Identification of a reference gene for the quantification of mRNA and miRNA expression during skin wound healing

Aim: Wound healing is a coordinated process to restore tissue homeostasis and reestablish the protective barrier of the skin. miRNAs may modulate the expression of target genes to contribute to repair processes, but due to the complexity of the tissue it is challenging to quantify gene expression during the distinct phases of wound repair. Here, we aimed to identify a common reference gene to quantify changes in miRNA and mRNA expression during skin wound healing. Methods: Quantitative real-time PCR and bioinformatic analysis tools were used to identify suitable reference genes during skin repair and their reliability was tested by studying the expression of mRNAs and miRNAs. Results: Morphological assessment of wounds showed that the injury model recapitulates the distinct phases of skin repair. Non-degraded RNA could be isolated from skin and wounds and used to study the expression of non-coding small nuclear RNAs during wound healing. Among those, RNU6B was most constantly expressed during skin repair. Using this reference gene we could confirm the transient upregulation of IL-1 and PTPRC/CD45 during the early phase as well as the increased expression of collagen type I at later stages of repair and validate the differential expression of miR-204, miR-205, and miR-31 in skin wounds. In contrast to Gapdh the normalization to multiple reference genes gave a similar outcome. Conclusion:RNU6B is an accurate alternative normalizer to quantify mRNA and miRNA expression during the distinct phases of skin wound healing when analysis of multiple reference genes is not feasible.