Single-cell lipidomics enabled by dual-polarity ionization and ion mobility-mass spectrometry imaging.

Single-cell (SC) analysis provides unique insight into individual cell dynamics and cell-to-cell heterogeneity. Here, we utilize trapped ion mobility separation coupled with dual-polarity ionization mass spectrometry imaging (MSI) to enable high-throughput in situ profiling of the SC lipidome. Multimodal SC imaging, in which dual-polarity-mode MSI is used to perform serial data acquisition runs on individual cells, significantly enhanced SC lipidome coverage. High-spatial resolution SC-MSI identifies both inter- and intracellular lipid heterogeneity; this heterogeneity is further explicated by Uniform Manifold Approximation and Projection and machine learning-driven classifications. We characterize SC lipidome alteration in response to stearoyl-CoA desaturase 1 inhibition and, additionally, identify cell-layer specific lipid distribution patterns in mouse cerebellar cortex. This integrated multimodal SC-MSI technology enables high-resolution spatial mapping of intercellular and cell-to-cell lipidome heterogeneity, SC lipidome remodeling induced by pharmacological intervention, and region-specific lipid diversity within tissue.

Next-generation pathology practices with mass spectrometry imaging.

Mass spectrometry imaging (MSI) is a powerful technique that reveals the spatial distribution of various molecules in biological samples, and it is widely used in pathology-related research. In this review, we summarize common MSI techniques, including matrix-assisted laser desorption/ionization and desorption electrospray ionization MSI, and their applications in pathological research, including disease diagnosis, microbiology, and drug discovery. We also describe the improvements of MSI, focusing on the accumulation of imaging data sets, expansion of chemical coverage, and identification of biological significant molecules, that have prompted the evolution of MSI to meet the requirements of pathology practices. Overall, this review details the applications and improvements of MSI techniques, demonstrating the potential of integrating MSI techniques into next-generation pathology practices.

Factors affecting clinical outcomes in women with non-gastric gastrointestinal stromal tumors.

OBJECTIVE: The clinical presentation of non-gastric GISTs might mimic adnexal cancer, and non-gastric GIST might be managed and treated by gynecologists. Knowledge of the clinical outcomes of women with non-gastric gastrointestinal stromal tumors (GISTs) is important. Our aim is to elucidate the factors affecting the clinical outcomes of women with non-gastric GISTs. MATERIALS AND METHODS: Between January 2000 and October 2019, all consecutive women with non-gastric GISTs who underwent surgery in a tertiary referral center were reviewed. RESULTS: Twenty-six women were reviewed. Eight (31%) women experienced recurrence. The probabilities of recurrence-free survival (RFS) at 60 and 120 months were 65.2% and 55.9%, respectively. The probabilities of overall survival (OS) at 60 and 120 months were 71.1% and 63.9%, respectively. Cancer stage was the only independent predictor of RFS (hazard ratio = 6.00, p = 0.007) and OS (hazard ratio = 3.88, p = 0.04). However, excluding cancer stage, metastasis (hazard ratio = 8.74) was the only independent predictor of RFS, and tumor size (hazard ratio = 1.20) and metastasis (hazard ratio = 6.03) were independent predictors of OS. Tumor size ≥13.9 cm was the optimum cut-off value to predict death and had an area under the receiver operating characteristic curve of 0.75 (95% confidence interval = 0.53 to 0.98). Among the above 5 women with non-gastric GISTs admitted to the Gynecology Department, optimal debulking surgery was performed in two women, and small bowel resection was performed in three women; and all five women remained alive without disease. CONCLUSION: Non-gastric GISTs may mimic gynecologic tumors. Metastasis was an independent predictor of PFS. In addition, metastasis and large tumor size (especially ≥13.9 cm) were independent predictors of OS in women with non-gastric GISTs.

Remodeling nanoDESI Platform with Ion Mobility Spectrometry to Expand Protein Coverage in Cancerous Tissue.

Nanospray desorption electrospray ionization mass spectrometry is an ambient ionization technique that is capable of mapping proteins in tissue sections. However, high-abundant molecules or isobaric interference in biological samples hampers its broad applications in probing low-abundant proteins. To address this challenge, herein we demonstrated an integrated module that coupled pneumatic-assisted nanospray desorption electrospray ionization mass spectrometry with high-field asymmetric ion mobility spectrometry. Using this module to analyze mouse brain sections, the protein coverage was significantly increased. This improvement allowed the mapping of low-abundant proteins in tissue sections with a 5 µm spatial resolution enabled by computationally assisted fusion with optical microscopic images. Moreover, the module was successfully applied to characterize melanoma in skin tissues based on the enhanced protein profiles. The results suggested that this integrating module will be potentially applied to discover novel proteins in cancers.

Toward the Rational Design of Universal Dual Polarity Matrix for MALDI Mass Spectrometry.

A series of novel anthranilic acid derivatives I-IV, of which COOH-NH2 (I) and COOH-NHMe (IV) are endowed with acid and base bifunctionality, were designed and synthesized for matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry applications in dual polarity molecular imaging of biological samples, particularly for lipids. The heat of protonation, deprotonation, and proton transfer reaction as well as the capability of analyzing biomolecules in both positive and negative ion modes for I-IV were systematically investigated under standard 355 nm laser excitation. The results indicate correlation between dual polarity and acid-base property. Further, COOH-NHMe (IV) showed a unique performance and was successfully applied as the matrix for MALDI-TOF mass spectrometry imaging (MSI) for studying the mouse brain. Our results demonstrate the superiority of COOH-NHMe (IV) in detecting more lipid and protein species compared to commercially available matrices. Moreover, MALDI-TOF MSI results were obtained for lipid distributions, making COOH-NHMe (IV) a potential next generation universal matrix.