Comparison of microRNA expression using different preservation methods of matched psoriatic skin samples

Abstract

MicroRNAs are non-coding RNA molecules modulating gene expression post-transcriptionally. Formalin-fixed, paraffin-embedding (FFPE) is a standard preservation method often used in clinical practices, but induces RNA degradation. Extracting high-quality RNA from human skin can be challenging as skin contains high levels of RNases. As microRNAs are 19-23 nucleotides long and lack a poly-A tail, they may be less prone to RNA degradation than mRNAs. We investigated whether microRNAs in psoriatic (FFPE) samples reliably reflect microRNA expression in samples less prone to RNA degradation such as fresh-frozen (FS) and Tissue-Tek-embedding (OCT). We found a strong correlation of the microRNA expression levels between all preservation methods of matched psoriatic skin samples (r(s) ranging from 0.91 to 0.95 (P < 0.001)). These observations were further confirmed with qRT-PCR. Our results demonstrate that microRNA detection in human skin is robust irrespective of preservation method; thus, microRNAs offer an appropriate and flexible approach in clinical practices and for diagnostic purposes in skin disorders.