Extracellular RNA Helps Diagnose Medical Conditions

For some diseases, biomarkers can be used to determine how far the illness has advanced, but not shed light on how quickly it will progress in the future. Circulating extracellular RNAs (exRNAs) have the potential to serve as biomarkers for a wide range of medical conditions.

However, limitations in existing exRNA isolation methods and a lack of knowledge on parameters affecting exRNA variability in human samples may hinder their successful discovery and clinical implementation. A new way has been found to probe blood samples for fragments of RNA released by tumors or diseased organs.

Scientists at The Rockefeller University (New York, NY, USA) and their colleagues recruited 13 healthy subjects, seven males and six females, were recruited from Bronx, New York, to participate in the study. Blood Sample collection was performed over a period of four months from November 19, 2014, to March 24, 2015. The team developed a new method, which involves multiple refinements in the preparation and processing of the plasma and serum samples tested, solves that longstanding scarcity problem, and it has other advantage as well.

In developing the new technique, the scientists processed and analyzed a total of 312 blood samples collected from 13 healthy subjects, including both men and women, over a two-month period. That schedule was designed to answer another critical question about exRNA: does it remain stable over time? Silica-matrix adsorption-based RNA purification was based on the commercial RNeasy MinElute Cleanup Kit (Qiagen, Hilden Germany; www.qiagen.com) following organic extraction showed greater tracer integrities when using the TRIzol-based protocol. Stability is essential for biomarkers, which, among other things, often need to be routinely monitored in long-term clinical studies. Results confirmed that the subjects' circulating exRNA, which came from muscle, neuroendocrine, and epithelial cells, remained consistent in composition and concentration over the two months.

Thomas Tuschl, PhD, a professor of Molecular Biology and senior author of the study, said, “We can survey thousands of pieces of RNA, with origins across all cell types. Identifying the specific tissue where the exRNA originates along with its molecular structure and its abundance in the circulation has enormous potential for detecting disease processes and discovering new abnormalities.”

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