Cadmium Toxicity in Testis Organoids: Validation of an In Vitro Model for Testicular Toxicology

Environmental toxicants are increasingly implicated in male reproductive disorders, highlighting the need for physiologically relevant in vitro testicular models for toxicological testing. We previously developed a testis organoid system that recapitulates key architectural and endocrine features of native tissue; however, its suitability for toxicological applications requires validation. In this study, cadmium, a well-characterized environmental heavy metal and testicular toxicant, was used as a positive control to evaluate model responsiveness. Testis organoids were exposed to increasing concentrations of cadmium (0.01, 1, 10, and 100 μM) to assess dose-dependent toxicological effects. Cadmium bioaccumulation within organoids was quantified, and multiple endpoints were evaluated, including testis cell assembly, cord formation, apoptosis/necrosis, germ cell number, DNA damage, cellular proliferation, and endocrine function. Cadmium accumulated in a concentration-dependent manner, with greater accumulation at 10 and 100 μM. At these concentrations, cadmium exposure reduced cord formation, germ cell numbers, and cellular proliferation, and decreased testosterone and estradiol production, while increasing apoptosis/necrosis and DNA damage. Disruption of testis cell assembly was observed only at 100 μM. Collectively, these findings demonstrate dose-dependent toxicological responses and support the use of this testis organoid system as a relevant in vitro model for reproductive toxicology and environmental toxicant evaluation.