Protein Biomarker Discovery Using Human Blood Plasma Microparticles

Cells shed into the extracellular space a population of membranous vesicles of plasma membrane origin called microparticles (MP). Given the fact that MP are abundantly present in body fluids including plasma, rich in cell-type or disease-specific proteins and formed in conditions of stress and injury, they have been extensively investigated as biomarkers in various diseases. With the advancement in the mass spectrometry-based proteome analysis, the knowledge of the protein composition of plasma MP (PMP) has been intensively expanded, which aids the discovery of novel diagnostic target proteins. However, the lack of standardized and accurate protocols for PMP isolation limits the implementation of PMP as biomarkers in clinical settings. Here, we describe in detail a robust protocol for PMP isolation from human blood plasma via ultracentrifugation followed by label-free quantitative proteome analysis of PMP.