Sequentially Site‐Specific Delivery of Apoptotic Protein and Tumor‐Suppressor Gene for Combination Cancer Therapy

Nanocarrier‐mediated codelivery of multiple anticancer drugs is a potential strategy for enhanced efficacy of combination cancer treatment by unifying differential pharmacokinetic properties and maintaining an optimal ratio of drug cargoes. However, a programmable codelivery system is highly desired to deliver different therapeutics to their specific sites of action to pursue maximized combinational effect. Herein a liposome‐based nanoassembly (p53/C‐rNC/L‐FA) is developed for intracellular site‐specific delivery of an apoptotic protein cytochrome c (CytoC) and a plasmid DNA encoding tumor‐suppressing p53 protein (p53 DNA). p53/C‐rNC/L‐FA consists of an acid‐activated fusogenic liposomal membrane shell modified with folic acid (L‐FA) and a DNA/protein complex core assembled by the p53 DNA, protamine and CytoC‐encapsulated redox‐responsive nanocapsule (C‐rNC). Intratumoral and intraendosomal acidities promote membrane fusion between liposome and biomembrane, resulting in release of the encapsulated p53/C‐rNC complex into the cytoplasm. The cytoplasmic reduction causes degradation of C‐rNC with release of CytoC that induces tumor cell apoptosis. The p53 DNA is transported into the nucleus by the aid of the cationic protamine and thus generates expression of the p53 protein that enhances apoptosis combined with CytoC. p53/C‐rNC/L‐FA is demonstrated to significantly induce tumor cell apoptosis and inhibit tumor growth in the orthotopic breast tumor mouse model.     

Rationally Designed DNA‐Origami Nanomaterials for Drug Delivery In Vivo

The recent decades have seen a surge of new nanomaterials designed for efficient drug delivery. DNA nanotechnology has been developed to construct sophisticated 3D nanostructures and artificial molecular devices that can be operated at the nanoscale, giving rise to a variety of programmable functions and fascinating applications. In particular, DNA‐origami nanostructures feature rationally designed geometries and precise spatial addressability, as well as marked biocompatibility, thus providing a promising candidate for drug delivery. Here, the recent successful efforts to employ self‐assembled DNA‐origami nanostructures as drug‐delivery vehicles are summarized. The remaining challenges and open opportunities are also discussed.     

In Vivo Studies of Nanostructure‐Based Photosensitizers for Photodynamic Cancer Therapy

Animal models, particularly rodents, are major translational models for evaluating novel anticancer therapeutics. In this review, different types of nanostructure‐based photosensitizers that have advanced into the in vivo evaluation stage for the photodynamic therapy (PDT) of cancer are described. This article focuses on the in vivo efficacies of the nanostructures as delivery agents and as energy transducers for photosensitizers in animal models. These materials are useful in overcoming solubility issues, lack of tumor specificity, and access to tumors deep in healthy tissue. At the end of this article, the opportunities made possible by these multiplexed nanostructure‐based systems are summarized, as well as the considerable challenges associated with obtaining regulatory approval for such materials. The following questions are also addressed: (1) Is there a pressing demand for more nanoparticle materials? (2) What is the prognosis for regulatory approval of nanoparticles to be used in the clinic?     

Targeted Liposome‐Loaded Microbubbles for Cell‐Specific Ultrasound‐Triggered Drug Delivery

One of the main problems in cancer treatment is disease relapse through metastatic colonization, which is caused by circulating tumor cells (CTCs). This work reports on liposome‐loaded microbubbles targeted to N‐cadherin, a cell–cell adhesion molecule expressed by CTCs. It is shown that such microbubbles can indeed bind to N‐cadherin at the surface of HMB2 cells. Interestingly, in a mixture of cells with and without N‐cadherin expression, binding of the liposome‐loaded microbubbles mainly occurs to the N‐cadherin‐expressing cells. Importantly, applying ultrasound results in the intracellular delivery of a model drug (loaded in the liposomes) in the N‐cadherin‐expressing cells only. As described in this paper, such liposome‐loaded microbubbles may find application as theranostics and in devices aimed for the specific killing of CTCs in blood.     

