Bone marrow stromal cells in acute promyelocytic leukemia: comparison with other acute leukemia subtypes

Acute promyelocytic leukemia (APL) with t(15;17), significantly differs from other acute myelogenous leukemias (AML) by the prognosis which has been significantly improved after introduction of retinoic acid, as a differentiating agent. In an attempt to clarify whether APL differs from AML with regards to the stromal cell compartment too, bone marrow mononucleated cells (BM/MNC) from 21 untreated AML patients (M0: 1; M1: 4; M2: 4; APL: 6; M4: 2; M5:4) were plated in long-term culture. The fibroblastoid clonogenic precursors (CFU-F/ 106 BM/MNC; Collagen I/II/III+, CD68+) and the endothelial colonies (CFUEn CD31+, factor VIII+) content were assessed after 15 days by an immunohistochemical technique. Fibroblast confluence , in the T25 flask, was evaluated after 40 days by inverted microscope. CFU-F % conference p (Wilcoxon) AML (all cases) (mean±s.d) 4.4±4.7 50±30 0.01 non-APL AML 3.4±2.9 38.1±31.2 0.01 APL 7.6±2.1 71±11 n.s Controls 12.3±4.4 90±10 Considering CFU-En, the non-APL group displayed a 3.8-fold higher value than the control group (1.1±1 vs 0.28±0.4; p=0.05), while this difference was not present in APL samples (0.5±1.1). In conclusion, the biological characteristc of bone marrow stromal cells was found to be different in APL, in comparison with other AML subvarieties. This may be due to the different nature of the diseases. Moreover, we give evidence of an high angiogenesis rate in AML which appeared more prominent in non-APL samples.