Plasma or serum? A qualitative study on rodents and humans using high-throughput microRNA sequencing for circulating biomarkers

Abstract

microRNAs are small non-coding RNAs gaining interest for their potential roles as reliable biomarkers for the diagnosis and therapeutics of numerous pathologies, ranging from cancer to neurodegenerative or psychiatric disorders. Indeed, microRNAs are present in various accessible biofluids, including peripheral blood, and specific dysregulation of their expression may be associated with these different pathological conditions. microRNAs can be isolated from plasma or serum for sequencing with commercial kits. However, these two biofluids might exhibit some differences in their microRNA contents, due notably to the coagulation process occurring during serum collection. It remains unclear from previous studies and commercial recommendations which blood fraction is preferable. Because of the small amount of circulating microRNAs in a given blood volume, this question appears crucial for qualitative and quantitative optimization of microRNA profiling, especially in animal models used for investigating the pathophysiological relevancy of this approach. We therefore evaluated the efficiency of RNA isolation and microRNA levels from plasma and sera isolated from rats and humans, with a widely used extraction kit (QIAGEN miRNeasy), and assessed microRNA quality and quantity with high-throughput sequencing. Fewer reads with length corresponding to non-miRNAs sequences were observed in plasma than in serum, both from rats and humans. Moreover, rat plasma produced twice as many aligned reads compared to sera, as well as more aligned reads corresponding to microRNAs (84.6% against 38.7%), differences that were not find in human samples. Our results, therefore, clearly indicate that plasma should be preferred for miRNA investigations, particularly for translational studies.

Potential diagnostic value of miRNAs in peripheral blood for osteosarcoma: A meta-analysis

“…Our results also supported the notion that plasma was more accurate than serum: sensitivity (0.81 vs. 0.79), specificity (0.93 vs. 0.88), PLR (11.0 vs. 6.6), NLR (0.21 vs. 0.23), DOR (53 vs. 28) and AUC (0.95 vs. 0.89). Have study found that the concentration of miRNAs was higher in plasma than in serum, so the choice of sample type played an important role in the diagnostic accuracy of peripheral blood miRNAs as a biomarker of disease [62] , this may be because plasma retains more protein for co-isolation of miRNAs [63] . Apart from that, the results with sample size more than 100 were a little greater than the studies with sample size <100 in the diagnosis of OS patients: sensitivity (0.80 vs. 0.78), specificity (0.89 vs. 0.89), PLR (7.2 vs. 7.4), NLR (0.23 vs. 0.24), DOR (32 vs. 31) and AUC (0.91 vs. 0.90).…”

Plasma-Derived miRNA-222 as a Candidate Marker for Papillary Thyroid Cancer

“…The expression of circulating miRNAs is usually evaluated in the plasma or serum [ 11 ]. Coagulation may affect the spectrum of extracellular miRNA in the blood [ 40 , 41 ]. We chose to analyze miRNA expression in plasma samples because this bioliquid is prevented from clotting [ 40 , 41 ].…”

miR-142-3p Expression Is Predictive for Severe Traumatic Brain Injury (TBI) in Trauma Patients

“…Although the choice between serum or plasma samples is rarely explained in publications. Previous reports on the export of miRNAs from cells have raised the question that plasma and serum may have certain differences in their miRNA content and concentrates [ 19 , 20 ]. Fibrinogen in plasma samples can be a source of contamination that affects extraction quality.…”

“…On the other hand, the process of clotting in serum samples can alter the actual result of circulating miRNAs and increases variability [ 21 ]. Differences in peripheral blood processing could lead to significant discrepancies between studies and make it difficult to identify reliable and relevant miRNA markers [ 19 , 22 , 23 ]. In our pilot study, which compared the miRNA concentration of corresponding serum and plasma samples, no significant difference between the two biofluids was found.…”

“…It is therefore of utmost importance to identify the best biofluid fraction to facilitate the discovery of miRNA-based biomarkers and to increase consistency between studies by using common reference RNA. small nuclear RNAs are widely used as an endogenous reference [ 19 ]. In our pilot study, SNORD95 (C/D Box 95) proved to be the most stable and reliable reference RNA among the snoRNAs investigated.…”