Limited value of testing for factor XIII and α2-antiplasmin deficiency in patients with a bleeding disorder of unknown cause.

INTRODUCTION: In patients with an increased bleeding tendency, extensive diagnostic blood testing is often performed. When results of tier 1 assays of primary haemostasis are normal, protocols recommend additional testing to rule out rare disorders including coagulation factor XIII (FXIII) and α2-antiplasmin (α2AP) deficiency. AIM: To evaluate the added diagnostic value of FXIII and α2AP levels in patients with a bleeding disorder of unknown cause (BDUC). METHODS: A retrospective monocentre cohort study between August 2011 and August 2023 was conducted. In all patients with bleeding tendencies and normal diagnostic tests for von Willebrand disease and platelet function, FXIII and α2AP were measured. RESULTS: We included 158 consecutive patients; mean ISTH-BAT scores were 8.2 (SD ± 3.7) in children, 6.2 (SD ± 2.1) in men and 10.6 (SD ± 3.3) in women. Median age was 37 (range 5-79) years, 88.6% of patients were female. Patients displayed median FXIII activity of 111% (IQR = 97-131) and median α2AP activity of 112% (IQR = 103-119). Three (1.9%) patients had FXIII levels < 50%, respectively 43%, 45% and 46%. Corresponding ISTH-BAT scores were 7, 12 and 14. No α2AP levels < 60% was observed. No significant association was found between FXIII levels and ISTH-BAT scores. CONCLUSION: In our cohort of BDUC patients, no clinical relevant FXIII deficiencies were detected; absolute values were well above the 30% cutoff considered adequate for normal haemostasis. No α2AP deficiencies were detected. These data suggest that in BDUC patients, measuring FXIII or AP activity is of limited value.

Whole blood PT/aPTT assay based on non-contact drop-of-sample acoustic tweezing spectroscopy.

Most coagulation tests are photo-optical turbidimetric assays that require the removal of cellular components from whole blood for optical clearing. If the resulting blood plasma samples are hemolyzed, they may become unsuitable for turbidimetric analysis. To resolve this issue, whole-blood analogs to plasma turbidimetric assays need to be developed. Using samples collected from non-smokers (normal group), smokers (thrombotic group), and hemophilia A (bleeding group) patients, we demonstrate that the reaction time assessed from whole blood viscosity data of the drop-of-blood acoustic tweezing spectroscopy (ATS) technique strongly correlates (Rp ≥ 0.95) with PT/aPTT values obtained from plasma turbidimetric data. Linear correlation (Rp ≥ 0.88) was also obtained between the viscous and elastic outputs of the ATS technique and the fibrinogen concentration. The integration of ATS data enabled the assessment of the functional level of fibrin cross-linkers such as factor XIII. Overall, ATS allows comprehensive sample-sparing analysis of whole blood coagulation for reliable and safe diagnosis of bleeding/thrombosis risks.

Acquired Low Factor XIII Activity Is Associated with an Increased Need for Blood Transfusions in Patients with Gastrointestinal Bleedings.

BACKGROUND: Factor XIII plays a key role within the coagulation cascade. OBJECTIVE: We aimed to investigate the relevance of factor XIII activity on the outcome of patients with gastrointestinal bleedings. METHODS: In this retrospective, single-center study patients with gastrointestinal bleeding and measurement of factor XIII activity were included. The primary endpoint was the number of red blood cell transfusions in patients with reduced factor XIII activity (< 70%) compared to patients with normal activity. Additionally, the influence of factor XIII substitution was assessed. RESULTS: Ninety-seven patients (median age: 64 [IQR 55, 77] years, 31 (32%) females) were included in the analysis. Fifty-six (58%) patients suffered from an upper gastrointestinal bleeding. 66 (68%) patients had a factor XIII activity < 70% and 24 (36%) of those received factor XIII substitution. Patients with reduced FXIII activity needed significantly more red blood cell transfusions than patients with normal activity (9 [5, 12] vs. 4 [1, 8], p < 0.001). Patients receiving factor XIII substitution showed a trend toward a decreased need for transfusions after substitution (0 [0, 5] vs. 3 [1, 6], p = 0.066). Factor XIII activity correlated negatively with the INR (rs = -0.24, p = 0.018) and positively with hemoglobin levels (rs = 0.28, p = 0.006) and with thrombocyte counts (rs = 0.30, p = 0.003). CONCLUSION: The present study shows an association of factor XIII activity with the requirement of blood transfusions in patients with gastrointestinal bleedings and indicates a potential benefit of factor XIII substitution. Factor XIII activity seems to be dependent from the amount of blood loss and the global coagulation parameters.