Cancer‐Cell‐Specific Induction of Apoptosis Using Mesoporous Silica Nanoparticles as Drug‐Delivery Vectors

Targeted delivery of the chemotherapeutic agent methotrexate (MTX) to cancer cells using poly(ethyleneimine)‐functionalized mesoporous silica particles as drug‐delivery vectors is reported. Due to its high affinity for folate receptors, the expression of which is elevated in cancer cells, MTX serves as both a targeting ligand and a cytotoxic agent. Enhanced cancer‐cell apoptosis (programmed cell death) relative to free MTX is thus observed at particle concentrations where nonspecific MTX‐induced apoptosis is not observed in the nontargeted healthy cell line, while corresponding amounts of free drug affect both cell lines equally. The particles remain compartmentalized in endo‐/lysosomes during the time of observation (up to 72 h), while the drug is released from the particle only upon cell entry, thereby inducing selective apoptosis in the target cells. As MTX is mainly attached to the particle surface, an additional advantage is that the presented carrier design allows for adsorption (loading) of additional drugs into the pore network for therapies based on a combination of drugs.     

Targeted Delivery of siRNA‐Generating DNA Nanocassettes Using Multifunctional Nanoparticles

Molecular therapy using a small interfering RNA (siRNA) has shown promise in the development of novel therapeutics. Various formulations have been used for in vivo delivery of siRNAs. However, the stability of short double‐stranded RNA molecules in the blood and efficiency of siRNA delivery into target organs or tissues following systemic administration have been the major issues that limit applications of siRNA in human patients. In this study, multifunctional siRNA delivery nanoparticles are developed that combine imaging capability of nanoparticles with urokinase plasminogen activator receptor‐targeted delivery of siRNA expressing DNA nanocassettes. This theranostic nanoparticle platform consists of a nanoparticle conjugated with targeting ligands and double‐stranded DNA nanocassettes containing a U6 promoter and a shRNA gene for in vivo siRNA expression. Targeted delivery and gene silencing efficiency of firefly luciferase siRNA nanogenerators are demonstrated in tumor cells and in animal tumor models. Delivery of survivin siRNA expressing nanocassettes into tumor cells induces apoptotic cell death and sensitizes cells to chemotherapy drugs. The ability of expression of siRNAs from multiple nanocassettes conjugated to a single nanoparticle following receptor‐mediated internalization should enhance the therapeutic effect of the siRNA‐mediated cancer therapy.     

Somatostatin Receptor‐Mediated Tumor‐Targeting Nanocarriers Based on Octreotide‐PEG Conjugated Nanographene Oxide for Combined Chemo and Photothermal Therapy

Nano‐sized in vivo active targeting drug delivery systems have been developed to a high anti‐tumor efficacy strategy against certain cancer‐cells‐specific. Graphene based nanocarriers with unique physical and chemical properties have shown significant potentials in this aspect. Here, octreotide (OCT), an efficient biotarget molecule, is conjugated to PEGylated nanographene oxide (NGO) drug carriers for the first time. The obtained NGO‐PEG‐OCT complex shows low toxicity and excellent stability in vivo and is able to achieve somatostatin receptor‐mediated tumor‐specific targeting delivery. Owing to the high loading efficiency and accurate targeting delivery of anti‐cancer drug doxorubicin (DOX), our DOX loaded NGO‐PEG‐OCT complex offers a remarkably improved cancer‐cell‐specific cellular uptake, chemo‐cytotoxicity, and decreased systemic toxicity compared to free DOX or NGO‐PEG. More importantly, due to its strong near‐infrared absorption, the NGO‐PEG‐OCT complex further enhances efficient photothermal ablation of tumors, delivering combined chemo and photothermal therapeutic effect against cancer cells.     

Ultrasound‐Propelled Nanocups for Drug Delivery

Ultrasound‐induced bubble activity (cavitation) has been recently shown to actively transport and improve the distribution of therapeutic agents in tumors. However, existing cavitation‐promoting agents are micron‐sized and cannot sustain cavitation activity over prolonged time periods because they are rapidly destroyed upon ultrasound exposure. A novel ultrasound‐responsive single‐cavity polymeric nanoparticle (nanocup) capable of trapping and stabilizing gas against dissolution in the bloodstream is reported. Upon ultrasound exposure at frequencies and intensities achievable with existing diagnostic and therapeutic systems, nanocups initiate and sustain readily detectable cavitation activity for at least four times longer than existing microbubble constructs in an in vivo tumor model. As a proof‐of‐concept of their ability to enhance the delivery of unmodified therapeutics, intravenously injected nanocups are also found to improve the distribution of a freely circulating IgG mouse antibody when the tumor is exposed to ultrasound. Quantification of the delivery distance and concentration of both the nanocups and coadministered model therapeutic in an in vitro flow phantom shows that the ultrasound‐propelled nanocups travel further than the model therapeutic, which is itself delivered to hundreds of microns from the vessel wall. Thus nanocups offer considerable potential for enhanced drug delivery and treatment monitoring in oncological and other biomedical applications.