Characterization of a genetically engineered mouse model of hemophilia A with complete deletion of the F8 gene

• Published in: Journal of thrombosis and haemostasis Vol. 14; no. 2; pp. 346 - 355
• Main Authors: Chao, B. N., Baldwin, W. H., Healey, J. F., Parker, E. T., Shafer‐Weaver, K., Cox, C., Jiang, P., Kanellopoulou, C., Lollar, P., Meeks, S. L., Lenardo, M. J.
• Format: Journal Article
• Language: English
• Published: England Elsevier Limited 01.02.2016
• Subjects: Animal model; Animals; Antibodies - blood; blood coagulation factor inhibitors; Blood Coagulation Tests; Chromogenic Compounds; Disease Models, Animal; Enzyme-Linked Immunosorbent Assay; factor VIII; Factor VIII - genetics; Factor VIII - immunology; Factor VIII - metabolism; Factor VIII - pharmacology; Gene Deletion; Genetic Predisposition to Disease; hemophilia A; Hemophilia A - blood; Hemophilia A - drug therapy; Hemophilia A - genetics; Hemophilia A - immunology; Hemostasis - drug effects; Hemostasis - genetics; Hemostatics - immunology; Hemostatics - pharmacology; knockout mouse; Mice, Inbred C57BL; Mice, Knockout; Phenotype; Rodents; Severity of Illness Index; Animal model; hemophilia A; blood coagulation factor inhibitors; factor VIII; knockout mouse
• ISSN: 1538-7933; 1538-7836; 1538-7836
• DOI: 10.1111/jth.13202

Essentials Anti‐factor VIII (FVIII) inhibitory antibody formation is a severe complication in hemophilia A therapy. We genetically engineered and characterized a mouse model with complete deletion of the F8 coding region. F8TKO mice exhibit severe hemophilia, express no detectable F8 mRNA, and produce FVIII inhibitors. The defined background and lack of FVIII in F8TKO mice will aid in studying FVIII inhibitor formation. Summary Background The most important complication in hemophilia A treatment is the development of inhibitory anti‐Factor VIII (FVIII) antibodies in patients after FVIII therapy. Patients with severe hemophilia who express no endogenous FVIII (i.e. cross‐reacting material, CRM) have the greatest incidence of inhibitor formation. However, current mouse models of severe hemophilia A produce low levels of truncated FVIII. The lack of a corresponding mouse model hampers the study of inhibitor formation in the complete absence of FVIII protein. Objectives We aimed to generate and characterize a novel mouse model of severe hemophilia A (designated the F8TKO strain) lacking the complete coding sequence of F8 and any FVIII CRM. Methods Mice were created on a C57BL/6 background using Cre‐Lox recombination and characterized using in vivo bleeding assays, measurement of FVIII activity by coagulation and chromogenic assays, and anti‐FVIII antibody production using ELISA. Results All F8 exonic coding regions were deleted from the genome and no F8 mRNA was detected in F8TKO mice. The bleeding phenotype of F8TKO mice was comparable to E16 mice by measurements of factor activity and tail snip assay. Similar levels of anti‐FVIII antibody titers after recombinant FVIII injections were observed between F8TKO and E16 mice. Conclusions We describe a new C57BL/6 mouse model for severe hemophilia A patients lacking CRM. These mice can be directly bred to the many C57BL/6 strains of genetically engineered mice, which is valuable for studying the impact of a wide variety of genes on FVIII inhibitor formation on a defined genetic background.