Laboratory diagnosis of dysfibrinogenemia

Guideline for diagnosis and management of congenital dysfibrinogenemia

INTRODUCTION

Congenital dysfibrinogenemia (CD) is characterized by dysfunction induced by an abnormal fibrinogen molecule structure that results in blood coagulation dysfunction. The clinical manifestations of CD patients are asymptomatic, bleeding and thrombosis. The majority of patient are asymptomatic. However, the single fibrinogen detection method is easy to cause missed diagnosis or misdiagnosis of CD patients. The treatment strategies of CD patients with different clinical manifestations are also different.

METHODS

Combing the existing experimental diagnosis technology, literature and our research results, a simple and practical CD diagnostic criteria was proposed. And based on the relevant literature and existing treatment guidelines, more comprehensive treatment recommendations are summarized.

RESULTS

In this new criteria, combination Clauss method and PT derived method was proposed to detect fibrinogen and its ratio was used to diagnose for CD. Diagnosis also needs to be combined the clinical manifestations, family investigation and genetic testing. According to different clinical manifestation (bleeding, thrombosis or asymptomatic), treatment methods and strategies are different. The treatment of CD patients should consider the patient's personal and family history of bleeding or thrombosis. Treatment of thrombosis and pregnancy may be more challenging. The risk of bleeding and thrombosis should be evaluated and balanced at all times during clinical treatment. These detailed treatment recommendations can provide reference for patients with different clinical manifestations of CD.

CONCLUSIONS

The new CD diagnosis criteria and comprehensive treatment recommendations can effectively improve the diagnosis and treatment of CD.

Laboratory Testing for Fibrinogen Disorders: From Routine Investigations to Research Studies

Congenital and acquired fibrinogen disorders often have heterogeneous clinical phenotypes and are challenging from a laboratory perspective. Fibrinogen determination using the Clauss method remains the gold standard, while the reproducibility and significance of the thrombin time and the reptilase time are limited. Molecular testing for causative mutations in fibrinogen genes is now recommended to confirm the diagnosis of congenital fibrinogen disorders. Research assays are used to evaluate alterations to fibrin formation and properties of plasma and purified fibrinogen-derived clots, characterized by fiber thickness, the number of branches, and pore sizes. Fibrin clot permeability (permeation, porosity) using a hydrostatic pressure system represents the most commonly used method for evaluating fibrin network density. Reduced clot permeability, which denotes the reduced size of an average pore in the network, results in tighter fibrin networks, typically associated with impaired susceptibility to lysis, leading to a thrombotic tendency. Biophysical properties of fibrin clots are largely assessed using rheometry, with atomic force microscopy and nanorheology being increasingly used in disease states. Thromboelastography and thromboelastometry, a simple modification of rheometry, have been used, mainly in intensive care units, for more than 50 years. Given growing evidence for altered fibrin clot properties in diseases with elevated risk of venous and arterial thromboembolism and in some bleeding disorders, further work on standardization and validation of the assessment of fibrin clot characteristics is needed. This review summarizes the current methods used to evaluate fibrinogen abnormalities in both diagnostic and research laboratories.

Thrombophilia Screening: Not So Straightforward

Although inherited thrombophilias are lifelong risk factors for a first thrombotic episode, progression to thrombosis is multifactorial and not all individuals with inherited thrombophilia develop thrombosis in their lifetimes. Consequently, indiscriminate screening in patients with idiopathic thrombosis is not recommended, since presence of a thrombophilia does not necessarily predict recurrence or influence management, and testing should be selective. It follows that a decision to undertake laboratory detection of thrombophilia should be aligned with a concerted effort to identify any significant abnormalities, because it will inform patient management. Deficiencies of antithrombin and protein C are rare and usually determined using phenotypic assays assessing biological activities, whereas protein S deficiency (also rare) is commonly detected with antigenic assays for the free form of protein S since available activity assays are considered to lack specificity. In each case, no single phenotypic assay is capable of detecting every deficiency, because the various mutations express different molecular characteristics, rendering thrombophilia screening repertoires employing one assay per potential deficiency, of limited effectiveness. Activated protein C resistance (APCR) is more common than discrete deficiencies of antithrombin, protein C, and protein S and also often detected initially with phenotypic assays; however, some centres perform only genetic analysis for factor V Leiden, as this is responsible for most cases of hereditary APCR, accepting that acquired APCR and rare F5 mutations conferring APCR will go undetected if only factor V Leiden is evaluated. All phenotypic assays have interferences and limitations, which must be factored into decisions about if, and when, to test, and be given consideration in the laboratory during assay performance and interpretation. This review looks in detail at performance and limitations of routine phenotypic thrombophilia assays.

Clinical phenotype and laboratory characteristics of 93 patients with congenital fibrinogen disorders from unrelated 36 families

Background

Congenital fibrinogen disorders (CFDs) are rare bleeding disorders (RBDs) caused by mutations in 1 of the 3 fibrinogen genes (FGA, FGB, and FGG).

Objectives

To investigate the clinical phenotype, laboratory features, diagnosis, treatment, and prognosis of CFDs.

Methods

Clinical data of 93 subjects with CFDs identified from June 2018 to December 2023 were retrospectively analyzed.

Results

Among the 93 patients, there were 46 males (49.5%) and 47 females (50.5%), with a median age of 23 years. Fifty-three of 93 (57%) subjects experienced bleeding, 3/93 (3.2%) experienced thrombosis, and 37/93 (39.8%) were asymptomatic. Females were more prone to experience bleeding (P < .0001). The 93 patients exhibited prolonged thrombin time, significantly decreased fibrinogen activity (Fg:C), and normal or decreased fibrinogen antigen. The 93 patients included 3 with hypofibrinogenemia, 16 with hypodysfibrinogenemia, and 74 with dysfibrinogenemia. Among the 53 patients with bleeding, bleeding episodes were identified in 3.8% (2/53), 20.8% (11/53), and 75.5% (40/53) patients with hypofibrinogenemia, hypodysfibrinogenemia, and dysfibrinogenemia, respectively. Genetic analysis was performed on 22 cases from 8 pedigrees, revealing 10 mutations, including 1 novel splice mutation. Twenty-eight (30.1%) subjects received replacement therapy to treat or prevent bleeding, consisting of 8 fresh frozen plasma transfusions, 3 packing and suture treatment, and 61 fibrinogen infusions.

