Lease of EVs per cell, higher purity EVs.OF11.Prolongation of allograft survival by means of donor MHC chimerism induced by extracellular vesicles Bruno Adonai Gonzalez Nolascoa, Mengchuan Wanga, William Orenta, Aurore Prunevieillea, Jane Oa, Kaitlan Ahrensa, Joren C Madsenb and Gilles BenichouaISEV2019 ABSTRACT BOOKa Department of Surgery, Center for Transplantation Sciences, Massachusetts Basic Hospital and Harvard Medical College, Boston, USA; P2Y1 Receptor Formulation bDepartment of Surgery, Center for Transplantation Sciences and Division of Cardiac Surgery, Massachusetts Common Hospital and Harvard Health-related School, Boston, USAOF11.Proteomic and transcriptomic characterization of exosomes-mimetic nanovesicles reveals their relevance as a therapeutic delivery method Amirmohammad Nasiri Kenaria, Kenneth Kastaniegaardb, Mitch C. Shambrooka, David Greeninga, Allan Stensballeb, Lesley Chenga and Andrew HillcaIntroduction: Achieving robust and sturdy host immune tolerance of allogeneic transplants will be the ultimate goal in clinical transplantation. Mixed chimerism induced by means of donor bone marrow transplantation and host non-myeloablative conditioning has reliably achieved tolerance of allogeneic organ transplants in mice and humans. Tolerance in this model is believed to rely essentially on the presentation of donor MHC molecules inside the host’s thymus. Within this study, we investigated whether or not donor MHC chimerism could possibly be accomplished by way of donor extracellular vesicles (EVs) injections and subsequent cross-dressing of recipient cells within the host’s thymus. Techniques: Conditioned SJL (CD45.1+, H2-Ks+) recipient mice received a single IV dose of purified bone marrow derived exosome-enriched EVs (BM-EVs) isolated from C57BL/6 (CD45.2+, H2-Kb+) donors by means of sequential centrifugation or using a commercially accessible exosome isolation kit. Nanoparticle tracking showed vesicles of approximately 100nm in size in the BM-EVs preparation and Western Blot showed the presence of MHCI. Image flow cytometry was made use of to detect the presence of cross-dressed cells from day 10 through one hundred following exosome injection. For NHP research, MHC class I H38+ BM-EVs had been injected into a H38- conditioned cynomolgus macaque before a combined heart and kidney transplant. PBMCs, thymus, spleen and mesenteric lymph nodes have been collected for image flow cytometry. Results: Intravenous injection of BM-EVs into conditioned mice resulted in the presentation of donor MHC and CD45.1 molecules by host’s thymic and splenic cells. Similarly, H38+cross-dressed cells had been detected at D33 soon after exosome injection in all the NHP recipient tissues collected. In mice, donor but not syngeneic or third-party BM-EVs significantly prolonged skin allograft survival (median survival = 17 VS 11 days, p 0.001). Summary/Conclusion: These benefits show that delivery of donor-derived extracellular vesicles can induce donor MHC chimerism by way of cross-dressing of recipient APCs with allogeneic MHC molecules inside the host’s thymus. This suggests that donor EVs might be employed in spot of bone marrow cells to induce chimerism and allograft survival with N-type calcium channel custom synthesis minimal conditioning and no threat of graft versus host illness (GVHD). Funding: NIH R01DK115618.bDepartment of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Australia; Department of Well being Science and Technology, Faculty of Medicine, Aalborg University, Denmark, Aalborg, Denmark; cThe Department of Biochemistry and Genetics, La Trobe Institute for Molec.