According to an investigation published today in The Journal of Molecular Diagnostics, MicroRNAs (miRNAs) that coordinate processes, such as development, aging and fertilization show promise as biomarkers of disease. MicroRNA’s can be routinely collected from fluids such as urine, blood, and saliva. In this study the investigators present clear methods for collecting and examining miRNA, considerably enhancing their diagnostic precision.

Lead researcher Dominik M. Duelli, PhD, Department of Cellular and Molecular Pharmacology, Chicago Medical School at Rosalind Franklin University of Medicine and Science, explains:

“Our study demonstrates that inherent differences in biological samples and the methods used to collect and analyze them can dramatically affect the detection and quantitation of microRNAs. We developed measures to overcome the interfering activities and improved the sensitivity of miRNA detection up to 30-fold.”

Scientists say there are over one thousand miRNAs in the human body. Deregulation of specific miRNAs is connected with disease. Measuring the amount of miRNAs in body fluids can help diagnose disease, conditions, or natural developments, such as pregnancy.

Dr. Duelli and his team measured the quantify of two miRNAs: MiR-223, involved in some malignant diseases, pregnancy and other conditions; and miR-16, which acts as a tumor suppressor and is lost or deregulated in some cancers, including breast cancer.

Researcher Sarah Linnstaedt, PhD, of Duke University, said:

“A fundamental challenge to making microRNA diagnostics broadly available has been inability to isolate enough high quality material to analyze. Our paper outlines ways of effectively collecting blood plasma samples, thus bringing us one step closer to the goal of making [miRNA] disease diagnostics a reality.”

The researchers report that quantitation is affected by choice of blood collection tubes. They found that the best results were provided by grey-top tubes containing the anticoagulant sodium fluoride and potassium oxalate (NaF/KOx), while traditional green-top tubes interfered almost completely with miRNA detection.

Even though miR-16 is approximately 500 times more bountiful in blood plasma compared to miR-223, the results for both were comparable, suggesting that the detection differences resulting from the choice of collection technique apply to other miRNAs. In addition, more variable results were produced collecting miR-223 in serum, indicating that for some miRNAs, examination of blood in plasma form is favored.

Finally, the researchers saw that differences in plasma structure among individual donors produced different miRNA measurements.

Dr. Duelli, explains:

“These results raise the possibility that factors including diet, exercise, circadian rhythms, and seasons, which alter the blood chemistry, might affect miRNA detection and quantitation.

The implications of this work are that without consideration of the variable we have identified, miRNA quantitation of human samples may not be reliable for the purpose of biomarker development. We provide approaches that enable faithful quantitation of miRNA abundance in body fluid,”

Written by Grace Rattue