Conclusion

Most patients with CFDs have mild or no bleeding symptoms. Fg:C combined with fibrinogen antigen and pedigree investigation can improve the feasibility and accuracy of diagnosis of CFDs. The severity of bleeding symptoms was negatively correlated with Fg:C.

Fibrinogen: Structure, abnormalities and laboratory assays

Fibrinogen is the primary precursor protein for the fibrin clot, which is the final target of blood clotting. It is also an acute phase reactant that can vary under physiologic and inflammatory conditions. Disorders in fibrinogen concentration and/or function have been variably linked to the risk of bleeding and/or thrombosis. Fibrinogen assays are commonly used in the management of bleeding as well as the treatment of thrombosis. This chapter examines the structure of fibrinogen, its role in hemostasis as well as in bleeding abnormalities and measurement thereof with respect to clinical management.

Investigation of acquired dysfibrinogenaemia in adult patients with sepsis using fibrinogen function vs. concentration ratios: a cross-sectional study

Introduction

Inherited or acquired molecular abnormalities form a clinically heterogeneous group of fibrinogen disorders called dysfibrinogenaemia. Apart from a pediatric case report and in contrast to other clinical conditions, acquired dysfibrinogenaemia has not been previously reported in septic patients.

Methods

In an observational cohort study, 79 adult septic patients were investigated for the presence of acquired dysfibrinogenaemia at the time of their admission to the intensive care unit (ICU) of the University Hospital Frankfurt. Following established recommendations, fibrinogen clotting activity vs. antigen ratios were analyzed using Clauss fibrinogen, prothrombin-derived fibrinogen, and radial immunodiffusion (RID) fibrinogen concentration.

Results

Prothrombin-derived fibrinogen levels were highest (527 ± 182 mg/dL) followed by Clauss fibrinogen (492 ± 209 mg/dL) and radial immunodiffusion fibrinogen (426 ± 159 mg/dL). Very few cases demonstrated hypofibrinogenaemia making overt disseminated intravascular coagulation (DIC) unlikely in the cohort investigated. Clauss/RID fibrinogen ratios were lower (1.17 ± 0.19) compared to prothrombin time-derived/RID ratios (1.35 ± 0.33). Using the Clauss/RID dataset, 21% of patients (16/76 patients) demonstrated values below a threshold ratio for suspected acquired dysfibrinogenaemia arbitrarily set at 1.0. In contrast, prothrombin-derived ratios were below the threshold in only 7% (4/58 patients).

Discussion

The results point to the presence of acquired dysfibrinogenaemia in part of adult septic patients. If confirmed in further studies, this may form part of a specific laboratory signature of a sepsis-associated coagulation phenotype.

Preoperative Fibrinogen Levels and Function as Predictive Factors for Acute Bleeding in the Hematoma Cavity After Burr Hole Drainage in Patients with CSDH

OBJECTIVE

Burr hole drainage (BHD) is the primary surgical intervention for managing chronic subdural hematoma (CSDH). However, it can lead to postoperative complications such as acute bleeding within the hematoma cavity and hematoma recurrence. The objective of this study is to identify the risk factors for these complications and develop a predictive model for acute hematoma cavity bleeding after BHD in patients with CSDH.

METHODS

This study presents a retrospective cohort investigation conducted at a single center. The clinical dataset of 308 CSDH patients who underwent BHD at a hospital from 2016 to 2022 was analyzed to develop and assess a prognostic model.

RESULTS

The nonbleeding group exhibited a significant correlation between fibrinogen (FIB) and thrombin time (TT), whereas no correlation was observed in the bleeding group. Notably, both FIB and TT were identified as risk factors for postoperative acute bleeding within the hematoma cavity. We developed a prognostic model to predict the occurrence of postoperative acute bleeding within the hematoma cavity after BHD in patients with CSDH. The model incorporated FIB, TT, coronary artery disease, and Glasgow Coma Scale scores. The model exhibited good discrimination (area under the curve: 0.725) and calibration (Hosmer-Leeshawn goodness of fit test: P > 0.1). Furthermore, decision curve analysis demonstrated the potential clinical benefit of implementing this prediction model.

CONCLUSIONS

The predictive model developed in this study can forecast the risk of postoperative acute bleeding within the hematoma cavity, thus aiding clinicians in selecting the optimal treatment approach for patients with CSDH.

Congenital dysfibrinogenemia misdiagnosed and inappropriately treated as acute fatty liver in pregnancy: A case report and review of literature

BACKGROUND

The purpose of this study was to report the rare case of a pregnant woman with congenital dysfibrinogenemia (CD) misdiagnosed as acute fatty liver. She was treated according to the principles of acute fatty liver but achieved good clinical results.

CASE SUMMARY

A 30-year-old woman presented with 39 (6/7) wk of menopause and 6 h of irregular abdominal pain and attended our hospital. Emergency surgery was performed due to fetal distress. Postoperative management followed the treatment principle of acute fatty liver. DNA sequencing was carried out on the pregnant woman and her pedigree. Coagulation values of the patient on admission were prothrombin time 33.7 s, activated partial thromboplastin time 60.4 s, thrombin time 45.2 s, and fibrinogen 0.60 g/L. DNA sequencing results showed that the woman carried a pathogenic heterozygous variation of the fibrinogen alpha chain gene (FGA), which is closely related to hereditary fibrinogen abnormality, and the mutation site was located in p.R350H. After a follow-up period of 12 mo, the mother and her newborn had a good prognosis without bleeding or thrombosis.

CONCLUSION

Pregnant women with CD may have atypical symptoms, which can easily lead to misdiagnosis. In addition, treatment can be attempted according to the principles of acute fatty liver management. This rare pregnant patient with CD was caused by a novel FGA (p.R350H) gene mutation.

Management of congenital dysfibrinogenemia in pregnancy: A challenging patient case

Afibrinogenemia and congenital dysfibrinogenemia (CD) are rare conditions with limited information available for appropriate management. Previous case reports have demonstrated the safe and efficacious use of fibrinogen replacement therapy (FRT) as a therapeutic approach to prevent hemorrhage and fetal loss in pregnant women with CD. In this case report, we present a 28-year-old pregnant woman who sought testing for CD given her family history. She denied any current or previous bleeding symptoms. Laboratory testing confirmed the diagnosis of CD. She was treated with FRT and prophylactic anticoagulation starting in her third trimester. She had preterm labor that prompted an urgent cesarean section with FRT support. This case adds to the sparse literature about fibrinogen disorders in pregnancy, and highlights the benefits, safety, and tolerability of FRT and prophylactic anticoagulation in pregnant women with CD. Finally, it emphasizes the importance of a multidisciplinary team approach for an uneventful delivery.

