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

Abstract 2191

Poster Board II-168

Aims: The stroma-forming cells in a bone marrow are derived from hematopoietic stem cells. We reported previously that non-adherent leukemia blast cells converted into myofibroblasts to create a microenvironment for proliferation of leukemia blasts in vitro. In this report we demonstrate that with severe combined immunodeficiency (SCID) mouse system chronic myelogenous leukemia (CML) cells are also differentiated into myofibroblasts to contribute to a bone marrow-stroma in vivo. Materials and Methods: Bone marrow cells were collected from informed CML patients, from which mononuclear cells were separated with density-gradient sedimentation method. After discarded an adherent cell-fraction, non-adherent mononuclear cells were injected to the priory 2.5 Gray-irradiated non-obese diabetes (NOD)/SCID mice 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 Bcr-Abl transcript, and mice were sacrificed after chimeric mRNA was demonstrated. Bone marrow cells were obtained, and sorted with anti-human CD133 antibody and -CD106 to select CML-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 Discussion: When non-adherent CML cells were transplanted to NOD/SCID mice, CML cells were engrafted after 2 months. In the murine bone marrow human stromal cells were identified, in which BCR and ABL gene was fused with FISH analysis. When the parental CML cells were cultured on the CML-derived myofibroblasts, CML cells grew extensively in a vascular endothelial growth factor-A-dependent fashion. These results indicate that CML cells can create their own microenvironment for proliferation in vivo.