Bone marrow stromal cells in acute promyelocytic leukemia: comparison with other acute myelogenous 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 differentiating agent. In the attempt to clarify if APL differs from AML regarding stromal cell compartment too, bone marrow mononucleated cells (bmmnc) from 21 untreated AML patients (MO: 1 ; Ml : 4; M2:4; APL: 6; M4: 2; M5:4) were plated in long-term culture. The fibroblastoid clonogenic precursors (CFU-F/ 106 bmmnc; Collagen I/II/1II+, CD68+) and the endothelial colonies (CFU-En CD31+, Factor VIII+) content, as expression of angiogenic potential of the AML samples, were assessed after 15 days by immunohistochemical technique. Fibroblast confluence (see table), in T25 flask, was evaluated after 40 days by inverted microscope. Results are in detail described in the table below. Considering CFU-En. no-APL group display 3.8-fold value than control (1.1+/-1 vs 0.28+/-0.4; p=0.05), while this difference is not present in APL samples (0.5+/-1.1). In conclusion, the biologic characteristics of bm stromal cell 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 no-APL samples. CFU-F %Confluence p(wilcoxon) AMLfall cases) 4.4+/-4.T 50+/-30 0.01 AML 3.4+/-2.9 38+/-31 0.01 APL 7.6+/-2.1 71+/-11 not signif. Controls 12.3+/-4.4 90+/-10.