(W1130-02-12) Polydopamine-Coated Nanoparticles as a Targeted Drug Delivery System for the Treatment of Helicobacter pylori-Infected Gastric Ulcer

Purpose: Successful treatment of Helicobacter pylori infected-gastric ulcer is a substantial challenge because of the global emergence of antibiotic resistance and the mucus layer lining the stomach epithelial tissues. To overcome these limitations, nanoparticle-based drug delivery systems have been investigated. Especially, polydopamine (PDA)-coated nanoparticles, which are biocompatible, biodegradable, and mussels-inspired naturally occurring products, have been applicated in diverse fields because of their versatile characteristics. PDA-coated nanoparticles can penetrate the mucus by minimizing the hydrophobic interaction between nanoparticles and the mucus layer. In addition, PDA has remarkable tissue adhesiveness and cellular uptake because of the diverse interactions with tissue. Taken together, we hypothesized that PDA-coated nanoparticles might be able to target gastric ulcer and enhance retention time by the mucus penetration and tissue adhesive properties of PDA. Therefore, this study aimed to develop a novel gastric ulcer-targeted drug delivery system and verify the impact of PDA coating of nanoparticles on delivery efficiency and therapeutic efficacy.

Methods: PDA-CPNPs (Polydopamine-coated clarithromycin-loaded poly(d,l-lactide-co-glycolide) nanoparticles) were fabricated via oil-in-water emulsification/solvent evaporation and self-oxidative polymerization of dopamine. HPLC analysis was used to determine the concentration of clarithromycin loaded in nanoparticles and the release of clarithromycin. Male ICR mice were used as model animal, and gastric ulcers were produced according to the method of Okabe et al. with slight modifications using acetic acid. To induce H. pylori infection, 3 x 10⁹ CFU of H. pylori were inoculated by oral gavage. In vitro and in vivo mucus penetration activity was examined in the porcine mucin solution and H. pylori-infected gastric ulcer mice. Ulcer-targeted delivery and biodistribution of nanoparticles were observed using in vivo imaging system and confocal laser scanning microscope. To investigate the in vivo therapeutic efficacy of PDA-CPNPs, H. pylori-infected gastric ulcer mouse was used as an animal model. PDA-CPNPs were administered orally once daily for 5 consecutive days and antibacterial and ulcer healing effects were evaluated by CFU method, ulcer size reduction, stomach/body weight ratio, and diverse staining method (H&E, Giemsa staining) after treatment.

Results: Particle size, zeta potential, and drug loading of PDA-CPNPs were 237.9 ± 2.83 nm, -15.0 ± 0.4 mV, and 2.5 ± 0.2 %, respectively and sustained drug release was observed for 12 hours. In vitro mucus penetration studies, the fluorescence intensity was measured after diffusion through the mucin solution. In vivo mucus penetration studies, distribution of the orally administered nanoparticles in the gastric ulcer tissue, and fluorescence intensity were examined after gentle washing to remove nanoparticles, which were trapped in the mucus. Mucus penetration studies demonstrated that PDA-CPNPs penetrated mucus via minimalized interaction with mucus and significantly improved the efficiency of ulcer delivery. In addition, PDA-CPNPs showed a strong tissue adhesive property, leading to prolonged retention of nanoparticles in the gastric ulcer tissues. In vitro antibacterial study, without mucin incubation, both CPNPs and PDA-CPNPs showed antibacterial activities in a concentration-dependent manner, especially there were no live bacteria at a concentration of 2 mg/mL NPs. However, with mucin incubation, CPNPs did not exhibit any antibacterial effects, whereas PDA-CPNPs showed almost 4-log reduction (99.99% killing) of H. pylori at a concentration of 2 mg/mL NPs. Because CPNPs were trapped in the mucin solution and got removed with mucin, whereas PDA-CPNPs diffused through the mucin solution and remained in the bottom of the tube during the mucin removal process. Finally, in vivo therapeutic assay, PDA-CPNPs eradicated H. pylori at a low dose of clarithromycin (1 mg/kg) and significantly reduced ulcer size compared to other groups (Untreated, free drug solution and CPNPs). Taken together, PDA-CPNPs can target the gastric ulcer and could be a promising treatment strategy for H. pylori-infected gastric ulcer.

Conclusion: In the present study, PDA-CPNPs were fabricated as a H. pylori-infected gastric ulcer-targeted drug delivery system. In vitro and in vivo mucus penetration studies demonstrated that PDA-CPNPs penetrate mucus via minimalized interaction with mucus and significantly improve the efficiency of ulcer delivery. Furthermore, PDA-CPNPs showed a strong tissue adhesive property, leading to prolonged retention of NPs in the gastric ulcer tissues. As a result, PDA-CPNPs eradicated H. pylori at a low dose of clarithromycin (1 mg/kg) and significantly reduced ulcer size compared to other groups in vivo. Taken together, PDA-CPNPs can target the gastric ulcer and could be a promising treatment strategy for H. pylori-infected gastric ulcer. To the best of our knowledge, this is the first research to examine the gastric ulcer-targeted delivery and therapeutic efficacy in vivo H. pylori-infected gastric ulcer animal model, which deserves further investigation.

Figure 1. Characterization and biodistribution of nanoparticles

Figure2. In vitro antibacterial activity of nanoparticles

Figure 3. In vivo therapeutic efficacy