Ovarian cancer cell fate regulation by the dynamics between saturated and unsaturated fatty acids.

Fatty acids are an important source of energy and a key component of phospholipids in membranes and organelles. Saturated fatty acids (SFAs) are converted into unsaturated fatty acids (UFAs) by stearoyl Co-A desaturase (SCD), an enzyme active in cancer. Here, we studied how the dynamics between SFAs and UFAs regulated by SCD impacts ovarian cancer cell survival and tumor progression. SCD depletion or inhibition caused lower levels of UFAs vs. SFAs and altered fatty acyl chain plasticity, as demonstrated by lipidomics and stimulated Raman scattering (SRS) microscopy. Further, increased levels of SFAs resulting from SCD knockdown triggered endoplasmic reticulum (ER) stress response with brisk activation of IRE1α/XBP1 and PERK/eIF2α/ATF4 axes. Disorganized ER membrane was visualized by electron microscopy and SRS imaging in ovarian cancer cells in which SCD was knocked down. The induction of long-term mild ER stress or short-time severe ER stress by the increased levels of SFAs and loss of UFAs led to cell death. However, ER stress and apoptosis could be readily rescued by supplementation with UFAs and reequilibration of SFA/UFA levels. The effects of SCD knockdown or inhibition observed in vitro translated into suppression of intraperitoneal tumor growth in ovarian cancer xenograft models. Furthermore, a combined intervention using an SCD inhibitor and an SFA-enriched diet initiated ER stress in tumors growing in vivo and potently blocked their dissemination. In all, our data support SCD as a key regulator of the cancer cell fate under metabolic stress and point to treatment strategies targeting the lipid balance.

Equilibration solution composition and extended exposure to equilibration phase affect embryo development and lipid profile of mouse oocytes.

RESEARCH QUESTION: Can exposure time to equilibration solutions during oocyte vitrification affect the lipid profile of oocytes and embryonic development? Could vitrification media supplemented with oleic, linoleic acids and L-carnitine effectively minimize damage induced by vitrification on embryo development and oocyte membrane lipid profile? DESIGN: Experimental study including 936 oocytes from C57BL/6J mice, randomly divided into fresh IVF (control) and equilibration solution groups. Oocytes were exposed to equilibration solution from Irvine Scientific, Tvitri-4 or Tvitri-4 supplemented with L-carnitine and fatty acids for 7 or 10 min, vitrified-warmed, and submitted to IVF. The lipid profile of oocytes immediately after equilibration solution exposure was also asessed using the same equilibration times and solution compositions. RESULTS: Longer equilibration time resulted in lower oocyte survival and blastocyst rates, and reduced relative abundance of structural lipids, i.e. phosphatidylcholines and sphingomyelins, varying according to equilibration solution composition. It also induced membrane disruptions resembling bubbles in the oocyte surface predominantly in equilibration solution from Irvine Scientific, rarely in Tvitri-4 and absent in Tvitri-4 supplemented with L-carnitine and fatty acids. To reveal the metabolic pathways associated with the equilibration phase of vitrification, lipid pathway analysis was conducted; both P-values and pathway impact values showed that the linoleic acid metabolism (P = 0.00223; impact =1) and alpha-Linolenic acid metabolism (P = 0.00084; impact = 0.33) were the most pathway perturbed, followed by glycerophospholipid metabolism (P = 0.0167; impact = 0.25) CONCLUSION: A longer equilibration phase pre-vitrification can influence embryo development and induce changes in oocyte lipid composition related to membrane integrity. The results suggest internalization of oleic and linoleic acids added to equilibration solution by the oocyte, which, to some extent, contributed to membrane phospholipids preservation, regardless of the equilibration times assessed.

Novel Quantification of Extracellular Vesicles with Unaltered Surface Membranes Using an Internalized Oligonucleotide Tracer and Applied Pharmacokinetic Multiple Compartment Modeling.