Dysfibrinogenemia-Potential Impact of Genotype on Thrombosis or Bleeding

The congenital dysfibrinogenemias, most often associated with bleeding disorders, encompass mutations in the amino-terminal end of fibrinogen α-chain consisting of Gly17-Pro18-Arg19-Val20, known as knob A, which is a critical site for fibrin polymerization. Here we review the studies reporting dysfibrinogenemia due to mutations affecting fibrinogen knob A and identified 29 papers. The number of reports on dysfibrinogenemias related to residues Gly17, Pro18, Arg19, and Val20 is 5, 4, 18, and 2, respectively. Dysfibrinogenemias related to residues Gly17, Pro18, and Val20 are exclusively associated with bleeding tendency. However, the clinical picture associated with dysfibrinogenemia related to residue Arg19 varies, with most patients suffering from bleeding tendencies, but also transitory ischemic attacks and retinal thrombosis may occur. The reason for this variation is unclear. To elaborate the genotype-phenotype associations further, we studied a Danish family with knob A-related dysfibrinogenemia caused by the Aα Arg19Gly (p.Arg19Gly) mutation using whole-exome sequencing and fibrin structure analysis. Our family is the first reported carrying the p.Arg19Gly mutation combined with one or more single nucleotide polymorphisms (SNP)s in FGA, FGB, and/or FGG and increased fibrin fiber thickness and fibrin mass-to-length ratio suffering from pulmonary emboli, suggesting that compound genotypes may contribute to the thrombogenic phenotype of these patients. Our review, accordingly, focuses on significance of SNPs, compound genotypes, and fibrin structure measures affecting the genotype-phenotype associations in fibrinogen knob A mutations.

Comparison of different activators of coagulation by turbidity analysis of hereditary dysfibrinogenemia and controls

Turbidity analysis is widely used as a quantitative technique in hereditary dysfibrinogenemia. We aimed to compare several coagulation triggers in hereditary dysfibrinogenemia and control plasmas. We included 20 patients with hereditary dysfibrinogenemia, 19 with hotspot mutations Aα Arg35His (n = 9), Aα Arg35Cys (n = 2), γ Arg301His (n = 6), γ Arg301Cys (n = 2), and one with Aα Phe27Tyr, and a commercial pooled normal plasma. Fibrin polymerization was activated by bovine or human thrombin or tissue factor (TF), in the presence or absence of tissue type plasminogen activator. The lag time (min), slope (mOD/s), maximum absorbance (MaxAbs, mOD), and area under the curve (AUCp, OD s) were calculated from the fibrin polymerization curves and the time for 50% clot degradation (T50, min), AUCf (OD s) and the overall fibrinolytic potential from fibrinolysis curves. The lag time was significantly shorter and AUC increased in Aα Arg35His patients with bovine thrombin as compared with human thrombin. The MaxAbs and AUCp were significantly higher in γArg301His patients with bovine thrombin compared with human thrombin. Fibrin polymerization parameters of patients' samples were closer to those of control when assessed with TF compared with both human and bovine thrombin. T50 and overall fibrinolytic potential were similar in all samples regardless of the coagulation trigger used, however, with TF the AUCf of Aα Arg35His and γ Arg301His groups were significantly decreased compared with control. Bovine and human thrombin cannot be used equally for studying fibrin polymerization in hotspot hereditary dysfibrinogenemia or control plasmas.

Whole Blood Thromboelastometry by ROTEM and Thrombin Generation by Genesia According to the Genotype and Clinical Phenotype in Congenital Fibrinogen Disorders

The outcome of congenital fibrinogen defects (CFD) is often unpredictable. Standard coagulation assays fail to predict the clinical phenotype. We aimed to assess the pheno- and genotypic associations of thrombin generation (TG) and ROTEM in CFD. We measured fibrinogen (Fg) activity and antigen, prothrombin fragments F1+2, and TG by ST Genesia^® with both Bleed- and ThromboScreen in 22 patients. ROTEM was available for 11 patients. All patients were genotyped for fibrinogen mutations. Ten patients were diagnosed with hypofibrinogenemia, nine with dysfibrinogenemia, and three with hypodysfibrinogenemia. Among the 17 mutations, eight were affecting the Fg γ chain, four the Fg Bβ chain, and five the Fg Aα chain. No statistical difference according to the clinical phenotypes was observed among FGG and FGA mutations. Median F1+2 and TG levels were normal among the different groups. Fg levels correlated negatively with F1+2 and peak height, and positively with lag time and time to peak. The pheno- and genotypes of the patients did not associate with TG. FIBTEM by ROTEM detected hypofibrinogenemia. Our study suggests an inverse link between low fibrinogen activity levels and enhanced TG, which could modify the structure–function relationship of fibrin to support hemostasis.

Unexpected, isolated activated partial thromboplastin time prolongation: A practical mini-review

A common inquiry in coagulation laboratories is how to interpret an unexpected, isolated prolonged activated partial thromboplastin time (APTT). In this context, isolated means together with a normal prothrombin time (PT) and/or normal international normalized ratio (INR). This finding may lead to contact with laboratory doctors for further advice on a diagnostic strategy. Occasionally, the need for a diagnostic algorithm can be subacute, where surgery has to be postponed until an explanation for the isolated, prolonged APTT has been established. Activated partial thromboplastin time as a coagulation test was developed to monitor patients with hemophilia. Different APTT reagents display considerable differences in their sensitivity to deficiencies of coagulation factors. An isolated, prolonged APTT is seen in (a) individuals/patients with lupus anticoagulants, (b) patients in treatment with anticoagulants, mainly heparin, and (c) patients with deficiencies of specific coagulation factors. In this tutorial review, we summarize what may cause an isolated prolonged APTT and we present a simple diagnostic algorithm to differentiate between lupus anticoagulants (common) and factor deficiencies (rare). The identification of an isolated prolonged APTT as well as the underlying cause can be of the utmost importance in ensuring the correct therapeutic follow-up.

