Differential Susceptibility to Heavy-Metal-Induced Injury in a Human Testis Tissue Equivalent (hTTE): Implications for Oxidative Stress

Oxidative stress driven by environmental and occupational exposure to heavy metals is increasingly recognized as a central, modifiable contributor to male infertility. Yet, the lack of physiologically relevant human models has limited mechanistic insight. We have previously described a three-dimensional Human Testis Tissue Equivalent (hTTE) that recapitulates the cellular composition and stem cell niche of the seminiferous tubule and is more resistant than two-dimensional (2D) culture to gonadotoxic chemotherapeutics. Here, we used the hTTE platform to compare heavy-metal cytotoxicity, cell-type-associated transcript responses, and exploratory microRNA (miRNA) profiles elicited by three prototypical pro-oxidant heavy metals: mercury (Hg2+), thallium (Tl+), and lead (Pb2+). Background and aim: To determine whether the hTTE model exhibits greater resistance to heavy-metal cytotoxicity than matched 2D cultures and whether cell-type-associated responses differ following heavy-metal exposure within the established redox biology of these toxicants.