Quantitative Analysis of Exosome Secretion Rates of Single Cells To study the inhomogeneity within a cell population including exosomes properties such as exosome secretion rate of cells and surface markers carried by exosomes, we need to quantify and characterize those exosomes secreted by each individual cell. Here we develop a method to collect and analyze exosomes secreted by an array of single cells using antibody-modified glass slides that are position-registered to each single cell. After each collection, antibody-conjugated quantum dots are used to label exosomes to allow counting and analysis of exosome surface proteins. Detailed studies of exosome properties related to cell behaviors such as responses to drugs and stress at single cell resolution can be found in the publication (Chiu et al., 2016).