Continuous Isolation of Stem-Cell-Derived Extracellular Vesicles (SC-EVs) by Recycled Magnetic Beads in Microfluidic Channels

Stem cells produce nanosized particles known as extracellular vesicles (SC-EVs), which therapeutically affect stem cells. EVs are more abundantly produced, exhibit better stability, and possess lower immune rejection rates than stem cells. However, the traditional methods of isolating EVs, such as ultracentrifugation, possess limitations that require a complex process and consume more time. Moreover, it is difficult to isolate specific EVs that have target surface proteins that affect regenerative effects. To address these limitations, a new dual-mode horseshoe-shaped orifice micromixer (DM-HOMM) chip that can bind antibody-conjugated micromagnetic beads and SC-EVs and sequentially elute specific SC-EVs on the beads using an eluent was developed. For effective elution from the microbead-SC-EV complex, four types of eluents were used to control pH and ionic strength between antibodies and surface proteins in EVs. In addition, we investigated the reusability of antibody-conjugated micromagnetic beads. The beads indicated identical binding efficiencies between the antibodies and specific SC-EVs for three repeated cycles using the dual-mode chip. CD63+ EVs collected by the chip exhibited higher cell viability and regeneration effects than untreated and total EVs. This SC-EVs’ isolation method possesses the potential for targeted therapeutic applications and enhanced regenerative effects.