Elimination of a disulfide bond in the light chain of coagulation factor VIII improves secretion of a BDD-FVIII variant with an engineered inter-chain disulfide / 药学学报

The coagulation VIII factor (FVIII) contains eight pairs of disulfide bonds, which are involved in maintaining its structure and function. It has been demonstrated that the disulfide bond between Cys1899/Cys1903 of the A3 domain in the light chain impedes secretion. In our previous work, an engineered inter-chain disulfide in the B domain-deleted FVIII (BDD-FVIII) promoted heterodimer assembly and secretion of separately expressed heavy and light chains. In this study, we constructed two BDD-FVIII variants, one of which contains an engineered inter-chain disulfide bond (F8C) between Met662 > Cys and Asp1828 > Cys mutations and another contains an endogenous A3 domain with a disrupted disulfide bond from F8C (F8CG) by replacement of Cys1899 and Cys1903 with Gly in F8C. We explored their function and secretion. By transducing F8C and F8CG into HEK293 and COS-7 cells, the formation of disulfide bonds and the secretion and coagulation activity of the two variants in the culture media and their binding affinity for von Willebrand factor (vWF) could be observed. The results show that variants F8C and F8CG are mainly the disulfide bonded heavy and light chain dimer, while the wild type BDD-FVIII (F8) is dominated by the easily dissociated heavy and light chain dimer. The secretion and activity of F8C was significantly higher than that of F8, while the secretion and activity of F8CG was significantly higher than that of F8C. The vWF binding of the two variants is similar to F8. This indicates that the BDD-FVIII variant F8CG may be attractive molecule for protein replacement and as a transgene in gene-therapy strategies. These findings are encouraging for future studies targeting disulfide bond elimination for further enhancement of FVIII secretion.

Human coagulation factor VIII domain-specific recombinant polypeptide expression

BACKGROUND: Hemophilia A is caused by heterogeneous mutations in F8. Coagulation factor VIII (FVIII), the product of F8, is composed of multiple domains designated A1-A2-B-A3-C1-C2. FVIII is known to interact with diverse proteins, and this characteristic may be important for hemostasis. However, little is known about domain-specific functions or their specific binding partners. METHODS: To determine F8 domain-specific functions during blood coagulation, the FVIII domains A1, A2, A3, and C were cloned from Hep3B hepatocytes. Domain-specific recombinant polypeptides were glutathione S-transferase (GST)- or polyhistidine (His)-tagged, over-expressed in bacteria, and purified by specific affinity chromatography. RESULTS: Recombinant polypeptides of predicted sizes were obtained. The GST-tagged A2 polypeptide interacted with coagulation factor IX, which is known to bind the A2 domain of activated FVIII. CONCLUSION: Recombinant, domain-specific polypeptides are useful tools to study the domain-specific functions of FVIII during the coagulation process, and they may be used for production of domain-specific antibodies.

Delivery of Factor VIII Gene into Skeletal Muscle Cells Using Lentiviral Vector

PURPOSE: This study was designed to investigate whether transduction of lentiviral vectors (LV) carrying human coagulation factor VIII (hFVIII) cDNA into skeletal muscle could increase circulating hFVIII concentrations. MATERIALS AND METHODS: A LV containing bacterial LacZ gene as a control or human FVIII gene was intramuscularly administered into the thigh muscle of 5 weeks old Sparague-Dawley rats. The plasma human FVIII concentration and neutralizing anti-FVIII antibodies were measured for up to 12 weeks in these experimental animals. RESULTS: The plasma human FVIII levels in the rats injected with LV carrying FVIII cDNA peaked at post-injection 1st week (5.19 +/- 0.14 ng/mL vs. 0.21 +/- 0.05 ng/mL in control rats , p < 0.05). Elevated hFVIII concentrations were maintained for 4 weeks (2.52 +/- 0.83 ng/mL vs. 0.17 +/- 0.08 ng/mL in control rats, p < 0.05) after a single intramuscular injection. In the Bethesda assay, neutralizing antibodies for FVIII protein were detected only in FVIII-LV injected rats by the 10th week, but not in control rats. CONCLUSION: This study suggested that a single administration of an advanced generation LV carrying the human FVIII cDNA resulted in elevation of FVIII level in immune competent rats, and that this gene transfer approach to the skeletal muscle could be an effective tool in treatment of hemophilia A.

Cloning of the gene encoding human recombinant blood \u2013 coagulation factor WIII

Background: Hemophilia A is a genetic bleeding disorder that results from a deficiency in factor VIII. The prevalence of Hemophilia in Vietnam is rather high (2/34830 people) and Vietnam has high usage demand for factor VIII in the treatment and prevention of the disease. Therefore, it is necessary to study and produce recombinant blood \u2013 coagulation factor WIII. Objective: To clone successfully A1A2 and A3C2 gen fragment encoding factor VIII. Subject and Method: Amplify A1A2 and A3C2 gene fragments by PCR from human cDNA. PCR products were ligated into cloning vector pQE \u2013 30UA. Recombinant plasmids were transformed into E.coli DH5 alpha host strain. Inserted A1A2 and A3C2 gene fragments were checked by PCR and restriction enzymes. Result: Successfully amplifying functional gene fragments encoding factor VIII using specific primers. Conclusion: Obtaining pQE \u2013 30UA vector carrying A1A2 and A3C2 fragments encoding factor VIII. This is the premise result for the next studies on synthesis of recombinant factor WIII and application of genetic therapy.

Recurrent Cerebral Venous Thrombosis Associated with Elevated Factor VIII

Cerebral venous thrombosis (CVT) rarely recurs, and the factors associated with a recurrence remain unclear. Recently, however, elevated plasma coagulation factor VIII has been considered a factor related to recurrent venous thromboembolism. Here we report a patient who had recurrent CVT associated with significantly elevated levels of factor VIII despite the chronic use of an antiplatelet agent. Factor IX was also elevated in this patient. These findings suggest that elevated factor VIII is a factor underlying the recurrence of CVT, and that prolonged anticoagulation therapy may have to be considered in patients with elevated coagulation factor levels.

Anesthetic Management for Patient with Hemophilia A / 대한마취과학회지

Numerous advances have been applied for the management of hemophiliac patients and the life expectancy of them was markedly improved. But they have many problems yet such as transmission of infections, adverse reactions to plasma products, development of factor VIII inhibitor and inadequate coagulation in the medical and/or surgical treatment. Anesthetic care should be managed with gentle, atraumatic intubation and careful positioning of patient pointing to the prevention of bleeding from hemorrhagic diathesis. We present a case of hemophilia A who had in operation for olecranon fracture of left ulna. It is important that anesthesiologist should realize that certain pathophysiological changes, especially coagulation disorders, might be occurred during surgical procedures and that perioperative preparation and management for them should be kept well.