Study on the mechanisms of defective spermatogenesis induced by TiO₂ NPs based on 3D blood-testis barrier...

Titanium dioxide nanoparticles (TiO₂ NPs) can reduce sperm number, but the mechanisms of defective spermatogenesis induced by TiO₂ NPs have not been studied through cell-cell interactions at present. A kind of biomimetic three-dimensional blood-testis barrier microfluidic chip capable of intercellular communication was constructed with soft lithography techniques, including Sertoli cell (TM4), spermatogonia (GC-1) and vascular endothelial cell units, to study the mechanisms of TiO₂ NPs-induced defective spermatogenesis. TM4 and GC-1 cells cultured in TiO₂ NPs exposure and control chips were collected for transcriptomics and metabonomics analysis, and key proteins and metabolites in changed biological processes were validated. In TM4 cells, TiO₂ NPs suppressed glucose metabolism, especially lactate production, which reduced energy substrate supply for spermatogenesis. TiO₂ NPs also decreased the levels of key proteins and metabolites of lactate production. In GC-1 cells, TiO₂ NPs disturbed chemokine signaling pathways regulating cell proliferation and interfered with glutathione metabolism. The Cxcl13, Stat3 and p-Stat3 levels and cell proliferation rate were decreased, and the GSR, GPX4 and GSH contents were increased in GC-1 cells in chips under TiO₂ NPs treatment. The decrease in energy substrate supply for spermatogenesis and inhibition of spermatogonia proliferation could be the main mechanisms of defective spermatogenesis induced by TiO₂ NPs.