Prevention of haemarthrosis in a murine model of acute joint bleeding

The F8(-/-) rat as a model of hemophilic arthropathy

Essentials Validating the F8 rat as a new intermediate-size animal model of hemophilic arthropathy. Factor VIII (FVIII) treated F8(-/-) rats suffered induced hemarthrosis analyzed by histopathology. F8 (-/-) animals develop hemophilic arthropathy upon hemarthrosis, preventable by FVIII treatment. The F8 (-/-) rat presents as a new pharmacologic model of hemophilic arthropathy.

SUMMARY

Background Translational animal models of hemophilia are valuable for determining the pathobiology of the disease and its co-morbidities (e.g. hemophilic arthropathy, HA). The biologic mechanisms behind the development of HA, a painful and debilitating condition, are not completely understood. We recently characterized a F8(-/-) rat, which could be a new preclinical model of HA. Objectives To establish the F8(-/-) rat as a model of HA by determining if the F8(-/-) rat develops HA resembling human HA after an induced joint bleed and whether a second joint bleed causes further disease progression. Methods Wild-type and F8(-/-) rats were treated with vehicle or recombinant human factor VIII (rhFVIII) prior to a needle-induced joint bleed. Joint swelling was measured prior to injury, the following 7 days and upon euthanasia. Histologic sections of the joint were stained, and athropathic changes identified and scored with regard to synovitis, bone remodelling, cartilage degradation and hemosiderin deposition. Results Vehicle-treated F8(-/-) rats experienced marked joint swelling and developed chronic degenerative joint changes (i.e. fibrosis of the subsynovial membrane, chondrocyte loss and excessive bone remodeling). Treatment with rhFVIII reduced or prevented swelling and degenerative joint changes, returning the F8(-/-) animals to a wild-type phenotype. Conclusion The hemophilic phenotype of the F8(-/-) rat resulted in a persistent hemarthrosis following an induced joint bleed. This caused development of HA resembling human HA, which was prevented by rhFVIII treatment, confirming the potential of the F8(-/-) rat as a model of HA.

Joint bleeding in factor VIII deficient mice causes an acute loss of trabecular bone and calcification of joint soft tissues which is prevented with aggressive factor replacement

While chronic degenerative arthropathy is the main morbidity of haemophilia, a very high prevalence of low bone density is also seen in men and boys with haemophilia. This study investigates bone degradation in the knee joint of haemophilic mice resulting from haemarthrosis and the efficacy of aggressive treatment with factor VIII in the period surrounding injury to prevent bone pathology. Skeletally mature factor VIII knock-out mice were subjected to knee joint haemorrhage induced by puncture of the left knee joint capsule. Mice received either intravenous factor VIII treatment or placebo immediately prior to injury and at hours 4, 24, 48, 72 and 96 after haemorrhage. Mice were killed 2-weeks after injury and the joint morphology and loss of bone in the proximal tibia was assessed using microCT imaging. Quantitative microCT imaging of the knee joint found acute bone loss at the proximal tibia following injury including loss of trabecular bone volumetric density and bone mineral density, as well as trabecular connectivity density, number and thickness. Unexpectedly, joint injury also resulted in calcification of the joint soft tissues including the tendons, ligaments, menisci and cartilage. Treatment with factor VIII prevented this bone and soft tissue degeneration. Knee joint haemorrhage resulted in acute changes in adjacent bone including loss of bone density and mineralization of joint soft tissues. The rapid calcification and loss of bone has implications for the initiation and progression of osteoarthritic degradation following joint bleeding.

A single intra-articular injection with IL-4 plus IL-10 ameliorates blood-induced cartilage degeneration in haemophilic mice

The combination of interleukin (IL)-4 and IL-10 protects against blood-induced cartilage damage in vitro. It has been hypothesized that the combination of these cytokines is effective if applied early in the process of cartilage damage. The present study investigated whether a single intra-articular injection of IL-4 plus IL-10 immediately after a joint bleed limits cartilage damage in an in vivo haemophilia mouse model of blood-induced joint damage. Factor VIII knockout mice with severe haemophilia A were punctured once with a needle below the patella to induce a joint haemorrhage. Subsequently IL-4 plus IL-10 (n = 24) or vehicle (n = 24) was injected intra-articularly. After 35 days, the time needed for development of detectable joint degeneration, knee joints were examined for cartilage damage by macroscopic and microscopic evaluation. A single intra-articular injection of IL-4 plus IL-10 ameliorated progression of cartilage degeneration caused by a single joint bleed to a certain extent. No effect on inflammation was observed at this time point. A single intra-articular injection of IL-4 plus Il-10 directly after a single joint bleed limits progression of cartilage degeneration over time. Improved bioavailability (half-life) of both cytokines might improve their protective ability in the development of cartilage degeneration, and probably also inflammation.

