In Vitro Cytocompatibility of Antibacterial Levels of Polymer Nitric Oxide Release

Although the antibacterial property of nitric oxide (NO) has been well documented in gram positive and gram negative bacteria cultures, its cytotoxic effects are not completely clear. To limit potential in vivo cytotoxicity, our group recently investigated the effects of a range of NO fluxes on S. epidermidis and S. aureus to determine a minimum effective NO level. In this study, we report the antibacterial function of this minimum NO level also on gram negative Pseudomonas aeruginosa as well as its cytocompatibility effects on lung and kidney cells. Standardized bacterial cultures were treated with NO releasing PDMS substrates followed by plating, 24hr incubation, and colony analyses. Cytocompatibility or cell viability was conducted on WI-38 human lung fibroblasts and HEK-293 human embryonic kidney cells after their exposure to NO in vitro. NO flux of 21.18 ± 5.31 × 10−10 mol/ min/ cm2 significantly reduced P. aeruginosa growth compared to controls and PDMS-treated samples (p value < 0.0001). No significant differences was seen between control and cells treated at this flux (total moles delivered in 24hrs = 0.76 ± 0.18), but a significant reduction was observed at 45.1 ± 2.55 ×10−10 mol/ min/ cm2 (total moles delivered = 1.6 ± 0.09). The results suggest that at the lower NO flux level pseudomonas aeruginosa growth is significantly inhibited while maintaining cell viability.