Elimination of fibrin γ-chain cross-linking by FXIIIa increases pulmonary embolism arising from murine inferior vena cava thrombi.

The onset of venous thromboembolism, including pulmonary embolism, represents a significant health burden affecting more than 1 million people annually worldwide. Current treatment options are based on anticoagulation, which is suboptimal for preventing further embolic events. In order to develop better treatments for thromboembolism, we sought to understand the structural and mechanical properties of blood clots and how this influences embolism in vivo. We developed a murine model in which fibrin γ-chain cross-linking by activated Factor XIII is eliminated (FGG3X) and applied methods to study thromboembolism at whole-body and organ levels. We show that FGG3X mice have a normal phenotype, with overall coagulation parameters and platelet aggregation and function largely unaffected, except for total inhibition of fibrin γ-chain cross-linking. Elimination of fibrin γ-chain cross-linking resulted in thrombi with reduced strength that were prone to fragmentation. Analysis of embolism in vivo using Xtreme optical imaging and light sheet microscopy demonstrated that the elimination of fibrin γ-chain cross-linking resulted in increased embolization without affecting clot size or lysis. Our findings point to a central previously unrecognized role for fibrin γ-chain cross-linking in clot stability. They also indirectly indicate mechanistic targets for the prevention of thrombosis through selective modulation of fibrin α-chain but not γ-chain cross-linking by activated Factor XIII to reduce thrombus size and burden, while maintaining clot stability and preventing embolism.

Successful perinatal management of a woman with congenital factor XIII deficiency using recombinant factor XIII: A case report and literature review.

Factor XIII deficiency is an extremely rare autosomal recessive genetic disorder, occurring in 1 of 3-5 million people, and is associated with perinatal complications, such as habitual abortion and prolonged bleeding. Although plasma-derived factor XIII (Fibrogamin®) carries a risk of infection and contains very low concentrated forms of factor XIII (FXIII) used for a pregnant woman with congenital coagulation factor XIII deficiency, recombinant factor XIII (rFXIII, Novo Thirteen®; Tretten®, Novo Nordisk, Bagsvaerd, Denmark), which has no risk of infection and is highly concentrated, has emerged as a novel formulation. Herein, we report the first case of a Japanese pregnant woman with congenital coagulation factor XIII deficiency successfully managed by rFXIII. She had a good perinatal course without pregnancy-related complications and transfusion through the perinatal period.

Characterization of a recombinant factor IX molecule fused to coagulation factor XIII-B subunit.

INTRODUCTION AND AIM: Severe haemophilia B (HB) is characterized by spontaneous bleeding episodes, mostly into joints. Recurrent bleeds lead to progressive joint destruction called haemophilic arthropathy. The current concept of prophylaxis aims at maintaining the FIX level >3-5 IU/dL, which is effective at reducing the incidence of haemophilic arthropathy. Extended half-life FIX molecules make it easier to achieve these target trough levels compared to standard FIX concentrates. We previously reported that the fusion of a recombinant FIX (rFIX) to factor XIII-B (FXIIIB) subunit prolonged the half-life of the rFIX-LXa-FXIIIB fusion molecule in mice and rats 3.9- and 2.2-fold, respectively, compared with rFIX-WT. However, the mechanism behind the extended half-life was not known. MATERIALS AND METHODS: Mass spectrometry and ITC were used to study interactions of rFIX-LXa-FXIIIB with albumin. Pharmacokinetic analyses in fibrinogen-KO and FcRn-KO mice were performed to evaluate the effect of albumin and fibrinogen on in-vivo half-life of rFIX-LXa-FXIIIB. Finally saphenous vein bleeding model was used to assess in-vivo haemostatic activity of rFIX-LXa-FXIIIB. RESULTS AND CONCLUSION: We report here the key interactions that rFIX-LXa-FXIIIB may have in plasma are with fibrinogen and albumin which may mediate its prolonged half-life. In addition, using the saphenous vein bleeding model, we demonstrate that rFIX-FXIIIB elicits functional clot formation that is indistinguishable from that of rFIX-WT.

