Studies on stress-induced changes at the subcellular level by Raman microspectroscopic mapping

Area of Science:

• Cell Biology
• Biophysics
• Spectroscopy

Background:

• Raman microspectroscopy offers label-free analysis of cellular chemical composition and molecular structure.
• Understanding cellular responses to stress, such as apoptosis, is crucial in cell biology.

Purpose of the Study:

• To investigate the morphological and molecular changes in lung fibroblast cells during apoptosis using Raman microspectroscopic mapping.
• To assess the potential of Raman microspectroscopy as a tool for single-cell analysis.

Main Methods:

• Lung fibroblast cells were exposed to glyoxal to induce stress and apoptosis.
• Raman microspectroscopic maps were acquired from fixed cells using 785-nm excitation and a 1-microm step width.
• Cluster analysis was employed to interpret the spectroscopic data and generate pseudocolor images.

Main Results:

• Raman mapping identified nuclear shrinkage (pyknosis) and decreased nucleic acid band intensity, indicative of DNA/RNA degradation in early apoptosis.
• Later stages of apoptosis showed cell rounding, further nucleic acid reduction, nuclear fragmentation, lipid body disappearance, and surface blister formation.
• Analysis of cell surface blisters revealed higher protein and incorporated nucleic acid content compared to undisturbed cell membranes.

Conclusions:

• Raman microspectroscopic mapping effectively visualizes subcellular chemical changes during apoptosis.
• The technique demonstrates potential as a powerful tool for label-free, single-cell analysis in cell biology.
• Glyoxal-induced apoptosis in lung fibroblasts involves significant molecular and structural alterations detectable by Raman spectroscopy.