Objective: Understanding structures of circulating RNA expands fundamental knowledge of cell communications and signaling pathways as well as allows developing new molecular diagnostic approaches. The aim of this study was to deploy a new approach to sequencing cDNA library construction which expands the capabilities of high-throughput sequencing analysis of small non-coding RNAs. With the approach, we performed massively parallel sequencing of human blood plasma RNA to document profile of common and peculiar RNA species normally circulating in blood of healthy individuals.
Methods: Total RNA was extracted from blood plasma samples of eight apparently healthy individuals. To obtain comprehensive cDNA libraries RNA was dephosphorylated and then 5'-phosphorylated. 5'-Phosphorylated total plasma RNA was ligated with adapters, reverse transcribed and eight personalized cDNA libraries were constructed. Libraries were sequenced with SOLiD(™) technology.
Results/conclusion: Fragments of rRNA, mitochondrial transcripts, microRNAs, fragments of scRNAs, snRNA and snoRNA, fragments of several mRNAs as well as the set of newly discovered transcripts were found to be permanent representatives of human blood plasma RNAs. Advanced mapping allowed to identify circulating herpes virus and enterobacterial transcripts. Documented profile of circulating RNA of healthy individuals provides basis for development of new approaches in research and diagnosis of human pathology.