Pathogenesis of haemophilic synovitis: experimental studies on blood-induced joint damage.

Hemarthrosis is a common manifestation of haemophilia, and joint arthropathy remains a frequent complication. Even though the exact mechanisms related to blood-induced joint disease have not yet been fully elucidated, it is likely that iron deposition in the synovium induces an inflammatory response that causes not only immune system activation but also stimulates angiogenesis. This process ultimately results in cartilage and bone destruction. Investigating the processes that occur in the early stages of blood-induced joint disease in humans has been very limited. Therefore, the use of haemophilic animal models is critical to augment the understanding of this phenomenon. This article discusses three cellular regulators (p53, p21 and TRAIL) induced in synovial tissue that are important for iron metabolism. A cartilage remodelling programme induced by the release of cytokines and growth factors that result in articular damage is also discussed. Full elucidation of the pathogenesis of haemophilic joint disease is required to identify new avenues for prevention and therapy.