Establishment of a Method for Direct Analysis of the Mouse Liver Metabolome Using the DPiMS-8060

Significance of the topic

Accurate profiling of endogenous metabolites in tissues is critical for understanding physiological and pathological states. Conventional metabolome analysis often involves extensive sample preparation that can introduce biases and cause analyte loss. Direct ionization methods, such as probe electrospray ionization, enable rapid, minimally invasive analysis of intact tissue sections, improving throughput and data fidelity.

Objectives and Overview

This work aims to establish and validate a direct analysis protocol for mouse liver metabolome using Shimadzu’s DPiMS-8060, which integrates probe electrospray ionization (PESI) with triple quadrupole tandem mass spectrometry. The method was tested on healthy mice and on a carbon tetrachloride (CCl4)–induced acute liver failure model to assess its capability to detect metabolomic alterations associated with disease.

Methodology

Standard solutions of 26 metabolites (amino acids, organic acids, sugars) were prepared in 50 % ethanol and 10 µL aliquots were spotted into dedicated liquid sample plates. For tissue analysis, 3 mm^2 sections of mouse liver, from both control and CCl4-treated animals, were placed directly into solid sample plates without further pretreatment. Multiple reaction monitoring (MRM) transitions and collision energies were optimized for each metabolite.

Used Instrumentation

• Shimadzu DPiMS-8060 probe electrospray ionization tandem mass spectrometer
• Dedicated sample plates for liquid and solid samples

Main Results and Discussion

Principal component analysis of the metabolomic data revealed clear separation between healthy and CCl4-treated liver samples along the first principal component. Taurine emerged as the primary discriminant metabolite, showing a significant decrease in the model group (p<0.001, Welch’s t-test). Correlation analysis demonstrated strong negative relationships between taurine levels and liver injury markers alanine aminotransferase (r=–0.975) and aspartate aminotransferase (r=–0.785), reflecting the role of taurine as a radical scavenger in CCl4-induced oxidative stress.

Benefits and Practical Applications

• Elimination of complex extraction steps reduces sample loss and analytical biases.
• Rapid analysis of intact tissue sections enhances throughput for basic research and QA/QC workflows.
• Capability to monitor disease-related metabolite changes supports toxicology studies and drug efficacy assessments.

Future Trends and Potential Applications

• Extension to broader metabolite panels, including lipids and signaling molecules.
• Integration with spatially resolved sampling to map metabolic heterogeneity within tissues.
• Coupling with high-resolution mass spectrometry for comprehensive untargeted discovery.
• Automation and miniaturization for high-throughput screening in clinical diagnostics and pharmaceutical research.

Conclusion

The DPiMS-8060 system enabled direct, intact metabolome profiling of mouse liver, distinguishing healthy and CCl4-induced liver failure samples without complex pretreatment. This streamlined approach holds promise for diverse applications in biomedical research and industrial analytics.

Reference

• Zaitsu K; Hayashi Y; Murata T et al. Anal Chem 2016 88 3556-3561