Factor XIII levels, clot strength, and impact of fibrinogen concentrate in infants undergoing cardiopulmonary bypass: a mechanistic sub-study of the FIBCON trial.

BACKGROUND: Acquired factor XIII (FXIII) deficiency after major surgery can increase postoperative bleeding. We evaluated FXIII contribution to clot strength and the effect of fibrinogen concentrate administration on FXIII activity in infants undergoing cardiac surgery using cardiopulmonary bypass. METHODS: We conducted a prospectively planned, mechanistic sub-study, nested within the Fibrinogen Concentrate Supplementation in the Management of Bleeding During Paediatric Cardiopulmonary Bypass: A Phase 1B/2A, Open-Label Dose Escalation Study (FIBCON) trial, which investigated fibrinogen concentrate supplementation during cardiopulmonary bypass (ISRCTN: 50553029) in 111 infants (median age 6.4 months). The relationships between platelet number, fibrinogen concentration, and FXIII activity with rotational thromboelastometry clot strength (EXTEM-MCF) in blood taken immediately before cardiopulmonary bypass and after separation from bypass were estimated using multivariable linear regression. Changes in coagulation variables over time were quantified using a generalised linear model comparing three groups: fibrinogen concentrate-supplemented infants, placebo, and a third cohort with lower bleeding risk. RESULTS: Overall, 48% of the variability (multivariable R2) in EXTEM-MCF clot strength was explained by three factors: the largest contribution was from FXIII activity (partial R2=0.21), followed by platelet number (partial R2=0.14), and fibrinogen concentration (partial R2=0.095). During cardiopulmonary bypass, mean platelet count fell by a similar amount in the three groups (-36% to -41%; interaction P=0.98). Conversely, fibrinogen concentration increased in all three groups: 132% in the fibrinogen concentrate-supplemented group, 26% in the placebo group, and 51% in the low-risk group. A similar increase was observed for FXIII activity (61%, 23%, and 25%, respectively; interaction P<0.0001). CONCLUSIONS: FXIII contribution to clot strength is considerable in infants undergoing cardiac surgery. Fibrinogen concentrate supplementation also increased FXIII activity, and hence clot strength. CLINICAL TRIAL REGISTRATION: ISRCTN: 50553029.

Perioperative therapeutic plasma exchange in a patient with rare Factor XIII inhibitor.

INTRODUCTION: Factor XIII deficiency is a rare bleeding disorder which could be severe if inherited or less severe if acquired. We report a case of acquired Factor XIII inhibitor in a 75-year-old male with a suspicious left renal mass treated perioperatively with therapeutic plasma exchange (TPE). PATIENT AND METHOD: To perform kidney biopsy and ablation of the renal mass, six daily TPE treatments were performed before and after biopsy to minimize bleeding risk because the patient did not respond to drug therapy. Both thromboelastography (TEG) and laboratory-based coagulation tests were performed to assess coagulation status prior to and after TPE. RESULTS: The biopsy indicated oncocytoma which was removed by surgical procedure. Factor XIII activity remained below 15 % throughout TPE treatments, but Factor XIII inhibitor titer reduced from initial positive value of 1:40 to negative following the third TPE and remained negative through the sixth TPE. Unfortunately, the inhibitor titer was positive at 1:20 in the fifth month and 1:5 in the sixth month during follow-up. CONCLUSIONS: TPE is useful in removing XIII inhibitory factor, but the effects are only short term.

Factor XIII in the Acute Care Setting and Its Relevance in Obstetric Bleeding.

Background: Major hemorrhage is one of the main causes of preventable mortality in either severe trauma, high-risk surgical patient, or the obstetric population. As underlined by the cell-based coagulation model, a resistant and stable clot is essential to prevent or to stop an ongoing bleeding. Coagulation factor XIII (FXIII) stabilizes the newly formed clot by cross-linking the fibrin monomers into a three-dimensional network and by impeding fibrinolysis. Thus, FXIII is an essential coagulation factor in the acutely bleeding patient. Summary: Acquired FXIII deficiency is much more common than the inherited form. On the basis of acute tissue injury which leads to major bleeding, acquired FXIII deficiency is traditionally considered to be secondary to consumption. However, recent evidence in the field of obstetrics and high-risk surgery suggests that it might be an associated factor rather than a consequence of the bleeding, which would mean that early replacement of FXIII could potentially improve outcomes. However, FXIII measurement is not universally available. Assessing FXIII through viscoelastic assays seems feasible, though likely it is not yet accurate. Moreover, the target population at risk and the aimed FXIII level required to achieve hemostasis in each condition are yet to be defined. Key Messages: FXIII should be assessed and replaced if necessary in the acutely bleeding patient. We recommend FXIII to be included in an escalating scheme of hemostatic therapies in the acute care setting.

