Use of a Near Infrared Probe to Assess Intracellular Hydrogen Sulfide Production

Hydrogen sulfide (H₂S) is a ubiquitous gas that has recently garnered significant interest as a potential therapeutic agent for various ischemic and inflammatory diseases. Therefore, effective H₂S detection methods may be beneficial for translational research applications for these diseases. In the current study, a near-infrared H₂S (NIR-HS) probe was synthesized and hypothesized that the probe would allow for qualitative assessment of H₂S in biological systems.

The NIR-HS probe was synthesized and purified using chromatography. The ability of the NIR-HS probe to detect H₂S was first determined in cell-free environments when H₂S salts sodium sulfide (Na₂S), sodium hydrosulfide (NaHS) and a H₂S-slow-releasing donor (p-methoxyphenyl)morpholino-phosphinodithioic acid (GYY4137), were used. Three mammalian cell lines (HIEC6, HEK293T, and vertebral bone adherent mesenchymal stem cell) were treated with NaHS (H₂S donor) or ZnCl₂ (negative control) in the presence of the NIR-HS probe. NIR-HS probe was also tested in cells that either overexpressed H2S synthases (CBS, CTH, and mercaptopyruvate sulfurtransferase) or had reduced levels of H2S synthases. The fluorescent responses of NIR-HS were determined by fluorescent microscopy and flow cytometry.

In a cell-free system, the NIR-HS probe showed a statistically significant increase in fluorescence with the addition of Na₂S, NaHS, or GYY4134 compared to vehicle alone, and dose-dependent responses to H₂S donors. In mammalian cells, H₂S donors increased and ZnCl₂ decreased the fluorescent responses of NIR-HS. Knocking down and overexpressing the endogenous H₂S synthases altered the production of H₂S, respectively.

This NIR-HS probe was shown to be a useful compound in the detection of H₂S in cell-free and cellular environments. Further studies are needed to demonstrate its use within in vivo applications of specific ischemic and inflammatory disease models prior to clinical translation.