Proliferation of normal and malignant human epithelial cells post irradiation.

Fragments of human oesophageal mucosa, urothelium, squamous and adenocarcinoma of the oesophagus and carcinoma of the bladder have been plated in culture and irradiated. The cells growing from the explanted tissues have then been studied for four weeks post irradiation to assess the overall rate of growth from the irradiated explants and the fraction of proliferating cells. The results show that when using cell number as an endpoint it is possible to derive growth curves from this type of data which permit a doubling time to be obtained for the cell population surviving different doses. In an attempt to determine the proliferating fraction of the cell population, cultures were labelled at appropriate intervals with tritiated thymidine and were also stained with Ki-67 antiproliferating antigen. The results show an interesting relationship between the dose response obtained for cell labelling with tritiated thymidine and area of cellular outgrowth. Ki-67 staining when used carefully and analysed as described was a useful indicator of proliferating cells. The results provide a means of determining the post irradiation growth potential of fragments of tissue from human organs and may be important for determined overall response of the tumour bulk to proposed treatment.