Light-Based 3D Bioprinting of Testicular Organoid as an In Vitro Model for Reproductive Toxicity Assessment.

Organoids can be used as an in vitro platform for studying tissue development and toxicology evaluation. While in vitro maturation of somatic and germ cells has been demonstrated in organoids, generating reproducible primary testicular cell-derived organoids for toxicity evaluation remains challenging. In this study, we developed testicular organoids using light-based 3D bioprinting of neonatal mouse primary testicular cells on transwell inserts. The bioprinting ink composition was specifically designed and optimized based on the extracellular matrix composition and mechanical properties of testicular tissue. The organoids were cultured for 21 days using an optimized medium to support testicular cell development and function. These bioprinted organoids recapitulated key features of the in vivo testicular architecture, forming tubule-like structures with cellular organization and gene expression profiles similar to native tissue. Following exposure to the known male reproductive toxic agent triptolide, testicular organoids showed loss of tight junction protein CLAUDIN-11 and altered transcript levels of somatic markers. Each bioprinted testicular organoid can be generated within 1 min, with toxicity evaluation results available within 1 month. This rapid turnaround makes it a promising high-throughput platform for toxicological studies, advancing our understanding of testicular development, function, and the impact of potential toxicants on male reproductive health.