56 Development of a model for the study of toxicity and carcinogenicity in vitro

A method has been developed which allows small samples of a variety of human tissues to be grown in culture. Explants established from surgical specimens of breast, bladder, oesophagus, skin, thyroid, larynx and colon can be maintained for at least one month. Cells from the explant migrate initially and then begin to divide. Quantitative analysis of cell growth and growth rate is possible using image analysis and autoradiography. Cell to cell contact and ultrastructural organisation has also been examined.Preliminary results indicate that carcinogens need to be applied at very specific concentrations in order to stimulate growth. Lower levels of carcinogen than those needed for growth stimulation have no apparent effect; at higher levels a toxic effect predominatesThis technique should prove useful in determining the threshold levels at which chemicals become carcinogenic.