A growth chamber for chronic exposure of mammalian cells to H₂S

H₂S is a redox-active signaling molecule that exerts an array of cellular and physiological effects. While intracellular H₂S concentrations are estimated to be in the low nanomolar range, intestinal luminal concentrations can be significantly higher due to microbial metabolism. Studies assessing H₂S effects are typically conducted with a bolus treatment with sulfide salts or slow releasing sulfide donors, which are limited by the volatility of H₂S, and by potential off-target effects of the donor molecules. To address these limitations, we describe the design and performance of a mammalian cell culture incubator for sustained exposure to 20-500 ppm H₂S (corresponding to a dissolved sulfide concentrations of ∼4-120 μM in the cell culture medium). We report that colorectal adenocarcinoma HT29 cells tolerate prolonged exposure to H₂S with no effect on cell viability after 24 h although ≥50 ppm H₂S (∼10 μM) restricts cell proliferation. Even the lowest concentration of H₂S used in this study (i.e. ∼4 μM) significantly enhanced glucose consumption and lactate production, revealing a much lower threshold for impacting cellular energy metabolism and activating aerobic glycolysis than has been previously appreciated from studies with bolus H₂S treatment regimens.