Yiye Li

Unraveling stress-induced toxicity properties of graphene oxide and the underlying mechanism.

Graphene oxide shows stress-induced toxicity properties in vivo under different pathophysiological conditions. A dual-path chemical mechanism, involving the overproduction of hydroxyl radicals and the formation of oxidizing cytochrome c intermediates, is responsible for the toxicity properties.

Chirality of Glutathione Surface Coating Affects the Cytotoxicity of Quantum Dots

Quantum dots (QDs) have been extensively investigated as fluorescent probes and are emerging as a new class of agents for biomedical imaging and diagnosis because of their broad absorption profiles, tunable emission wavelengths, and high photooxidation stability. QDs consist of an inorganic core surrounded by an organic shell. Normally, different types of biomolecules, such as amino acids, DNA, or peptides, are used for the organic shell to facilitate water solubility and biocompatibility of the QDs. However, because the core may contain toxic heavy metals (e.g., Cd, Hg, Pb, and Zn), the potential cytotoxicity of QDs has been a major impediment to their widespread application. It has therefore become critical to fully understand the interactions between QDs and living cells in order to develop nontoxic and biocompatible QDs for clinical use. Early studies have suggested that the release of core components, the generation of reactive oxygen species (ROS), and nonspecific binding to cellular membranes and intracellular proteins are the major mechanisms of the observed cytotoxic effects of QDs. Despite a significant surge in the number of investigations into the cytotoxicity of QDs, there is currently only limited knowledge about the cytological and physiological mediators of these effects. Interestingly, recent data have suggested that the induction of autophagy by certain sizes of QDs could play an important role in their toxic actions. Autophagy is a metabolic process involved in protein and organelle degradation and plays key roles in maintaining cellular homeostasis and contributing to cellular defense. It has been recognized as a third pathway of cell death, after apoptosis and necrosis, and is responsive to various physicopathological stimuli. Recent work has shown that small QDs (< 10 nm) rather than those with larger sizes (40–50 nm) induce autophagy in cultured cells. This size-dependent induction of autophagy has also been reported for other nanoparticles (NPs). However, all the above studies focused on the effects of type and size of the NPs, while other factors that may induce autophagy remain unexplored. Although many studies have demonstrated that surface modification of QDs with biomolecules endows them with various biological functionalities, the impact on living organisms of the chirality of the surface biomolecules has been largely neglected. Chirality is an important phenomenon in living systems and nearly all biological polymers must be homochiral to function. For example, all amino acids in proteins are “left-handed”, whereas all sugars in DNA and RNA are “right-handed”. Different chiral properties of biomolecules may determine their ability to interact with other biomolecules and thereby modulate a range of downstream processes. More recently, several attempts to develop chiral QDs with optical activities using different chiral stabilizers have been reported. Herein, the effects of QDs capped with different chiral forms of the tripeptide glutathione (GSH) on cytotoxicity and induction of autophagy were examined. Two different sizes of cadmium telluride (CdTe) QDs coated with either l-GSH (lGSH-QDs) or d-GSH (d-GSH-QDs) were found to show dose-dependent cytotoxicity and to significantly increase the levels of autophagic vacuoles. The activation of autophagy was chirality-dependent, with l-GSH-QDs being more effective than d-GSH-QDs. The ability of QDs to induce cell death was correlated with their ability to induce autophagy. This chirality-associated regulation of cellular metabolism and cytotoxicity highlights the important role of the conformation of the stabilizers, and has important implications for the design of novel QDs with enhanced optical properties and reduced or no toxicity. In this study, negatively charged water-soluble CdTe QDs were synthesized according to the Rogach–Weller method and coated with different chiral forms of GSH as stabilizers (Figure 1a). To clearly understand the chirality effect, two series of QDs were prepared. Group 1 comprised small-sized [*] Y. Li, Prof. Y. Zhao, Prof. G. Nie CAS Key Laboratory for Biological Effects of Nanomaterials & Nanosafety, National Center for Nanoscience and Technology 11 Beiyijie, Zhongguancun, Beijing 100190 (China) E-mail: niegj@nanoctr.cn