The Impact of Prepartum Platelet Count on Postpartum Blood Loss and Its Association with Coagulation Factor XIII Activity.

Background: Postpartum hemorrhage is a leading cause of maternal morbidity and mortality worldwide. Contradictory information exists regarding the relevance of prepartum platelet count on postpartum hemorrhage. We have shown prepartum coagulation factor XIII to be associated with postpartum blood loss; however, little is known about the association of platelet count with factor XIII activity. Our objectives were, first, to evaluate the impact of prepartum platelet count on measured postpartum blood loss in the context of prepartum measurements of coagulation factors I, II, and XIII and, second, to evaluate the association of platelet count with coagulation factor XIII, both pre- and postpartum. Material and Methods: This is a secondary analysis of a prospective cohort study (PPH 1,300 study) which analyzed the impact of prepartum blood coagulation factors on postpartum blood loss in 1,300 women. Blood loss was quantified using a validated technique. The impact of prepartum platelet count on measured blood loss was assessed by continuous outcome logistic regression; the association of platelet count with factor XIII activity by Spearman rank correlation. Results: Prepartum platelet count was significantly associated with measured postpartum blood loss: every one unit (G/L) increase in prepartum thrombocytes was associated with an odds ratio of 1.002 (95% confidence interval, 1.001-1.004, p = 0.005) to keep blood loss below any given cut-off level. This means that the probability of postpartum hemorrhage decreases with increasing prepartum platelet levels. Moreover, a significant association of platelet count with factor XIII activity was shown (Spearman rank correlation coefficient for prepartum values 0.228, p < 0.001, and for postpartum values 0.293, p < 0.001). Discussion/Conclusion: The significant association of prepartum platelet count and postpartum blood loss as well as the association of platelet count with blood coagulation factor XIII activity support the likely role of platelets in preventing postpartum hemorrhage and support the new guidelines for the treatment of postpartum hemorrhage in Germany, Austria, and Switzerland, which calls for optimizing platelet counts peripartally in case of postpartum hemorrhage. A possible effect of platelets on the level of circulating factor XIII cannot be ruled out and should prompt further investigation.

Cellular FXIII in Human Macrophage-Derived Foam Cells.

Macrophages express the A subunit of coagulation factor XIII (FXIII-A), a transglutaminase which cross-links proteins through Nε-(γ-L-glutamyl)-L-lysyl iso-peptide bonds. Macrophages are major cellular constituents of the atherosclerotic plaque; they may stabilize the plaque by cross-linking structural proteins and they may become transformed into foam cells by accumulating oxidized LDL (oxLDL). The combination of oxLDL staining by Oil Red O and immunofluorescent staining for FXIII-A demonstrated that FXIII-A is retained during the transformation of cultured human macrophages into foam cells. ELISA and Western blotting techniques revealed that the transformation of macrophages into foam cells elevated the intracellular FXIII-A content. This phenomenon seems specific for macrophage-derived foam cells; the transformation of vascular smooth muscle cells into foam cells fails to induce a similar effect. FXIII-A containing macrophages are abundant in the atherosclerotic plaque and FXIII-A is also present in the extracellular compartment. The protein cross-linking activity of FXIII-A in the plaque was demonstrated using an antibody labeling the iso-peptide bonds. Cells showing combined staining for FXIII-A and oxLDL in tissue sections demonstrated that FXIII-A-containing macrophages within the atherosclerotic plaque are also transformed into foam cells. Such cells may contribute to the formation of lipid core and the plaque structurization.

Peptidic Inhibitors and a Fluorescent Probe for the Selective Inhibition and Labelling of Factor XIIIa Transglutaminase.

