Neovascularisation and its role in the osteoarthritic process.

In osteoarthritis angiogenesis is involved in the reinitiation of cartilage growth and mineralisation. A number of heparin binding protein growth factors have been proposed as angiogenic factors, but none of them is specific for microvessel cells. Another factor which is specific for microvessel cells, is of low molecular weight and non-profit has been called endothelial cell stimulating angiogenic factor (ESAF). ESAF has been found in significantly increased amounts in sera and synovial fluids of osteoarthritic patients and dogs. In addition to its angiogenic activity ESAF is able to activate neutral prometalloproteinases and to reactive the active enzyme-inhibitor complex. The implication of these observations in the pathogenesis of osteoarthritis is discussed.