Analytical Techniques for Single-Cell Biochemical Assays of Lipids

Thin Layer Chromatography Goes Ultrasmall to Assay Sphingosine Kinase Activation in Single Primary Leukemic Cells

Cell-to-cell heterogeneity in lipid signaling underlies variations in response and recurrence for many cancers, including leukemias. A highly parallel, miniaturized thin-layer chromatographic platform capable of assaying single cells was developed. Ultrasmall volumes (50 pL) of standard fluorescent lipids were separated with excellent repeatability, reproducibility, and limits of detection. Sphingosine-cyanine 5 (Sph-Cy5) was loaded into cells, and the single-cell contents were separated to identify Sph-Cy5 and two metabolites, Sph-1-phosphate-Cy5 (S1P-Cy5) and hexadecanoic acid Cy5 (HA-Cy5). In leukemic cells, the CD34+ blast cells demonstrated significantly greater conversion of Sph-Cy5 to its phosphorylated form compared to that of the CD34- cells. After treatment with a sphingosine kinase (SphK) inhibitor, the level of formation of S1P-Cy5 remained significantly greater for the inhibited CD34+ cells relative to that of the inhibited CD34- cells. Over 1200 single cells were rapidly assayed using 8 chips within 4 h. Sphingosine kinase activity in the CD34+ blast cells of 3 patients with acute myeloid leukemia was assayed with and without inhibitors. The patient cells displayed intertumor and intratumor heterogeneity, and subsets of cells with distinct enzymatic activities and products, highlighting the diversity of the cells within a clinical sample and between patients.

Exosome: an overview on enhanced biogenesis by small molecules

Exosomes are extracellular vesicles that received attention for their potential use in the treatment of various injuries. They communicate intercellularly by transferring genetic and bioactive molecules from parent cells. Although exosomes hold immense promise for treating neurodegenerative and oncological diseases, their actual clinical use is very limited because of their biogenesis and secretion. Recent studies have shown that small molecules can significantly enhance exosome biogenesis, thereby remarkably improving yield, functionality, and therapeutic effects. These molecules modulate critical pathways toward optimum exosome production in a mode that is either ESCRT dependent or ESCRT independent. Improved exosome biogenesis may provide new avenues for targeted cancer therapy, neuroprotection in neurodegenerative diseases, and regenerative medicine in wound healing. This review explores the role of small molecules in enhancing exosome biogenesis and secretion, highlights their underlying mechanisms, and discusses emerging clinical applications. By addressing current challenges and focusing on translational opportunities, this study provides a foundation for advancing cell-free therapies in regenerative medicine and beyond.

Single cell lipid biology

Lipids are major cell constituents endowed with astonishing structural diversity. The pathways responsible for the assembly and disposal of different lipid species are energetically demanding, and genes encoding lipid metabolic factors and lipid-related proteins comprise a sizable fraction of our coding genome. Despite the importance of lipids, the biological significance of lipid structural diversity remains largely obscure. Recent technological developments have enabled extensive lipid analysis at the single cell level, revealing unexpected cell-cell variability in lipid composition. This new evidence suggests that lipid diversity is exploited in multicellularity and that lipids have a role in the establishment and maintenance of cell identity. In this review, we highlight the emerging concepts and technologies in single cell lipid analysis and the implications of this research for future studies.

Multimodal techniques and strategies for chemical and metabolic imaging at the single-cell level

Single-cell chemical and metabolic imaging technologies provide unprecedented insights into individual cell dynamics, advancing our understanding of cellular processes, molecular interactions, and metabolic activities. Advances in fluorescence, Raman, optoacoustic (photoacoustic), or mass spectrometry methods have paved the way to characterize metabolites, signaling molecules, and other moieties within individual cells. These modalities can also lead to single-cell imaging capabilities by targeting endogenous cell contrast or by employing exogenous contrast generation techniques, including contrast agents that target specific cell structure or function. In this review, we present key developments, summarize recent applications in single-cell interrogation and imaging, and illustrate their advantages, limitations, and outlook.

Lipid metabolism analysis in esophageal cancer and associated drug discovery

Esophageal cancer is an upper gastrointestinal malignancy with a bleak prognosis. It is still being explored in depth due to its complex molecular mechanisms of occurrence and development. Lipids play a crucial role in cells by participating in energy supply, biofilm formation, and signal transduction processes, and lipid metabolic reprogramming also constitutes a significant characteristic of malignant tumors. More and more studies have found esophageal cancer has obvious lipid metabolism abnormalities throughout its beginning, progress, and treatment resistance. The inhibition of tumor growth and the enhancement of antitumor therapy efficacy can be achieved through the regulation of lipid metabolism. Therefore, we reviewed and analyzed the research results and latest findings for lipid metabolism and associated analysis techniques in esophageal cancer, and comprehensively proved the value of lipid metabolic reprogramming in the evolution and treatment resistance of esophageal cancer, as well as its significance in exploring potential therapeutic targets and biomarkers.