Evaluation of an alternative in vitro testicular cell co-culture model for male reproductive toxicity testing

The development of in vitro models for detecting testicular toxicity to serve as an animal-friendly, cost-effective and simple alternative is important. Different in vitro primary cells co-culture models have been reported, but none of them have been widely applied due to the complexity of the cell isolation procedure, animal difference and the poor ability to replicate the tests. As a continuation of previous studies, a new co-culture model using cell lines from rat testis was established to reduce the usage of animals. The ability of the model in discriminating testicular toxicants was also explored by using neutral red uptake assay. I also treated each single cell type to compare with the co-culture and identify chemicals sensitive cell types. Specifically, the cytotoxicity of 32 compounds was examined in co-culture for 24 h and 48 h. I observed that this model was able to distinguish testicular toxic and non-toxic chemicals, and more importantly, prioritize the chemicals at high risk by cluster analysis. The linear regression and Pearsons correlation results from the co-culture model after 48 h treatment had the highest correlation with in vivo reproductive lowest observed adverse effect level. These results demonstrate that our in vitro co-culture model may be a useful tool in screening testicular toxicants.