A haemophilic mouse synovitis histopathology grading system has been validated by Valentino and Hakobyan [14]. A joint haemorrhage model consisting of a single puncture of the knee joint capsule with a 30-G needle to induce bleeding of

joint vasculature has been standardized in FIX knockout (FIX−/−) and FVIII knockout (FVIII−/−) mice. Haemostatically normal mice do not develop synovitis, but NVP-BGJ398 purchase greater than 95% of haemophilic mice develop synovitis after the haemostatic challenge [11,15]. To compare the potential therapeutic value of extravascular clotting factor replacement within the joint, intraarticular (i.a.) haemorrhage was induced by joint capsule needle puncture; at the same time, the mice received human FIX via the needle into the joint space (i.a.) or were Rapamycin cell line alternatively treated with FIX intravenously (i.v.). Examining joint histopathology 2 weeks after the injury, FIX injected in the joint coincident with bleeding protected haemophilia

B mice from synovitis at doses that were 80–90% lower than doses required i.v. to achieve the same protection. The experimental design was reproduced using FVIII−/− mice. Factor VIII delivered locally in the joint prevented synovitis using doses 80–90% lower than required i.v. to achieve the same degree of protection [12]. Similar to human haemophilia, haemophilia A mice develop neutralizing antibodies (inhibitors) after protein replacement more frequently than haemophilia B mice. Following exposure to FVIII i.a., when compared with i.v. exposure, FVIII−/− mice developed both a lower incidence and lower titre of inhibitors. The efficacy of i.a. FVIII

and FIX has been examined also in joints in which the normal anatomy was disrupted. Synovitis was induced in haemophilic mice by joint capsule injury. Clotting factor given coincident with a subsequent induced haemarthrosis in the inflamed find more joint prevented additive pathological changes resulting from the ‘recurrent’ injury. Taken together, the results suggest that clotting factor’s action to protect joints need not occur solely via circulating factor (i.e. through action at the intraluminal surface of the blood vessel) and support the potential efficacy and safety of a strategy to confer endogenous factor expression to tissues within the joint space. To examine joint-directed gene therapy, human FIX packaged in different serotype capsids of adeno-associated virus (AAV2, AAV5 or AAV8) was delivered directly to the left knees of FIX−/− mice; the right knee received only normal saline [12]. After 4 weeks of AAV expression, bilateral knee bleed was induced by needle puncture. Two weeks later, at the time of killing, 100% of negative control knees that did not receive gene therapy had histological evidence of bleeding-induced synovitis.