Hemophilia A and B mice, but not VWF -/-mice, display bone defects in congenital development and remodeling after injury

Sarah Taves (1, 2) , Junjiang Sun (3) , Eric W Livingston (1) , Xin Chen (3, 4) , Jérôme Amiaud (5) , Régis Brion (5) , William B Hannah (3) , Ted A Bateman (1, 6) , Dominique Heymann (7, 8) , Paul E Monahan (3, 9, 10)

1 Department of Biomedical Engineering [Chapel Hill, NC, USA]
2 Global Research [Maløv, Denmark]
3 Gene Therapy Center [Chapel Hill, NC, USA]
4 Eshelman School of Pharmacy - Division of Molecular Pharmaceutics [Chapel Hill, NC, USA]
5 Phy-Os - Sarcomes osseux et remodelage des tissus calcifiés - Phy-Os [Nantes - INSERM U1238]
6 Department of Radiation Oncology [Chapel Hill, NC, USA]
7 CRCINA - Centre de Recherche en Cancérologie et Immunologie Nantes-Angers
8 European Associated Laboratory “Sarcoma Research Unit” - Department of Oncology and Metabolism [Sheffield, UK]
9 Harold R. Roberts Comprehensive Hemophilia Diagnosis and Treatment Center [Chapel Hill, NC, USA]
10 Spark Therapeutics [Philadelphia, PA, USA]

While joint damage is the primary co-morbidity of hemophilia, osteoporosis and osteopenia are also observed. Coagulation factor VIII deficient (FVIII-/-) mice develop an osteoporotic phenotype in the absence of induced hemarthrosis that is exacerbated two weeks after an induced joint injury. Here we have compared comprehensively the bone health of clotting factor VIII, factor IX, and Von Willebrand Factor knockout (FVIII-/-, FIX-/-, and VWF-/- respectively) mice both in the absence of joint hemorrhage and following induced joint injury. We found FVIII-/- and FIX-/- mice, but not VWF-/- mice, developmentally have an osteoporotic phenotype. Unilateral induced hemarthrosis causes further bone damage in both FVIII-/- and FIX-/- mice, but has little effect on VWF-/- bone health, indicating that the FVIII.VWF complex is not required for normal bone remodeling in vivo. To further investigate the bone healing following hemarthrosis in hemophilia we examined a two week time course using microCT, serum chemistry, and histological analysis. Elevated ratio of osteoprotegerin (OPG)/receptor activator of nuclear factor-kappa B ligand (RANKL), increased osterix+ osteoblastic cells, and decreased smoothness of the cortical bone surface were evident within several days of injury, indicative of acute heterotopic mineralization along the cortical surface. This was closely followed by increased interleukin-6 (IL-6) levels, increased osteoclast numbers, and significant trabecular bone loss. Uncoupled and disorganized bone formation and resorption continued for the duration of the study resulting in significant deterioration of the joint. Further elucidation of the shared mechanisms underlying abnormal bone homeostasis in the absence of FVIII or FIX is needed to guide evidence-based approaches to the screening and treatment of the prevalent bone defects in hemophilia A and B.

Mots clés: hemophilia; factor VIII; factor IX; VWF; bone

Domaines: Rhumatologie et système ostéo-articulaire; Cancer; Endocrinologie et métabolisme; Pédiatrie

Sarah Taves, Junjiang Sun, Eric W Livingston, Xin Chen, Jérôme Amiaud, et al.. Hemophilia A and B mice, but not VWF -/-mice, display bone defects in congenital development and remodeling after injury: Bone health in FVIII FIX and VWF deficient mice. Scientific Reports, 2019, 9 (1), pp.14428. ⟨10.1038/s41598-019-50787-9⟩. ⟨inserm-02319204v2⟩