Ganglioside Detection from Formalin-Fixed Human Brain Tissue Utilizing MALDI Imaging Mass Spectrometry

Area of Science:

• Biochemistry
• Analytical Chemistry
• Neuroscience

Background:

• Matrix-assisted laser desorption ionization (MALDI) imaging mass spectrometry (IMS) provides spatial molecular information from biological tissues.
• MALDI-IMS is typically performed on fresh-frozen tissues, as formalin fixation can suppress lipid signals.
• Formalin fixation is standard for clinical tissue preservation, limiting MALDI-IMS applications.

Purpose of the Study:

• To investigate the feasibility of MALDI-IMS on formalin-fixed tissues for ganglioside analysis.
• To evaluate the impact of an ammonium formate (AF) wash on signal enhancement and image quality in formalin-fixed tissues.
• To compare MALDI-IMS data from fresh-frozen and formalin-fixed tissues.

Main Methods:

• Comparison of MALDI-IMS data from fresh-frozen rat brain and formalin-fixed rat brain samples.
• Application of an ammonium formate (AF) wash to postfixed rat and human brain samples prior to MALDI-IMS analysis.
• Analysis of ganglioside spectra and spatial distribution, focusing on GM1.

Main Results:

• An AF wash significantly enhanced MALDI-IMS spectra for gangliosides, including GM1, in both fresh-frozen and formalin-fixed rat and human brain samples.
• Improvements in MALDI-IMS image quality were observed with the AF wash.
• The spatial distribution of molecules was successfully retained in fixed and washed tissue samples.

Conclusions:

• An ammonium formate wash is effective in overcoming signal suppression in formalin-fixed tissues for MALDI-IMS.
• This method enables robust ganglioside analysis in formalin-fixed clinical samples.
• The findings open new possibilities for neurodegenerative disease research using archival tissue samples.