The volume of a cell is an important indicator of growth rate, osmotic pressure regulation, and cell cycle. We have developed a method to measure cell height maps, and consequently cell volume, using dye exclusion. Unlike measurements based on interferometry, this method is not sensitive to the refractive index of a cell, which is commonly not known and can be heterogeneous.
This method, called dye exlusion microfluidic (DEM) microscopy, relies on measuring the cells in an absorbing refractive index matched buffer. The cell membrane excludes the absorbing dye, so the presence of the cell reduces the number of dye molecules in the detection region, and consequently the cell thickness can be quantitatively retrieved.
This data set shows thickness maps of more than 1600 cells of three different leukemia cell lines. Volume distributions compare well to results from an impedance based Coulter counter. In addition, subcellular features such as blebs or membrane protrusions can be quantitatively evaluated.