Localized Electric Field of Plasmonic Nanoplatform Enhanced Photodynamic Tumor Therapy

Near-infrared plasmonic nanoparticles demonstrate great potential in disease theranostic applications. Herein a nanoplatform, composed of mesoporous silica-coated gold nanorods (AuNRs), is tailor-designed to optimize the photodynamic therapy (PDT) for tumor based on the plasmonic effect. The surface plasmon resonance of AuNRs was fine-tuned to overlap with the exciton absorption of indocyanine green (ICG), a near-infrared photodynamic dye with poor photostability and low quantum yield. Such overlap greatly increases the singlet oxygen yield of incorporated ICG by maximizing the local field enhancement, and protecting the ICG molecules against photodegradation by virtue of the high absorption cross section of the AuNRs. The silica shell strongly increased ICG payload with the additional benefit of enhancing ICG photostability by facilitating the formation of ICG aggregates. As-fabricated AuNR@SiO2-ICG nanoplatform enables trimodal imaging, near-infrared fluorescence from ICG, and two-photon luminescence/photoacoustic tomography from the AuNRs. The integrated strategy significantly improved photodynamic destruction of breast tumor cells and inhibited the growth of orthotopic breast tumors in mice, with mild laser irradiation, through a synergistic effect of PDT and photothermal therapy. Our study highlights the effect of local field enhancement in PDT and demonstrates the importance of systematic design of nanoplatform to greatly enhancing the antitumor efficacy.

Lysosomal Proteolysis Is the Primary Degradation Pathway for Cytosolic Ferritin and Cytosolic Ferritin Degradation Is Necessary for Iron Exit

Cytosolic ferritins sequester and store iron, consequently protecting cells against iron-mediated free radical damage. However, the mechanisms of iron exit from the ferritin cage and reutilization are largely unknown. In a previous study, we found that mitochondrial ferritin (MtFt) expression led to a decrease in cytosolic ferritin. Here we showed that treatment with inhibitors of lysosomal proteases largely blocked cytosolic ferritin loss in both MtFt-expressing and wild-type cells. Moreover, cytosolic ferritin in cells treated with inhibitors of lysosomal proteases was found to store more iron than did cytosolic ferritins in untreated cells. The prevention of cytosolic ferritin degradation in MtFt-expressing cells significantly blocked iron mobilization from the protein cage induced by MtFt expression. These studies also showed that blockage of cytosolic ferritin loss by leupeptin resulted in decreased cytosolic ferritin synthesis and prolonged cytosolic ferritin stability, potentially resulting in diminished iron availability. Lastly, we found that proteasomes were responsible for cytosolic ferritin degradation in cells pretreated with ferric ammonium citrate. Thus, the current studies suggest that cytosolic ferritin degradation precedes the release of iron in MtFt-expressing cells; that MtFt-induced cytosolic ferritin decrease is partially preventable by lysosomal protease inhibitors; and that both lysosomal and proteasomal pathways may be involved in cytosolic ferritin degradation.

Triple-punch strategy for triple negative breast cancer therapy with minimized drug dosage and improved antitumor efficacy.

Effective therapeutics against triple negative breast cancer (TNBC), which has no standard-of-care therapy, needs to be developed urgently. Here we demonstrated a strategy of integrating indocyanine green (ICG), paclitaxel (PTX), and survivin siRNA into one thermosensitive poly(2-(2-methoxyethoxy)ethyl methacrylate-co-oligo(ethylene glycol) methacrylate)-co-2-(dimethylamino)ethyl methacrylate-b-poly(D,L-lactide-co-glycolide) (P (MEO2MA-co-OEGMA-co-DMAEMA)-b-PLGA) nanoparticle (NP-IPS) for triple-punch strategy against TNBC. The NP-IPS significantly enhanced the stability of ICG. Controlled release of the PTX in tumor regions was triggered by the hyperthermia produced by laser irradiated ICG. The NP-IPS exhibited remarkable antitumor efficacy (almost complete ablation of the tumor xenografts) due to the combinational effects of chemotherapy, photothermal therapy, and gene therapy with low drug dose (ICG, 0.32 μmol/kg; PTX, 0.54 μmol/kg; siRNA, 1.5 mg/kg) and minimal side effects. Taken together, our current study demonstrates a nanoplatform for triple-therapy, which reveals a promising strategy for TNBC treatment.

