Aggregates of misfolded proteins, which occur in so-called prion diseases such as Creutzfeldt-Jakob disease, have the ability to pass from one cell to another, where they transfer their abnormal shape to proteins of the same kind. As a result, the disease spreads across the brain. A similar phenomenon is discussed for Alzheimer's and Parkinson's disease, which also exhibit assemblies of misfolded proteins.

Transmission of aggregates could involve direct cell-to-cell contact, the release of "naked" aggregates into extracellular space or packaging in vesicles, which are tiny bubbles surrounded by a lipid envelope that are secreted for communication between cells. "The precise mechanisms of transmission are unknown", says Ina Vorberg, a research group leader at the DZNE's Bonn site and professor at the University of Bonn. "However, it is an obvious guess, that aggregate exchange by both direct cell contact and via vesicles depends on ligand-receptor interactions. This is because in both scenarios, membranes need to make contact and fuse. This is facilitated when ligands are present that bind to receptors on the cell surface and then cause the two membranes to fuse."

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