The Transferability from Animal Models to Humans: Challenges Regarding Aggregation and Protein Corona Formation of Nanoparticles.

Nanomaterials are interesting candidates for applications in medicine as drug delivery or diagnostic agents. For safe application, they have to be evaluated in in vitro and in vivo models to finally be translated to human clinical trials. However, often those transfer processes fail, and it is not completely understood whether in vitro models leading to these animal models can reliably be compared to the situation in humans. In particular, the interaction of nanomaterials with components from different blood plasma sources is difficult to compare, and the outcomes of those interactions with respect to body distribution and cell uptake are unclear. Therefore, we investigated the interactions of differently functionalized polymeric and inorganic nanoparticles with human, mouse, rabbit, and sheep plasma. The focus was put on the determination of aggregation events of the nanoparticles occurring in concentrated plasma and the correlation with the respectively formed protein coronas. Both the stability in plasma as well as the types of adsorbed proteins were found to strongly depend on the plasma source. Thus, we suggest evaluating the potential use of nanocarriers always in the plasma source of the chosen animal model for in vitro studies as well as in human plasma to pin down differences and eventually enable transfer into clinical trials in humans.