The Fourth Annual Meeting of the International Network for Pediatric Hemophilia: Current Challenges and Recommendations in the Clinical Care of Children with Hemophilia

The International Network for Pediatric Hemophilia (INPH) comprises a group of physicians committed to the unique care of and challenges facing pediatric hemophilia patients. By collaborating on an international level, extensive experience can be shared on current practice, new trends can be discussed and scientifically valid studies can be developed and performed. The three overall objectives of the group (scientific progress, education and networking) are achieved at each annual meeting starting with a round table on the members' current research and clinical activities, project reports of INPH study initiatives, followed by invited educational presentations and interactive discussions. The meetings close with proposals of new projects, future directions of the group and concluding remarks. The Fourth Annual INPH meeting, held in 2009 in Boston, MA, USA, focused on inhibitor development and hemophilic arthropathy in the clinical care of children with hemophilia.

A ferric chloride induced arterial injury model used as haemostatic effect model

A number of experimental bleeding models have been applied to animal models of haemophilia in order to evaluate the acute haemostatic effect of procoagulant compounds. In contrast, in vivo thrombosis models (including the FeCl(3) induced injury model) have mainly been used to study antithrombotic pharmacological intervention. However, as there are limitations to existing bleeding models and as new recombinant FVIII, FIX, and FVIIa variants with increased and prolonged activity are generated there is an increasing need for new and optimized in vivo animal models for testing the efficacy of these haemostatic drug candidates. This led us to look at existing thrombosis models in a new perspective. We have studied the effect of a FeCl(3) induced arterial injury in both F8-KO and F9-KO mice using optimized conditions where exposure to FeCl(3) induces occlusion within 4.2 +/- 0.2 min in wild type mice with a normal coagulation system. In contrast, no occlusion was observed in haemophilic mice providing a therapeutic window in the model making it suitable for pharmacological testing of therapeutic intervention. We demonstrate that replacement therapy with a clinical relevant dose of rFVIII (Advate 20-80 U kg(-1)) and rFIX [(0.75 mg kg(-1) BeneFIX) approximately 50 IU kg(-1)] restored coagulation and normalized the time to occlusion following FeCl(3) induced injury in F8-KO mice and restored coagulation and nearly normalized the time to occlusion in F9-KO mice. In conclusion, we have demonstrated that under optimized conditions the FeCl(3) induced arterial injury model provides a therapeutic window that makes it an useful effect model for evaluation of the haemostatic potential of procoagulant drugs.

Faster onset of effect and greater efficacy of NN1731 compared with rFVIIa, aPCC and FVIII in tail bleeding in hemophilic mice

BACKGROUND

Recombinant factor VIIa (rFVIIa, Novoseven) is currently used to control bleeding in hemophiliacs with inhibitors. A new rFVIIa variant, NN1731, with increased activity on the surface of activated platelets, has demonstrated a more potent and faster onset of reactivity than rFVIIa in various in vitro models. The present study aimed to investigate whether this translates into greater efficacy and faster promotion of hemostasis in vivo.

METHOD AND RESULTS

In a severe tail-bleeding model in hemophilia A mice, NN1731 demonstrated significantly greater efficacy than rFVIIa, plasma-derived activated prothrombin complex concentrate (pd-aPCC, FEIBA or FVIII (Refacto). Assessment of the blood loss over time showed that NN1731 significantly and dose-dependently reduced the blood loss in the first 5-min observation period, whereas the effect of rFVIIa, FVIII and pd-aPCC first became evident 5-10 min after injury.

CONCLUSION

This study shows that NN1731 has a greater efficacy and faster resolution of bleeding in a severe bleeding model in hemophilia A mice compared with any of the other agents tested.