While the homing hypothesis is supported by preclinical studies showing recruitment of bone marrow-derived cells to sites of inflamed joints in experimental arthritis and by the observation that VEGF blockade in murine collagen-induced arthritis (CIA) significantly reduces synovial inflammation [19], it is unclear to what extent can EPC recruitment to the synovial tissue reduce the steady-state circulating EPC levels. This evidence concerns the gene VEGFA and inflammation.