Are biologically active exosomes stable in blood plasma? — ASN Events
  1. Schedule
  2. Session Twelve - Poster Session D including Happy Hour & Trade Display
  3. Are biologically active exosomes stable in blood plasma?

Are biologically active exosomes stable in blood plasma? (#445)

Suresh Mathivanan 1 , Mark Hulett 1 , Christopher Adda 1 , Adam Mechler 1 , Richard Simpson 1 , Hina Kalra 1
  1. La Trobe Institute for Molecular Science, Bundoora, VIC, Australia

Exosomes are biologically active membranous vesicles of endocytic origin released by a variety of cells in vivo and in vitro. As cells release exosomes into theextracellular space, they can also be detected in bodily fluids including saliva, urine, breast milk, blood, amniotic fluid and malignant ascites. Depending on the originating tissue, exosomes contain a subset of the host cell-specific molecular cargo including proteins, lipids and RNA. The affordability of accessing exosomes in bodily fluids and the presence of host-cell specific cargo have created immense interest in utilizing exosomes for biomarker analysis. While blood plasma is the specimen of choice for exosomes based biomarker analysis, its high complexity and viscosity creates significant obstacles in isolating pure population of exosomes. In addition, the stability of exosomes in blood plasma is poorly understood. To optimize exosome isolation methods from blood plasma, it is critical to evaluate the commonly used methods in the context of purity. In the first part of this study, a comparative evaluation of three exosome isolation techniques (differential centrifugation coupled with ultracentrifugation (UC), epithelial cell adhesion molecule immunoaffinity pull down (EI) and OptiPrepTM density gradient (DG) separation) was performed using normal human plasma. Western blotting, microscopic and mass spectrometry analyses revealed that DG exosomes contained membranous vesicles and were enriched with exosomal markers. However, EI and UC were enriched with high abundant plasma proteins highlighting DG method as relatively superior in isolating pure exosomal population. In the second part of this study, the stability of exosomes in plasma over 90 days at various storage conditions was tested. LIM 1863 derived exosomes were spiked at known concentrations in plasma and stored at 4ºC, -20ºC and -80ºC for up to three months. Western blotting analysis based on exosomal marker TSG101 revealed that exosomes are highly stable at -20ºC, -80ºC and to a lesser extent at 4ºC for 90 days.