Response of Factor VIII and IX-Deficient Blood to Wild Type and High Membrane Affinity Mutant Factor VIIa in an In Vitro Whole Blood Clotting Assay: Possible Correlation to Clinical Outcome

Henderson, Nicole; Key, Nigel S.; Christie, Beverly; Kisiel, Walter; Foster, Donald C.; Nelsestuen, Gary L.

doi:10.1055/s-0037-1613160

Cited by 14 publications

(25 citation statements)

References 9 publications

(10 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…25 We have found that the ACT-LR is particularly useful for mouse blood, because it can accurately quantify low-level hFVIII activity (0.5%-5% normal) and is less prone to yield false positives relative to other clotting assays. A standard curve was generated by adding increasing amounts of recombinant hFVIII protein to hemophilia A mice mouse blood to reconstitute clotting function (0.5%-100% normal hFVIII levels; Figure 5).…”

Section: Correction Of Clotting Function In Murine Hemophilia a By Sbmentioning

confidence: 97%

“…Similar application of this test to human hemophilia has been described. 25 hFVIII level was quantified by generating a standard curve using hemophilia A mouse blood with known concentrations of added recombinant hFVIII (ReFacto). To generate the standard curve, ReFacto was reconstituted to a working concentration of 0.06 U/L and was added to hemophilia A mouse blood in a dilution series (ie, 1 L stock to 59 L blood ϭ 1 U/mL or 100% normal hFVIII level).…”

Section: Blood Collection Fviii Analysis and Anti-hfviii Antibodiesmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Phenotypic correction and long-term expression of factor VIII in hemophilic mice by immunotolerization and nonviral gene transfer using the Sleeping Beauty transposon system

Ohlfest

Frandsen

Fritz

et al. 2005

Blood

Self Cite

125

104

View full text Add to dashboard Cite

Hemophilia A is a lead candidate for treatment by gene therapy because small increments in the missing secreted protein product, coagulation factor VIII (FVIII), would result in substantial clinical amelioration. Clinically relevant therapy might be achieved by stably delivering a human FVIII cDNA to correct the bleeding disorder. We used the Sleeping Beauty (SB) transposon, delivered as naked plasmid DNA by tail-vein injection, to integrate B-domain-deleted FVIII genes into the chromosomes of hemophilia A mice and correct the phenotype. Since FVIII protein is a neoantigen to these mice, sustaining therapeutic plasma FVIII levels was problematic due to inhibitory antibody production. We circumvented this problem by tolerizing 82% of neonates by a single facial-vein injection of recombinant FVIII within 24 hours of birth (the remaining 18% formed inhibitors). Achievement of high-level (10%-100% of normal) FVIII expression and phenotypic correction required co-injection of an SB transposaseexpressing plasmid to facilitate transgene integration in immunotolerized animals. Linker-mediated polymerase chain reaction was used to clone FVIII transposon insertion sites from liver genomic DNA, providing molecular evidence of transposition. Thus, SB provides a nonviral means for sustained IntroductionHemophilia A is an X-linked, recessive, genetic disorder that is caused by insufficient coagulation factor (F) VIII synthesis resulting in sustained bleeding after trauma or injury. 1 Recombinant FVIII protein is currently used to treat bleeding episodes at the cost of approximately $55 000 per person year and is not available in many parts of the world. 2 Gene therapy for hemophilia has recently been an intense area of study because even modest levels (2%-5% normal) of FVIII or FIX can improve clinical outcomes. Considerable progress has been made in developing both nonviral and viral vectors to this end. Viral vectors have been extremely effective in delivering FVIII and FIX transgenes, in some cases curing animal models of hemophilia A and B, respectively (reviewed in Nathwani et al 3 ).However, problems related to triggering of the host inflammatory response have resulted in cessation of clinical trials with both adenovirus 4 and adeno-associated virus. 5 Accordingly, improved adenoviral vectors are being developed that may be less immunogenic (reviewed in Ritter et al 6 ), and the use of alternative serotypes also has shown promise in adeno-associated virus re-administration. 7 Nevertheless, these kinds of problems, along with large-scale vector production challenges, have fueled intense interest in development of nonviral approaches for the treatment of hemophilia by gene therapy.The benefits of nonviral vectors include simplicity, ease of storage, and amenability to large-scale manufacture. 3,8 They are also potentially less immunogenic than viral vectors, which could allow for safer administration and/or re-administration. Integrating and nonintegrating plasmid-based vectors have been developed and successfully tested...

