Utilizing large-scale produced exosomes in a hepatocellular carcinoma model as an antigen delivery system

Since the discovery of exosomes, research has focused on their potential as delivery systems and immunomodulatory platforms for early diagnosis and therapy in various diseases. However, the problems related to the production, isolation and various loading strategies of sufficient amounts of exosomes for clinical use have not been fully resolved. In this study, the large-scale production of human monocyte cell line THP-1 which were adapted to chemically defined medium that did not contain serum and animal protein, the optimization of the ultrafiltration method, which is more suitable for large-scale exosomes during exosome isolation from cells, detailed characterization of the obtained exosomes, loading with hepatitis B antigen and testing in the established hepatocellular carcinoma model by hanging drop were carried out. THP-1 cells were successfully grown in a stirred tank bioreactor with a working volume of 1 L and exosomes were isolated in an ultrafiltration system with a flow rate of 125 rpm. Additionally, it was determined that loading 5 µg recombinant HBsAg/mL antigen into the exosomes isolated as a result of large-scale production by the co-incubation method was effective on both spheroid formation and the formed spheroid. These findings demonstrate that large-scale-produced exosomes can serve as an effective antigen delivery platform and highlight their potential application in vaccine-related strategies targeting HBV-associated hepatocellular carcinoma.