The AllPrep DNA/RNA FFPE Kit is specially designed for simultaneous purification of genomic DNA and total RNA from FFPE tissue sections. Pure DNA and RNA are obtained from the entire sample, in contrast to other procedures where the biological sample is divided into two before being processed separately. Simply dividing a sample in half for separate DNA and RNA purification procedures results in the purification of DNA and RNA from different populations of cells, which may differ in their properties. Purification of DNA and RNA from the same sample also helps to prevent waste, since FFPE samples are precious, often difficult to retrieve, and limited in amount.
Due to fixation and embedding conditions, nucleic acids in FFPE samples are usually heavily fragmented and are often of a lower molecular weight than those obtained from fresh or frozen samples. A major obstacle to isolating DNA and RNA from the same FFPE sample is that fragmented DNA is short and can be partly single-stranded and therefore more closely resembles RNA than intact DNA. This property of fragmented DNA makes physical separation of DNA and RNA difficult. The AllPrep DNA/RNA FFPE Kit uses a patent-pending solubilization method to differentially release DNA and RNA from a single FFPE sample.
Nucleic acids in FFPE samples are also chemically modified by formaldehyde. Although formaldehyde modification cannot be detected in standard quality control assays, such as gel electrophoresis or lab-on-a-chip analysis, it does strongly interfere with enzymatic analyses. The AllPrep DNA/RNA FFPE Kit is optimized to reverse as much formaldehyde modification as possible without further DNA and RNA degradation.