A comparative study of cytotoxic effects of N-ethyl-N-nitrosourea, adriamycin, and mono-(2-ethylhexyl)phthalate on mouse primordial germ cells

Several strategies for the assessment of reproductive toxicity of chemical compounds has have been proposed. In the present work, we devised experimental in vitro assays to test the effect of potential toxicants on proliferating primordial germ cells (PGCs) in vitro using recently developed methods for isolation and culture of mouse PGCs. Primordial germ cells are the embryonic precursors of gametes of the adult that carry the genome from generation to generation. Any damage or mutations caused to these cells by potential toxicants might impair normal reproduction and be transmitted to next generation. Three representative compounds, N-ethyl-N-nitrosourea (ENU), adriamycin (ADR), and mono-(2-ethylhexyl)phthalate (MEHP), toxic to different targets and known to affect germ cell development and impair fertility, were tested on PGCs in culture using three different experimental protocols. Survival and growth of PGCs and their ability to adhere to cell monolayers, were taken as endpoints for drug effects. For each compound, sublethal and acute toxicity doses were determined. In addition, information about the mechanisms of action of these compounds on PGCs was obtained. Whereas the effects of ENU and ADR on PGCs were attributable to growth inhibition and apoptosis induction, MEHP affected PGC adhesion to somatic cells without significantly altering their growth and survival. The results of our in vitro tests were not always exactly predictive of the effects of the tested compounds on PGCs in vivo, determined in parallel experiments in which pregnant mice were exposed to the same compounds. Nevertheless, they can provide information on the sensitivity of PGCs to the direct action of drugs or the mechanisms of action of such agents.