PURPOSE: We developed an accessible method for labeling small extracellular vesicles (sEVs) without disrupting endogenous ligands. Using labeled sEVs administered to conscious rats, we developed a multiple compartment pharmacokinetic model to identify potential differences in the disposition of sEVs from three different cell types. METHODS: Crude sEVs were labeled with a non-homologous oligonucleotide and isolated from cell culture media using a commercial reagent. Jugular vein catheters were used to introduce EVs to conscious rats (n = 30) and to collect blood samples. Digital PCR was leveraged to allow for quantification over a wide dynamic range. Non-linear mixed effects analysis with first order conditional estimation - extended least squares (FOCE ELS) was used to estimate population-level parameters with associated intra-animal variability. RESULTS: 86.5% ± 1.5% (mean ± S.E.) of EV particles were in the 45-195 nm size range and demonstrated protein and lipid markers of endosomal origin. Incorporated oligonucleotide was stable in blood and detectable over five half-lives. Data were best described by a three-compartment model with one elimination from the central compartment. We performed an observation-based simulated posterior predictive evaluation with prediction-corrected visual predictive check. Covariate and bootstrap analyses identified cell type having an influence on peripheral volumes (V2 and V3) and clearance (Cl3). CONCLUSIONS: Our method relies upon established laboratory techniques, can be tailored to a variety of biological questions regarding the pharmacokinetic disposition of extracellular vesicles, and will provide a complementary approach for the of study EV ligand-receptor interactions in the context of EV uptake and targeted therapeutics.

A novel experimental workflow to determine the impact of storage parameters on the mass spectrometric profiling and assessment of representative phosphatidylethanolamine lipids in mouse tissues.

Evaluation of signaling lipids is essential for measuring biological processes. There is a lack of experimental data regarding the proper storage of extracts for signaling lipid analysis, potentially impacting the procedures that can lead to accurate and reproducible evaluation. In this study, the importance of pre-analytical conditions for analyzing ion transitions for phosphatidylethanolamines (PEs), an abundant signaling phospholipid, was systematically assessed. A novel workflow was utilized involving an MRM-based experimental approach followed by statistical analysis. Specifically, lipids were extracted from the brain, heart, lungs, and serum of C57BL/6 mice. Extract subsets were resuspended in organic solvents prior to storage in various temperature conditions. Mass spectrometry analysis by multiple reaction monitoring (MRM) profiling was performed at four time points (1 day, 2 weeks, 2 months, or 6 months) to measure relative amounts of PEs in distinct lipid extract aliquots. We introduce an innovative statistical workflow to measure the changes in relative amounts of PEs in the profiles over time to determine lipid extract storage conditions in which fewer profile changes occur. Results demonstrated that time is the most significant factor affecting the changes in lipid samples, with temperature and solvent having comparatively minor effects. We conclude that for lipid extracts obtained by Bligh & Dyer extraction, storage at - 80.0 °C without solvent for less than 2 weeks before analysis is ideal. By considering the data generated by this study, lipid extract storage practices may be optimized and standardized, enhancing the validity and reproducibility of lipid assessments.

Characterization and regulation of extracellular vesicles in the lumen of the ovine uterus†.

Secretions of the endometrium are vital for peri-implantation growth and development of the sheep conceptus. Extracellular vesicles (EVs) are present in the uterine lumen, emanate from both the endometrial epithelia of the uterus and trophectoderm of the conceptus, and hypothesized to mediate communication between those cell types during pregnancy establishment in sheep. Size-exclusion chromatography and nanoparticle tracking analysis determined that total EV number in the uterine lumen increased from days 10 to 14 of the cycle but was lower on days 12 and 14 of pregnancy in sheep. Intrauterine infusions of interferon tau (IFNT) did not affect total EV number in the uterine lumen. Quantitative mass spectrometric analyses defined proteins and lipids in EVs isolated from the uterine lumen of day 14 cyclic and pregnant sheep. In vitro analyses found that EVs decreased ovine trophectoderm cell proliferation and increased IFNT production without effects on gene expression as determined by RNA-seq. Collective results support the idea EVs impact conceptus growth during pregnancy establishment via effects on trophectoderm cell growth.

Multiple Reaction Monitoring Profiling (MRM-Profiling) of Lipids To Distinguish Strain-Level Differences in Microbial Resistance in Escherichia coli.

