Insulin-Based Regulation of Glucose-functionalized Nanoparticle Uptake in Muscle Cells

Transporter-Mediated Drug Delivery

Transmembrane transport of small organic and inorganic molecules is one of the cornerstones of cellular metabolism. Among transmembrane transporters, solute carrier (SLC) proteins form the largest, albeit very diverse, superfamily with over 400 members. It was recognized early on that xenobiotics can directly interact with SLCs and that this interaction can fundamentally determine their efficacy, including bioavailability and intertissue distribution. Apart from the well-established prodrug strategy, the chemical ligation of transporter substrates to nanoparticles of various chemical compositions has recently been used as a means to enhance their targeting and absorption. In this review, we summarize efforts in drug design exploiting interactions with specific SLC transporters to optimize their therapeutic effects. Furthermore, we describe current and future challenges as well as new directions for the advanced development of therapeutics that target SLC transporters.

Transporter-Targeted Nano-Sized Vehicles for Enhanced and Site-Specific Drug Delivery

Nano-devices are recognized as increasingly attractive to deliver therapeutics to target cells. The specificity of this approach can be improved by modifying the surface of the delivery vehicles such that they are recognized by the target cells. In the past, cell-surface receptors were exploited for this purpose, but plasma membrane transporters also hold similar potential. Selective transporters are often highly expressed in biological barriers (e.g., intestinal barrier, blood-brain barrier, and blood-retinal barrier) in a site-specific manner, and play a key role in the vectorial transfer of nutrients. Similarly, selective transporters are also overexpressed in the plasma membrane of specific cell types under pathological states to meet the biological needs demanded by such conditions. Nano-drug delivery systems could be strategically modified to make them recognizable by these transporters to enhance the transfer of drugs across the biological barriers or to selectively expose specific cell types to therapeutic drugs. Here, we provide a comprehensive review and detailed evaluation of the recent advances in the field of transporter-targeted nano-drug delivery systems. We specifically focus on areas related to intestinal absorption, transfer across blood-brain barrier, tumor-cell selective targeting, ocular drug delivery, identification of the transporters appropriate for this purpose, and details of the rationale for the approach.

C2C12 cell model: its role in understanding of insulin resistance at the molecular level and pharmaceutical development at the preclinical stage

OBJECTIVES

The myoblast cell line, C2C12, has been utilised extensively in vitro as an examination model in understanding metabolic disease progression. Although it is indispensable in both preclinical and pharmaceutical research, a comprehensive review of its use in the investigation of insulin resistance progression and pharmaceutical development is not available.

KEY FINDINGS

C2C12 is a well-documented model, which can facilitate our understanding in glucose metabolism, insulin signalling mechanism, insulin resistance, oxidative stress, reactive oxygen species and glucose transporters at cellular and molecular levels. With the aid of the C2C12 model, recent studies revealed that insulin resistance has close relationship with various metabolic diseases in terms of disease progression, pathogenesis and therapeutic management. A holistic, safe and effective disease management is highly of interest. Therefore, significant efforts have been paid to explore novel drug compounds and natural herbs that can elicit therapeutic effects in the targeted sites at both cellular (e.g. mitochondria, glucose transporter) and molecular level (e.g. genes, signalling pathway).

SUMMARY

The use of C2C12 myoblast cell line is meaningful in pharmaceutical and biomedical research due to their expression of GLUT-4 and other features that are representative to human skeletal muscle cells. With the use of the C2C12 cell model, the impact of drug delivery systems (nanoparticles and quantum dots) on skeletal muscle, as well as the relationship between exercise, pancreatic β-cells and endothelial cells, was discovered.

The synthesis of rare earth metal-doped upconversion nanoparticles coated with d-glucose or 2-deoxy-d-glucose and their evaluation for diagnosis and therapy in cancer

Silica coated NaY_0.8Yb_0.16Tm_0.04F₄ NPs functionalized with d-glucose or 2-deoxy-d-glucose were prepared. Cytotoxicity and uptake studies on MCF-7 cells revealed the potential of formulation in bioimaging, therapy.

TiO2 nanoparticles and BPA are combined to impair the development of offspring zebrafish after parental coexposure

Titanium dioxide (TiO₂) nanoparticles and bisphenol A (BPA) in aquatic environments interact reciprocally to enhance the maternal transfer of pollutants to offspring, thus varying the innate toxicities during early embryonic development. However, it remains unexplored regarding the molecular mechanisms of developmental toxicity in offspring after parental coexposure. In the present study, adult zebrafish were exposed to TiO₂ nanoparticles (100 μg/L), BPA (20 μg/L) or their binary mixture for four months. Then, eggs of F1 generation were collected and reared in clean water until 5 days post-fertilization. In characteristic of larval survival and growth, parental coexposure to TiO₂ particles and BPA caused a severer inhibition of F1 offspring larvae compared with single exposure. Mechanistic investigation by shotgun proteomics found that development of larval offspring from coexposed parents was impaired through a distinct mode of toxicity, that is, specifically altering the activity of phagosome and lysosome. Single exposure of adult zebrafish to TiO₂ mainly affected insulin-responsive compartment; and BPA parental exposure mainly affected carbohydrate metabolism and calcium signaling of larval offspring. Furthermore, considering the tight regulation of sex hormones in the expression of vitellogenin (VTG), addition of nanoparticles during parental exposure led to inconsistencies between VTG induction and endogenous levels of sex hormones (estradiol and testosterone) in F1 offspring fish. This implied that transfer of nanoparticles to offspring larvae may change the availability of hormonal molecules and BPA at target tissues. Overall, current results provided mechanistic clues into the multigenerational developmental toxicity by parental coexposure to TiO₂ particles and BPA.

