Amyloid precursor protein (APP) processing is central in Alzheimer's disease 
(AD) pathogenesis. The healthy unaffected neurons suffer the transmission of 
amyloid protein from pathologically affected neurons, which may play an 
important role in the anatomical spread of the disease. Exosomes are appropriate 
candidates for transmission of amyloid species, because of their potential role 
as "intercellular transportation". To address a role of secreted exosomes in 
neuronal homeostasis in AD, we harvested exosomes from the conditioned medium of 
HEK293-APP Swe/Ind cells. We have demonstrated that these exosomes contained APP 
and were capable of efficiently transferring APP to normal primary neurons. 
Moreover, these exosomes had dose-dependent detrimental effect on cultured 
neurons. Our results suggest a key mechanism underlying the spread of amyloid 
protein in the brain and the acceleration of pathology in AD; exosomes secretion 
serves to amplify and propagate Alzheimer's disease related pathology.