The worldwide increase in antimicrobial resistance is due to antibiotic overuse in agriculture and overprescription in medicine. For appropriate and timely patient support, faster diagnosis of antimicrobial resistance is required. Current methods for bacterial identification rely on genomics and proteomics and use comparisons with databases of known strains, but the diagnostic value of metabolites and lipids has not been explored significantly. Standard mass spectrometry/chromatography methods involve multiple dilutions during sample preparation and separation. To increase the amount of chemical information acquired and the speed of analysis of lipids, multiple reaction monitoring profiling (MRM-Profiling) has been applied. The MRM-Profiling workflow includes a discovery stage and a screening stage. The discovery stage employs precursor (PREC) ion and neutral loss (NL) scans to screen representative pooled samples for functional groups associated with particular lipid classes. The information from the first stage is organized in precursor/product ion pairs, or MRMs, and the screening stage rapidly interrogates individual samples for these MRMs. In this study, we performed MRM-Profiling of lipid extracts from four different strains of Escherichia coli cultured with amoxicillin or amoxicillin/clavulanate, a ß-lactam and ß-lactamase inhibitor, respectively. t tests, analysis of variance and receiver operating characteristic (ROC) curves were used to determine the significance of each MRM. Principal component analysis was applied to distinguish different strains cultured under conditions that allowed or disallowed development of bacterial resistance. The results demonstrate that MRM-Profiling distinguishes the lipid profiles of resistant and nonresistant E. coli strains.

Histologic analysis and lipid profiling reveal reproductive age-associated changes in peri-ovarian adipose tissue.

BACKGROUND: Reproductive aging is a robust phenotype that occurs in all females and is characterized by a significant reduction in gamete quantity and quality, which can have negative consequences on both endocrine function and fertility. Age-associated differences in the oocyte, follicle, and ovary have been well-documented, but how the broader environment changes with age is less well understood. Fat is one of the largest organs in the body, and peri-gonadal adipose tissue surrounds the rodent ovary and comprises a local ovarian environment. The goal of this study was to characterize how peri-ovarian adipose tissue changes with advanced reproductive age. METHODS: We isolated peri-gonadal adipose tissue from two cohorts of CB6F1 mice: reproductively young (6-12 weeks) and reproductively old (14-17 months). A comparative histological analysis was performed to evaluate adipocyte architecture. We then extracted lipids from the tissue and performed multiple reaction monitoring (MRM)-profiling, a mass spectrometry-based method of metabolite profiling, to compare the lipid profiles of peri-gonadal adipose tissue in these age cohorts. RESULTS: We found that advanced reproductive age was associated with adipocyte hypertrophy and a corresponding decrease in the number of adipocytes per area. Of the 10 lipid classes examined, triacylglycerols (TAGs) had significantly different profiles between young and old cohorts, despite quantitative analysis revealing a decrease in the total amount of TAGs per weight of peri-gonadal adipose tissue with age. CONCLUSIONS: These findings pinpoint age-associated physiological changes in peri-gonadal adipose tissue with respect to adipocyte morphology and lipid profiles and lay the foundation for future studies to examine how these alterations may influence both adipocyte and ovarian function.

Multiple reaction monitoring (MRM)-profiling with biomarker identification by LC-QTOF to characterize coronary artery disease.

Metabolite profiling by mass spectrometry (MS) is an area of interest for disease diagnostics, biomarker discovery, and therapeutic evaluation. A recently developed approach, multiple reaction monitoring (MRM)-profiling, searches for metabolites with precursor (Prec) and neutral loss (NL) scans in a representative sample and creates a list of ion transitions. These are then used in an MRM method for fast screening of individual samples and discrimination between healthy and diseased. A large variety of functional groups are considered and all signals discovered are recorded in the individual samples, making this a largely unsupervised method. MRM-profiling is described here and then demonstrated with data for over 900 human plasma coronary artery disease (CAD) samples. Representative pooled samples for each condition were interrogated using a library of over a hundred Prec and NL scans on a triple quadrupole MS. The data from the Prec and NL experiments were converted into ion transitions, initially some 1266 transitions. Each ion transition was examined in the individual samples on a time scale of milliseconds per transition, which allows for rapid screening of large sample sets (<5 days for 1000 samples). Use of univariate and multivariate statistics allowed classification of the sample set with high accuracy. The metabolite profiles classified the CAD female, CAD male, and peripheral artery disease (PAD) samples relative to controls with an accuracy of 90%, 78%, and 85%, respectively. The compounds responsible for informative ion transitions were identified by chromatography and high resolution MS; some have been previously reported and found to be associated with coronary artery disease metabolism, indicating that the methodology generates a meaningful metabolite profile while being faster than traditional methodologies.

