A cell culture model for monitoring α-synuclein cell-to-cell transfer

The transfer of alpha-synuclein (alpha-syn) between cells has been proposed to be the primary mechanism of disease spreading in Parkinson's disease. Several cellular models exist that monitor the uptake of recombinant alpha-syn from the culture medium. Here we established a more physiologically relevant model system in which alpha-syn is produced and transferred between mammalian neurons. We generated cell lines expressing either alpha-syn tagged with fluorescent proteins or fluorescent tags alone then we co-cultured these cell lines to measure protein uptake. We used live-cell imaging to demonstrate intercellular alpha-syn transfer and used flow cytometry and high content analysis to quantify the transfer. We then successfully inhibited intercellular protein transfer genetically by down-regulating dynamin or pharmacologically using dynasore or heparin. In addition, we differentiated human induced pluripotent stem cells carrying a triplication of the alpha-syn gene into dopaminergic neurons. These cells secreted high levels of alpha-syn, which was taken up by neighboring neurons. Collectively, our co-culture systems provide simple but physiologically relevant tools for the identification of genetic modifiers or small molecules that inhibit alpha-syn cell-to-cell transfer. (C) 2014 Published by Elsevier Inc.