Project description:Early detection of biofilms is crucial for limiting infection-based damage. Imaging these biofilms is challenging: conventional imaging agents are unable to penetrate the dense matrix of the biofilm, and many imaging agents are susceptible to false positive/negative responses due to phenotypical mutations of the constituent microbes. We report the creation of pH-responsive nanoparticles with embedded transition metal catalysts (nanozymes) that effectively target the acidic microenvironment of biofilms. These pH-switchable nanozymes generate imaging agents through bioorthogonal activation of profluorophores inside biofilms. The specificity of these nanozymes for imaging biofilms in complex biosystems was demonstrated using coculture experiments.
Project description:Bioorthogonal transformation of prodrugs and profluorophores using transition metal catalysts (TMCs) offers a promising strategy for therapeutic and imaging applications. Here, we report the surface engineering of nanoparticles to specifically localize gold nanoparticles (AuNPs) with encapsulated TMCs (nanozymes) to either the inside or outside of cells. The ability to control nanozyme localization and hence activity was demonstrated by the activation of pro-fluorophores and prodrugs intra- and extracellularly, establishing the potential of engineered nanozyme platforms for both diagnostic and therapeutic purposes.
Project description:Bioorthogonal activation of prodrugs provides a strategy for on-demand on-site production of therapeutics. Intracellular activation provides a strategy to localize therapeutics, potentially minimizing off-target effects. To this end, nanoparticles embedded with transition metal catalysts (nanozymes) were engineered to generate either "hard" irreversible or "soft" reversible coronas in serum. The hard corona induced nanozyme aggregation, effectively inhibiting nanozyme activity, whereas only modest loss of activity was observed with the nonaggregating soft corona nanozymes. In both cases complete activity was restored by treatment with proteases. Intracellular activity mirrored this reactivation: endogenous proteases in the endosome provided intracellular activation of both nanozymes. The role of intracellular proteases in nanozyme reactivation was verified through treatment of the cells with protease inhibitors, which prevented reactivation. This study demonstrates the use of intracellular proteolysis as a strategy for localization of therapeutic generation to within cells.
Project description:We demonstrate here the protection of biorthogonal transition metal catalysts (TMCs) in biological environments by using self-assembled monolayers on gold nanoparticles (AuNPs). Encapsulation of TMCs in this hydrophobic environment preserves catalytic activity in presence of pH conditions and complex biological media that would deactivate free catalyst. Significantly, the protection affords by these nanozymes extends to isolation of the catalyst active site, as demonstrated by the independence of rate over a wide pH range, in strong contrast to the behavior of the free catalyst.
Project description:Current cancer targeting relying on specific biological interaction between cell surface antigen and respective antibody or its analogue has proven to be effective in the treatment of different cancers; however, this strategy has its own limitations, such as heterogeneity of cancer cells and immunogenicity of the biomacromolecule binding ligands. Bioorthogonal chemical conjugation has emerged as an attractive alternative to biological interaction for in vivo cancer targeting. Here, we report an in vivo cancer targeting strategy mediated by bioorthogonal oxime ligation. Oxyamine group, the artificial target, is introduced onto 4T1 murine breast cancer cells through liposome delivery and fusion. Poly(ethylene glycol) -polylactide (PEG-PLA) nanoparticle (NP) is surface-functionalized with aldehyde groups as targeting ligands. The improved in vivo cancer targeting of PEG-PLA NPs is achieved through specific and efficient chemical reaction between the oxyamine and aldehyde groups.
Project description:BackgroundExtracellular vesicles (EVs) derived from tumor-associated macrophages are implicated in the progression and metastasis of gastric cancer (GC) via the transfer of molecular cargo RNAs. We aimed to decipher the impact of microRNA (miR)-15b-5p transferred by M2 macrophage-derived EVs in the metastasis of GC.MethodsExpression of miR-15b-5p was assessed and the downstream genes of miR-15b-5p were analyzed. GC cells were subjected to gain- and loss-of function experiments for miR-15b-5p, BRMS1, and DAPK1. M2 macrophage-derived EVs were extracted, identified, and subjected to co-culture with GC cells and their biological behaviors were analyzed. A lung metastasis model in nude mice was established to determine the effects of miR-15b-5p on tumor metastasis in vivo.ResultsmiR-15b-5p was upregulated in GC tissues and cells as well as in M2 macrophage-derived EVs. miR-15b-5p promoted the proliferative and invasive potentials, and epithelial-mesenchymal transition (EMT) of GC cells. M2 macrophage-derived EVs could transfer miR-15b-5p into GC cells where it targeted BRMS1 by binding to its 3'UTR. BRMS1 was enriched in the DAPK1 promoter region and promoted its transcription, thereby arresting the proliferative and invasive potentials, and EMT of GC cells. In vivo experiments demonstrated that orthotopic implantation of miR-15b-5p overexpressing GC cells in nude mice displayed led to enhanced tumor metastasis by inhibiting the BRMS1/DAPK1 axis.ConclusionsOverall, miR-15b-5p delivered by M2 macrophage-derived EVs constitutes a molecular mechanism implicated in the metastasis of GC, and may thus be considered as a novel therapeutic target for its treatment.
