Relationship between bone marrow angiogenesis and plasma cell infiltration and serum beta2-microglobulin levels in patients with multiple myeloma.

There is growing evidence that angiogenesis is important not only in solid tumors but also in hematological malignancies. Recently, we found that bone marrow angiogenesis is a prognostic factor for disease-related survival in patients with multiple myeloma. In this report, we addressed the question of whether the microvessel density in bone marrow biopsies is correlated to other myeloma parameters, e.g., serum beta2-microglobulin (beta2-MG) and plasma cell infiltration in the bone marrow. In 22 multiple myeloma patients, immunohistochemical, CD34-stained, paraffin-embedded bone marrow biopsies before and after chemotherapy were studied. Microvessels were counted in 400x magnification, and the mean number of vessels per area in each sample was noted as the microvessel density (MVD). Pretreatment bone marrow MVD (median: 44, range: 11-175 vessels/mm2) correlated significantly with the bone marrow plasma cell infiltration (median: 30%, range: 5-90%, r = 0.642, P=0.001) and beta2-MG (median: 2.74, range: 1.4-26.1 mg/l, r = 0.749, P < 0.0005). In contrast, there was no correlation between posttreatment MVD and plasma cell infiltration or beta2-MG (median: MVD 31, range: 0-221 vessels/mm2, median plasma cell infiltration: 15%, range: 5-80%, r = 0.229, P = 0.306 and median beta2-MG: 2.65, range: 1-27.6 mg/l, r = -0.042, P = 0.853). These findings show that the strong correlations between bone marrow MVD and plasma cell infiltration as well as serum beta2-MG levels disappear after chemotherapy. The underlying mechanisms need further investigations.