A colony-forming assay for human tumour xenografts using agar in diffusion chambers

A technique for growing colonies from single-cell suspensions of human tumour xenografts using agar in diffusion chambers is described. Modified Millipore diffusion chambers containing tumour cells in semi-solid agar-medium were implanted into the peritoneal cavity of pre-irradiated mice and provided standard culture conditions for the study of colony-forming cells. All 11 xenograft tumours so far studied produced colonies. The incubation period for colony growth ranged from 12 to 28 days and the plating efficiency ranged from 0-3% to 16% for different tumours, but both parameters were constant for each individual tumour. The reproducibility of the system provides a colony-forming assay which can be used to study the effects of irradiation and cytotoxic drugs on human tumour clonogenic cells and may therefore have some advantages over similar assays based on experimental animal tumours.