BioString^TM FFPE RNA Plus Kit extends the standard FFPE RNA purification workflow by integrating DNase digestion during RNA extraction. Removal of genomic DNA contamination improves reliability of downstream transcription and gene expression analysis.

The workflow maintains the same column-based RNA purification chemistry while incorporating a dedicated cleanup step to improve RNA purity.

This product is based on silica column purification. Remove paraffin by Buffer DPS. Sample lysis with proteinase K digestion requires only 15 minutes. After lysis, samples are incubated at 80ºC for 15 minutes. Transfer to an adsorption column and RNA is adsorbed on the membrane, while protein is not adsorbed and is removed with filtration. After washing proteins and other impurities, RNA was finally eluted with low-salt buffer.

BioString^TM FFPE RNA Kit was evaluated as a silica column-based RNA extraction workflow for formalin-fixed, paraffin-embedded tissue samples. The workflow includes deparaffinization, proteinase K digestion, 80°C heat treatment for reversal of formaldehyde-related modifications, and column-based RNA purification without phenol / chloroform extraction or alcohol precipitation.

In FFPE tissue testing, RNA was extracted from 9 mg paraffin-embedded tissue samples, including grass carp liver, grass carp muscle, chicken liver, and chicken heart. From 9 mg FFPE fish liver input, RNA yields were 14.8–22.9 µg. From 9 mg FFPE chicken liver input, RNA yields were 21.2–25.1 µg. Lower-yielding tissue types, including fish muscle and chicken heart, produced 1.5–1.7 µg and approximately 2.8 µg RNA, respectively, under the tested conditions.

Additional workflow testing showed that RNA integrity was maintained after the 80°C heat-treatment step used in the FFPE protocol. Using 200 µL cell input and 6 mg plant leaf input as model materials, RNA extracted after 55°C digestion followed by 80°C treatment showed clear electrophoresis band patterns, and the eluted RNA remained stable after overnight storage at 4°C before electrophoresis analysis.

In a paired comparison using six lung cancer FFPE samples, two tissue sections were processed per extraction with BioString^TM FFPE RNA Plus Kit and a leading commercial FFPE RNA extraction workflow. R4144 generated Qubit-measured RNA amounts of 2.8–18.1 µg in a 50 µL elution volume, compared with 1.53–15.8 µg from the reference workflow. Across the six paired samples, R4144 provided comparable or higher RNA recovery in most cases, with A260/280 and A260/230 values remaining in a comparable range. These results support for FFPE RNA extraction from clinical FFPE tissue sections where both RNA recovery and genomic DNA control are required.

Proteinase K should be stored at 2–8°C upon arrival. DNase I should be stored at -20°C. However, short-term storage (DNase I up to 1 weeks, Proteinase K up to 8 weeks) at room temperature (15–25°C) does not affect their performance. The remaining kit components can be stored at room temperature (15–25°C) and are stable for at least 18 months under these conditions.