Lipid profile of bovine blastocysts exposed to insulin during in vitro oocyte maturation.

Insulin is a key hormone with important functions in energy metabolism and is involved in the regulation of reproduction. Hyperinsulinaemia is known to impair fertility (for example, in obese mothers); therefore, we aimed to investigate the impact of elevated insulin concentrations during the sensitive period of oocyte maturation on gene expression and lipid profiles of the bovine Day-8 embryo. Two different insulin concentrations were used during in vitro oocyte maturation (INS10=10µgmL-1 and INS0.1=0.1µgmL-1) in order to observe possible dose-dependent effects or thresholds for hyperinsulinaemia in vitro. By investigating gene expression patterns by an mRNA microarray in combination with lipid profile analysis by desorption electrospray ionisation-mass spectrometry (DESI-MS) of embryos derived from insulin-treated oocytes, we gained further insights regarding molecular responses of embryos to insulin provocation during the first days of development. Lipid metabolism appeared to be influenced on multiple levels according to gene expression results but the profiles collected in positive-ion mode by DESI-MS (showing mostly ubiquinone, cholesteryl esters and triacylglycerols) did not differ significantly from controls. There are parallels in follicular development of ruminants and humans that make this bovine model relevant for comparative research on early human embryonic development during hyperinsulinaemia.

Probabilistic Segmentation of Mass Spectrometry (MS) Images Helps Select Important Ions and Characterize Confidence in the Resulting Segments.

Mass spectrometry imaging is a powerful tool for investigating the spatial distribution of chemical compounds in a biological sample such as tissue. Two common goals of these experiments are unsupervised segmentation of images into newly discovered homogeneous segments and supervised classification of images into predefined classes. In both cases, the important secondary goals are to characterize the uncertainty associated with the segmentation and with the classification and to characterize the spectral features that define each segment or class. Recent analysis methods have focused on the spatial structure of the data to improve results. However, they either do not address these secondary goals or do this with separate post hoc procedures.We introduce spatial shrunken centroids, a statistical model-based framework for both supervised classification and unsupervised segmentation. It takes as input sets of previously detected, aligned, quantified, and normalized spectral features and expresses both spatial and multivariate nature of the data using probabilistic modeling. It selects informative subsets of spectral features that define each unsupervised segment or supervised class and quantifies and visualizes the uncertainty in spatial segmentations and in tissue classification. In the unsupervised setting, it also guides the choice of an appropriate number of segments. We demonstrate the usefulness of this framework in a supervised human renal cell carcinoma experimental dataset and several unsupervised experimental datasets, including a pig fetus cross-section, three rodent brains, and a controlled image with known ground truth. This framework is available for use within the open-source R package Cardinal as part of a full pipeline for the processing, visualization, and statistical analysis of mass spectrometry imaging experiments.

Multiple reaction monitoring (MRM)-profiling for biomarker discovery applied to human polycystic ovarian syndrome.