Factor XIIIa (FXIIIa) is a transglutaminase of major therapeutic interest for the development of anticoagulants due to its essential role in the blood coagulation cascade. While numerous FXIIIa inhibitors have been reported, they failed to reach clinical evaluation due to their lack of metabolic stability and low selectivity over transglutaminase 2 (TG2). Furthermore, the chemical tools available for the study of FXIIIa activity and localization are extremely limited. To combat these shortcomings, we designed, synthesised, and evaluated a library of 21 novel FXIIIa inhibitors. Electrophilic warheads, linker lengths, and hydrophobic units were varied on small molecule and peptidic scaffolds to optimize isozyme selectivity and potency. A previously reported FXIIIa inhibitor was then adapted for the design of a probe bearing a rhodamine B moiety, producing the innovative KM93 as the first known fluorescent probe designed to selectively label active FXIIIa with high efficiency (kinact/KI = 127,300 M-1 min-1) and 6.5-fold selectivity over TG2. The probe KM93 facilitated fluorescent microscopy studies within bone marrow macrophages, labelling FXIIIa with high efficiency and selectivity in cell culture. The structure-activity trends with these novel inhibitors and probes will help in the future study of the activity, inhibition, and localization of FXIIIa.

[Autoimmune acquired coagulation factor XIII/13 deficiency caused by type Ab anti-FXIII-A autoantibody].

An 88-year-old man became unconscious and was admitted to our hospital due to severe anemia. Extensive subcutaneous hemorrhage around the chest and back and pectoralis major muscle hematoma were observed. Coagulation screening tests showed moderately reduced factor XIII/13 (FXIII) activity. During hospitalization, the patient had repeated bleeding events in the gastrointestinal tract and muscles, leading to hemorrhagic shock. We suspected the presence of FXIII inhibitors from FXIII infusion test results. The cross-mixing test for cross-linking of fibrin revealed inhibition of polymerization of α-chain and α2-plasmin inhibitor incorporation into fibrin. In addition, by detecting IgG autoantibody to thrombin-activated FXIII, we confirmed the presence of type Ab anti-FXIII-A subunit autoantibody, which represses the catalytic subunit activity of activated FXIII. Autoimmune FXIII deficiency should be considered when a patient presents with severe hemorrhagic diathesis with no other cause than moderately reduced of FXIII activity, as reported in this case.

Fibrinogen ß chain and FXIII polymorphisms affect fibrin clot properties in acute pulmonary embolism.

BACKGROUND: Prothrombotic fibrin clot properties, including increased clot density, are in part genetically determined. We investigated whether fibrinogen alpha-chain gene (FGA) c.991A>G (rs6050), fibrinogen beta chain gene (FGB) -455G>A (rs1800790) and factor XIII gene (F13) c.103G>T (rs5985) polymorphisms affect plasma fibrin clot properties in patients with acute pulmonary embolism (PE). METHODS: As many as 126 normotensive patients with PE, free of cancer, were genotyped by TaqMan assay. Fibrin clot permeability (Ks ), clot lysis time (CLT) and endogenous thrombin potential (ETP) were assessed on admission. RESULTS: The minor allele frequencies were as follows: FGA rs6050 (n = 62, 0.31), FGB rs1800790 (n = 40, 0.17) and F13 rs5985 (n = 49, 0.23). There were no differences related to any of the polymorphisms with regard to demographic, clinical and laboratory data, except for fibrinogen concentration, which was higher in carriers of F13 rs5985 polymorphism (p = .024), and PE combined with deep-vein thrombosis, which was less prevalent in FGB rs1800790 polymorphism carriers (p = .004). Carriers of FGB rs1800790 A allele and F13 rs5985 T allele had lower Ks , prolonged CLT and higher ETP compared with major homozygotes (all p < .05). After adjustment for fibrinogen, all differences remained significant (all p < .01). There were no associations between the FGA rs6050 polymorphism and Ks , CLT or ETP. CONCLUSION: Our study showed that FGB rs1800790 and F13 rs5985 polymorphisms contribute to the prothrombotic fibrin clot phenotype and these effects are strong enough to be observed in the acute phase of PE.

Fibrin clot quality in acutely ill cirrhosis patients: Relation with outcome and improvement with coagulation factor concentrates.

