Enhanced and controlled chromatin extraction from FFPE tissues and the application to ChIP-seq

Area of Science:

• Epigenetics
• Molecular Biology
• Pathology

Background:

• Epigenetic alterations are crucial in human disease development.
• Formalin-fixed paraffin-embedded (FFPE) tissues are vital for clinical research but challenging for epigenetic studies.
• Existing methods yield insufficient chromatin from FFPE samples for reliable epigenetic analysis.

Purpose of the Study:

• To develop an efficient chromatin extraction method for FFPE tissues.
• To enable chromatin-based epigenetic assays using archived FFPE samples.
• To overcome limitations of low chromatin yield and damage in FFPE samples.

Main Methods:

• Introduced Chrom-EX PE, a novel chromatin extraction technique for FFPE tissues.
• Applied tissue-level cross-link reversal at 65°C during rehydration of deparaffinized FFPE tissues.
• Investigated chromatin fragmentation patterns at various incubation temperatures.

Main Results:

• Chrom-EX PE significantly increased soluble chromatin yield from FFPE tissues.
• The extracted chromatin is suitable for targeted ChIP-qPCR and genome-wide ChIP-seq.
• Controlled chromatin fragmentation (mononucleosomal to >1kb) is achievable by adjusting incubation temperature.

Conclusions:

• Chrom-EX PE provides efficient, high-quality chromatin extraction from FFPE samples with minimal damage.
• This method facilitates epigenetic assays on FFPE tissues, expanding their utility in research.
• The approach addresses the over-fixed nature of FFPE tissues, enabling future technological advancements.