Tigecycline Interferes with Fibrinogen Polymerization Independent of Peripheral Interactions with the Coagulation System

Tigecycline offers broad anti-bacterial coverage for critically ill patients with complicated infections. A described but less researched side effect is coagulopathy. The aim of this study was to test whether tigecycline interferes with fibrinogen polymerization by peripheral interactions. To study the effect of unmetabolized tigecycline, plasma of healthy volunteers were spiked with increasing concentrations of tigecycline. In a second experimental leg, immortalized human liver cells (HepG2) were treated with the same concentrations to test an inhibitory effect of hepatic tigecycline metabolites. Using standard coagulation tests, only the activated thromboplastin time in humane plasma was prolonged with increasing concentrations of tigecycline. Visualization of the fibrin network using confocal live microscopy demonstrated a qualitative difference in tigecycline treated experiments. Thrombelastometry and standard coagulation tests did not indicate an impairment of coagulation. Although the discrepancy between functional and immunologic fibrinogen levels increased in cell culture assays with tigecycline concentration, fibrinogen levels in spiked plasma samples did not show significant differences determined by functional versus immunologic methods. In our in vitro study, we excluded a direct effect of tigecycline in increasing concentrations on blood coagulation in healthy adults. Furthermore, we demonstrated a rapid loss of mitochondrial activity in hepatic cells with supra-therapeutic tigecycline dosages.

Congenital fibrinogen disorders with repeated thrombosis

Congenital dysfibrinogenemia is characterized with undetectable or low fibrinogen level by Clauss assay complicated by bleeding and/or thrombosis. These may lead to a diagnostic problem to some clinicians unfamiliar with this disease. We reported a case of congenital dysfibrinogenemia manifested as hemorrhage, repeated thrombosis, low fibrinogen levels through Clauss assay and but normal levels of fibrinogen through PT-derived tests. In conclusion, to patients with thrombosis complicated by decreased fibrinogen level, clinicians and laboratory physicians should be alert to the possibility of congenital dysfibrinogenemia.

The central role of thrombin in bleeding disorders

Maintaining normal hemostasis relies on a regulated system of procoagulant and anticoagulant pathways, and disruption of these processes leads to the loss of hemostatic control, with the potential for excessive bleeding or thrombosis. Evaluation of bleeding disorders has conventionally been achieved by laboratory assays that measure the activity of individual coagulation factors. While such assays have proven effective for detecting abnormalities of the coagulation system and aiding diagnosis, inherent limitations prevent them from capturing a complete picture of hemostatic function. An improved understanding of thrombin activity and its central role in hemostasis and bleeding disorders has led to the clinical development of global assays that are more physiologically relevant than traditional assays; furthermore, these global assays are able to monitor responses to therapy. In this review, we provide an overview of the role of thrombin in hemostasis, and describe the clinical benefits of thrombin monitoring in patients with bleeding disorders. Moreover, we discuss recent advances in thrombin-targeting therapeutic strategies that aim to correct thrombin deficiency and prevent bleeding in patients with hemophilia and other rare bleeding disorders.

Modified approach to fibrinogen replacement in the setting of dysfibrinogenaemia

Most fibrinogen replacement strategies focus on quantitative deficiencies. A thrombin time (TT) mixing study helped to assess qualitative defects caused by dysfibrinogens. Plasma samples were collected from non-anticoagulated subjects (n=6) meeting laboratory criteria for suspected dysfibrinogenaemia (TT > 22 s; fibrinogen activity <180) and from a control group. TT mixing studies were performed on subject plasma with increasing volumes of pooled normal plasma at 1:2, 1:4 and 1:5 dilutions. No subjects with dysfibrinogenaemia demonstrated a complete TT correction at 1:2, but 50% corrected at 1:4 and 100% at 1:5 dilution. Based on these data, a correction factor (CF), defined as the reciprocal dilution yielding complete correction, was incorporated into our clinical practice formula for fibrinogen dosing in patients with dysfibrinogenaemias. Our study incorporates TT mixing studies for assessment of dysfibrinogens. The addition of a mix-derived CF to classical formulae may better approximate dosing in patients with dysfibrinogenaemia.

Attenuation of Thrombin-Mediated Fibrin Formation via Changes in Fibrinogen Conformation Induced by Reaction with S-nitroso-N-acetylpenicillamine, but not S-nitrosoglutathione

Previous work in a 4 h rabbit thrombogenicity model has shown that a nitric oxide- (NO) generating polymer extracorporeal circuits (ECC) with infusion of S-nitroso-N-acetyl-penicillamine (SNAP) preserved platelets eventhough platelets were activated as shown by an increase in the glycoprotein, p-selectin. The platelet preservation mechanism was shown to be due to a changing fibrinogen structure leading to attenuation of platelet aggregation. Understanding the effects that SNAP, another RSNO, S-nitroso-glutathione (GSNO) as well as the non-RSNO, sodium nitroprusside (SNP), may have on human fibrinogen polymerization, this in vitro study evaluated the released NO effects on the thrombin-mediated fibrin formation and fibrinogen structure. Thrombin-induced fibrin formation at 300 μM SNAP (50 + 11% of baseline) was significantly reduced compared to SNAP's parent, N-acetyl-penicillamine (NAP) (95 + 13%) after 1 h of RSNO exposure. GSNO, its parent, glutathione (GSH) and 1000 ppm NO gas did not attenuate the thrombin-mediated fibrin formation. SNAP, NAP and SNP exposure for 1 h, however, did not decrease thrombin activity by directly inhibiting thrombin itself. Changes in fibrinogen conformation as measured by intrinsic tryptophan fluorescence significantly decreased in the 300 μM SNAP (38057 + 1196 mean fluorescence intensity (MFI) and SNP (368617 + 541 MFI) groups versus the NAP control (47937 + 1196 MFI). However, infused 1000 ppm NO gas had no direct effect on the ITF after 1 h incubation at 37°C. High performance liquid chromatography (HPLC) showed that fibrinogen degradation by 0.03 U/ml thrombin was concentration-dependently reduced after 1 h with SNAP but not with NAP or SNP. Western blotting showed RSNOs, SNAP, NAP and the non-RSNO, SNP-incubated fibrinogen solutions showed that the percent level of the Aγ dimer to total Aγ dimer + γ monomer was significantly reduced in the case of the SNAP group when compared to SNP group. These results suggest that NO donors such as SNAP and SNP induce fibrinogen conformational changes by potentially nitrosating fibrinogen tyrosine residues. These NO-mediated fibrinogen changes induced via NO donors may provide another mechanism of NO for improving thromboresistance in ECC.

A novel fibrinogen variant in a Chinese pedigree with congenital dysfibrinogenemia caused by FGA P. Arg38Thr mutation: A case report

RATIONALE

Congenital dysfibrinogenemia (CD) is characterized by altered functional properties of the fibrinogen; people who suffer from CD often have a low activity of fibrinogen and the mutation in the genomic DNA.

