Growth Characteristics of KB and RAJI Cells in the Liquid Culture Medium in Relation to the Human Tumor Stem Cell Assay for Anti-Tumor Agents
Recently the chemosensitivity assay with clonal human tumor stem cells in liquid medium have been developed. We have investigated the optimal conditions for culture and counting of KB cells, which derived from a human epidermoid carcinoma and grow as a sheet adhered to the bottom surface of the culture, and RAJI cells, which derived from Burkitt lymphoma and grow as a suspension in liquid medium, as the representatives of the human tumor cells. Both stock cells were maintained in Eagle's MEM medium plus 10 per cent calf serum in C02 incubator at 37°C. Trypsinized cell suspensions were delivered in plastic wells with different culture media and incubated for different periods. Then the cell number was counted by the Coulter Counter in ISOTON II solvent. For KB cells, the culture medium should not be changed for 72 hours, otherwise enough cell number could not be obtained. To prevent the aggregation of KB cells in ISOTON II, calf serum (10%) was effective and EDTA (0.02%) had an additive effect. RAJI cells did not aggregate in ISOTON II. Ethanol and dimethylsulfoxide inhibited the growth of RAJI cells, but almost no inhibition was noted when the initial cell number was more than 8×l04/ml. Ethanol was more toxic. Both solvents, however, did not affect the growth of KB cells.