Characterization of cellular response to extracellular vesicles using two-photon FLIM of NAD(P)H

Extracellular vesicles (EVs) are plasma-membrane formed particles released by cells, and range in diameter from 50 to 2000 nm. Interest in EVs is growing, and recent work has aimed to employ nonlinear optical microscopy techniques to better characterize the size, function, and biochemical makeup of EVs. Previous studies have shown that EVs can modulate gene expression and metabolism of cells that uptake them. Here, we use fluorescence lifetime imaging microscopy (FLIM) of reduced nicotinamide adenine dinucleotide and reduced nicotinamide adenine dinucleotide phosphate (NAD(P)H) to monitor the metabolic response of macrophages and other cells to native and foreign EVs and other known cellular activators.