Nanosecond Infrared Laser Sampling of Mouse and Human Liver Tissues for LC-MS/MS Analysis of Bile Acids

Accurate quantification of bile acids is vital as they are potential biomarkers for several diseases. To solubilize bile acids from tissues, homogenization is required, typically performed using mechanical methods such as the TissueLyser method. Drawbacks like available tissue amount and low abundance of bile acids interfere with the analysis. We aim to establish a nanosecond infrared laser (NIRL) as a possible tissue homogenization tool to circumvent problems associated with limited sample amounts for research and to target low abundance bile acids. We quantify bile acids from mouse and human liver tissues comparing both the classic TissueLyser and the NIRL methods for homogenization prior to LC-MS/MS analysis. The applicability of our approach is tested using mice lacking Cyp2c70, a well-established mouse model with an altered bile acid composition compared to wild type mice. We found the NIRL method to require an almost 14 times smaller starting tissue amount than the TissueLyser method. The NIRL is also comparable to the TissueLyser for high abundance bile acids. While the TissueLyser provides efficient mechanical homogenization, the NIRL potentially enables quantification of low abundance bile acids. The well-established biological differences in bile acid profiles from the Cyp2c70 knockout mouse model were also observed with NIRL homogenization. These results show that the NIRL is potentially useful as smaller tissue amounts are required for analysis and low abundance bile acids are quantifiable.