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. Researchers from the University of California at San Diego La Jolla have developed 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, anti-body 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).
Workflow for single-cell assay used for analyzing exosome secretion
A and B. Loading single cells onto a culture dish with a cell loading chip that contains through hole arrays. C. The cell loading chip may be removed after cell attachment. D. A surface functionalized glass slide is placed in a CNC machined frame 100 μm above the cells. E. The glass slide with collected exosomes secreted by the corresponding cells. The captured exosomes are labeled with another biotinylated antibody and streptavidin-conjugated quantum dots to become visible under fluorescent microscope.