Objectives: In a variety of (patho-) physiological situations microRNAs, small noncoding RNA fragments of 20-24 bp of length, display import post-transcriptional gene regulators. Current pathology of pre-perfusion kidney biopsies lacks the potential to predict post-transplant organ function, especially the occurrence of delayed graft function (DGF) as a consequence of ischemia reperfusion injury (I/R injury). Therefore next generation sequencing profiling of microRNA might offer the ability to obtain specific molecular patterns to understand pathways in I/R injury helping to predict clinical graft injury.

Methods: Pre-perfusion kidney transplant biopsies, embedded in formalin-fixed paraffin, were used for microRNA profiling performed by next generation sequencing (NGS) "Ion torrent". Different clinical graft injuries, i.e. DGF or immediate graft function were analyzed using biopsies from nephrectomies as normal controls. Data were analyzed by Geneious Pro.

Results: The use of the new technique of NGS offered the possibility of robust and reproducible microRNA profiles in high quality and adequate coverage out of small amounts of FFPE transplant biopsies, which were suitable for further analyses. According to clinical graft injury differential expression could be shown in different microRNA profiles, and unsupervised hierarchical clustering revealed specific microRNA expression patterns related to thwÉir clinical outcome.

Conclusions: These data proved the feasibility of microRNA profiling by the new NGS platform (“Ion torrent”) of FFPE samples with small amount of tissue input and offer the potential to reveal specific pathways involved in I/R-injury in renal transplantation. Further research is warranted to elucidate the interaction between microRNA, gene expression and clinical outcome to confirm these specific pathways.

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