Acute Myelogenous Leukemia Blasts Contribute to a Bone Marrow-Stroma in In Vivo NOD/SCID Mouse System..

Abstract

Abstract 1621Poster Board I-647Aims: Cancer stem cell theory has been developed, and whose precise characteristics have been reported. However, there have been no reports on the differentiation of cancer stem cells into the environmental stromal cells. We reported previously that non-adherent acute myelogenous leukemia (AML) cells were differentiated into myofibroblasts to create a microenvironment for proliferation of AML blasts in vitro. In this report we demonstrate that with severe combined immunodeficiency (SCID) mouse system AML blast cells also convert to myofibroblasts to form stroma in vivo. Materials and MethodsBone marrow cells were collected from informed AML (M2) patients who had chromosomal translocation of RUNX1 and ETO, from which mononuclear cells were separated with density-gradient sedimentation method. After discarded an adherent cell-fraction, the non-adherent mononuclear cells were injected to the 3.0 Gray-irradiated non-obese diabetes (NOD)/SCID mouse intravenously. For the inactivation of NK cells, anti-Asialo GM1 antibody was injected intra-peritoneally prior to the transplantation, and on each 11th day thereafter. Blood was collected to monitor Runx1 and ETO fusion transcript, and mice were sacrificed after chimeric mRNA was observed. Bone marrow cells were obtained, and sorted with anti-human CD133 antibody and -CD106 to select AML-derived human stromal myofibroblasts referred to the in vitro data. The isolated positive fraction was further cultured, and the biological and the molecular characteristics were analyzed. Results and DiscussionWhen non-adherent AML (M2) blast cells were transplanted to NOD/SCID mice, cells were engrafted after 10 weeks. In murine bone marrow cells human stromal cells were identified, in which RUNX1 and ETO gene was fused with FISH analysis. When the parental AML blast cells were cultured on the expanded AML-derived myofibroblasts, AML cells grew extensively. These results indicate that AML cells can create their own microenvironment for proliferation in vivo. DisclosuresNo relevant conflicts of interest to declare.