The further development of rainbow trout primary epithelial cell cultures as a diagnostic tool in ecotoxicology risk assessment

The use of short-term cytotoxicity assays for the initial screening of chem icals not only aids in establishing priorities for the selection of chemica ls that should be tested in vivo, but also decreases the time in which pote ntial toxicants can be valued. Rainbow trout primary skin epithelial cell c ultures are one such assay. Rainbow trout primary skin cell cultures contai n two cell types, keratinocytes and goblet mucus cells. Two aquatic polluta nts, copper and prochloraz were screened using this cell system. The influe nce of media composition on the effects of the aquatic pollutants was also studied by testing the chemicals in both serum-containing and serum-free me dium and the morphological changes that occurred within the cell cultures r ecorded. The concentration of copper that causes a reduction of 90% in the residual of day 3 growth of the primary cell culture system was found to be approximately 10 fold more than that of prochloraz. Prochloraz was found t o cause a greater reduction in growth area when added to the primary cell c ulture system in serum-free medium than in serum-containing medium. Copper, in contrast, was found to exert reduced toxicity when added to the test cu ltures in serum-free medium compared with addition in serum-containing medi um. Prochloraz was found to kill the epithelial cells by a process of necro sis. Copper, was found to kill the epithelial cells by both necrosis and ap optosis in a ratio of 2:1. It was also observed that as the dose of both ch emicals increased, the number of goblet cells contained in the cell culture s decreased. A PAS stain was carried out to determine if the goblet cells w ere exocytosing their contents onto the cell culture surface. It was found that as chemical exposure increased the number of cells expressing positivi ty for mucus also increased. The results of this study add further evidence to support that primary cell cultures are a very appropriate model for tox icity risk assessment. (C) 2001 Elsevier Science B.V. All rights reserved.