Transporter-Guided Delivery of Nanoparticles to Improve Drug Permeation across Cellular Barriers and Drug Exposure to Selective Cell Types

Targeted nano-drug delivery systems conjugated with specific ligands to target selective cell-surface receptors or transporters could enhance the efficacy of drug delivery and therapy. Transporters are expressed differentially on the cell-surface of different cell types, and also specific transporters are expressed at higher than normal levels in selective cell types under pathological conditions. They also play a key role in intestinal absorption, delivery via non-oral routes (e.g., pulmonary route and nasal route), and transfer across biological barriers (e.g., blood–brain barrier and blood–retinal barrier. As such, the cell-surface transporters represent ideal targets for nano-drug delivery systems to facilitate drug delivery to selective cell types under normal or pathological conditions and also to avoid off-target adverse side effects of the drugs. There is increasing evidence in recent years supporting the utility of cell-surface transporters in the field of nano-drug delivery to increase oral bioavailability, to improve transfer across the blood–brain barrier, and to enhance delivery of therapeutics in a cell-type selective manner in disease states. Here we provide a comprehensive review of recent advancements in this interesting and important area. We also highlight certain key aspects that need to be taken into account for optimal development of transporter-assisted nano-drug delivery systems.

Cell membrane-derived nanomaterials for biomedical applications

The continued evolution of biomedical nanotechnology has enabled clinicians to better detect, prevent, manage, and treat human disease. In order to further push the limits of nanoparticle performance and functionality, there has recently been a paradigm shift towards biomimetic design strategies. By taking inspiration from nature, the goal is to create next-generation nanoparticle platforms that can more effectively navigate and interact with the incredibly complex biological systems that exist within the body. Of great interest are cellular membranes, which play essential roles in biointerfacing, self-identification, signal transduction, and compartmentalization. In this review, we explore the major ways in which researchers have directly leveraged cell membrane-derived biomaterials for the fabrication of novel nanotherapeutics and nanodiagnostics. Such emerging technologies have the potential to significantly advance the field of nanomedicine, helping to improve upon traditional modalities while also enabling novel applications.

Nanotechnology in Glycomics: Applications in Diagnostics, Therapy, Imaging, and Separation Processes

This review comprehensively covers the most recent achievements (from 2013) in the successful integration of nanomaterials in the field of glycomics. The first part of the paper addresses the beneficial properties of nanomaterials for the construction of biosensors, bioanalytical devices, and protocols for the detection of various analytes, including viruses and whole cells, together with their key characteristics. The second part of the review focuses on the application of nanomaterials integrated with glycans for various biomedical applications, that is, vaccines against viral and bacterial infections and cancer cells, as therapeutic agents, for in vivo imaging and nuclear magnetic resonance imaging, and for selective drug delivery. The final part of the review describes various ways in which glycan enrichment can be effectively done using nanomaterials, molecularly imprinted polymers with polymer thickness controlled at the nanoscale, with a subsequent analysis of glycans by mass spectrometry. A short section describing an active glycoprofiling by microengines (microrockets) is covered as well.

Copper nanoclusters trigger muscle cell apoptosis and atrophy in vitro and in vivo

Copper nanoclusters (CuNCs) are increasingly being used in nanomedicine owing to their utility in cellular imaging and as catalysts. Additionally, nanotoxicology research of CuNCs is gaining attention. We report here the synthesis and characterization of CuNCs and their cytotoxic impact on muscle cells. A simple protein-directed synthesis of stable CuNCs was prepared, using bovine serum albumin as the stabling agent. Physicochemical characterization of the synthesized CuNCs was performed using transmission electron microscopy. To evaluate the in vitro cytotoxicity, C2C12 cells were exposed to increasing doses (from 0.1 to 50 µg ml(-1)) of CuNCs. CuNCs affected the viability of C2C12 cells in a dose-dependent manner, as detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and a lactate dehydrogenase release assay. Further studies indicated that CuNCs induced the formation of reactive oxygen species and decreased the activities of catalase and glutathione. CuNC treatment decreased the mitochondrial membrane potential and induced apoptosis, accompanied by an increase in the protein expression ratio of Bax/Bcl-2 and caspase-3/9 activity in C2C12 cells. CuNCs treatment resulted in atrophy of the C2C12 myotubes, which was characterized by the increased expression of atrophy-related genes, such as atrogin-1 and MuRF1. Finally, CuNCs induce morphological atrophy of primary muscle cells and mouse gastrocnemius muscle. Taken together, these results suggest that exposure to CuNCs may be a risk factor for the skeletal muscle system.

Glycopolymer-based nanoparticles: synthesis and application

This review focuses on the different approaches to synthesizing glycopolymer-based nanoparticles and their various applications.

Facile preparation of cancer-specific polyelectrolyte nanogels from natural and synthetic sugar polymers

Glycosylated polyelectrolyte nanogels prepared from natural and synthetic sugar polymers with excellent colloidal stability, specific bioactivities and imaging ability.

Glycopolymer-coated iron oxide nanoparticles: shape-controlled synthesis and cellular uptake

Serum-stable glyco-nanoparticles with controlled shape were easily obtained and exhibit shape-dependent cell uptake behaviors as well as enhanced activity toward specific lectins.