Lipid extraction from dried blood spots and dried milk spots for untargeted high throughput lipidomics

Targeted and untargeted metabolomics and lipidomics in dried blood microsampling: Recent applications and perspectives

Blood microsampling (BµS) offers an alternative to conventional methods that use plasma or serum for profiling human health, being minimally invasive and cost effective, especially beneficial for vulnerable populations. We present a non-systematic review that offers a synopsis of the analytical methods, applications and perspectives related to dry blood microsampling in targeted and untargeted metabolomics and lipidomics research in the years 2022 and 2023. BµS shows potential in neonatal and paediatric studies, therapeutic drug monitoring, metabolite screening, biomarker research, sports supervision, clinical disorders studies and forensic toxicology. Notably, dried blood spots and volumetric absorptive microsampling options have been more extensively studied than other volumetric technologies. Therefore, we suggest that a further investigation and application of the volumetric technologies will contribute to the use of BµS as an alternative to conventional methods. Conversely, we support the idea that harmonisation of the analytical methods when using BµS would have a positive impact on its implementation.

Advances and perspectives in the analytical technology for small peptide hormones analysis: A glimpse to gonadorelin

In the last twenty years, we have witnessed an important evolution of bioanalytical approaches moving from conventional lab bench instrumentation to simpler, easy-to-use techniques to deliver analytical responses on-site, with reduced analysis times and costs. In this frame, affinity reagents production has also jointly advanced from natural receptors to biomimetic, abiotic receptors, animal-free produced. Among biomimetic ones, aptamers, and molecular imprinted polymers (MIPs) play a leading role. Herein, our motivation is to provide insights into the evolution of conventional and innovative analytical approaches based on chromatography, immunochemistry, and affinity sensing referred to as peptide hormones. Indeed, the analysis of peptide hormones represents a current challenge for biomedical, pharmaceutical, and anti-doping analysis. Specifically, as a paradigmatic example, we report the case of gonadorelin, a neuropeptide that in recent years has drawn a lot of attention as a therapeutic drug misused in doping practices during sports competitions.

Lipid profile variability in children at different ages measured in dried blood spots

Dried blood spot (DBS) is a minimally invasive sampling technique that has several advantages over conventional venipuncture/arterial blood sampling. More recently, DBS has also been applied for lipidomics analysis, but this is an area that requires further research. The few works found in the literature on lipidomics of DBS samples performed the analysis in adult samples, leaving pediatric ages unmapped. The objective of this study was to assess the variability of the lipid profile (identified by high-resolution C18 RP-LC-MS/MS) of DBS at pediatric age (0-10 days, 2-18 months, and 3-13 years) and to identify age-related variations. The results revealed that the lipidomic signature of the three age groups is significantly different, especially for a few species of neutral lipids and phosphatidylcholines. The main contributors to the differentiation of the groups correspond to 3 carnitine (Car), 2 cholesteryl ester (CE), 2 diacylglycerol (DG), 2 triacylglycerol (TG), 3 phosphatidylcholine (PC), 1 ether-linked PC, 1 phosphatidylethanolamine (PE), 1 ether-linked PE and 1 phosphatidylinositol (PI) species, all with statistically significant differences. Additionally, lipid species containing linoleic acid (C18:2) were shown to have significantly lower levels in the 0-10 days group with a gradual increase in the 2-18 month, reaching the highest concentrations in the 3-13 year group. The results of this study highlighted the adaptations of the lipid profile at different pediatric ages. These results may help improve understanding of the evolution of lipid metabolism throughout childhood and should be investigated further.

Metabolic alterations in dairy cattle with lameness revealed by untargeted metabolomics of dried milk spots using direct infusion-tandem mass spectrometry and the triangulation of multiple machine learning models

Lameness is a major challenge in the dairy cattle industry in terms of animal welfare and economic implications. Better understanding of metabolic alteration associated with lameness could lead to early diagnosis and effective treatment, there-fore reducing its prevalence. To determine whether metabolic signatures associated with lameness could be discovered with untargeted metabolomics, we developed a novel workflow using direct infusion-tandem mass spectrometry to rapidly analyse (2 min per sample) dried milk spots (DMS) that were stored on commercially available Whatman® FTA® DMPK cards for a prolonged period (8 and 16 days). An orthogonal partial least squares-discriminant analysis (OPLS-DA) method validated by triangulation of multiple machine learning (ML) models and stability selection was employed to reliably identify important discriminative metabolites. With this approach, we were able to differentiate between lame and healthy cows based on a set of lipid molecules and several small metabolites. Among the discriminative molecules, we identified phosphatidylglycerol (PG 35:4) as the strongest and most sensitive lameness indicator based on stability selection. Overall, this untargeted metabolomics workflow is found to be a fast, robust, and discriminating method for determining lameness in DMS samples. The DMS cards can be potentially used as a convenient and cost-effective sample matrix for larger scale research and future routine screening for lameness.