RATIONALE: We describe multiple reaction monitoring (MRM)-profiling, which provides accelerated discovery of discriminating molecular features, and its application to human polycystic ovary syndrome (PCOS) diagnosis. The discovery phase of the MRM-profiling seeks molecular features based on some prior knowledge of the chemical functional groups likely to be present in the sample. It does this through use of a limited number of pre-chosen and chemically specific neutral loss and/or precursor ion MS/MS scans. The output of the discovery phase is a set of precursor/product transitions. In the screening phase these MRM transitions are used to interrogate multiple samples (hence the name MRM-profiling). METHODS: MRM-profiling was applied to follicular fluid samples of 22 controls and 29 clinically diagnosed PCOS patients. Representative samples were delivered by flow injection to a triple quadrupole mass spectrometer set to perform a number of pre-chosen and chemically specific neutral loss and/or precursor ion MS/MS scans. The output of this discovery phase was a set of 1012 precursor/product transitions. In the screening phase each individual sample was interrogated for these MRM transitions. Principal component analysis (PCA) and receiver operating characteristic (ROC) curves were used for statistical analysis. RESULTS: To evaluate the method's performance, half the samples were used to build a classification model (testing set) and half were blinded (validation set). Twenty transitions were used for the classification of the blind samples, most of them (N = 19) showed lower abundances in the PCOS group and corresponded to phosphatidylethanolamine (PE) and phosphatidylserine (PS) lipids. Agreement of 73% with clinical diagnosis was found when classifying the 26 blind samples. CONCLUSIONS: MRM-profiling is a supervised method characterized by its simplicity, speed and the absence of chromatographic separation. It can be used to rapidly isolate discriminating molecules in healthy/disease conditions by tailored screening of signals associated with hundreds of molecules in complex samples.

Membrane lipid profile of in vitro-produced embryos is affected by vitrification but not by long-term dietary supplementation of polyunsaturated fatty acids for oocyte donor beef heifers.

Dietary rumen-protected polyunsaturated fatty acids (PUFAs) rich in linoleic acid (LA) may affect embryo yield, and LA can modulate the molecular mechanisms of lipid uptake in bovine blastocysts produced in vitro. In embryos, membrane lipids, such as phosphatidylcholines (PCs) and sphingomyelins (SMs), affect cryopreservation success. The aim of the present study was to evaluate embryonic developmental rates after the IVF of oocytes retrieved from Nellore heifers fed for approximately 90 days with rumen-protected PUFAs rich in LA. In addition, we evaluated embryo cryotolerance and the membrane structure lipid composition using matrix-assisted laser desorption ionisation mass spectrometry of fresh and vitrified embryos. Embryo development to the blastocyst stage (mean 43.2%) and embryo survival after vitrification and warming (mean 79.3%) were unaffected by diet. The relative abundance of one lipid species (PC ether (PCe; 38:2, which means that this lipid has 38 carbon atoms and 2 double bonds in the fatty acyl residues) was increased after PUFAs supplementation. However, 10 ions were affected by cryopreservation; ions consistent with PC 32:0, PC 34:1, SM 24:1, PC 40:6 or PC 42:9, PC plasmalogen (PCp) 44:10 or PC 42:7, triacylglycerol (TAG) 54:9 and a not assigned ion (m/z 833.2) were lower in blastocysts that survived to the cryopreservation process compared with fresh blastocysts, whereas the abundance of the ions PC 36:3 or PC 34:0, PCe 38:2 or PC 36:6 and PC 36:5 or PCe 38:1 were increased after cryopreservation. Thus, the results demonstrate that the mass spectrometry profiles of PC, SM and TAG species differ significantly in bovine blastocysts upon cryopreservation. Because the lipid ion abundances of fresh and vitrified-warmed embryos were distinct, they can be used as potential markers of post-cryopreservation embryonic survival.

Ambient Ionization Mass Spectrometry for Point-of-Care Diagnostics and Other Clinical Measurements.

BACKGROUND: One driving motivation in the development of point-of-care (POC) diagnostics is to conveniently and immediately provide information upon which healthcare decisions can be based, while the patient is on site. Ambient ionization mass spectrometry (MS) allows direct chemical analysis of unmodified and complex biological samples. This suite of ionization techniques was introduced a decade ago and now includes a number of techniques, all seeking to minimize or eliminate sample preparation. Such approaches provide new opportunities for POC diagnostics and rapid measurements of exogenous and endogenous molecules (e.g., drugs, proteins, hormones) in small volumes of biological samples, especially when coupled with miniature mass spectrometers. CONTENT: Ambient MS-based techniques are applied in diverse fields such as forensics, pharmaceutical development, reaction monitoring, and food analysis. Clinical applications of ambient MS are at an early stage but show promise for POC diagnostics. This review provides a brief overview of various ambient ionization techniques providing background, examples of applications, and the current state of translation to clinical practice. The primary focus is on paper spray (PS) ionization, which allows quantification of analytes in complex biofluids. Current developments in the miniaturization of mass spectrometers are discussed. SUMMARY: Ambient ionization MS is an emerging technology in analytical and clinical chemistry. With appropriate MS instrumentation and user-friendly interfaces for automated analysis, ambient ionization techniques can provide quantitative POC measurements. Most significantly, the implementation of PS could improve the quality and lower the cost of POC testing in a variety of clinical settings.

