Confirmation of sub-cellular resolution using oversampling imaging mass spectrometry

Area of Science:

• Lipidomics
• Mass Spectrometry Imaging
• Cell Biology

Background:

• Oversampling in MALDI-IMS is used to enhance lateral resolution but its impact on spectral intensity is debated.
• Previous studies using oversampling characterized the colon epithelium lipidome.
• K-means analysis revealed an epithelial cluster corresponding to nuclei, prompting investigation into its origin.

Purpose of the Study:

• To confirm the nuclear origin of a distinct cluster identified via K-means analysis in MALDI-IMS data.
• To validate the use of oversampling for high-resolution lipidomic analysis of cellular components.
• To characterize the nuclear lipidome within the human colon epithelium.

Main Methods:

• MALDI-IMS with oversampling at 10 μm/pixel lateral resolution.
• Comparison of spectra from tissue sections with isolated colon nuclei.
• K-means clustering analysis of lipidomic data.

Main Results:

• A high spectral correlation confirmed the nuclear origin of the identified cluster.
• The nuclear lipidome was successfully identified in MALDI-IMS experiments.
• Phosphatidylinositol 38:4 levels were stable within the colon crypt nuclei, ruling out inter-pixel contamination.

Conclusions:

• Oversampling is a valuable technique for high-resolution MALDI-IMS, enabling detailed lipidomic analysis.
• This study successfully identified the nuclear lipidome in human colon tissue.
• MALDI-IMS holds significant promise for future single-cell lipidomic studies.