Imaging and mapping of mouse bone using MALDI-imaging mass spectrometry

Area of Science:

• Biochemistry
• Analytical Chemistry
• Histology

Background:

• Matrix-assisted laser desorption/ionization-imaging mass spectrometry (MALDI-IMS) is a powerful technique for analyzing biomolecule distribution in tissues.
• Hydroxyapatite crystals in bone present challenges for MALDI-IMS analysis, with limited existing research on bone tissue applications.
• Comprehensive biomolecule mapping in bone using MALDI-IMS requires optimized sample preparation methods.

Purpose of the Study:

• To evaluate the feasibility of MALDI-IMS for comprehensive biomolecule mapping in mouse bone.
• To characterize and optimize fixation and decalcification methods for bone tissue preparation for MALDI-IMS.
• To identify specific biomolecules and their distribution within bone tissue.

Main Methods:

• Dissection of mouse femurs and tibiae from 8-week-old males.
• Characterization of various fixation and decalcification techniques.
• Cryosectioning, mounting on ITO-coated slides, matrix application, and MALDI-IMS data acquisition (100-1000 m/z).
• Histological and histochemical staining (H&E, Alcian blue, Azan, PAS) for comparative analysis.

Main Results:

• Trichloroacetic acid treatment yielded samples optimal for both histology and comprehensive MALDI-IMS.
• Histotypic mass spectrometry signals were detected across all tested sample preparations.
• Phosphocholine was identified as a candidate metabolite within the bone tissue.
• MALDI-IMS successfully detected biomolecules, demonstrating its potential for bone tissue analysis.

Conclusions:

• MALDI-IMS is a viable tool for determining biomolecule distribution in bone tissues.
• Optimized sample preparation, particularly using trichloroacetic acid, is crucial for successful bone MALDI-IMS.
• Further development in analytical procedures and instrument calibration is needed to enhance MALDI-IMS performance in bone analysis.