In children with haemophilia A and a history of target-joint and/or FVIII inhibitor, abnormalities may occur in the long bones as were revealed by pQCT, where low trabecular density and weak cortical bone quality in upper and lower extremities, respectively, were confirmed.
Our data show a correlation between FVIII:C and thrombin generation testing with a clear differentiation between patients with haemophilia and normal controls.
The Fc fusion has no impact on FVIII-specific activity. rFVIIIFc has comparable acute efficacy as rFVIII in treating tail clip injury in HemA mice, and fully corrects whole blood clotting time (WBCT) in HemA dogs immediately after dosing.
Together, these technologies contribute to an AAV-fVIII vector that confers sustained, curative levels of fVIII at a minimal dose in hemophilia A mice.
To determine its capacity for in vivo excision and/or genomic integration, Ad/AAV/FVIIIDelta761-1639 was injected by tail vein into three groups of hemophilia A mice (2 x 10(11) vp [n = 3]; 4 x 10(11) vp [n = 3]; 8 x 10(11) vp [n = 3]), with clear concentration-dependent increase in FVIII activity (range 160-510 mU/ml; plasma activity 16%-51% of normal).
Given the decades of experience using sheep to study both normal physiology and a wide array of diseases and the high homology between human and sheep FVIII, this new model will enable a better understanding of HA and facilitate the development and testing of novel treatments that can directly translate to HA patients.
SUMMARY: Background We have previously demonstrated that von Willebrand factor (VWF) is essential in platelet-specific FVIII (2bF8) gene therapy of hemophilia A (HA) with inhibitory antibodies (inhibitors).
Moreover, CD4(+)CD25(+) Tregs from tolerized mice adoptively transferred dominant tolerance in syngeneic hFVIII plasmid-treated hemophilia A mice and reduced the production of antibodies against FVIII.
Potential uses of platelet-directed therapeutics will be discussed, focusing on targeted delivery of urokinase as a thromboprophylactic agent and FVIII for the treatment of hemophilia A patients with intractable inhibitors.
To date, research in the field of gene therapy for haemophilia has largely relied on retroviruses, adenoviruses and adeno-associated viruses as transfer vectors and the major aims will be to achieve stable longlasting in vivo expression of factors VIII or IX (FVIII or FIX) at therapeutic levels.
Thus, a significant number of haemophilia patients form antibodies, called inhibitors, which neutralize the procoagulant functions of therapeutic cofactors FVIII (haemophilia A) or FIX (haemophilia B).
This study suggested that a single administration of an advanced generation LV carrying the human FVIII cDNA resulted in elevation of FVIII level in immune competent rats, and that this gene transfer approach to the skeletal muscle could be an effective tool in treatment of hemophilia A.
The used ARMS methods are rapid and can easily be applied in conjunction with other FVIII gene linked polymorphisms for indirect mutation detection of hemophilia A where they are informative.
Approximately 5% of hemophilia A patients have normal amounts of a dysfunctional factor VIII (FVIII) protein and are termed cross-reacting material (CRM)-positive.
These results suggest that transduction of the adipocytes with vectors carrying the human FVIII gene may be potentially applicable for gene therapy of hemophilia A.
A review of the literature and the assay of FVIII antigen in 5 hemophilia A patients with previously identified missense mutations from this laboratory yielded a total of 20 other unique CRM-reduced and CRM-positive mutations.
This mechanism, commonly related to genetic human disorders, may be involved in a significant number of hemophilia cases considering that FVIII is coded by an Alu-rich gene.
ClotChip T<sub>peak</sub> values correlate very well with ROTEM, TGA and FVIII assays, opening up possibilities for its use in personalized coagulation factor replacement therapy in haemophilia.
Conclusion We conclude that, in mice, more than 30-fold higher levels of platelet-expressed FVIII than are required for therapeutic efficacy in hemophilia A are not associated with a thrombotic predilection.