Analysis of circulating DNA has had a major impact in the last couple of years with 100s of publications in the last few years. I've previously posted about work at the Institute on circulating tumour DNA analysis of amplicons and exomes, but what about RNA?
RNAs can also be found circulating in blood, with one of the first reports of cancer associated circulating RNA being published in 1999. A 2013 paper in PlosOne described the analysis of circulating miRNAs: in Circulating MicroRNAs and Aerobic Fitness – The HUNT-Study, Anja-Bye and colleagues aimed to discover new biomarkers for aerobic fitness. They discovered an increase in miR-210, -21, and -222 in healthy patients with low VO2max which they suggest might be used as biomarkers of fitness and potential cardio-vascular disease risk. They extracted circulating RNA using Qiagen's miRNeasy Mini Kit from 200ul of serum and analysed mir's with Exiqon's miRCURY LNA microRNA qPCR kits. Another paper in Clinical Biochemistry describes a new device for collection and stablisation of circulating RNA in blood.
Circulating nucleic acids are increasingly being adopted in the clinic and tools for their extraction and analysis are getting more and more sensitive. RNA offers the tantalising possibility of long-distance regulation of cells but designing the experiments to prove or disprove this is challenging. Scientists at the Institute for Systems Biology in Seattle recently published a Frontiers in Genetics review on circulating RNA and explore some of those challenges. There remains lots of opportunity for exciting discovery, and the potential for new treatments.