Targeted delivery of emodin to adipocytes by aptamer-functionalized PEG-PLGA nanoparticles in vitro

Targeted delivery of antiobesity drugs to adipocytes presents a novel strategy for obesity treatment. The 11 beta-hydroxysteroid dehydrogenase type 1 (11β-HSD1) in adipose tissue is an attractive therapeutic target of obesity. Emodin (EMO) has been proven to be a potent and selective inhibitor of 11β-HSD1, but it frequently exerts low bioavailability owing to its poor water solubility and lack of tissue specificity. In this work, we conjugated a nanoscale drug delivery polymer with Adipo8 (Ap), a DNA aptamer with high affinity to mature white adipocytes, as a targeting modality that enabled selective delivery of emodin to adipocytes. Emodin-loaded PEG-PLGA nanoparticles (EMO-NPs) were formulated by a modified oil-in-water (O/W) emulsion solvent evaporation method, and Ap was covalently bound to the NP surface via the EDC/NHS method. The NPs were structurally investigated by TEM imaging, DLS and UV-VIS spectroscopy. The resulting aptamer-conjugated, emodin-loaded nanoparticles (Ap-EMO-NPs) had a spherical shape and an average particle size of 146.7 ± 27.85 nm with a drug loading of around 6.8% and a sustained-release property. Confocal microscopy and flow cytometry demonstrated a significant increase in the internalization of Ap-EMO-NP in differentiated 3T3-L1 cells compared to EMO-NP functionalized with nonspecific aptamer. As confirmed by Oil Red O coloring, the Ap-EMO-NPs reduced lipid stacking in 3T3-L1 adipocytes in a sustained-release and dose-dependent manner. The results indicated that Adipo8-functionalized PEG-PLGA NPs could be a potential targeted therapeutic delivery vehicle for obesity treatment.