Microproteomics application for the limited number of cells

Mass spectrometry (MS)-based proteomics explores in-depth proteome, however, the analysis of cell subsets, which might be minor population, is hampered due to a multistep procedure for sample preparation and purification. Along those lines, optimization of proteomics workflow toward limited number of cells is an asset. Here, we report our workflow of microproteomics, proteomics for a limited number of cells: a microfluidic-chip based cell sorter was applied for a damage-free cell sorting, and each 100 or 1000 THP-1 cells were collected in hydrophilic or albumin-coated microtubes. Following in-solution enzymatic digestions, peptide mixtures were purified and applied to nanoLC-MS (Orbitrap Elite) analysis with 3 hr gradient. Our method enabled proteome mapping from 1000-sorted cells, with a similar in-depth map from 1 μg of cell lysate. This approach would be useful for cell subsets and limited materials such as circulating tumor cells, inflammatory cells in cancer tissues and clinical materials.