Faculty Collaboration Database

Comparison of platelet-derived and plasma factor VIII efficacy using a novel native whole blood thrombin generation assay. J Thromb Haemost 2015 Dec;13(12):2210-9

Date

10/11/2015

Pubmed ID

26453193

Pubmed Central ID

PMC4715732

DOI

10.1111/jth.13169

Scopus ID

2-s2.0-84958773657 (requires institutional sign-in at Scopus site)   12 Citations

Abstract

BACKGROUND: We have recently developed a successful gene therapy approach for hemophilia A in which factor VIII (FVIII) expression is targeted to platelets by the αIIb promoter. Levels of platelet-expressed FVIII (2bF8) achieved by gene therapy may vary between individuals due to differences in ex vivo transduction and gene expression efficiency. Accurate assays to evaluate 2bF8 efficacy are desirable.

OBJECTIVE: To compare the hemostatic efficacy of 2bF8 with replacement therapy over a wide therapeutic dose range.

METHODS: Efficacy of 2bF8 was assessed using a new transgenic mouse model expressing high 2bF8 levels (LV18(tg) ). Blood from LV18(tg) mice or FVIII(null) mice infused with recombinant FVIII was mixed with FVIII(null) blood at different ratios ex vivo to achieve several concentrations of 2bF8 or plasma FVIII. Samples were evaluated with a novel native whole blood thrombin generation assay that uses recalcified whole blood without the addition of tissue factor to initiate coagulation.

RESULTS: FVIII dose dependency was observed in all five thrombin generation parameters. While the total amount of thrombin generated was similar, 2bF8 significantly accelerated thrombin generation compared with plasma FVIII. Remarkably, a 10-fold lower dose of 2bF8 than plasma FVIII (0.2% vs. 2%) significantly shortened the onset and peak of thrombin generation compared with FVIII(null) blood.

CONCLUSION: Using a new transgenic mouse model, we showed that the novel native whole blood thrombin generation assay established here can be used to monitor platelet targeted FVIII gene therapy. The higher therapeutic efficacy of 2bF8 compared with factor replacement therapy seemed to be due to acceleration of thrombin generation.

Author List

Baumgartner CK, Zhang G, Kuether EL, Weiler H, Shi Q, Montgomery RR

Authors

Robert R. Montgomery MD Adjunct Professor in the Pediatrics department at Medical College of Wisconsin
Qizhen Shi MD, PhD Professor in the Pediatrics department at Medical College of Wisconsin
Hartmut Weiler PhD Associate Professor in the Physiology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Animals
Blood Coagulation
Blood Coagulation Tests
Coagulants
Dose-Response Relationship, Drug
Factor VIII
Genotype
Humans
Kinetics
Mice, Inbred C57BL
Mice, Knockout
Mice, Transgenic
Phenotype
Platelet Membrane Glycoprotein IIb
Promoter Regions, Genetic
Recombinant Proteins
Thrombin