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

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