Endocytic uptake and intracellular trafficking of bis-MPA-based hyperbranched copolymer micelles in breast cancer cells.

Dendrimers and their less well-defined cousins, hyperbranched polymers, are widely investigated as scaffold materials in tissue engineering, as drug delivery agents, and in diagnostic imaging applications. Despite the large interest of using these unique materials as polymer-based nanoparticles in biomedical applications, a clear understanding of the cellular uptake and transport of these polyester-based nanoparticles is still lacking. The objective of this study is to evaluate the cellular uptake profiles and intracellular trafficking of polymer micelles built from the hyperbranched polyester Boltorn, fitted with poly(ethylene glycol) and fluorescent groups in MDA-MB468 breast cancer cells. Results show that the uptake of these nanoparticles correlated positively to both time and concentration, and that the uptake of the nanoparticles was energy dependent. These polyesterbased nanoparticles appear to translocate across cells via clathrin- and macropinocytosis-mediated endocytosis. Observations of the intracellular trafficking of the nanoparticles indicate that particles could be released from early endosomes after being internalized, and the particles exhibit perinuclear localization. The uptake behavior of the nanoparticles was further evaluated in a range of cell lines. These results allow the generation of the knowledge base required to design polyester-based nanocarriers that can be used efficiently and specifically for drug delivery applications and imaging applications.