Fluorescence in situ hybridization on formalin-fixed and paraffin-embedded tissue: optimizing the method

Area of Science:

• Molecular Biology
• Genetics
• Histology

Background:

• Fluorescence in situ hybridization (FISH) is a key technique for detecting genetic abnormalities in cells.
• FISH is commonly applied to cytologic samples but also to tissue sections for morphological context or when cytologic material is unavailable.
• Analyzing genetic changes in formalin-fixed, paraffin-embedded (FFPE) tissues presents technical challenges.

Purpose of the Study:

• To systematically optimize Fluorescence In Situ Hybridization (FISH) protocols for FFPE tissues.
• To improve the reliability and accuracy of genetic analysis using isolated nuclei and tissue sections from FFPE samples.

Main Methods:

• Investigated critical factors affecting FISH on FFPE tissues, including fixation variables, enzymatic pretreatment, hybridization, and washing conditions.
• Developed and validated a systematic approach to enhance FISH performance on isolated nuclei and tissue sections.
• Compared results from optimized protocols with standard methods.

Main Results:

• Identified key parameters influencing hybridization efficiency and signal quality in FFPE samples.
• Demonstrated significant improvements in FISH signal detection and specificity using the optimized protocols.
• Successfully applied the improved methods to both isolated nuclei and tissue sections from FFPE blocks.

Conclusions:

• The developed systematic approach effectively overcomes technical challenges in applying FISH to FFPE tissues.
• Optimized FISH protocols enhance the ability to detect numerical and structural genetic abnormalities in FFPE samples.
• This advancement expands the utility of FISH for genetic analysis in challenging tissue specimens.