Local gene delivery via endovascular stents coated with dodecylated chitosan–plasmid DNA nanoparticles

Development of efficacious therapeutic strategies to prevent and inhibit the occurrences of restenosis after percutaneous transluminal coronary angioplasty is critical for the treatment of cardiovascular diseases. In this study, the feasibility and efficiency of stents coated with dodecylated chitosan–plasmid DNA nanoparticles (DCDNPs) were evaluated as scaffolds for localized and prolonged delivery of reporter genes into the diseased blood vessel wall. Dodecylated chitosan–plasmid DNA complexes formed stable positive charged nanospheres with mean diameter of approximately 90–180 nm and zeta potential of +28 ± 3 mV. As prepared DCDNPs were spray-coated on stents, a thin layer of dense DCDNPs was successfully distributed onto the metal struts of the endovascular stents as demonstrated by scanning electron microscopy. The DCDNP stents were characterized for the release kinetics of plasmid DNA, and further evaluated for gene delivery and expression both in vitro and in vivo. In cell culture, DCDNP stents containing plasmid EGFP-C1 exhibited high level of GFP expression in cells grown on the stent surface and along the adjacent area. In animal studies, reporter gene activity was observed in the region of the artery in contact with the DCDNP stents, but not in adjacent arterial segments or distal organs. The DCDNP stent provides a very promising strategy for cardiovascular gene therapy

Local gene delivery via endovascular stents coated with dodecylated chitosan–plasmid DNA nanoparticles

Dunwan Zhu1*, Xu Jin2*, Xigang Leng1, Hai Wang1, Junbo Bao1, Wenguang Liu3, Kangde Yao3, Cunxian Song11Tianjin Key Laboratory of Biomedical Materials, Institute of Biomedical Engineering, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, China; 2Department of Anesthesia and Pain Therapy, Capital Medical University Affiliated Beijing Tiantan Hospital, Beijing, China; 3Research Institute of Polymeric Materials, Tianjin University, Tianjin, China; *Both investigators contributed equally to this work and are senior authors.Abstract: Development of efficacious therapeutic strategies to prevent and inhibit the occurrences of restenosis after percutaneous transluminal coronary angioplasty is critical for the treatment of cardiovascular diseases. In this study, the feasibility and efficiency of stents coated with dodecylated chitosan–plasmid DNA nanoparticles (DCDNPs) were evaluated as scaffolds for localized and prolonged delivery of reporter genes into the diseased blood vessel wall. Dodecylated chitosan–plasmid DNA complexes formed stable positive charged nanospheres with mean diameter of approximately 90–180 nm and zeta potential of +28 ± 3 mV. As prepared DCDNPs were spray-coated on stents, a thin layer of dense DCDNPs was successfully distributed onto the metal struts of the endovascular stents as demonstrated by scanning electron microscopy. The DCDNP stents were characterized for the release kinetics of plasmid DNA, and further evaluated for gene delivery and expression both in vitro and in vivo. In cell culture, DCDNP stents containing plasmid EGFP-C1 exhibited high level of GFP expression in cells grown on the stent surface and along the adjacent area. In animal studies, reporter gene activity was observed in the region of the artery in contact with the DCDNP stents, but not in adjacent arterial segments or distal organs. The DCDNP stent provides a very promising strategy for cardiovascular gene therapy.Keywords: gene delivery, endovascular stent, chitosan, gene nanoparticle

Effects of Carboxylated Multiwalled Carbon Nanotubes on the Function of Macrophages

Multiwalled carbon nanotubes (MWCNTs) have tremendous potential in many areas of research and applications. Modification of MWCNTs with carboxyl group is one of the widely used strategies to increase their water dispersibility. However, the effect of carboxylation of MWCNTs on their interaction with macrophages remains unclear. The current study compared the impact of pristine MWCNTs (p-MWCNTs) and carboxylic acid functionalized MWCNTs (MWCNTs-COOH) on RAW264.7 cells by looking at the cell viability, phagocytic activity, production of cytokines (IL-1β, IL-10, IL-12, and TNF-α), and intracellular reactive oxygen species (ROS). It was revealed that exposure to either p-MWCNTs or MWCNTs-COOH induced decreased viability of murine macrophage RAW 264.7 cells and moderately elevated phagocytic activity of murine peritoneal macrophages, but no statistical significance was found between the two groups. Increased production of ROS in macrophages was induced after exposure to either p-MWCNTs or MWCNTs-COOH. However, no significantly elevated production of cytokines (IL-1β, IL-10, IL-12, and TNF-α) was observed from RAW 264.7 cells after exposure to the CNTs. Those data suggested that modification with carboxyl group did not exert obvious impact on the interaction of MWCNTs with macrophages

Simultaneous monitoring of the drug release and antitumor effect of a novel drug delivery system-MWCNTs/DOX/TC

