haematologica/the hematology journal | 2006; 91(9) | 1203 |

Expression of angiopoietins and their receptor Tie2 in the bone marrow of patients with acute myeloid leukemia Angiogenesis, the formation of newblood vessels from pre-existing ones, isrequired for the growth of solid tumors and hematologic neoplasias such as acute myeloid leukemia (AML). We and other groups have demonstrated increased neovas-cularization in the bone marrow of AML patients.1-3 The mutual interplay of bone mar-row endothelial cells and growth factors derived from leukemic blasts contributes to the pathogenesis of hematologic malignan-cies.4,5 Moreover, it has become increasingly clear that angiogenic factors produced by leukemic blasts may also act in an autocrine o