The importance of metabolites and their isomeric structures in biological function and dysfunction is increasingly recognized. However, achieving quantitative mapping of metabolites within tissue regions, particularly with isomeric specificity, remains an analytical challenge. This work presents the development of a quantitative surface sampling capillary electrophoresis method for spatial metabolomics with isomeric resolution. Five quantitation strategies were evaluated, with the optimal approach identified as sequential injection of metabolites directly from tissue alongside standards. This methodology was applied to a rat brain tissue section in a proof-of-principle study, enabling quantitative spatial analysis of metabolites, neurotransmitters, and isomeric species. Among the findings, the aromatic amino acids tyrosine, phenylalanine, and tryptophan exhibited the most dynamic distributions across four brain regions, while leucine and isoleucine demonstrated distinct spatial profiles, with leucine consistently being the more abundant isomer. This method offers a promising tool for advancing the understanding of spatially resolved biochemical processes underlying biological function and dysfunction.

Psychotic and affective disorders, including schizophrenia (SCZ) and depression (MDD), affect millions of people globally. The overlapping symptoms of these diseases and the lack of objective diagnostic tools could lead to misdiagnosis. Recent studies suggest that the analysis of plasma lipid levels may help to develop new diagnostic tools. In this study, we investigated the plasma lipidome of psychiatric patients and healthy controls to identify disease-specific lipid species. Using untargeted mass spectrometry, we profiled blood plasma lipids from 416 patients with common psychotic and affective disorders and 272 healthy individuals from two different cohorts. We observed lipidome alterations in SCZ and MDD consistent with earlier findings. In total, 144 lipids showed significant changes, with 107 of them being concordant across both disorders, and 37 being discordant. Lipids that differentiated SCZ from MDD were mainly triacylglycerols with polyunsaturated fatty acid residues decreased in MDD. In an additional group of 111 patients with bipolar, schizotypal, and schizoaffective disorders, these lipid markers suggested a trend toward separating psychotic and affective disorders. Furthermore, a logistic regression model trained on lipid data distinguished SCZ from MDD with an ROC AUC of 0.83. Taken together, these results suggest that blood lipid profiling may aid in the objective differentiation of psychotic and affective disorders.

Asthma is a chronic respiratory disease with one of the largest numbers of cases in the world; thus, constant investigation and technical development are needed to unravel the underlying biochemical mechanisms. In this study, we aimed to develop a nano-DESI MS method for the in vivo characterization of the cellular metabolome. Using air–liquid interface (ALI) cell layers, we studied the role of Interleukin-13 (IL-13) on differentiated lung epithelial cells acting as a lung tissue model. We demonstrate the feasibility of nano-DESI MS for the in vivo monitoring of basal–apical molecular transport, and the subsequent endogenous metabolic response, for the first time. Conserving the integrity of the ALI lung-cell layer enabled us to perform temporally resolved metabolomic characterization followed by “bottom-up” proteomics on the same population of cells. Metabolic remodeling was observed upon histamine and corticosteroid treatment of the IL-13-exposed lung cell monolayers, in correlation with alterations in the proteomic profile. This proof of principle study demonstrates the utility of in vivo nano-DESI MS for characterizing ALI tissue layers, and the new markers identified in our study provide a good starting point for future, larger-scale studies.