PATIENT CONCERNS

A 6-year-old child was examined with a low activity of fibrinogen measured by Von Clauss method and PT-derived method which indicated a normal level of fibrinogen; this abnormality was also detected in her mother. The genomic DNA of all the family members was extracted, and all exons of 3 fibrinogen genes which encode fibrinogen alpha chain (FGA), fibrinogen beta chain (FGB), and fibrinogen gamma chain (FGG) were amplified by polymerase chain reaction (PCR), in addition, sanger sequencing, homologous sequence alignment and bioinformatics software were performed for the further analysis.

DIAGNOSES

CD in this pedigree is associated with c.113G>C in the exon 2 of FGA which caused Arg38Thr mutation.

OUTCOMES

The child and her mother showed a low plasma concentration of fibrinogen measured by Von Clauss method, whereas a normal result measured by PT-derived method; finally, c.113G>C in the exon 2 of FGA was detected in the pedigree which caused Arg38Thr mutation and it is the first report on a pedigree with CD caused by AαArg38Thr.

LESSONS

This case gives us the lesson that not all patients with CD showed typical symptoms and laboratory test results; the result of fibrinogen concentration and antigen which is tested by Von Clauss method and immunoturbidimetric assay is various according to the condition of each CD patient.

A novel fibrinogen mutation: FGA g. 3057 C > T (p. Arg104 > Cys) impairs fibrinogen secretion

Background

Abnormal fibrinogens can be caused by clinically silent hereditary mutations. A new case was detected accidentally in an 11-year-old girl when routine pre-operative coagulation tests were performed for nasal turbinate surgery.

Methods

The fibrinogen genes FGA, FGG and FGB were sequenced using standard protocols. The kinetics of fibrin formation were followed by turbidity at 350 nm. Purified fibrinogen was incubated with plasmin, and the degradation products analyzed by SDS/PAGE. The formation of fibrinogen-albumin complexes was analyzed by immunobloting. Fibrin structure was examined in a Nikon Eclipse TE 2000-U laser microscope. Secretion of the variant protein was analyzed directly by reverse phase-electrospray time of flight-mass spectrometry (TOF-MS).

Results

DNA sequencing revealed a novel heterozygous g. 3057 C > T mutation in the FGA that predicts a p. Arg104 > Cys substitution, in the proband and her father. Both patients were asymptomatic with low functional and antigen fibrinogen concentrations. The proband's plasma fibrinogen polymerization was almost normal, with a 12% decrease in the final turbidity, while, the father's fibrin formation had a diminished slope and final turbidity (2.5× and 40%, respectively). Aα Arg104 is located at a plasmin cleavage site in the coiled-coil region of fibrinogen. However, the father's fibrinogen plasmin degradation was normal. Although the exchanged Cys introduces an unpaired -SH, immunoblotting showed no fibrinogen-albumin complexes. Furthermore, the plasma clot structure observed by confocal microscopy appeared almost normal. TOF-MS showed that the variant Aα chain was underrepresented in plasma and made up only about 25% of the total.

Conclusions

The low expression of the Aα Arg104 > Cys chain in circulation could account for the observed hypodysfibrinogenemia.

Management of dysfibrinogenemia in pregnancy: A case report

BACKGROUND

Dysfibrinogenemia is a rare coagulation disorder caused by mutations in the fibrinogen gene that results in abnormal fibrinogen function. Dysfibrinogenemia has a wide spectrum of clinical manifestations including asymptomatic(55%), hemorrhage (25%), and thrombosis (20%).

METHODS

We reported a 30-year-old woman with 35 weeks gestation. She was misdiagnosed with hypofibrinogenemia in a local hospital, and then she was treated with fibrinogen concentrate. However, she was diagnosed as dysfibrinogenemia in our hospital base on her low function fibrinogen level (0.55 g/L) and her normal immunologic fibrinogen level (3.80 g/L). This patient had neither bleeding symptom nor thromboembolic event. Her obstetrical history included one normal pregnancy in 2008 with uneventful full-term delivery.

RESULTS

Multidisciplinary experts suggested that there should be no specific intervention in this case because of the patient had no previous episodes of abnormal bleeding or thrombotic. She had an uneventful delivery with no abnormal bleeding symptom or thromboembolic.

CONCLUSION

Dysfibrinogenemia patients without personal or family history of bleeding and thromboembolic events, do not need specific therapeutic intervention.

Combined use of Clauss and prothrombin time-derived methods for determining fibrinogen concentrations: Screening for congenital dysfibrinogenemia

BACKGROUND

In this study, the significance of fibrinogen concentration assessed by a combination of Clauss and prothrombin time (PT)-derived methods for screening for congenital dysfibrinogenemia were investigated, and the screening efficiency of fibrinogen PT-derived/Clauss ratio on congenital dysfibrinogenemia was analyzed.

METHODS

We compared fibrinogen concentrations determined by the Clauss, PT-derived, and enzyme-linked immunosorbent assay (ELISA) methods in 73 patients with congenital dysfibrinogenemia and 81 normal controls. Receiver operating characteristic (ROC) curves were utilized to evaluate the efficacy of fibrinogen PT-derived/Clauss ratio in screening for congenital dysfibrinogenemia.

RESULTS

Fibrinogen concentrations determined by the Clauss method were dramatically lower than by the PT-derived method and ELISA, and correlated poorly with the latter two methods in patients with congenital dysfibrinogenemia. Fibrinogen concentrations in normal controls were slightly lower according to the Clauss method than to the PT-derived method and ELISA; however, each method yielded results within the normal range and the correlation was good. The area under the ROC curve of fibrinogen PT-derived/Clauss ratio for diagnosis of congenital dysfibrinogenemia was 1 with a standard error of 0, 95% confidence interval of 0.976-1.00, and optimal critical diagnosis point of 1.43. When fibrinogen PT-derived/Clauss ratio was >1.43, the sensitivity and specificity for diagnosis of congenital dysfibrinogenemia were both 100%.

CONCLUSIONS

The combined use of Clauss and PT-derived methods for determining fibrinogen concentrations improves the efficiency of screening for congenital dysfibrinogenemia, as the fibrinogen PT-derived/Clauss ratio has high sensitivity and specificity in diagnosis of congenital dysfibrinogenemia. This ratio could serve an important screening tool for this disease.

