Ribonucleases may limit recovery of ribonucleic acids from archival human temporal bones

Messenger ribonucleic acid (mRNA) for actin was detected in celloidin-embedded archival human temporal bone sections with reverse transcription polymerase chain reaction (RT-PCR). Actin mRNA was detected in 10% of sections analyzed. One possible reason for this modest detection incidence is enzymatic degradation of RNA by exogenously introduced ribonucleases (RNases). We have identified steps of the temporal bone processing protocol for archival storage in which exogenous RNases could be introduced to the tissue, and have verified that the bone sections are exposed to these enzymes. We have demonstrated that implementing precautions to minimize exogenous RNase contamination during processing improves recovery of intact RNA. This study indicates that although gene expression analysis of archival human temporal bones may be limited by enzymatic degradation of RNA, simple modification of processing protocol can improve yield of informative data.