Analysis of the impact of cellular miRNA signatures on the profiles of circulating miRNA biomarkers (fractionation data)

Circulating miRNAs are an emerging class of biomarkers correlating their specific expression patterns to disease states. A considerable proportion of hematopoietically-derived miRNAs are present in plasma with the ability to confound the signature of true circulating miRNA species. We use microarray analysis to catalogue a list of 313 haemotopoetic miRNAs and analyze expression profiles of cell-free miRNAs in individual plasma fractions after calibrating for cellular miRNA signals. Comprehensive global maps of bona fide circulating miRNA species are presented, and inter-individual variability and gender-specific expression is explored in populations of healthy individuals. Healthy Caucasian individuals were used to segregate blood into 8 subfractions: white blood cells (WBC)/buffy coat, leukocytes, red blood cells (red blood cells (RBC)), cloudy supernatant (CS), supernatant 1 (S1), supernatant 2 (S2), pellet 1 (P1) and pellet 2 (P2) through differential centrifugation to understand the proportion of cellular miRNAs in each category.