BACKGROUND & AIMS: Patients with liver disease may acquire substantial changes in their hemostatic system, which are most pronounced in patients who are critically ill. Changes in the quality of the fibrin clot in critically ill patients have not been studied in detail. Here we assessed markers of fibrin clot quality and effects of coagulation factor concentrates in patients with acutely decompensated (AD) cirrhosis and acute on chronic liver failure (ACLF). METHODS: We measured plasma levels of fibrinogen, factor XIII, prothrombin and performed thrombin generation assays in 52 AD patients, 58 ACLF patients and 40 controls. In addition, we examined the effects of coagulation factor concentrates on functional assays of fibrin quality. RESULTS: We found increased thrombin generating capacity in both AD and ACLF in comparison with healthy controls. Plasma levels of prothrombin, fibrinogen, and factor XIII were lower in patients compared to controls, appeared lower in ACLF compared to AD patients, and were related to clinical outcomes. Fibrinogen concentrate, but not factor XIII or prothrombin complex concentrate, improved clot quality in vitro. Prothrombin complex concentrate increased the resistance of the clot to break down. CONCLUSIONS: We have demonstrated elevated thrombin generation but decreased plasma levels of prothrombin, fibrinogen and FXIII in acutely ill patients with cirrhosis. In addition, we showed that fibrinogen concentrate and PCCs, but not factor XIII concentrate, improve clot properties in patient plasma. Whether there is true clinical benefit from coagulation factor concentrates in prevention or treatment of bleeding requires further study. LAY SUMMARY: Patients with liver diseases are at risk of bleeding, but mechanisms involved in this bleeding risk are incompletely understood. We studied components that determine the stability of the blood clot and found that concentrations of certain proteins involved in clot stability are present in low levels in acutely ill patients with liver disease. We furthermore demonstrated that some clinically available drugs improve the stability of blood clots from these patients in a test tube.

The impact of acquired coagulation factor XIII deficiency in traumatic bleeding and wound healing.

Factor XIII (FXIII) is a protein involved in blood clot stabilisation which also plays an important role in processes including trauma, wound healing, tissue repair, pregnancy, and even bone metabolism. Following surgery, low FXIII levels have been observed in patients with peri-operative blood loss and FXIII administration in those patients was associated with reduced blood transfusions. Furthermore, in patients with low FXIII levels, FXIII supplementation reduced the incidence of post-operative complications including disturbed wound healing. Increasing awareness of potentially low FXIII levels in specific patient populations could help identify patients with acquired FXIII deficiency; although opinions and protocols vary, a cut-off for FXIII activity of ~ 60-70% may be appropriate to diagnose acquired FXIII deficiency and guide supplementation. This narrative review discusses altered FXIII levels in trauma, surgery and wound healing, diagnostic approaches to detect FXIII deficiency and clinical guidance for the treatment of acquired FXIII deficiency.

The role of factor XIII in surgery for advanced stage of epithelial ovarian cancer.

INTRODUCTION: Hereditary factor (F) XIII-deficiency is a known risk factor for postoperative complications, but data of acquired FXIII-deficiency in malignancies are limited. Therefore, we evaluated the role of acquired FXIII-deficiency in surgery for advanced epithelial ovarian cancer (EOC). MATERIALS AND METHODS: We performed a retrospective analysis of patients with known serum FXIII status and treatment between 2011 and 2018 at our center. We defined cohorts according to FXIII with values > 75% as normal (group A), 55-75% as reduced (group B) and < 55% as low (group C). Complications were classified according to the Clavien-Dindo Classification, class III-V complications were defined as severe. RESULTS: 347 patients with EOC were identified. 180 patients (51.2%) were in group A, 82 patients (23.6%) in group B, and 85 patients (24.4%) in group C. Lower levels of FXIII were associated with higher amount of ascites, FIGO IV, high grade serous histology, low albumin, and higher CA-125 levels. Regarding intraoperative variables, low FXIII was associated with longer duration of surgery, higher blood loss, higher surgical complexity score/number of bowel anastomosis and a higher probability for macroscopic residual disease. The risk of severe complications in group A was 12.2%, 24.4% in group B, and 31.8% in group C. In a multivariate model, low FXIII (OR 2.8), > 1 bowel anastomosis (OR 2.7), age-adjusted Charlson comorbidity index ≥ 4 (OR 3.6) and a longer duration of surgery (> 285 min.) were significant predictive factors for severe complications. CONCLUSION: FXIII is associated with tumor and treatment burden. A low level of FXIII is associated with postoperative complications. The knowledge about the presurgical serum FXIII-level might be helpful to plan the treatment strategy.

The Effect of Activated FXIII, a Transglutaminase, on Vascular Smooth Muscle Cells.

