Clonogenic assay for Wilms' tumor: improved technique for obtaining single-cell suspensions and evidence for tumor cell specificity.

Wilms' tumors from seven patients were dissociated by mechanical and enzymatic means; this technique resulted in single-cell suspensions for five specimens and a few aggregates for two. By dye exclusion, cell viability ranged from 56 to 100% (median, 92%). All seven preparations produced more than five colonies/2 x 10(5) cells plated. Forty-three colonies grown from cells of a glucose-6-phosphate dehydrogenase heterozygote were of the same glucose-6-phosphate dehydrogenase isoenzyme type as the original tumor, indicating that the assay is specific for tumor cells. We attribute the high rate of colony formation to an improved method of cell preparation (combined mechanical and enzymatic dissociation of tumors) which may be applicable to other primary human tumors assayed in the soft agar system.