ATLA::Alternatives to Laboratory Animals

Volume 29, Number 5

In vitro assessment of cytotoxicity and carcinogenic potential of chemicals: evaluation of the cytotoxicity induced by 58 metal compounds in the Balb/3T3 cell line.

ATLA 29, 601-611, September/October 2001

Francesca Mazzotti, Enrico Sabbioni, Michela Ghiani, Barbara Cocco, Raffaella Ceccatelli and Salvado Fortaner

ECVAM, Institute for Health & Consumer Protection, European Commission Joint Research Centre, 21020 Ispra (VA), Italy

SUMMARY

A new, mechanistically based, in uitro strategy involving Balb/c 3T3 clone A31-1-1 mouse embryo fibroblasts has been proposed for the determination of the carcinogenic potential of inorganic chemicals, in order to establish priority of metal compounds to be tested and. whenever possible, to compare the in vitro results with the corresponding in vivo data. As a first step in this research, this study reports on the cytotoxic effects of 58 metal compounds in the Balb '3T3 cell line. After harmonisation and standardisation of the Balb/3T3 protocol, cells were exposed for 72 hours to a fixed dose (100 µM) of 58 individual compounds. The cytotoxicity induced by some metal compounds was found to be related to their chemical form (for example, Cr(N0₃)₃ and Na₂CrO₄), suggesting that the Balb/3T3 cell line is a valuable cellular model in relation to this aspect of metal speciation. The results of the systematic study on the metal-induced cytotoxic effects in the Balb/3T3 cell line could be arbitrarily classified into three groups according to the degree of cytotoxicity Group I includes 26 species that induced no observable effect or only a slight cytotoxic effect; Group II includes 13 metal compounds that exhibited an obvious degree of cytotoxicity; and Group III includes 19 metal species that displaved a strong cytotoxic response. Metal compounds of Groups II and III are considered to be of the highest priority for setting of dose-effect relationships for a subsequent in vitro study on metal-induced concurrent cytotoxicity and morphological transformation in the Balb/3T3 cell line.

Keywords: in vitro cytotoxicity, carcinogenic potential, trace metals, Balb/c 3T3 assay