VEGF expression correlates with microvessel density in Philadelphia chromosome-negative chronic myeloproliferative disorders

Abstract

We examined microvessel density (MVD) and immunohistochemical expression of vascular endothelial growth factor (VEGF) in the bone marrow biopsy specimens of 98 patients with Philadelphia chromosome-negative (Ph-) chronic myeloproliferative disorders (CMPDs). There were significantly more MVD "hot spots" in chronic idiopathic myelofibrosis (CIMF; mean +/- SD, 25.6 +/- 6.3) and polycythemia vera (PV; 20.7 +/- 10.2) cases than in essential thrombocythemia (ET) cases (10.1 +/- 4.5) and normal control (NC) samples (7.5 +/- 3.6) (P < .05). Similar results were found using a semiquantitative method (P < .0001). A calculated VEGF index (VEGF(i)) was higher in CIMF (0.29 +/- 0.15) and PV (0.28 +/- 0.20) cases than in ET (0.12 +/- 0.05) and NC (0.08 +/- 0.04) cases (P < .0001). MVD and VEGF(i) were higher in the myelofibrotic phases of CIMF and PV. There was a direct correlation between VEGF(i) and MVD when considering the Ph- CMPDs together (r = 0.67; P < .001) and when considering PV (r = 0.79; P < .001) and CIMF (r = 0.40; P = .013) as individual entities. Our data could provide a rationale for directly targeting VEGF or endothelial cells in CIMF and PV.