A Simple Benchtop Filtration Method to Isolate Small Extracellular Vesicles from Human Mesenchymal Stem Cells

The ultracentrifugation-based process is considered the common method for small extracellular vesicles (sEVs) isolation. However, the yield from this isolation method is relatively lower, and these methods are inefficient in separating sEV subtypes. This study demonstrates a simple benchtop filtration method to isolate human umbilical cord-derived MSC small extracellular vesicles (hUC-MSC-sEVs), successfully separated by ultrafiltration from the conditioned medium of hUC-MSCs. The size distribution, protein concentration, exosomal markers (CD9, CD81, TSG101), and morphology of the isolated hUC-MSC-sEVs were characterized with nanoparticle tracking analysis, BCA protein assay, western blot, and transmission electron microscope, respectively. The isolated hUC-MSC-sEVs' size was 30-200 nm, with a particle concentration of 7.75 × 10¹⁰ particles/mL and a protein concentration of 80 µg/mL. Positive bands for exosomal markers CD9, CD81, and TSG101 were observed. This study showed that hUC-MSC-sEVs were successfully isolated from hUC-MSCs conditioned medium, and characterization showed that the isolated product fulfilled the criteria mentioned by Minimal Information for Studies of Extracellular Vesicles 2018 (MISEV 2018).