Gestational Changes in Placental Iron Homeostasis are Associated With Ferroptosis-Associated Redox Signaling and...

Well-regulated trophoblast proliferation, migration, invasion, and cell turnover are essential for normal placental development in humans and rodents. Given the established role of oxidative stress in placentation and the redox activity of iron, we investigated whether ferroptosis-associated redox signaling contributes to trophoblast function and placental development. Placental iron profiling revealed significantly elevated total and ferrous iron levels in first-trimester human villi compared with term placentas, accompanied by the transcript levels of several iron uptake- and reduction-related genes, including TFRC, DMT1, ZIP8, STEAP3, and STEAP4, which were elevated in first-trimester villi. Murine placentas also exhibited gestational changes in iron abundance and iron-homeostasis-related gene expression. HO-1 protein abundance was highest during early gestation and declined thereafter, suggesting a potential association between heme degradation and gestational iron homeostasis. In contrast, placental labile iron pool (LIP) levels showed only modest, statistically nonsignificant changes across gestation, suggesting a relatively stable redox-active iron pool. Immunofluorescence analyses demonstrated spatially distinct expression of ferroptosis-associated regulators, with ACSL4 enriched in invasive trophoblast populations and GPX4 predominantly localized in surrounding decidual tissues, suggesting regional heterogeneity in ferroptosis-associated molecular features during placentation. Functional studies in HTR-8/SVneo trophoblast cells further demonstrated that mild ferroptosis-associated redox perturbation induced by low-dose erastin or ferrous iron enhanced trophoblast migration and invasion without overt cytotoxicity. These effects were attenuated by ferrostatin-1, deferoxamine mesylate (DFOM), or the mitochondria-targeted antioxidant MitoQ and were blunted following FTH1 and TFRC knockdown, indicating that trophoblast responsiveness depends on iron availability and ferroptosis-associated redox signaling. Importantly, these pro-invasive effects were preserved under physiologically relevant hypoxic conditions. Together, our findings support a model in which gestational changes in placental iron homeostasis are associated with ferroptosis-related molecular features, while experimentally induced iron-dependent redox signaling modulates trophoblast behavior. Rather than inducing overt ferroptotic cell death, sublethal iron-dependent redox perturbation may act as a signaling mechanism influencing trophoblast function during placental development.