Exosomes and other extracellular vesicles (EVs) play a significant yet poorly understood role in cell-cell communication during homeostasis and various pathological conditions. Conventional in vitro and in vivo approaches for studying exosome/EV function depend on time-consuming and expensive vesicle purification methods to obtain sufficient vesicle populations. Moreover, the existence of various EV subtypes with distinct functional characteristics and submicron size makes their analysis challenging.
To help address these challenges, researchers at George Mason University have developed a unique chip-based approach for real-time monitoring of cellular EV exchange between physically separated cell populations. The extracellular matrix (ECM)-mimicking Matrigel is used to physically separate cell populations confined within microchannels, and mimics tissue environments to enable direct study of exosome/EV function. The submicron effective pore size of the Matrigel allows for the selective diffusion of only exosomes and other smaller EVs, in addition to soluble factors, between co-cultured cell populations. Furthermore, the use of PEGDA hydrogel with a very small pore size of 1.2 nm in lieu of Matrigel allows us to block EV migration and, therefore, differentiate EV effects from effects that may be mediated by soluble factors. This versatile platform bridges purely in vitro and in vivo assays by enabling studies of EV-mediated cellular crosstalk under physiologically relevant conditions, enabling future exosome/EV investigations across multiple disciplines through real-time monitoring of vesicle exchange.
Microfluidic chip design and conceptual use
(a) Schematic of the 5-channel (left) and 3-channel (right) microfluidic chip designs depicting the matrix, donor, recipient, and accessory channels. (b) Fully assembled chip loaded with blue ink to visualize the channels. (c) Schematic of the donor and recipient cells in the donor channel (DC) and recipient channel (RC). The matrix channel (MaC) can be filled with either Matrigel or PEGDA to permit size-based diffusion of either EVs and soluble factors or only soluble factors, respectively.