GLADIATOR: a global approach for elucidating disease modules

BACKGROUND

Understanding the genetic basis of disease is an important challenge in biology and medicine. The observation that disease-related proteins often interact with one another has motivated numerous network-based approaches for deciphering disease mechanisms. In particular, protein-protein interaction networks were successfully used to illuminate disease modules, i.e., interacting proteins working in concert to drive a disease. The identification of these modules can further our understanding of disease mechanisms.

METHODS

We devised a global method for the prediction of multiple disease modules simultaneously named GLADIATOR (GLobal Approach for DIsease AssociaTed mOdule Reconstruction). GLADIATOR relies on a gold-standard disease phenotypic similarity to obtain a pan-disease view of the underlying modules. To traverse the search space of potential disease modules, we applied a simulated annealing algorithm aimed at maximizing the correlation between module similarity and the gold-standard phenotypic similarity. Importantly, this optimization is employed over hundreds of diseases simultaneously.

RESULTS

GLADIATOR's predicted modules highly agree with current knowledge about disease-related proteins. Furthermore, the modules exhibit high coherence with respect to functional annotations and are highly enriched with known curated pathways, outperforming previous methods. Examination of the predicted proteins shared by similar diseases demonstrates the diverse role of these proteins in mediating related processes across similar diseases. Last, we provide a detailed analysis of the suggested molecular mechanism predicted by GLADIATOR for hyperinsulinism, suggesting novel proteins involved in its pathology.

CONCLUSIONS

GLADIATOR predicts disease modules by integrating knowledge of disease-related proteins and phenotypes across multiple diseases. The predicted modules are functionally coherent and are more in line with current biological knowledge compared to modules obtained using previous disease-centric methods. The source code for GLADIATOR can be downloaded from http://www.cs.tau.ac.il/~roded/GLADIATOR.zip .

Congenital afibrinogenemia: from etiopathogenesis to challenging clinical management

INTRODUCTION

Congenital afibrinogenemia belongs to the group of autosomal recessive bleeding disorders and represents the absolute deficiency of fibrinogen detected by an antigenic test. This can lead to severe clinical manifestations of the disorder. Therefore, it is very important to take afibrinogenemia into account in the process of the differential diagnostics of the patients.

AREAS COVERED

The authors provide a summary of currently available literature about afibrinogenemia. They collected the information from the scientific journals dedicated to thrombosis and hemostasis and searched world-wide databases. Expert commentary: The most frequent clinical manifestation of this disorder is mucosal bleeding, but musculoskeletal bleeding pattern, gynecologic and obstetric issues, spontaneous bleeding, episodes provoked by minor injury or any other intervention, and even paradoxical thromboembolic events have been published. Afibrinogenemia is the consequence of mutations of the homozygous or compound heterozygous type in gene FGA, FGB or FGG encoding fibrinogen. Pregnant women with a family history, or with a history of consanguinity ought to be properly counselled. However, primary prophylaxis of bleeding events is not suggested. The article deals with actual information about afibrinogenemia contributing to its early diagnosis and effective treatment, which in many cases requires multidisciplinary approach.

A novel mutation in exon 2 of FGB caused by c.221G>T † substitution, predicting the replacement of the native Arginine at position 74 with a Leucine (p.Arg74Leu † ) in a proband from a Kurdish family with dysfibrinogenaemia and familial venous and arterial thrombosis

Dysfibrinogenaemias may present in either congenital or acquired form and are disorders of fibrinogen structure which may or may not be associated with abnormal function. More than 100 point mutations with single amino acid substitutions have been identified in over 400 families. These lead to defective DNA in the translated fibrinogen molecule. Such cases have improved our understanding of the fibrinogen–fibrin structure. Six members of a consanguineous family including a female proband, a female sibling, three male siblings and a daughter, with ages between 29 years and 53 years presented with early onset venous and premature arterial thromboembolic disease were investigated for a pro-thrombotic tendency associated with dysfibrinogenaemia. The family was investigated using standard coagulation assays and DNA sequencing of the genes encoding the FGA, FGB and FGG. All cases have dysfibrinogenaemia with a fibrinogen level 1.4 to 1.5 (1.9–4.3 g/L). Thrombophilia testing (including AT, PS & PC, F5 G1691A (FV Leiden)/F2 (prothombin G20210A) genotypes, homocysteine, antiphosphlipid antibody, paroxysmal nocturnal haemoglobinuria by flow cytometry and Janus Kinase-2 (exon 14)) were normal. PCR amplification and sequencing of exon 2 of FBG revealed a heterozygous mutation for a c.221G> T^†substitution, predicting the replacement of the native Arginine at position 74 with a Leucine (p.Arg74Leu^†). In silico analysis of p.Arg74Leu strongly support pathogenicity. A novel mutation was identified in exon 2 of FGB caused by c.221G> T^† substitution, predicting the replacement of Arginine at position 74 with a Leucine (p.Arg74Leu^†) in a proband from a Kurdish family with dysfibrinogenaemia and familial venous and arterial thrombosis.

The amplitude of coagulation curves from thrombin time tests allows dysfibrinogenemia caused by the common mutation FGG-Arg301 to be distinguished from hypofibrinogenemia

INTRODUCTION

Thrombin time (TT) tests are useful for diagnosing coagulation disorders involving abnormal fibrinogen but do not allow us to distinguish between qualitative and quantitative defects. However, with the widening availability of optical coagulation automates, more information about the coagulation process is becoming increasingly accessible.

METHODS

In this study, we compared the coagulation curves of TT tests carried out with plasma from healthy donors with those from patients with acquired low Clauss fibrinogen levels or with dysfibrinogenemia caused by a heterozygous point mutation in the fibrinogen γ-chain that results in a p.Arg301(275)Cys substitution. The functional fibrinogen levels of these three groups of samples were also measured with the Clauss method, and their fibrinogen protein levels were determined by ELISA.

RESULTS

Our data indicate that the amplitude and maximal velocity of coagulation curves from plasma samples from FGG p.Arg301(275)Cys dysfibrinogenemic patients were comparable to those from plasma samples with fibrinogen in the normal range, whereas the amplitude of coagulation curves from patients with acquired low fibrinogen levels was lower.

CONCLUSIONS

Examination of the amplitude of coagulation curves generated during TT tests may provide additional information to enable the differential diagnoses of diseases following a low fibrinogen measurement by the Clauss method.

