Comparing extracellular vesicles from four different cell origins for intracellular drug delivery to pancreatic cancer cells: Small or large vesicles?

Extracellular vesicles (EVs), including small EVs (sEVs) and large EVs (lEVs), have been recently explored as drug delivery carriers. EVs properties vary depending on their cell origins, and selection of EVs sources is critical to maximise their drug delivery potential. This study aimed to compare sEVs and lEVs derived from mesenchymal stem cells (MSCs), and human cancerous lymphoma U937, monocytic leukaemia THP-1, and pancreatic cancer MIA PaCa-2 cells for pancreatic cancer drug delivery. Their total protein, EVs markers, physicochemical properties, yield and cellular uptake by MIA PaCa-2 cells were compared. Gemcitabine (GEM) was loaded into the selected EVs (GEM@sEVs, GEM@lEVs) and their cytotoxicity to MIA PaCa-2 cells was evaluated. The results showed that total protein content in sEVs and lEVs largely varied between cells. Western blotting confirmed expression of sEVs (CD81 or TSG101). The EVs were spherical or oval-shaped with an average size ranging 140–180 nm for sEVs and 210–270 nm for lEVs and a similar zeta potential (−20 to −30 mV). MIA PaCa-2 cells had the highest EVs yield with both sEVs and lEVs that were almost twice likely to be taken by their parental cells than other cell-derived EVs counterparts. The lEVs had 14.2-fold greater GEM loading capacity compared to sEVs (120.3 ± 30.5 μg/1010 lEVs vs. 8.5 ± 1.4 μg/1010 sEVs). GEM@sEVs and GEM@lEVs exhibited similar cytotoxicity to MIA PaCa-2 cells, 4-fold more potent than free GEM. Overall, this study revealed the different properties of sEVs and lEVs derived from the four different cells, and demonstrated the different potential of autologous sEVs and lEVs for targeted intracellular drug delivery.