Study on the mechanisms of defective spermatogenesis induced by TiO 2 NPs based on 3D blood-testis barrier microfluidic chip.

Titanium dioxide nanoparticles (TiO 2 NPs) can reduce sperm number, but the mechanisms of defective spermatogenesis induced by TiO 2 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 TiO 2 NPs-induced defective spermatogenesis. TM4 and GC-1 cells cultured in TiO 2 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, TiO 2 NPs suppressed glucose metabolism, especially lactate production, which reduced energy substrate supply for spermatogenesis. TiO 2 NPs also decreased the levels of key proteins and metabolites of lactate production. In GC-1 cells, TiO 2 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 TiO 2 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 TiO 2 NPs.