Monitoring drug release and therapeutic efficacy is crucial for developing drug delivery systems. Our preliminary study demonstrated that, as compared with pristine multiwalled carbon nanotubes (MWCNTs), transactivator of transcription (TAT)-chitosan functionalized MWCNTs (MWCNTs-TC) were a more promising candidate for drug delivery in cancer therapy. In the present study, a MWCNTs/TC-based drug delivery system was developed for an anticancer drug, doxorubicin (DOX). The drug loading and in vitro release profiles, cellular uptake and cytotoxicity were assessed. More importantly, the in vivo drug release and antitumor effect of MWCNTs/DOX/TC were evaluated by noninvasive fluorescence and bioluminescence imaging. It was demonstrated that MWCNTs/DOX/TC can be efficiently taken up by BEL-7402 hepatoma cells. The release of DOX from MWCNTs/DOX/TC was faster under lower pH condition, which was beneficial for intrcellular drug release. The in vivo release process of DOX and antitumor effect in animal model were monitored simultaneously by noninvasive fluorescence and luminescence imaging, which demonstrated the application potential of MWCNTs/DOX/TC for cancer therapy

O2-generating multifunctional polymeric micelles for highly efficient and selective photodynamic-photothermal therapy in melanoma

Photothermal therapy (PTT) and photodynamic therapy (PDT) have received tremendous attention owing to their great potential for tumor treatment. However, two main issues hamper the antitumor performance of PDT: overexpression of glutathione (GSH) in tumors, which consumes PDT-induced reactive oxygen species (ROS), and hypoxia within the tumor microenvironment. The drawbacks of PTT include uneven temperature distribution and the upregulation of the heat-shock proteins in tumors, both of which result in ineffective treatment. To address these issues, a MnO2 doped nano-delivery system (HTIM-PMs) was synthesized by one-step self-assembly of disulfide bond bridged copolymers for indocyanine green (ICG) and MnO2 loading. The surface of polymeric micelles was layered with hyaluronan (HA) and transactivator (TAT) peptides to improve active targeting and increase cell penetration. After internalization, HTIM-PMs showed responsiveness to the tumor microenvironment (acid pH, high glutathione, high H2O2). Breaking the disulfide bond reduced the intratumoral GSH level and simultaneously released the MnO2 and ICG. The released MnO2 further reduced the GSH level and promoted O2 generation, thus enhancing the PDT effect. The PTT-mediated hyperthermia accelerated blood flow, which is beneficial for O2 distribution, and promotes ROS diffusion. These PTT-mediated adjuvant effects further overcame the limitations of PDT and the robust PDT effect in turn compensated for the deficiency of PTT. This promising platform exhibited a significant improvement in the PTT-PDT cancer treatment strategy compared to previously reported nanostructures

Bubble-Generating Polymersomes Loaded with Both Indocyanine Green and Doxorubicin for Effective Chemotherapy Combined with Photothermal Therapy

The combination of chemotherapy and photothermal therapy (PTT) via stimuli-responsive nanovesicles has great potential in tumor treatment. In the present study, bubble-generating polymersomes, which can generate bubbles in response to low pH or hyperthermia, were fabricated to simultaneously encapsulate chemotherapeutic drug and photosensitizing agent for the synergistic chemo-photothermal tumor therapy. Photosensitizer indocyanine green (ICG) was encapsulated into the bilayer of polymersomes formed by amphiphilic triblock copolymer PCL8000-PEG8000-PCL8000 through thin film re-hydration method, while chemotherapeutic doxorubicin (DOX) was loaded into the hydrophilic lumen using a transmembrane ammonium bicarbonate gradient loading procedure. Under acidic condition or laser irradiation, the ammonium bicarbonate (NH4HCO3) encapsulated in the bubble-generating DOX-ICG-co-delivery polymersomes (BG-DIPS) would decompose to produce CO2 bubbles, resulting in destruction of vesicle structure and rapid drug release. In vitro drug release study confirmed that acidic environment and NIR laser irradiation could accelerate DOX release from the BG-DIPS. Cellular uptake study indicated that laser-induced hyperthermia highly enhanced endocytosis of BG-DIPS into 4T1-Luc cancer cells. In vitro cytotoxicity study demonstrated that BG-DIPS exhibited much higher cytotoxicity than free drugs under laser irradiation. In vivo biodistribution study indicated that BG-DIPS could accumulate in the tumor region, prolong drug retention, and increase photothermal conversion efficiency. Furthermore, in vivo antitumor study showed that BG-DIPS with laser irradiation efficiently inhibited 4T1-Luc tumor growth with reduced systemic toxicity. Hence, the formulated bubble-generating polymersomes system was a superior multifunctional nanocarrier for stimuli-response controlled drug delivery and combination chemo-photothermal tumor therapy. Statement of Significance: The combination of chemotherapy and photothermal therapy via stimuli-responsive nanovesicles has great potential in tumor treatment. Herein, bubble-generating polymersomes, which can generate bubbles in response to low pH or hyperthermia, were fabricated to simultaneously encapsulate chemotherapeutic drug (DOX) and photosensitizing agent (ICG) for the synergistic chemo-photothermal tumor therapy. The results in vitro and in vivo demonstrated that bubble-generating DOX-ICG-co-delivery polymersomes (BG-DIPS) would accelerate DOX release from the BG-DIPS and accumulate in the tumor region, prolong drug retention, and increase photothermal conversion efficiency. BG-DIPS with laser irradiation could efficiently inhibited 4T1-Luc tumor growth with reduced systemic toxicity. Hence, the formulated bubble-generating polymersomes system was a superior multifunctional nanocarrier for stimuli-response controlled drug delivery and combination chemo-photothermal tumor therapy