certain clinical manifestations of these conditions.