BackgroundMicroRNAs (miRNAs) have been linked to several diseases and to regulation of almost every biological process. This together with their stability while freely circulating in blood suggests that they could serve as minimal-invasive biomarkers for a wide range of diseases. Successful miRNA-based biomarker discovery in plasma is dependent on controlling sources of preanalytical variation, such as cellular contamination and hemolysis, as they can be major causes of altered miRNA expression levels. Analysis of plasma quality is therefore a crucial step for the best output when searching for novel miRNA biomarkers.
MethodsPlasma quality was assessed by three different methods in samples from mother-child duos (maternal and cord blood, N = 2x38), with collection and storage methods comparable to large cohort study biobanks. Total RNA was isolated and the expression profiles of 201 miR-NAs was obtained by qPCR to identify differentially expressed miRNAs in cord and maternal plasma samples.
ConclusionsOur findings suggest that good quality plasma samples suitable for miRNA profiling can be achieved from samples collected and stored by large biobanks. Incorporation of extensive quality control measures, such as those established here, would be beneficial for future projects. The overall low correlation of miRNA expression between cord and maternal samples is an interesting observation, and promising for our future studies on identification of miRNA-based biomarkers in cord blood plasma, considering that these samples were collected at term and some exchange of blood components between cord and maternal blood frequently occur.
IntroductionThe finding of circulating microRNAs (miRNA) in body fluids (blood plasma, serum or urine) [1,2] has opened up for the possibility of using blood-based miRNAs as a new approach for diagnostic screening. MiRNAs have been linked to cancer and several other diseases [3], and they have been implicated in promoting neurodevelopmental processes, such as neurogenesis, synapse precursor formation, and synaptic plasticity [4,5]. The stability of miRNAs circulating in blood, and their role as key regulators of almost every biological process, including precise control of neuronal gene expression and thus fine-tuning signaling pathways [6], suggests that they could serve as non-invasive biomarkers for a wide range of diseases [7][8][9], and possibly help explain basic disease etiology. Furthermore, miRNAs have been shown to be targeted by epigenetic modification, and in turn, miRNAs can target regulators of epigenetic pathways [10,11].Blood-based biobanks, which include collection of umbilical cord blood, such as the Mother, Father and Child Cohort Study (MoBa) biobank [12] at the Norwegian Institute of Public Health (NIPH), and other multi-center studies, increasingly incorporate studies identifying candidate mRNA and miRNA expression profile-based biomarkers for a wide range of disorders. The combination of biological specimens and questionnaire data on lifestyle and exposures in MoBa prov...