Determination of Fibrinogen and Thrombin Time (TT)

Fibrinogen is measured in plasma most commonly using the Clauss method, based on the comparison of thrombin clotting times of dilutions of plasma against a plasma standard. Thrombin time (TT) is a coagulation assay, which reflects the conversion of fibrinogen to fibrin after addition of thrombin reagent. Measurement of clottable fibrinogen and TT allows detecting inborn (congenital) and acquired qualitative and quantitative disorders of fibrinogen that can lead to thrombotic or bleeding events.

A novel mutation in the fibrinogen Aα chain (Gly13Arg, fibrinogen Nanning) causes congenital dysfibrinogenemia associated with defective peptide A release

Dysfibrinogenemia is characterized by blood coagulation dysfunction induced by an abnormal molecular structure of fibrinogen. Here, we describe a new case. A 32-year-old female was suspected of having dysfibrinogenemia during routine laboratory screening, based on her decreased functional fibrinogen level, normal fibrinogen antigen level, and prolonged thrombin time. We extracted DNA and performed polymerase chain reaction and DNA sequencing to identify genetic mutation. Fibrin polymerization, the kinetics of the fibrinopeptide release, scanning electron microscopy, mass spectrometric analysis, fibrin cross-linking, sodium dodecyl sulfate polyacrylamide gel electrophoresis and western blot were conducted. DNA sequencing identified a heterozygous point mutation, Gly13Arg in Aα chain. Fibrin polymerization was markedly impaired (prolonged lag phase and decreased final turbidity). The rate and extent of fibrinopeptide A release from the patient were abnormal and reduced. The mass spectrometry analysis revealed the presence of mutant fibrinogen chains in the patient's circulation. Electron micrographs revealed abnormal fibrin clots. Fibrin cross-linking was normal. Sodium dodecyl sulfate polyacrylamide gel electrophoresis and western blot showed no difference. We report a new case with a mutation in the fibrinopeptide A region, AαGly13Arg. These results indicated that the functional abnormalities were related to delayed and defective fibrinopeptide A cleavage and likely impaired thrombin binding.

Acquired hypofibrinogenemia: current perspectives

Acquired hypofibrinogenemia is most frequently caused by hemodilution and consumption of clotting factors. The aggressive replacement of fibrinogen has become one of the core principles of modern management of massive hemorrhage. The best method for determining the patient's fibrinogen level remains controversial, and particularly in acquired dysfibrinogenemia, could have major therapeutic implications depending on which quantification method is chosen. This review introduces the available laboratory and point-of-care methods and discusses the relative advantages and limitations. It also discusses current strategies for the correction of hypofibrinogenemia.

Structural properties of fracture haematoma: current status and future clinical implications

Blood clots (haematomas) that form immediately following a bone fracture have been shown to be vital for the subsequent healing process. During the clotting process, a number of factors can influence the fibrin clot structure, such as fibrin polymerization, growth factor binding, cellular infiltration (including platelet retraction), protein concentrations and cytokines. The modulation of the fibrin clot structure within the fracture site has important clinical implications and could result in the development of multifunctional scaffolds that mimic the natural structure of a haematoma. Artificial haematoma structures such as these can be created from the patient's own blood and can therefore act as an ideal bone defect filling material for potential clinical application to accelerate bone regeneration. Copyright © 2016 John Wiley & Sons, Ltd.

Can the phenotype of inherited fibrinogen disorders be predicted?

Congenital fibrinogen disorders are rare diseases affecting either the quantity (afibrinogenaemia and hypofibrinogenaemia) or the quality (dysfibrinogenaemia) or both (hypodysfibrinogenaemia) of fibrinogen. In addition to bleeding, unexpected thrombosis, spontaneous spleen ruptures, painful bone cysts and intrahepatic inclusions can complicate the clinical course of patients with quantitative fibrinogen disorders. Clinical manifestations of dysfibrinogenaemia include absence of symptoms, major bleeding or thrombosis as well as systemic amyloidosis. Although the diagnosis of any type of congenital fibrinogen disorders is usually not too difficult with the help of conventional laboratory tests completed by genetic studies, the correlation between all available tests and the clinical manifestations is more problematic in many cases. Improving accuracy of diagnosis, performing genotype, analysing function of fibrinogen variants and carefully investigating the personal and familial histories may lead to a better assessment of patients' phenotype and therefore help in identifying patients at increased risk of adverse clinical outcomes. This review provides an update of various tests (conventional and global assays, molecular testing, fibrin clot analysis) and clinical features, which may help to better predict the phenotype of the different types of congenital fibrinogen disorders.

Fibrin clot structure in patients with congenital dysfibrinogenaemia

The clinical phenotype of patients with congenital dysfibrinogenaemia is highly heterogeneous, from absence of symptoms to mild bleeding, or thrombosis. A few mutations are associated with a specific phenotype, but generally the clinical course is not predictable. We investigated whether fibrin clot properties are correlated with the patient's phenotype and/or genotype. Ex vivo plasma fibrin clot characteristics, including turbidity, fibrinolysis, clot permeability and fibrin fibre density assessed by laser scanner confocal microscopy were investigated in 24 genotyped patients with congenital dysfibrinogenaemia compared to normal pool plasma. Compared to normal pool plasma, the patients were characterised by slower fibrin polymerisation (lag time, 345.10 ± 22.98 vs. 166.00s), thinner fibrin fibres (maximum absorbance, 0.15 ± 0.01 vs. 0.31), prolonged clot lysis time (23.72 ± 0.97 vs. 20.32 min) and larger clot pore size (21.5×10(-9) ± 4.48×10(-9) vs. 7.96×10(-9)cm(2)). Laser scanning confocal microscopy images confirmed disorganised fibrin networks in all patients. Patients with tendency to bleed showed an increased permeability compared to asymptomatic patients (p=0.01) and to patients with a thrombotic history (p=0.02) while patients with thrombotic history had a tendency to have a prolonged clot lysis time. Fibrin clot properties were similar among hotspot mutations. Further studies including a larger number of patients are needed to evaluate whether analysis of permeability and clot lysis time may help to distinguish the clinical phenotype in these patients and to assess differences according to the genotype.

Prothrombin Time and Activated Partial Thromboplastin Time Testing: A Comparative Effectiveness Study in a Million-Patient Sample

Background

A substantial fraction of all American healthcare expenditures are potentially wasted, and practices that are not evidence-based could contribute to such waste. We sought to characterize whether Prothrombin Time (PT) and activated Partial Thromboplastin Time (aPTT) tests of preoperative patients are used in a way unsupported by evidence and potentially wasteful.

