3D visualization of extracellular vesicle uptake by endothelial cells.

Background: Extracellular vesicles are small vesicles that contain cytoplasmic and membrane components from their paternal cells. They enter target cells through uptake to transfer their biological cargo. In this study, we investigated the process of endothelial EV internalization and created a 3D visualization of their intracellular distribution.

Methods and results: Two immortalized endothelial cell lines that express h-TERT (human telomerase) were used for EV release: microvascular TIME and macrovascular HUVEC. EVs were isolated from the cell culture medium via differential centrifugation and used for the uptake experiments. The size distribution of the EVs was measured using TRPS technology on a qNano instrument. Internalization of EVs was observed using a Zeiss LSM 710 confocal laser microscope after staining of the EVs with PKH26. EVs were observed intracellularly and distributed in the perinuclear region of the target cells. The distribution patterns were similar in both cell lines.

Conclusion: The perinuclear localization of the internalized EVs shows their biological stability after their uptake to the endothelial cells. The 3D visualization allows the determination of a more accurate location of EVs relative to the donor cell nucleus.