Circulating miRNA microarray analysis from archival plasma samples

Using a microarray-based method we report on: i) adequate intra- and interarray reproducibility of miRNA profiling; ii) feasibility of using archival plasma samples stored for an extended period of time and available in limited amounts; and iii) good correlation between different batches. A total of 11 archived plasma samples collected between 1988 and 1999 were evaluated in this study. Firstly, RNA extracted from two samples (S1 and S2) were hybridized in triplicate. The same samples were also hybridized in triplicate after increasing the starting material volume from 2 to 2.5. Nine additional plasma samples were processed and RNA was hybridized on two different batches of arrays. Finally, two samples (S3 and S4) were re-hybridized on an array of the same batch of the first hybridization but close to the chip expiration date.