Chemical profiling of cerebrospinal fluid by multiple reaction monitoring mass spectrometry.

We report an accelerated biomarker discovery workflow and results of sample screening by mass spectrometry based on multiple reaction monitoring (MRM). This methodology shows promising initial results for the currently unsolved challenge of Parkinson's disease (PD) laboratory diagnosis by biomarker screening. Small molecules present in cerebrospinal fluid (CSF) at low parts per million levels are monitored using specific transitions connecting ion pairs. A set of such transitions constitutes a multidimensional chemical profile used to distinguish and characterize different CSF samples using multivariate statistical methods.

Effects of long-term dietary supplementation with conjugated linoleic acid on bovine oocyte lipid profile.

Nutritional and environmental conditions around conception and during early embryonic development may have significant effects on health and well-being in adult life. Here, a bovine heifer model was used to investigate the effects of rumen-protected fat supplementation on oocyte quality and embryo development. Holstein-Friesian heifers (n=84) received a dietary supplement consisting of rumen-protected conjugated linoleic acid (CLA) or stearic acid (SA), each on top of an isocaloric basic diet. Oocytes were collected via ultrasound-guided follicular aspiration and subjected to in vitro maturation followed by either desorption electrospray ionisation mass spectrometry (DESI-MS) for lipid profiling of individual oocytes or in vitro fertilisation and embryo culture. The type of supplement significantly affected lipid profiles of in vitro-matured oocytes. Palmitic acid and plasmalogen species were more abundant in the mass spectra of in vitro-matured oocytes after rumen-protected SA supplementation when compared with those collected from animals supplemented with CLA. Lipid concentrations in blood and follicular fluid were significantly affected by both supplements. Results show that rumen-protected fatty-acid supplementation affects oocyte lipid content and may pave the way for the establishment of a large-animal model for studies towards a better understanding of reproductive disorders associated with nutritional impairments.

Ambient ionisation mass spectrometry for lipid profiling and structural analysis of mammalian oocytes, preimplantation embryos and stem cells.

Lipids play fundamental roles in mammalian embryo preimplantation development and cell fate. Triacylglycerol accumulates in oocytes and blastomeres as lipid droplets, phospholipids influence membrane functional properties, and essential fatty acid metabolism is important for maintaining the stemness of cells cultured in vitro. The growing impact that lipids have in the field of developmental biology makes analytical approaches to analyse structural information of great interest. This paper describes the concept and presents the results of lipid profiling by mass spectrometry (MS) of oocytes and preimplantation embryos, with special focus on ambient ionisation. Based on our previous experience with oocytes and embryos, we aim to convey that ambient MS is also valuable for stem cell differentiation analysis. Ambient ionisation MS allows the detection of a wide range of lipid classes (e.g. free fatty acids, cholesterol esters, phospholipids) in single oocytes, embryos and cell pellets, which are informative of in vitro culture impact, developmental and differentiation stages. Background on MS principles, the importance of underused MS scan modes for structural analysis of lipids, and statistical approaches used for data analysis are covered. We envisage that MS alone or in combination with other techniques will have a profound impact on the understanding of lipid metabolism, particularly in early embryo development and cell differentiation research.

Membrane lipid profile monitored by mass spectrometry detected differences between fresh and vitrified in vitro-produced bovine embryos.

