OBJECTIVETo investigate the effect of daunorubicin on the number and procoagulant activity of Microparticles derived from acute promyelocytic leukemia(APL) cells.

METHODSAPL cells were isolated from bone Marrow of 5 newly diagnosed APL patients, the bone marrow mononuclear cells were collected from 5 patients with iron deficiency anemia as control.APL cells were treated with different concentration of daunorubicin(0.1,0.5,1.0 and 2.0µmol/L) for 24 h. Microparticles were extracted from the cell culture medium for qualitative anaysis of the extracted microparticles.The morphologic features of the microparticles were observed by transmission electron microscopy.The number of microparticles was detected by flow cytometry.The procoagulant activity of microparticles was measured by recalcification time assays.

RESULTSUnder a transmission electron microscope, theextracted microparticles took a round or oval morphology with a transparent center,and their diameters were arund 100nm, consistent with the morphological characteristics of microparticles. Compared with bone marrow mononuclear cells-derived microparticles,the counts of the bone marrow APL cells-derived microparticles significantly increased(P<0.05).Daunorubicin increased the shedding of microparticles in a dose-dependent manner(r=0.73,P<0.01).Compared with normal bone marrow mononuclear cells-derived microparticles,bone marrow APL cells-derived microparticles showed higher procoagulant activity(P<0.05).Daunorubicin treatment enhanced the prccoagulant activity of APL cells-derived microparticles which paralleled the increasing drug concentrations(r=-0.78,P<0.01).

CONCLUSIONDaunorubicin can promote the release of APL cells-derived microparticles and enhance their related procoagulan activity.