Self-assembled PEG- b-PDPA- b-PGEM copolymer nanoparticles as protein antigen delivery vehicles to dendritic cells: preparation, characterization and cellular uptake

Pan Li; Junhui Zhou; Pingsheng Huang; Chuangnian Zhang; Weiwei Wang; Chen Li; Deling Kong

doi:10.1093/rb/rbw044

Self-assembled PEG- b-PDPA- b-PGEM copolymer nanoparticles as protein antigen delivery vehicles to dendritic cells: preparation, characterization and cellular uptake

Regen Biomater. 2017 Feb;4(1):11-20. doi: 10.1093/rb/rbw044.

Authors

Pan Li¹, Junhui Zhou², Pingsheng Huang¹, Chuangnian Zhang¹, Weiwei Wang¹, Chen Li¹, Deling Kong¹

Affiliations

¹ Tianjin Key Laboratory of Biomaterial Research, Institute of Biomedical Engineering, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin 300192, China.
² School of Chemical Engineering and Technology, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin 300072, China.

Abstract

Antigen uptake by dendritic cells (DCs) is a key step for initiating antigen-specific T cell immunity. In the present study, novel synthetic polymeric nanoparticles were prepared as antigen delivery vehicles to improve the antigen uptake by DCs. Well-defined cationic and acid-responsive copolymers, monomethoxy poly(ethylene glycol)-block-poly(2-(diisopropyl amino) ethyl methacrylate)-block-poly(2-(guanidyl) ethyl methacrylate) (mPEG-b-PDPA-b-PGEM, PEDG) were synthesized by reversible addition-fragmentation chain transfer polymerization of 2-(diisopropylamino)ethyl methacrylate) and N-(tert-butoxycarbonyl) amino ethyl methacrylate monomers, followed by deprotection of tert-butyl protective groups and guanidinylation of obtained primary amines. ¹H NMR, ¹³C NMR and GPC results indicated the successful synthesis of well-defined PEDG copolymers. PEDG copolymers could self-assemble into nanoparticles in aqueous solution, which were of cationic surface charges and showed acid-triggered disassembly contributed by PGEM and PDPA moieties, respectively. Significantly, PEDG nanoparticles could effectively condense with negatively charged model antigen ovalbumin (OVA) to form OVA/PEDG nanoparticle formulations with no influence on its secondary and tertiary structures demonstrating by far-UV circular dichroism and UV-vis spectra. In vitro antigen cellular uptake by bone marrow DCs (BMDCs) indicated using PEDG nanoparticles as antigen delivery vehicles could significantly improve the antigen uptake efficiency of OVA compared with free OVA or the commercialized Alum adjuvant. Moreover, as the surface cationic charges of OVA/PEDG nanoparticle formulations reduced, the uptake efficiency decreased correspondingly. Collectively, our work suggests that guanidinylated, cationic and acid-responsive PEDG nanoparticles represent a new kind of promising antigen delivery vehicle to DCs and hold great potential to serve as immunoadjuvants in the development of vaccines.

Keywords: antigen delivery; dendritic cells; guanidyl; nanoparticles; synthetic copolymer.