Dried blood spots in clinical lipidomics: optimization and recent findings

Dried blood spots (DBS) are being considered as an alternative sampling method of blood collection that can be used in combination with lipidomic and other omic analysis. DBS are successfully used in the clinical context to collect samples for newborn screening for the measurement of specific fatty acid derivatives, such as acylcarnitines, and lipids from whole blood for diagnostic purposes. However, DBS are scarcely used for lipidomic analysis and investigations. Lipidomic studies using DBS are starting to emerge as a powerful method for sampling and storage in clinical lipidomic analysis, but the major research work is being done in the pre- and analytical steps and procedures, and few in clinical applications. This review presents a description of the impact factors and variables that can affect DBS lipidomic analysis, such as the type of DBS card, haematocrit, homogeneity of the blood drop, matrix/chromatographic effects, and the chemical and physical properties of the analyte. Additionally, a brief overview of lipidomic studies using DBS to unveil their application in clinical scenarios is also presented, considering the studies of method development and validation and, to a less extent, for clinical diagnosis using clinical lipidomics. DBS combined with lipidomic approaches proved to be as effective as whole blood samples, achieving high levels of sensitivity and specificity during MS and MS/MS analysis, which could be a useful tool for biomarker identification. Lipidomic profiling using MS/MS platforms enables significant insights into physiological changes, which could be useful in precision medicine.

Liquid extraction surface analysis-mass spectrometry: An advanced and environment-friendly analytical tool in modern analysis

The Liquid Extraction Surface Analysis technique is a new high-throughput instrument for ambient mass spectrometry. The benefits of the Liquid Extraction Surface Analysis-Mass Spectrometry approach are the high throughput screening of samples and the absence of sample preparation. Liquid Extraction Surface Analysis-Mass Spectrometry also consumes less solvent for extraction, making it more environmentally friendly and there is no substrate restriction. It utilizes advanced instrumentation like the use of robotic pipettes, nanoelectrospray systems, electronspray ionization chips which makes it highly efficient. In recent years, Liquid Extraction Surface Analysis-Mass Spectrometry has seen widespread use in a variety of analytical fields including drug metabolite analysis, mapping drug distribution in tissues, protein and lipid characterization etc. In this review, we have summarized the basic working principles of the Liquid Extraction Surface Analysis-Mass Spectrometry approach in detail along with a detailed description of the recently reported applications in the analysis of proteins, lipids, drugs and foods. The investigated analytes along with detection methodologies and significant outcomes of various research reports have been presented with the help of tables. This tool has also been utilized in clinical investigations of biological fluids, fingerprint analysis and authentication of agarwood. This article is protected by copyright. All rights reserved.

The biosynthesis of phospholipids is linked to the cell cycle in a model eukaryote

The structural challenges faced by eukaryotic cells through the cell cycle are key for understanding cell viability and proliferation. We tested the hypothesis that the biosynthesis of structural lipids is linked to the cell cycle. If true, this would suggest that the cell's structure is important for progress through and perhaps even control of the cell cycle. Lipidomics (31P NMR and MS), proteomics (Western immunoblotting) and transcriptomics (RT-qPCR) techniques were used to profile the lipid fraction and characterise aspects of its metabolism at seven stages of the cell cycle of the model eukaryote, Desmodesmus quadricauda. We found considerable, transient increases in the abundance of phosphatidylethanolamine during the G1 phase (+35%, ethanolamine phosphate cytidylyltransferase increased 2·5×) and phosphatidylglycerol (+100%, phosphatidylglycerol synthase increased 22×) over the G1/pre-replication phase boundary. The relative abundance of phosphatidylcholine fell by ~35% during the G1. N-Methyl transferases for the conversion of phosphatidylethanolamine into phosphatidylcholine were not found in the de novo transcriptome profile, though a choline phosphate transferase was found, suggesting that the Kennedy pathway is the principal route for the synthesis of PC. The fatty acid profiles of the four most abundant lipids suggested that these lipids were not generally converted between one another. This study shows for the first time that there are considerable changes in the biosynthesis of the three most abundant phospholipid classes in the normal cell cycle of D. quadricauda, by margins large enough to elicit changes to the physical properties of membranes.

A pipeline for making 31P NMR accessible for small- and large-scale lipidomics studies

Detailed molecular analysis is of increasing importance in research into the regulation of biochemical pathways, organismal growth and disease. Lipidomics in particular is increasingly sought after as it provides insight into molecular species involved in energy storage, signalling and fundamental cellular structures. This has led to the use of a range of tools and techniques to acquire lipidomics data. 31P NMR for lipidomics offers well-resolved head group/lipid class analysis, structural data that can be used to inform and strengthen interpretation of mass spectrometry data and part of a priori structural determination. In the present study, we codify the use of 31P NMR for lipidomics studies to make the technique more accessible to new users and more useful for a wider range of questions. The technique can be used in isolation (phospholipidomics) or as a part of determining lipid composition (lipidomics). We describe the process from sample extraction to data processing and analysis. This pipeline is important because it allows greater thoroughness in lipidomics studies and increases scope for answering scientific questions about lipid-containing systems.