Mesenchymal Stromal Cells Promote Tumor Progression in Fibrosarcoma and Gastric Cancer Cells

BACKGROUND: Extensive evidence has accumulated regarding the role of mesenchymal stromal cells (MSCs) in tumor progression, but the exact effects and mechanisms underlying this role remain unclear. We investigated the effects of MSC-associated tumor progression in MSC-sarcoma models and a gastric cancer metastatic model. METHODS: We conducted an in vitro growth kinetics assay and an in vivo tumor progression assay for sarcoma cells and gastric cancer cells in the presence or absence of MSCs. RESULTS: MSC-cocultured human fibrosarcoma cells (HT1080) showed accelerated growth compared with HT1080 alone (79- vs 37-fold change, p<.050). For HT1080, human MSC-coinjected tumors showed significantly greater and highly infiltrative growth compared to those of HT1080 alone (p=.035). For mouse fibrosarcoma cells (WEHI164), mouse MSC-coinjected tumors had greater volume than those of WEHI164 alone (p=.141). For rat sarcoma cells (RR1022), rat MSC-coinjected tumors exhibited greater volume and infiltrative growth than those of RR1022 alone (p=.050). For human gastric cancer cells (5FU), tumors of 5FU alone were compact, nodular in shape, and expansile with good demarcation and no definite lung metastatic nodules, whereas tumors grown in the presence of human MSCs showed highly desmoplastic and infiltrative growth and multiple lung metastasis. CONCLUSIONS: We observed morphological evidence for MSC-associated tumor progression of fibrosarcomas and gastric cancer cells.

Detection Limit of Monoclonal B-Cells Using Multiplex PCR and Laser-Induced Fluorescence Capillary Electrophoresis

BACKGROUND: The identification of monoclonality has been widely used for making diagnoses of lymphoproliferative lesions. Awareness of the sensitivity and detection limit of the technique used would be important for the data to be convincing. METHODS: We investigated the minimum requirement of cells and sensitivity of gel electrophoresis (GE) and laser-induced fluorescence capillary electrophoresis (LFCE) for identifying IgH gene rearrangement using BIOMED-2 protocols. DNA extracted from Raji cells were diluted serially with peripheral blood mononuclear cells (PBMNCs) DNA. DNA from mixtures of diffuse large B-cell lymphoma (DLBCL) and reactive lymph nodes were also serially diluted. RESULTS: For Raji cells, the detection limit was 62 and 16 cell-equivalents for GE and LFCE, respectively. In the condition with PBMNCs mixture, 2.5% and 1.25% of clonal cells was the minimum requirement for GE and LFCE, respectively. In 23% of DLBCL cells in tissue section, the detection limit was 120 and 12 cell-equivalents for GE and LFCE, respectively. In 3.2% of DLBCL cells, that was 1,200 and 120 cell-equivalents for GE and LFCE, respectively. CONCLUSIONS: These results show that LFCE method is more sensitive than GE and the sensitivity of clonality detection can be influenced by the amount of admixed normal lymphoid cells.