Stain-free subcellular-resolution astrocyte imaging using third-harmonic generation.

Area of Science:

• Neuroscience
• Biomedical Optics
• Cell Biology

Background:

• Traditional cell imaging often requires fluorescent labeling, which can interfere with cellular function or introduce artifacts.
• High-resolution imaging of glial cells, particularly astrocytes, is crucial for understanding brain function and disease.
• Existing label-free imaging techniques may lack the contrast or resolution needed for detailed subcellular analysis.

Purpose of the Study:

• To demonstrate a novel stain-free imaging technique for astroglial cells.
• To achieve high-contrast, subcellular-resolution imaging of astrocytes.
• To validate the utility of epi-detected third-harmonic generation (THG) for astrocyte visualization.

Main Methods:

• Utilized epi-detected third-harmonic generation (THG) microscopy for label-free imaging.
• Optimized the point-spread function (PSF) of the THG microscope for enhanced resolution.
• Verified THG imaging results by colocalization with fluorescence microscopy of genetically encoded reporters in astrocytes.

Main Results:

• Achieved stain-free, high-contrast imaging of astroglial cells with subcellular resolution.
• Demonstrated THG imaging's capability to visualize astrocyte nuclei, soma shape, and boundaries.
• Confirmed THG signal colocalization with astrocyte-specific fluorescent markers, validating the technique.

Conclusions:

• Epi-detected THG microscopy is a powerful tool for label-free, high-resolution imaging of astrocytes.
• The optimized THG method reliably detects subcellular structures in astrocytes without the need for stains.
• This technique offers a promising alternative for studying astrocyte morphology and dynamics in biological and pathological contexts.