Exosomes as Extrapulmonary Signaling Conveyors for Nanoparticle‐Induced Systemic Immune Activation

Evaluation of systemic biosafety of nanomaterials urgently demands a comprehensive understanding of the mechanisms of the undesirable interference and systemic signaling that arises between man-made nanomaterials and biological systems. It is shown that exosomes may act as signal conveyors for nanoparticle-induced systemic immune responses. Exosomes are extracellularly secreted membrane vesicles which act as Trojan horses for the dissemination and intercellular communication of natural nanosized particles (like viruses). Upon exposure to magnetic iron oxide nanoparticles (MIONs), it is possible to dose-dependently generate a significant number of exosomes in the alveolar region of BALB/c mice. These exosomes are quickly eliminated from alveoli into systemic circulation and largely transfer their signals to the immune system. Maturation of dendritic cells and activation of splenic T cells are significantly induced by these exosomes. Furthermore, exosome-induced T-cell activation is more efficient toward sensitized T cells and in ovalbumin (OVA)-sensitized mice than in the unsensitized counterparts. Activation of systemic T cells reveals a T helper 1 polarization and aggravated inflammation, which poses potential hazards to the deterioration of allergic diseases in OVA-sensitized mice. The studies suggest that exosomes may act as conveyors for extrapulmonary signal transduction in nanoparticle-induced immune systemic responses, which are the key in vivo processes of manufactured nanoparticles executing either biomedical functions or toxic responses.

Nanoparticle‐Induced Exosomes Target Antigen‐Presenting Cells to Initiate Th1‐Type Immune Activation

The mechanisms associated with the induction of systemic immune responses by nanoparticles are not fully understood, but their elucidation is critical to address safety issues associated with the broader medical application of nanotechnology. In this study, a key role of nanoparticle-induced exosomes (extracellularly secreted membrane vesicles) as signaling mediators in the induction of T helper cell type 1 (Th1) immune activation is demonstrated. In vivo exposure to magnetic iron oxide nanoparticles (MIONs) results in significant exosome generation in the alveolar region of Balb/c mice. These act as a source of nanoparticle-induced, membrane-bound antigen/signaling cargo, which transfer their components to antigen-presenting cells (APCs) in the reticuloendothelial system. Through exosome-initiated signals, immature dendritic cells (iDCs) undergo maturation and differentiation to the DC1 subtype, while macrophages go through classical activation and differentiation to the M1 subtype. Simultaneously, iDCs and macrophages release various Th1 cytokines (including interleukin-12 and tumor necrosis factor α) driving T-cell activation and differentiation. Activated APCs (especially DC1 and M1 subtypes) consequently prime T-cell differentiation towards a Th1 subtype, thereby resulting in an orchestrated Th1-type immune response. Th1-polarized immune activation is associated with delayed-type hypersensitivity, which might underlie the long-term inflammatory effects frequently associated with nanoparticle exposure. These studies suggest that nanoparticle-induced exosomes provoke the immune activation and inflammatory responses that can accompany nanoparticle exposure.

An MMP-2 Responsive Liposome Integrating Antifibrosis and Chemotherapeutic Drugs for Enhanced Drug Perfusion and Efficacy in Pancreatic Cancer.