This study aimed to evaluate the impact of vitrification on membrane lipid profile obtained by mass spectrometry (MS) of in vitro-produced bovine embryos. Matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS) has been used to obtain individual embryo membrane lipid profiles. Due to conditions of analysis, mainly membrane lipids, most favorably phosphatidylcholines (PCs) and sphingomyelins (SMs) have been detected. The following ions described by their mass-to-charge ratio (m/z) and respective attribution presented increased relative abundance (1.2-20×) in the vitrified group: 703.5 [SM (16:0) + H]+; 722.5 [PC (40:3) + Na]+; 758.5 [PC (34:2) + H]+; 762.5 [PC (34:0) + H]+; 790.5 [PC (36:0) + H]+ and 810.5 [PC (38:4) + H]+ and/or [PC (36:1) + Na]+. The ion with a m/z 744.5 [PCp (34:1) and/or PCe (34:2)] was 3.4-fold more abundant in the fresh group. Interestingly, ions with m/z 722.5 or 744.5 indicate the presence of lipid species, which are more resistant to enzymatic degradation as they contain fatty acyl residues linked through ether type bonds (alkyl ether or plasmalogens, indicated by the lowercase 'e' and 'p', respectively) to the glycerol structure. The results indicate that cryopreservation impacts the membrane lipid profile, and that these alterations can be properly monitored by MALDI-MS. Membrane lipids can therefore be evaluated by MALDI-MS to monitor the effect of cryopreservation on membrane lipids, and to investigate changes in lipid profile that may reflect the metabolic response to the cryopreservation stress or changes in the environmental conditions.

Implementation of multiomic mass spectrometry approaches for the evaluation of human health following environmental exposure.

Omics analyses collectively refer to the possibility of profiling genetic variants, RNA, epigenetic markers, proteins, lipids, and metabolites. The most common analytical approaches used for detecting molecules present within biofluids related to metabolism are vibrational spectroscopy techniques, represented by infrared, Raman, and nuclear magnetic resonance (NMR) spectroscopies and mass spectrometry (MS). Omics-based assessments utilizing MS are rapidly expanding and being applied to various scientific disciplines and clinical settings. Most of the omics instruments are operated by specialists in dedicated laboratories; however, the development of miniature portable omics has made the technology more available to users for field applications. Variations in molecular information gained from omics approaches are useful for evaluating human health following environmental exposure and the development and progression of numerous diseases. As MS technology develops so do statistical and machine learning methods for the detection of molecular deviations from personalized metabolism, which are correlated to altered health conditions, and they are intended to provide a multi-disciplinary overview for researchers interested in adding multiomic analysis to their current efforts. This includes an introduction to mass spectrometry-based omics technologies, current state-of-the-art capabilities and their respective strengths and limitations for surveying molecular information. Furthermore, we describe how knowledge gained from these assessments can be applied to personalized medicine and diagnostic strategies.

Targeted Lipidomics Analysis of Adipose and Skeletal Muscle Tissues by Multiple Reaction Monitoring Profiling.

Lipid homeostasis is critical for maintaining normal cellular functions including membrane structural integrity, cell metabolism, and signal transduction. Adipose tissue and skeletal muscle are two major tissues involved in lipid metabolism. Adipose tissue can store excessive lipids in the form of triacylglyceride (TG), which can be hydrolyzed to release free fatty acids (FFAs) under insufficient nutrition states. In the highly energy-demanding skeletal muscle, lipids serve as oxidative substrates for energy production but can cause muscle dysfunction when overloaded. Lipids undergo fascinating cycles of biogenesis and degradation depending on physiological demands, while dysregulation of lipid metabolism has been increasingly recognized as a hallmark of diseases such as obesity and insulin resistance. Thus, it is important to understand the diversity and dynamics of lipid composition in adipose tissue and skeletal muscle. Here, we describe the use of multiple reaction monitoring profiling, based on lipid class and fatty acyl chain specific fragmentation, to explore various classes of lipids in skeletal muscle and adipose tissues. We provide a detailed method for exploratory analysis of acylcarnitine (AC), ceramide (Cer), cholesteryl ester (CE), diacylglyceride (DG), FFA, phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), phosphatidylinositol (PI), phosphatidylserine (PS), sphingomyelin (SM), and TG. Characterization of lipid composition within adipose tissue and skeletal muscle under different physiological situations will provide biomarkers and therapeutic targets for obesity-related diseases.