Methods and Findings

We evaluated prospectively-collected patient data from 19 major teaching hospitals and 8 hospital-affiliated surgical centers in 7 states (Delaware, Florida, Maryland, Massachusetts, New Jersey, New York, Pennsylvania) and the District of Columbia. A total of 1,053,472 consecutive patients represented every patient admitted for elective surgery from 2009 to 2012 at all 27 settings. A subset of 682,049 patients (64.7%) had one or both tests done and history and physical (H&P) records available for analysis. Unnecessary tests for bleeding risk were defined as: PT tests done on patients with no history of abnormal bleeding, warfarin therapy, vitamin K-dependent clotting factor deficiency, or liver disease; or aPTT tests done on patients with no history of heparin treatment, hemophilia, lupus anticoagulant antibodies, or von Willebrand disease. We assessed the proportion of patients who received PT or aPTT tests who lacked evidence-based reasons for testing.

Conclusions

This study sought to bring the availability of big data together with applied comparative effectiveness research. Among preoperative patients, 26.2% received PT tests, and 94.3% of tests were unnecessary, given the absence of findings on H&P. Similarly, 23.3% of preoperative patients received aPTT tests, of which 99.9% were unnecessary. Among patients with no H&P findings suggestive of bleeding risk, 6.6% of PT tests and 7.1% of aPTT tests were either a false positive or a true positive (i.e. indicative of a previously-undiagnosed potential bleeding risk). Both PT and aPTT, designed as diagnostic tests, are apparently used as screening tests. Use of unnecessary screening tests raises concerns for the costs of such testing and the consequences of false positive results.

Dysfibrinogenemia: from molecular anomalies to clinical manifestations and management

Congenital dysfibrinogenemia is a qualitative congenital fibrinogen disorder characterized by normal antigen levels of a dysfunctional fibrinogen. The diagnosis is usually based on discrepancies between fibrinogen activity and antigen levels, but could require more specialized techniques for the assessment of fibrinogen function, owing to some limitations in routine assays. Molecular abnormalities, which are frequently heterozygous missense mutations localized in exon 2 of FGA and exon 8 of FGG, lead to defects in one or more phases of fibrinogen to fibrin conversion, fibrin network formation, and other important functions of fibrinogen. The clinical phenotype is highly heterogeneous, from no manifestations to bleeding and/or thrombotic events. Asymptomatic propositi and relatives with the predisposing genotype are at risk of developing adverse outcomes during the natural course of the disease. Correlations between genotype and phenotype have not yet been clearly established, with the exception of some abnormal fibrinogens that severely increase the risk of thrombosis. Functional analysis of polymerization and fibrinolysis, structural studies of the fibrin network and the viscoelastic properties of fibrin clot could help to predict the phenotype of congenital dysfibrinogenemia, but have not yet been evaluated in detail. The management is essentially based on personal and family history; however, even individuals who are still asymptomatic and without a family history should be carefully assessed and monitored. Particular situations, such as pregnancy, delivery, and surgery, require a multidisciplinary approach.

Subacute Oral Toxicity of Yukmijiwhang-Tang in Crl:CD Sprague-Dawley Rats and Its Cytotoxicity

Background. The traditional herbal formula Yukmijiwhang-tang (YMJ) consists of six medicinal herbs and has been used to treat dysuria, diabetic mellitus, and neurosis in Korea, China, and Japan. Here we report safety information on its subacute toxicity and the cytotoxicity. Methods. YMJ extract was administered to SD rats at various dosages for 4 weeks. We monitored clinical signs, mortality, body and organ weights, food intake, and hematological and serum biochemistry factors. For cytotoxicity testing, each cell line was treated with various concentrations of YMJ for 24 h. Results. YMJ treatment had no significant effects on changes in clinical signs, body weight, or food intake in male or female rats. In male rats, YMJ treatment decreased the absolute weights of the epididymides and serum Na levels. In female rats, YMJ significantly reduced the prothrombin time (PT) and serum creatine level. However, the changes were not severe and were considered to be in the normal physiological range for rats. The no-observed-adverse-effect-level (NOAEL) was estimated to be 2000 mg/kg/day. YMJ extract did not exert any cytotoxicity against 23 tested cell lines. Conclusions. Our data provide scientific evidence on the safety of YMJ for potential development as a prescription drug.

Hypercoagulable states: an algorithmic approach to laboratory testing and update on monitoring of direct oral anticoagulants

Hypercoagulability can result from a variety of inherited and, more commonly, acquired conditions. Testing for the underlying cause of thrombosis in a patient is complicated both by the number and variety of clinical conditions that can cause hypercoagulability as well as the many potential assay interferences. Using an algorithmic approach to hypercoagulability testing provides the ability to tailor assay selection to the clinical scenario. It also reduces the number of unnecessary tests performed, saving cost and time, and preventing potential false results. New oral anticoagulants are powerful tools for managing hypercoagulable patients; however, their use introduces new challenges in terms of test interpretation and therapeutic monitoring. The coagulation laboratory plays an essential role in testing for and treating hypercoagulable states. The input of laboratory professionals is necessary to guide appropriate testing and synthesize interpretation of results.

Development and hemocompatibility testing of nitric oxide releasing polymers using a rabbit model of thrombogenicity

Hemocompatibility is the goal for any biomaterial contained in extracorporeal life supporting medical devices. The hallmarks for hemocompatibility include nonthrombogenicity, platelet preservation, and maintained platelet function. Both in vitro and in vivo assays testing for compatibility of the blood/biomaterial interface have been used over the last several decades to ascertain if the biomaterial used in medical tubing and devices will require systemic anticoagulation for viability. Over the last 50 years systemic anticoagulation with heparin has been the gold standard in maintaining effective extracorporeal life supporting. However, the biomaterial that maintains effective ECLS without the use of any systemic anticoagulant has remained elusive. In this review, the in vivo 4-h rabbit thrombogenicity model genesis will be described with emphasis on biomaterials that may require no systemic anticoagulation for extracorporeal life supporting longevity. These novel biomaterials may improve extracorporeal circulation hemocompatibility by preserving near resting physiology of the major blood components, the platelets and monocytes. The rabbit extracorporeal circulation model provides a complete assessment of biomaterial interactions with the intrinsic coagulation players, the circulating platelet and monocytes. This total picture of blood/biomaterial interaction suggests that this rabbit thrombogenicity model could provide a standardization for biomaterial hemocompatibility testing.