Sulforaphane improves syncytiotrophoblast mitochondrial function after in vitro hypoxic and superoxide injury.

INTRODUCTION: Placental mitochondrial dysfunction contributes to the oxidative stress that underlies preeclampsia. Here, we assessed whether sulforaphane (SFN) could improve syncytiotrophoblast mitochondrial function after in vitro hypoxic and superoxide injury. METHODS: Placental cytotrophoblasts were isolated from healthy term placentae (n = 12) and incubated for 48 h in 8% O2 ± 1 µM SFN before acute (4hrs) or chronic (24hrs) hypoxic (1% O2), or superoxide (xanthine/xanthine oxidase) injury. Cytotrophoblasts were also isolated from preeclamptic placentae (n = 5) and cultured in 8% O2 ± 1 µM SFN. Mitochondrial respiration was measured using the Seahorse MitoStress XF assay. Cells were stained with mitotracker red to assess mitochondrial membrane health and mitochondrial gene expression assessed using RT-qPCR. RESULTS: SFN prevented significant reductions in syncytiotrophoblast mitochondrial maximal respiration, spare respiratory capacity, basal respiration and ATP production following acute hypoxia. Chronic hypoxia only reduced maximal and spare respiratory capacity. SFN prevented these negative changes and increased respiration overall. Alternatively, acute superoxide injury significantly increased mitochondrial maximal respiration and spare respiratory capacity. SFN treatment further increased basal respiration following superoxide injury and prevented significant decreases in ATP production and coupling efficiency. In preeclamptic placentae, SFN significantly increased mitochondrial maximal respiration, spare respiratory capacity, basal respiration and ATP production, and decreased proton leak. SFN up-regulated mRNA expression of mitochondrial complexes and corrected an up-regulation in fission gene expression observed after hypoxic-superoxide injury. Finally, preliminary results suggest SFN prevented hypoxia-induced impairment of mitochondrial membrane structure. DISCUSSION: SFN mitigated hypoxia and superoxide induced changes to syncytiotrophoblast mitochondrial function in vitro, and improved mitochondrial respiration in trophoblast cells from preeclamptic placentae.