Abstract: Objective: To establish an efficient method for extracting exosomes from large-volume cell perfusate. Methods: EA.HY926, an immortalized cell line produced by the hybridization of human umbilical vein endothelial cells and human lung adenocarcinoma cell line A549, was cultured with M199 culture medium containing 10% fetal bovine serum. Flexcell STR-4000 parallel plate flow chamber system was employed to apply shear stress to EA.HY926. And then the perfusate was collected. The cell debris was removed by centrifugation. The supernatant was freeze-dried into the dry powder and was resuspended by small-volume medium. The dialysis was used to desalt and purify the suspension. The exoEasy Maxi Kit was used to extract the exosomes. The morphology of exosomes was observed by electron microscopy. The size of exosomes was detected by nanometer particle size analyzer. The activity of exosomes was detected by PKH26 staining. BCA protein quantification method was used to detect the protein concentration of exosomes. The expressions of exosomal specific proteins CD9 and CD81 were detected by Western blot. The quantitative RT-PCR was used to detect the expression of related genes in the exosomes. Results: The exosomes extracted by this method were uniform in size, showing a typical and complete vesicle-like structure. The particle size was concentrated at 30～150 nm, and the peak value was at 97.63 nm, indicating that the size was appropriate and the purity was high. Moreover, exosomes-specific protein CD9 and CD81 were expressed. PKH26 could bind to the membranous structure of exosomes and exosomes could be efficiently taken up by cells. Endothelial cells-associated CD31, vWF mRNA, and microRNA molecules such as miR-126, miR-21, miR-155 were expressed in exosomes secreted by EA.HY926. Conclusion: This method can effectively extract structurally intact, high-concentration, high-quality exosomes from large-volume cell perfusate.

Key words: exosomes, cell perfusate, shear stress, human umbilical vein endothelial cell line