Influence of preanalytical sampling conditions on the 1H NMR metabolic profile of human blood plasma and introduction of the Standard PREanalytical Code used in biobanking

Abstract

Variations in sample collection, processing and storage within the field of clinical metabolomics might hamper its effective implementation. In this study, the impact of relevant preanalytical conditions on the plasma 1 H NMR metabolic profile was examined. The biobanking community recently developed a method for coding preanalytical conditions called the Standard PREanalytical Code (SPREC). It is envisaged that SPREC will ultimately identify which samples are fit for a particular analysis, based on prior validation by a panel of experts in the respective field. In an effort to validate SPREC for 1 H NMR plasma metabolomics, we have coded the conditions used here, when possible, according to SPREC and evaluated its power to identify preanalytical conditions that affect the plasma 1 H NMR metabolic profile. From all preanalytical conditions studied, only prolonged processing delays (3 and 8 h) have a significant impact on the plasma 1 H NMR metabolic profile as compared to the reference condition (30 min). Principal component analysis shows a clear systematic shift as a function of increasing processing delay. Nevertheless, the inter-individual variation is clearly much larger than this preanalytical variation, indicating that the impact on multivariate group classification will be minimal. Nonetheless, we recommend to keep the time gap between blood collection and centrifugation similar for all samples within a study. The implementation of SPREC within clinical metabolomics allows for an appropriate sample encoding and exclusion of samples that were subjected to unwanted, interfering preanalytical conditions. Without doubt, it will contribute to the validation of 1 H NMR metabolomics in clinical, biobank and multicenter research settings.

A Systematic Evaluation of Blood Serum and Plasma Pre-Analytics for Metabolomics Cohort Studies

“…To our knowledge, several parameters, such as individual variations of centrifugation times or rotational speeds evaluated both on plasma and serum 1 H NMR metabolic profiles, are reported here for the first time, while others have previously been investigated on very small sets of samples [25,26,27,28,29,30,31,32]. Several studies have focused on defining standard pre-analytical guidelines for omics investigations.…”

“…Similarly, the UK biobank showed that storage of serum spectra at 4 °C for 24 h before freezing significantly affects the NMR-based metabolic profile [25]. Clot time, clot temperature as well as the number of freeze-thaw cycles have also been shown to influence NMR-based metabolic profiles for blood serum [23,26,30,31,32,33]. Despite the definition of standardized protocols, a strict execution of these protocols within single- or multi-center clinical studies can be challenging when dealing with continuous fluxes of samples, and analytical approaches to monitor the compliance to best practices or to qualify samples available from biobanks are yet to be implemented at the large-scale.…”

LacaScore: a novel plasma sample quality control tool based on ascorbic acid and lactic acid levels

“…Many standard operating procedures do not use ice for blood collection. However, for metabolomics applications, sample processing on ice is crucial and documentation of the critical pre-analytical steps in a Standard PREanalytical Code (SPREC) is recommended (Betsou et al 2010 ; Bervoets et al 2015 ). Two known metabolites, ascorbic acid and lactic acid, showed the highest temperature-dependent instability and we have demonstrated that their ratio can be used as quality control marker for plasma sample quality evaluation.…”

Nutrimetabolomics: An Integrative Action for Metabolomic Analyses in Human Nutritional Studies

“…demonstrated that a high number of metabolites are significantly altered as a consequence of prolonged processing times at different temperatures, including signaling metabolites, lipids, carbohydrates, and amino acids. However, the most important changes can be associated with energy‐related metabolites (i.e., increased lactate, decreased glucose, and pyruvate), which could be attributable to the anaerobic metabolism of erythrocytes . Thus, as a general recommendation, blood processing times should be reduced to the minimum (preferably no longer than 2 h) and samples should be kept cool in the meantime.…”