Pancreatic Cancer Stem Cells-derived Exosomes Activites Dendritic Cell For Cancer Immunotherapy

Pancreatic cancer is a highly malignant digestive tract disease,with a five-year survival rate of 6%,it is known as the "king of cancer".Due to the limitations of surgical treatment,chemotherapy is still the main method for the treatment of advanced pancreatic cancer.Gemcitabine is a first-line chemotherapy drug in the treatment of pancreatic cancer.Although it can improve the symptoms of patients,its effect on prolonging survival rate is still limited,mainly due to the drug resistance of cancer stem cells.CSCs is a small number of cells with the ability of self-renewal and multi-directional differentiation in tumor tissue,which plays an important role in the process of tumorigenesis,progression and recurrence.CSCs expresses ABC transporter and has the ability of natural anti-chemotherapy drugs,which has become one of the fundamental reasons for poor therapeutic effect and easy recurrence of pancreatic cancer.Therefore,the effective killing of CSCs is expected to overcome the drug resistance of tumors,so as to eradicate cancer completely.Immunotherapy uses the patient's own immune system to fight the disease.By strengthening the immune system against tumors,it has been proved to be the most promising strategy for the treatment of cancer.Major histocompatibility complex(MHC I),which can present internal antigens of pancreatic cancer stem cells.Due to the low expression of MHC I,the internal antigens can not be recognized by T cells,which achieves immune escape.Dendritic cells are full-time antigen presenting cells in the body,can effectively present antigens to T cells and stimulate T cell immune response.Therefore,the application of tumor vaccine based on dendritic cells has become an important way of tumor immunotherapy.Exosomes are small vesicles(40-150 nm)containing DNA,RNA and proteins,which secreted by cells.Exosomes can be used as tumor antigens to activate dendritic cells and are expected to more accurately induce anti-tumor effects.In this work,the exosomes secreted by PCSCs modified by aCD11 c was designed,under the action of aCD11 c,the system can effectively target dendritic cells in vivo and promote the exosomes uptake and processing of dendritic cells.Dendritic cells present the PCSCs foreign antigens to T cells,which in turn kill PCSCs,to produce specific anti-tumor immune response.In this work,the exosomes with average particle size of 73 nm were successfully isolated by ultracentrifugation,the targeting ligands of aCD11 c were prepared by linking aCD11 c with DSPE-PEG-NHS,and the system of aCD11c-Exosomes was prepared based on the principle of lipid intercalation between phospholipid double strands and phospholipid bilayers on the surface of exosomes membrane.Through a variety of experimental methods in vitro to verify that the system can effectively target dendritic cells,promote dendritic cells to mature and present antigens to T cells.Establish a BALB/c mouse subcutaneous tumor model,in vivo verified that aCD11c-Exosomes can induce a strong anti-tumor immune response.Thus,the exosomes-based individualized tumor vaccine designed in this work is expected to provide an important idea for clinical treatment of pancreatic cancer.