Improved Technique of Digoxigenin Labeled RNA in situ Hybridization

ABSTRACT

BACKGROUND: A practical RNA in situ hybridization method using digoxigenin labeled RNA probes is described in order to evaluate the technical difficulties and problems in RNA in situ hybridization. METHODS: The paraffin sections, routinely processed in the Pathology Laboratory, were tested for the possibility of RNA in situ hybridization instead of the RNase free paraffin sections, fixed in 4% paraformaldehyde and prepared using RNase protection procedures. RESULTS: Most of the paraffin sections, fixed in 10% neutral formalin solution in fresh condition, showed relatively good reaction of RNA in situ hybridization, although the necrotic tissue and autopsy specimens showed poor reaction of RNA in situ hybridization. A refixation procedure using a 4% paraformaldehyde solution was evaluated for optimal expression of mRNA in the paraffin sections. CONCLUSION: The treatment of 4% paraformaldehyde before the treatment of proteinase K showed better in situ hybridization than did the treatment of 4% paraformaldehyde after the treatment of proteinase K. Also a new Polymerase Chain Reaction (PCR)-based method of RNA probe production showed consistently good results.