Voelcker, N. H. | Search bioRxiv

bioRxiv2024

Optimizing Angiopep-2 Density on Polymeric Nanoparticles for Enhanced Blood-Brain Barrier Penetration and Glioblastoma Targeting: Insights from In Vitro and In Vivo Experiments

The blood-brain barrier (BBB) poses a formidable challenge to efficient drug delivery into the brain. One promising approach involves leveraging receptor-mediated transcytosis facilitated by Angiopep-2 peptide (Ang-2)-conjugated nanoparticles. However, the precise impact of Ang-2 density on BBB penetration remains poorly understood. In this study, we developed a versatile polymeric nanoparticle system with tuneable Ang-2 surface density and systemically examined its influence on BBB penetration through various in vitro assays and an in vivo study. Our findings revealed a nuanced relationship between Ang-2 surface density and BBB penetration across the different experimental setups. In 2D cell culture, we observed a positive correlation between Ang-2 surface density and cellular association in hCMEC/D3 cells, characterized by a distinctive inflection point. Conversely, in the Transwell model, higher Ang-2 density correlated negatively with BBB penetration, whereas the BBB-GBM-on-a-chip showed the opposite trend. These disparities may arise from differences in avidity under static versus dynamic conditions, potentially modulating nanoparticle interactions due to fluidic forces. In vivo studies revealed that higher Ang-2 densities facilitated nanoparticle transport across the BBB, consistent with the findings of the BBB-GBM-on-a-chip model. Furthermore, loading doxorubicin into nanoparticles with optimal Ang-2 density resulted in controlled pH-responsive release and enhanced anticancer effect against U87 GBM cells in both 2D cell cultures and a 3D BBB-GBM-on-a-chip model. These results underscore the critical importance of optimizing Ang-2 surface density for efficient BBB penetration and emphasize the utility of dynamic models in preclinical in vitro assessment of novel nanoparticle formulations for targeted delivery to the brain.

bioengineering↗

bioRxiv2020

Bacteriophage uptake by Eukaryotic cell layers represents a major sink for phages during therapy

For over 100 years, bacteriophages have been known as viruses that infect bacteria. Yet it is becoming increasingly apparent that bacteriophages, or phages for short, have tropisms outside their bacterial hosts. During phage therapy, high doses of phages are directly administered and disseminated throughout the body, facilitating broad interactions with eukaryotic cells. Using live cell imaging across a range of cell lines we demonstrate that cell type plays a major role in phage internalisation and that smaller phages (< 100 nm) are internalised at higher rates. Uptake rates were validated under physiological shear stress conditions using a microfluidic device that mimics the shear stress to which endothelial cells are exposed to in the human body. Phages were found to rapidly adhere to eukaryotic cell layers, with adherent phages being subsequently internalised by macropinocytosis and functional phages accumulating and stably persisting intracellularly. Finally, we incorporate these results into an established pharmacokinetic model demonstrating the potential impact of phage accumulation by these cell layers, which represents a major sink for circulating phages in the body. Understanding these interactions will have important implications on innate immune responses, phage pharmacokinetics, and the efficacy of phage therapy.

microbiology↗