show abstract

Section: Correction Of Clotting Function In Murine Hemophilia a By Sbmentioning

confidence: 97%

Section: Blood Collection Fviii Analysis and Anti-hfviii Antibodiesmentioning

confidence: 99%

See 1 more Smart Citation

Phenotypic correction and long-term expression of factor VIII in hemophilic mice by immunotolerization and nonviral gene transfer using the Sleeping Beauty transposon system

Ohlfest

Frandsen

Fritz

et al. 2005

Blood

Self Cite

125

104

View full text Add to dashboard Cite

show abstract

“…Candidate monitoring strategies currently under investigation include rotational thromboelastography (ro-TEG) which measures changes in whole blood clot elasticity, 33 the platelet contractile force, 34 and a modified whole blood activated clotting time, the ACT-LR assay. 35 As yet, however, none of these assays has been shown to predict individual responsiveness to rFVIIa, or to correlate with clinical outcomes in a sufficiently large patient sample.…”

Section: Hemostatic Agents Used To Control Bleeding Inmentioning

confidence: 99%

Congenital Bleeding Disorders

Rick

Walsh²,

Key

2003

Hematology

View full text Add to dashboard Cite

Both clinical and basic problems related to the congenital bleeding disorders continue to confront hematologists. On the forefront are efforts to bring genetic correction of the more common bleeding disorders such as hemophilia A to the clinic in a safe and accessible manner. A second issue, particularly for patients with hemophilia, is the development of inhibitors-questions of how they arise and how to prevent and treat these problems that confound otherwise very successful replacement therapy and allow patients to maintain normal lifestyles. A third issue is the continuing question of diagnosis and management of von Willebrand disease, the most common congenital bleeding disorder, especially in individuals who have borderline laboratory values, but have a history of clinical bleeding.In Section I, Dr. Christopher Walsh discusses general principles of effective gene transfer for the hemophilias, specific information about viral vectors and non-viral gene transfer, and alternative target tissues for factor VIII and factor IX production. He highlights information about the immune response to gene transfer and reviews data from the hemophilia gene transfer trials to date. The future prospects for newer methods of therapy such as RNA repair and the use of genemodified circulating endothelial progenitors are presented as possible alternatives to the more traditional gene therapy approaches.In Section II, Dr. Nigel Key focuses on inhibitor development in patients with hemophilia A. He reviews the progress in our understanding of the risk factors and presents newer information about the immunobiology of inhibitor development. He discusses the natural history of these inhibitors and the screening, laboratory diagnosis, and treatment, including the use of different modalities for the treatment of acute bleeding episodes. Dr. Key also presents information about the eradication of inhibitors by immune tolerance induction and reviews recent information from the international registries regarding the status and success of immune tolerance induction.In Section III, Dr. Margaret Rick discusses the diagnosis, classification, and management of von Willebrand disease. Attention is given to the difficulty of diagnosis in patients with mild bleeding histories and borderline laboratory test results for von Willebrand factor. She presents the value of different laboratory assays for both diagnosis and classification, and she relates the classification of von Willebrand disease to the choice of treatment and to the known genetic mutations. Practical issues of diagnosis and treatment, including clinical cases, will be presented.

show abstract

“…1 However, the "standard" dose of 90 g/kg (Ϸ26 nmol/L) has also been used for the treatment of a variety of bleeding disorders, 1 leading to reports of either success or failure to provide normal hemostasis. [2][3][4] These observations emphasize the importance of knowledge related to the mechanism by which supraphysiological concentrations of factor VIIa may act to produce a desirable response.…”

mentioning

confidence: 99%