Project description:Parkinson's disease is a common progressive neurodegenerative disorder associated with profound nigrostriatal degeneration. Regrettably, no therapies are currently available that can attenuate disease progression. To this end, we developed a cell-based nanoformulation delivery system using the antioxidant enzyme catalase to attenuate neuroinflammatory processes linked to neuronal death.Nanoformulated catalase was obtained by coupling catalase to a synthetic polyelectrolyte of opposite charge, leading to the formation of a polyion complex micelle. The nanozyme was loaded into bone marrow macrophages and its transport to the substantia nigra pars compacta was evaluated in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-intoxicated mice.Therapeutic efficacy of bone marrow macrophages loaded with nanozyme was confirmed by twofold reductions in microgliosis as measured by CD11b expression. A twofold increase in tyrosine hydroxylase-expressing dopaminergic neurons was detected in nanozyme-treated compared with untreated MPTP-intoxicated mice. Neuronal survival was confirmed by magnetic resonance spectroscopic imaging. Bone marrow macrophage-loaded catalase showed sustained release of the enzyme in plasma.These data support the importance of macrophage-based nanozyme carriage for Parkinson's disease therapies.
Project description:Hypovascularization in tumors such as liver metastases originating from breast and other organs correlates with poor chemotherapeutic response and higher mortality. Poor prognosis is linked to impaired transport of both low- and high-molecular weight drugs into the lesions and to high washout rate. Nanoparticle albumin-bound-paclitaxel (nAb-PTX) has demonstrated benefits in clinical trials when compared to paclitaxel and docetaxel. However, its therapeutic efficacy for breast cancer liver metastasis is disappointing. As macrophages are the most abundant cells in the liver tumor microenvironment, we design a multistage system employing macrophages to deliver drugs into hypovascularized metastatic lesions, and perform in vitro, in vivo, and in silico evaluation. The system encapsulates nAb-PTX into nanoporous biocompatible and biodegradable multistage vectors (MSV), thus promoting nAb-PTX retention in macrophages. We develop a 3D in vitro model to simulate clinically observed hypo-perfused tumor lesions surrounded by macrophages. This model enables evaluation of nAb-PTX and MSV-nab PTX efficacy as a function of transport barriers. Addition of macrophages to this system significantly increases MSV-nAb-PTX efficacy, revealing the role of macrophages in drug transport. In the in vivo model, a significant increase in macrophage number, as compared to unaffected liver, is observed in mice, confirming the in vitro findings. Further, a mathematical model linking drug release and retention from macrophages is implemented to project MSV-nAb-PTX efficacy in a clinical setting. Based on macrophage presence detected via liver tumor imaging and biopsy, the proposed experimental/computational approach could enable prediction of MSV-nab PTX performance to treat metastatic cancer in the liver.
Project description:Methotrexate (MTX) is a folate analogue antimetabolite widely used for the treatment of rheumatoid arthritis and cancer. A number of studies have shown that MTX delivered via nanoparticle carriers is more potent against cancer cells than free MTX, a phenomenon attributed to higher cellular uptake of the particles compared to the saturable folate receptor pathway. In this study, a cell-based global metabolic profiling approach was applied to study the effects of MTX in both free drug form and when encapsulated in -poly(lactide-co-glycolide) (PLGA) nanoparticles on a cancer cell line, A549, and also on human-like THP-1 macrophages. The results showed that MTX loaded nanoparticles had less impact on the macrophages than free MTX, and the effects on macrophages were limited to changes in nucleotide metabolism and suppression of the tricarboxylic acid cycle, whereas free MTX also led to a drop in glycolytic activity and impairment in redox homeostasis. In contrast, MTX loaded nanoparticles showed a greater impact on A549 cells than the free drug, which was in accord with studies in other cell lines in prior literature with MTX-carrier nanoparticles.
Project description:Liposomes are attractive vehicles for the controlled release of drugs and cytotoxins and have a long-standing history in medical research and clinical practice. In addition to established therapeutic indications, liposomes have several favorable properties for molecular imaging, including high stability and the ability to be labeled with radioisotopes, as well as paramagnetic and fluorescent contrast agents. However, long circulation times and difficulties in creating targeted liposomes have proven challenges for imaging. In this study, we have addressed these limitations using a recently developed strategy for bioorthogonal conjugation, the reaction between tetrazines and trans-cyclooctenes. By coating radiolabeled liposomes with trans-cyclooctene and pretargeting with a tetrazine coupled to a targeted peptide, we were able to selectively enhance the retention of liposomes and bind them to tumor tissue in live animals. The rapid reaction between tetrazines and trans-cyclooctenes allowed imaging to be performed with the short-lived PET tracer (18)F, yielding signal-to-background activity ratios of 7:1. The covalent, bioorthogonally driven tumor-targeting of liposomes by in vivo click chemistry is promising and should be explored for more selective and rapid delivery of radiodiagnostics and radiotherapeutics, two classes of drugs which particularly benefit from fast clearance, low nonspecific binding, and the associated reduced toxicity to kidneys and bone marrow.