Abstract

Background: The development of polymeric micelles for site-specific drug delivery is an exponentially growing field of research. In this context, we have designed two degradable amphiphilic copolymers, the poly(ethylene glycol)-b-poly(benzyl malate) (PEG₄₂-b-PMLABe₇₃) and the biotin-poly(ethylene glycol)- b-poly(benzyl malate) (Biot-PEG₆₂-b-PMLABe₇₃). The copolymer bearing biotin residue was synthesized in order to formulate micelles for grafting biotinylated cyclic RGD peptide onto their surface via the bridging streptavidin.

Objective: Our study aimed at investigating the in vitro and in vivo toxicity of such micelles and to evaluate the potential of these nanovectors for hepatocyte-targeted drug delivery. Methods: The toxicity of micelles obtained by the nanoprecipitation method and characterized by dynamic light scattering and zeta potential measurement was evaluated in vitro using the differentiated hepatocyte-like HepaRG cells and in vivo in mice.

Results: The micelles derived from PEG₄₂-b-PMLABe₇₃, Biot-PEG₆₂-b-PMLABe₇₃ and RGDBiot-Strept- Biot-PEG62-b-PMLABe73 did not affect the cell proliferation and apoptotic indexes in HepaRG hepatoma cells and were well tolerated in mice following systemic injection. The hydrophobic fluorescent probes DiD oil and DiR were efficiently encapsulated in PEG-b-PMLABe-derived micelles allowing the visualization of their uptake into HepaRG cells. Furthermore, the addition of RGD peptide onto micelles strongly enhanced the cell uptake in vitro and liver targeting in vivo.

Conclusion: These data demonstrate the low toxicity of poly(benzyl malate) derived copolymers towards hepatocyte- like cells and emphasize their potential use for the design of liver targeting nanovectors.

Keywords: Biocompatible copolymer, biodistribution, biotin, cyclic RGD peptide, HepaRG cells, Poly(benzyl malate) derivatives, polymeric micelles.

Graphical Abstract