Fibrotic stroma, a critical character of pancreatic tumor microenvironment, provides a critical barrier against the penetration and efficacy of various antitumor drugs. Therefore, new strategies are urgently needed to alleviate the fibrotic mass and increase the drug perfusion within pancreatic cancer tissue. In our current work, we developed a β-cyclodextrin (β-CD) modified matrix metalloproteinase-2 (MMP-2) responsive liposome, integrating antifibrosis and chemotherapeutic drugs for regulation of pancreatic stellate cells (PSCs), a key source of the fibrosis, and targeted delivery of cytotoxic drugs for pancreatic cancer therapy. These liposomes disassembed into two functional parts upon MMP-2 cleavage at the tumor site. One part was constituted by the β-CDs and the antifibrosis drug pirfenidone, which was kept in the stroma and inhibited the expression of collagen I and TGF-β in PSCs, down-regulating the fibrosis and decreasing the stromal barrier. The other segment, the RGD peptide-modified-liposome loading the chemotherapeutic drug gemcitabine, targeted and killed pancreatic tumor cells. This integrated nanomedicine, showing an increased drug perfusion without any overt side effects, may provide a potential strategy for improvement of the pancreatic cancer therapy.

Precision combination therapy for triple negative breast cancer via biomimetic polydopamine polymer core-shell nanostructures

Photothermal-based combination therapy using functional nanomaterials shows great promise in eradication of aggressive tumors and improvement of drug sensitivity. The therapeutic efficacy and adverse effects of drug combinations depend on the precise control of timely tumor-localized drug release. Here a polymer-dopamine nanocomposite is designed for combination therapy, thermo-responsive drug release and prevention of uncontrolled drug leakage. The thermo-sensitive co-polymer poly (2-(2-methoxyethoxy) ethyl methacrylate-co-oligo (ethylene glycol) methacrylate)-co-2-(dimethylamino) ethyl methacrylate-b-poly (D, l-lactide-co-glycolide) is constructed into core-shell structured nanoparticles for co-encapsulation of two cytotoxic drugs and absorption of small interfering RNAs against survivin. The drug-loaded nanoparticles are surface-coated with polydopamine which confers the nanoformulation with photothermal activity and protects drugs from burst release. Under tumor-localized laser irradiation, polydopamine generates sufficient heat, resulting in nanoparticle collapse and instant drug release within the tumor. The combination strategy of photothermal, chemo-, and gene therapy leads to triple-negative breast cancer regression, with a decrease in the chemotherapeutic drug dosage to about 1/20 of conventional dose. This study establishes a powerful nanoplatform for precisely controlled combination therapy, with dramatic improvement of therapeutic efficacy and negligible side effects.

Integration of photothermal therapy and synergistic chemotherapy by a porphyrin self-assembled micelle confers chemosensitivity in triple-negative breast cancer.

Triple-negative breast cancer is a malignant cancer type with a high risk of early recurrence and distant metastasis. Unlike other breast cancers, triple-negative breast cancer is lack of targetable receptors and, therefore, patients largely receive systemic chemotherapy. However, inevitable adverse effects and acquired drug resistance severely constrain the therapeutic outcome. Here we tailor-designed a porphyrin-based micelle that was self-assembled from a hybrid amphiphilic polymer comprising polyethylene glycol, poly (d, l-lactide-co-glycolide) and porphyrin. The bilayer micelles can be simultaneously loaded with two chemotherapeutic drugs with synergistic cytotoxicity and distinct physiochemical properties, forming a uniform and spherical nanostructure. The drug-loaded micelles showed a tendency to accumulate in the tumor and can be internalized by tumor cells for drug release in acidic organelles. Under near-infrared laser irradiation, high density of self-quenched porphyrins in the hydrophobic layer absorbed light efficiently and converted into an excited state, leading to the release of sufficient heat for photothermal therapy. The integration of localized photothermal effect and synergistic chemotherapy conferred great chemosensitivity to cancer cells and achieved tumor regression using about 1/10 of traditional drug dosage. As a result, chemotherapy-associated adverse effects were successfully avoided. Our present study established a novel porphyrin-based nanoplatform with photothermal activity and expanded drug loading capacity, providing new opportunities for challenging conventional chemotherapy and fighting against stubborn triple-negative breast cancer.