Plasma factor XIII (pFXIII) is a heterotetramer of FXIII-A and FXIII-B subunits. The cellular form (cFXIII), a dimer of FXIII-A, is present in a number of cell types. Activated FXIII (FXIIIa), a transglutaminase, plays an important role in clot stabilization, wound healing, angiogenesis and maintenance of pregnancy. It has a direct effect on vascular endothelial cells and fibroblasts, which have been implicated in the development of atherosclerotic plaques. Our aim was to explore the effect of FXIIIa on human aortic smooth muscle cells (HAoSMCs), another major cell type in the atherosclerotic plaque. Osteoblastic transformation induced by Pi and Ca2+ failed to elicit the expression of cFXIII in HAoSMCs. EZ4U, CCK-8 and CytoSelect Wound Healing assays were used to investigate cell proliferation and migration. The Sircol Collagen Assay Kit was used to monitor collagen secretion. Thrombospondin-1 (TSP-1) levels were measured by ELISA. Cell-associated TSP-1 was detected by the immunofluorescence technique. The TSP-1 mRNA level was estimated by RT-qPCR. Activated recombinant cFXIII (rFXIIIa) increased cell proliferation and collagen secretion. In parallel, a 67% decrease in TSP-1 concentration in the medium and a 2.5-fold increase in cells were observed. TSP-1 mRNA did not change significantly. These effects of FXIIIa might contribute to the pathogenesis of atherosclerotic plaques.

Recombinant Destabilase from Hirudo medicinalis Is Able to Dissolve Human Blood Clots In Vitro.

Leeches are amazing animals that can be classified as conditionally poisonous animals since the salivary cocktail they produce is injected directly into the victim, and its components have strictly defined biological purposes, such as preventing blood clot formation. Thrombolytic drugs are mainly aimed at treating newly formed blood clots. Aged clots are stabilized by a large number of isopeptide bonds that prevent the action of thrombolytics. These bonds are destroyed by destabilase, an enzyme of the leech's salivary glands. Here, we conducted a pilot study to evaluate the feasibility and effectiveness of the use of destabilase in relation to blood clots formed during real pathological processes. We evaluated the isopeptidase activity of destabilase during the formation of a stabilized fibrin clot. We showed that destabilase does not affect the internal and external coagulation cascades. We calculated the dose-response curve and tested the ability of destabilase to destroy isopeptide bonds in natural blood clots. The effect of aged and fresh clots dissolving ability after treatment with destabilase coincided with the morphological characteristics of clots during surgery. Thus, recombinant destabilase can be considered as a potential drug for the treatment of aged clots, which are difficult to treat with known thrombolytics.

Pathological coagulation parameters in as many as 54 patients with autoimmune acquired factor XIII deficiency due to anti-factor XIII autoantibodies.

INTRODUCTION: Autoimmune factor XIII (FXIII) deficiency (AiF13D) due to anti-FXIII autoantibodies is an extremely rare, life-threatening bleeding disorder that mostly occurs in the elderly. The number of patients diagnosed with AiF13D has been increasing in Japan, probably because of the nationwide survey on AiF13D supported by the Japanese Ministry of Health, Labour and Welfare. AIM: To explore the pathologic characteristics of coagulation parameters in AiF13D. METHODS: AiF13D-suspected cases were consulted, and underwent unified/integrated coagulation screening and were definitively diagnosed as AiF13D separately. RESULTS: AiF13D patients had lower FXIII antigen levels than non-AiF13D patients, but their values overlapped. Among a series of 22-item screening tests and their resulting parameters, the 'FXIII inhibitory potential' yielded by a 1:1 mixing test of the patient's and healthy control's plasma and its 'residual FXIII activity' in 54 AiF13D cases were most distinguishable from 139 non-AiF13D cases, followed by FXIII activity per se and FXIII-specific activity. While the cross-linked α2 -plasmin inhibitor level reduced, the levels of D-dimer, fibrin/fibrinogen degradation products and plasmin-plasmin inhibitor complex increased, probably because the patients' haematoma nonspecifically induced secondary fibrinolysis in both AiF13D and non-AiF13D patients. CONCLUSION: AiF13D appears to induce a hypocoagulopathy combined with a hyper-fibrinolytic state secondary to severe FXIII deficiency caused by anti-FXIII autoantibodies, and the consequent bleeding further modifies its pathological conditions. In addition, the 1:1 mixing test of FXIII activity was confirmed to be a reliable screening method for AiF13D, especially when its derivative parameter, such as the 'FXIII inhibitory potential' or 'FXIII inhibitory potential ratio', is employed.