Increased bone marrow angiogenesis in B cell chronic lymphocytic leukemia

Recent studies have shown that angiogenesis may be involved in the pathogenesis of hematopoietic malignancies, apart from its well-characterized role in the growth and metastasis of solid tumors. In this study, we quantified the degree of angiogenesis in B cell chronic lymphocytic leukemia (B-CLL) by measuring the microvessel density and hotspot density in bone marrow trephine biopsy sections with B-CLL involvement (n = 12) and compared it to normal bone marrow sections (n = 11). The B-CLL samples had a mean microvessel count/high power field (hpf) of 7.64 while the control samples had a mean microvessel count/hpf of 2.11 (P = 0.0001). The mean hotspot density in the B-CLL sections (14.83/hotspot) was also significantly higher (P = 0.0008) than the mean hotspot density in control bone marrow sections (7.09/hotspot). Both the microvessel density and hotspot density correlated positively with the clinical stage of the B-CLL patients. In a separate cohort of B-CLL patients, the median urine level of the angiogenic peptide, basic fibroblast growth factor (2216.5 pg/g, n = 14), was significantly higher (P = 0.0001) than the bFGF level in normal controls (1084 pg/g, n = 58). These results indicate that angiogenesis may be involved in the pathogenesis of B-CLL.