PB0731 - Biology and pharmacokinetic study of natural and engineered megakaryoblastic exosomes

Monday, June 24, 2024

13:45 – 14:45 ICT

Room: Exhibition Hall

Presenting Author(s)

Tuan Huu Nguyen, MD

PhD Student
Australian Centre for Blood Diseases (ACBD), Central Clinical School, Faculty of Medicine, Nursing and Health Sciences, Monash University
Melbourne, Victoria, Australia

Co-Author(s)

RX

Rong Xu

Research Fellow
Australian Centre for Blood Diseases (ACBD), Central Clinical School, Faculty of Medicine, Nursing and Health Sciences, Monash University
Melbourne, Victoria, Australia
BW

Bamlaku Walie

PhD Student
Australian Centre for Blood Diseases (ACBD), Central Clinical School, Faculty of Medicine, Nursing and Health Sciences, Monash University
Melbourne, Victoria, Australia
AR

Amir Roointan

PhD Student
Australian Centre for Blood Diseases (ACBD), Central Clinical School, Faculty of Medicine, Nursing and Health Sciences, Monash University
Melbourne, Victoria, Australia
SL

Siqi Li

PhD Student
Australian Centre for Blood Diseases (ACBD), Central Clinical School, Faculty of Medicine, Nursing and Health Sciences, Monash University
Melbourne, Victoria, Australia
CH

Christoph Hagemeyer

Lab Head
Australian Centre for Blood Diseases (ACBD), Central Clinical School, Faculty of Medicine, Nursing and Health Sciences, Monash University
Melbourne, Victoria, Australia

Background: Exosomes are nanosized extracellular vesicles produced by living cells. In the normal human body, most exosomes originate from platelets and their progenitors, megakaryocytes and megakaryoblasts. However, limited data is currently available regarding the biology and pharmacokinetic study of megakaryoblastic exosomes.

Aims: To study the biodistribution and blood clearance of natural and engineered megakaryoblastic exosomes.

Methods: Exosomes were collected by ultracentrifugation from MEG-01 cells, a human megakaryoblastic cell line. These MEG-01 exosomes were characterized by sulfate/aldehyde bead-based flow cytometry. MEG-01-exosomes were labeled using NHS-Cy5.5. 100 ug protein equivalent of exosomes was injected intravenously (IV) into wild-type C57BL/6 mice. Blood samples were collected starting from 2.5 minutes until 48 hours after injection. Organs were harvested after 48 and 96 hours. Fluorescent signals were analyzed using Odyssey® DLx scanner.

Results: Compared to activated platelet-derived exosomes, MEG-01 - exosomes have similar expression of exosomal (CD81, CD9 and CD63), and platelet markers (CD41, CD61 and CD42b), but express a lower level of CD62P. The half-life of MEG-01-exosomes is 159.6 minutes (n=3), and they can be detected mostly in the liver and spleen as well as plasma at 48 hours after IV injection. While most MEG-01-exosomes concentrate in the liver and spleen, intriguingly, a significant amount of exosomes home to bone marrow, and a reduction in the plasma can be observed 96 hours after one dose of IV injection. MEG-01-exosomes were detected in the major lymph nodes (LNs) including mesenteric LNs, and identified in the thymus at 48 and 96 hours after IV injection.

Conclusion(s): This observation may serve as a foundation for future studies into the roles of megakaryoblastic exosomes in bone marrow megakaryocyte biology and pharmacokinetic study of natural and engineered exosomes originating from the platelet lineage. However, 64Cu-SCE5 (scFv for activated GPIIb/IIIa)-MeCOsar and 64Cu-anti-CD63scFv-MeCOsar radiolabeled exosomes and positron emission tomography (PET) are warranted to confirm our results.