Encapsulation and Delivery of Neutrophic Proteins andHydrophobic Agents Using PMOXA?PDMS?PMOXA TriblockPolymersomes

摘要

Polymersomes are attractive nanocarriers for hydrophilic and lipophilic drugs; they are more stable thanliposomes, tunable, and relatively easy to prepare. The copolymer composition and molar mass are critical features thatdetermine the physicochemical properties of the polymersomes including the rate of drug release. We used the triblockcopolymer, poly(2-methyl-2-oxazoline)-block-poly-(dimethysiloxane)-block-poly(2-methyl-2-oxazoline) (PMOXA?PDMS?PMOXA), to form amphipathic polymersomes capable of loading proteins and small hydrophobic agents. The selectedagents were unstable neurotrophins (nerve growth factor and brain-derived neurotrophic factor), a large protein CD109, andthe fluorescent drug curcumin. We prepared, characterized, and tested polymersomes loaded with selected agents in 2D and 3Dbiological models. Curcumin-loaded and rhodamine-bound PMOXA?PDMS?PMOXA polymersomes were used to visualizethem inside cells. N-Methyl-D-aspartate receptor (NMDAR) agonists and antagonists were also covalently attached to thesurface of polymersomes for targeting neurons. Labeled and unlabeled polymersomes with or without loaded agents werecharacterized using dynamic light scattering (DLS), UV?vis fluorescence spectroscopy, and asymmetrical flow field-flowfractionation (AF4). Polymersomes were imaged and tested for biological activity in human and murine fibroblasts, murinemacrophages, primary murine dorsal root ganglia, and murine hippocampal cultures. Polymersomes were rapidly internalizedand there was a clear intracellular co-localization of the fluorescent drug (curcumin) with the fluorescent rhodamine-labeledpolymersomes. Polymersomes containing CD109, a glycosylphosphatidylinositol-anchored protein, promoted cell migration inthe model of wound healing. Nerve growth factor-loaded polymersomes effectively enhanced neurite outgrowth in dissociatedand explanted dorsal root ganglia. Brain-derived neurotrophic factor increased dendritic spine density in serum-deprivedhippocampal slice cultures. NMDAR agonist- and antagonist-functionalized polymersomes targeted selectively neurons overglial cells in mixed cultures. Collectively, the study reveals the successful incorporation into polymersomes of biologically activetrophic factors and small hydrophilic agents that retain their biological activity in vitro, as demonstrated in selected central andperipheral tissue models.