Development of Single Cell Printing-Liquid Vortex Capture-Mass Spectrometry for the Metabolic Profiling of Single Cells

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Project Summary The mechanisms underpinning heterogeneous metabolic response between individual cells remain poorly understood, though such mechanisms have ramifications across nearly all of medicine, e.g., disease detection, response to stress, treatment, and more. Intracellular small molecule metabolite, lipid and therapeutic concentrations are often inferred through protein expression or directly measured as the average of 1000’s of cells at once, providing only a population-level view of heterogeneous metabolic response. This obfuscates differentiation of anomalous metabolic cell phenotypes and small molecule associations occurring within cells. Currently there exists a gap in analytical technologies for the measure of small molecules (<1000 Dalton) in single mammalian cells. Most technologies lack the sensitivity, broad chemical coverage, quantitative capability, and/or the sampling throughput needed to enable the mechanisms of heterogeneous metabolic response of cells to be explored, but recently the development of single cell printing-liquid vortex capture-mass spectrometry (SCP-LVC-MS) has overcome many of these limitations. We hypothesize that this technology could resolve the current analytical gap in the quantitative measure of small molecules from single cells. The goal of this research is to address key technical challenges regarding validation of the quantitative accuracy of SCP-LVC-MS (Aim #1), representativeness of SCP-LVC-MS measured cellular chemical profiles (Aim #2), and ability to relate SCP-LVC-MS measurements to established single-cell technologies (Aim #3) so that SCP-LVC-MS can become an effective research tool in the biomedical community and enable associations between metabolites and therapeutics to be investigated on an individual cellular basis for the first time. These technical challenges are addressed by measure of localized intracellular compounds and comparison with in- capillary fluorescence measurements, by validating the representativeness of SCP-LVC-MS measured chemical profiles through comparison of spectra acquired before and after single cell isolation and by incorporating fluorescence microscopy into the SCP-LVC-MS optical detection and cell isolation system. These aims work together to validate and improve the capabilities of SCP-LVC-MS to answer questions regarding the central challenge of understanding the cellular mechanisms underpinning heterogeneous metabolic response, by filling in the technological gap that exists in this area for quantitative, high throughput analysis of metabolites, lipids and drugs in single cells. The completion of this research will enable fundamental biomedical questions to be pursued that could not be before, such as how intracellular metabolite concentrations relate to each other or how expression of a protein quantitatively impacts therapeutic response in the same cell. Fundamental questions like these have impacts in how we understand disease, how single-cell chemistry links across biological scales (e.g., organ level phenotypes), and many other fundamental aspects of medicine.