A novel mouse model of type 2N VWD was developed by CRISPR/Cas9 gene editing and recapitulates human type 2N VWD

Abstract

Type 2N von Willebrand disease is caused by mutations in the factor VIII (FVIII) binding site of von Willibrand factor (VWF), resulting in dysfunctional VWF with defective binding capacity for FVIII. Here we developed a novel type 2N mouse model using CRISPR/Cas9 technology. In homozygous VWF2N/2N mice, plasma VWF levels were normal (1167±257 mU/ml) but the VWF was completely incapable of binding FVIII, resulting in 53±23 mU/ml of plasma FVIII levels that were similar to those in VWF deficient (VWF-/-) mice. When wild-type human or mouse VWF was infused into VWF2N/2N mice, endogenous plasma FVIII was restored, peaking at 4-6 hours post-infusion, demonstrating that FVIII expressed in VWF2N mice is viable, but short-lived unprotected in plasma due to dysfunctional 2N-VWF. The whole blood clotting time and thrombin generation were impaired in VWF2N/2N but not in VWF-/- mice. The bleeding time and blood loss in VWF2N/2N mice were similar to wild-type mice in the lateral tail vein or ventral artery injury model. However, VWF2N/2N, but not VWF-/- mice, lost a significant amount of blood during the primary bleeding phase after a tail tip amputation injury model, indicating that there are other alternative pathway(s) that can at least partially restore hemostasis when VWF is absent. In summary, we have developed a novel mouse model by gene editing with both the pathophysiology and clinical phenotype found in severe type 2N patients. This unique model can be used to investigate the biological properties of VWF/FVIII association in hemostasis and beyond.

Progress in von Willebrand Disease Treatment: Evolution towards Newer Therapies

“…A novel mouse model has recently been developed that may help in the search for treatment of type 2N VWD subtype. 86 Clotting times and thrombin generation were impaired in homozygous VWD type 2N mice after Clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) gene editing because only nonfunctional VWF is produced. Compared with VWF knockout mice, VWF 2N gene-edited mice had significantly more blood loss in the primary bleeding phase.…”

“…A novel mouse model has recently been developed that may help in the search for treatment of type 2N VWD subtype. 86…”

“…Therefore, this model expressing the phenotype of severe type 2N VWD might help to further investigate the disease and possible treatment options. 86…”