Specific cellular internalization and pH-responsive behavior of doxorubicin loaded PLGA-PEG nanoparticles targeted with anti EGFRvIII antibody

Abstract

Aim: Antibody-conjugated nanoparticles have attracted much attention in the field of cancer treatment due to the enhancement of the tumor cell response to anticancer drugs as well as reducing the side effects of chemotherapeutic agents on healthy tissues. However, most studies in this field generally mentioned the specific cellular uptake of conjugated nanoparticles. In this study, we loaded doxorubicin (DXR: as an effective antineoplastic agent) in PLGA-PEG (D,L-lactic-co-glycolic acid)-(polyethylene glycol) biocompatible polymeric nanoparticles (NPs) and then conjugated with anti-EGFRvIII antibody. The resulting nanoparticles had remarkable sensitivity to pH decrease and were capable of targeting specific cells.

Materials and methods: To this aim, PLGA-PEG-COOH was used for the synthesis of nanoparticles and stabilized by polyvinyl alcohol (PVA) according to the nanoprecipitation method. The carboxylic groups on the surface of PLGA-PEG NPs were activated by EDC/NHS and covalently conjugated to amino groups of the monoclonal antibody. The prepared NPs were characterized by Zetasizer and transmission electron microscopy (TEM). The resulting NPs were evaluated in terms of entrapment efficiency (EE), drug loading efficiency (DLE), drug-release profile, and cell internalization. Intrinsic cytotoxicity was assessed by the MTT, apoptosis (Annexin V-PI) and cell cycle assays.

Key findings: The in vitro drug release assessment of conjugated particles (MAb-DXR-PLGA NPs) showed a slow sustained DXR release in physiological pH (7.4) values, while the initial drug release was markedly higher (the 1.9 fold) in acidic pH (6.5) ranges. The selectivity for cellular internalization of MAb-DXR-PLGA NPs into U87MG vIII cells (overexpressing EGFRvIII) in comparison with U87MG cells (lacking EGFRvIII expression) was also confirmed. The MTT assay demonstrated that the cytotoxicity of MAb-DXR-PLGA NPs against U87MG vIII cells was more pronounced when compared with BSA-DXR-PLGA NPs. The results of the MTT assay were also confirmed by apoptosis and cell cycle assays.

Significance: Our findings suggest that the designed anti-EGFRvIII MAb-DXR-PLGA NPs could be considered as a proper option for targeted drug delivery systems due to pH sensitivity and specific cellular internalization.

Keywords: Apoptosis; Cell cycle; Doxorubicin; EGFRvIII; Monoclonal antibody; PLGA-PEG-COOH; pH responsive.