Dynamic Protein Corona of Gold Nanoparticles with an Evolving Morphology.

Much has been learned about the protein coronae and their biological implications within the context of nanomedicine and nanotoxicology. However, no data is available about the protein coronae associated with nanoparticles undergoing spontaneous surface-energy minimization, a common phenomenon during the synthesis and shelf life of nanomaterials. Accordingly, here we employed gold nanoparticles (AuNPs) possessing the three initial states of spiky, midspiky, and spherical shapes and determined their acquisition of human plasma protein coronae with label-free mass spectrometry. The AuNPs collected coronal proteins that were different in abundance, physicochemical parameters, and interactive biological network. The size and structure of the coronal proteins matched the morphology of the AuNPs, where small globular proteins and large fibrillar proteins were enriched on spiky AuNPs, while large proteins were abundant on spherical AuNPs. Furthermore, the AuNPs induced endothelial leakiness to different degrees, which was partially negated by their protein coronae as revealed by confocal fluorescence microscopy, in vitro and ex vivo transwell assays, and signaling pathway assays. This study has filled a knowledge void concerning the dynamic protein corona of nanoparticles possessing an evolving morphology and shed light on their implication for future nanomedicine harnessing the paracellular pathway.

Gold Nanoparticles Induced Endothelial Leakiness Depends on Particle Size and Endothelial Cell Origin.

The endothelium presents a formidable barrier for cancer nanomedicine, as the intravenously introduced nanomedicine needs to leave the blood vessel at the tumor site. Endothelial permeability and retention effect (EPR) is not dependable since it is derived from tumors. Certain nanoparticles with specific characteristics are able to induce micrometer sized gaps between endothelial cells. This effect is called "nanoparticle induced endothelial leakiness" (NanoEL). NanoEL therefore allows the nanotechnology to control access to the tumor even in the absence of any EPR effect. Morever, NanoEL can be applicable to noncancer issues, thereby expanding its usefulness in other subfields of nanomedicine. In this paper, we have shown that Gold (Au) nanoparticles within the range of 10-30 nm are good NanoEL inducing particles. As not all endothelial cells have the same permeability, we found that human mammary endothelial cells and human skin endothelial cells are sensitive to Au induced NanoEL, while human umbilical vein endothelial cells are insensitive, reflective of their innate nature of endothelial permeability. The size window and endothelial cell type sensitivity then helps the nanotechnologists to design future nanoparticles that either exploit NanoEL as a nanotechnology driven strategy to access immature tumors, which do not induce the EPR effect, or avoid NanoEL as a nanotoxic side effect.

Mesoporous Silica Nanoparticles as an Antitumoral-Angiogenesis Strategy.

Tumors depend heavily on angiogenesis for nutrient derivation and their subsequent metastasis. Targeting tumor induced angiogenesis per se can address both tumor growth and progression simultaneously. Here, we show that we could elegantly restrict the endothelial cells angiogenic behavior through digital size control of mesoporous silica nanoparticle (MSN). This antiangiogenesis effect was derived from the particle size dependent uptake and production of intracellular reactive oxygen species (ROS) that directly interfered with p53 tumor suppressor pathway. The resulting signaling cascade wrestled back the tumoral control of endothelial cells' migration, invasion, and proliferation. Overall, a mere control over the size of a highly oxidative reactive surfaced nanoparticle could provide an alternative strategy to curb the tumor induced angiogenesis process in a conventional drug-free manner.

Cytotoxic Effects of Phosphonate-Functionalized Mesoporous Silica Nanoparticles.

In this work, we synthesized pristine mesoporous silica nanoparticles (MSN) and functionalized these with phosphonate groups (MSN-Phos). We report, for the first time, cell death in MCF-7 cells (human breast adenocarcinoma cell line) when exposed to the empty MSN and MSN-Phos nanoparticles. In comparison, the same nanoparticles were found to elicit few deleterious effects on normal human foreskin fibroblast cells (BJ cells). MCF-7 cells were found to exhibit a concentration-dependent uptake, whereas no detectable nanoparticle uptake was observed in the BJ cells, irrespective of treatment dosage. A disruption of the cell cycle in the MCF-7 cells was determined to be the cause of cell death from the nanoparticle exposure, thereby suggesting the role of nondrug loaded MSN and MSN-Phos as effective anticancer drugs.

Tuning Endothelial Permeability with Functionalized Nanodiamonds.

Cancer nanomedicine vehicles are required to cross the vascular barrier to reach the tumor site in order to ensure the successful delivery of their therapeutic load. Here, nanodiamond (ND) variants were shown to induce surface dependent vascular barrier leakiness. The ND-induced leakiness was found to be mediated by the increase in intracellular reactive oxygen species (ROS) and Ca(2+). These then in turn triggered the loss in endothelial cell-endothelial cell connections of the vascular barrier and also triggered their quasi-stable cytoskeletal remodelling. This ND driven increase in leakiness allowed more doxorubicin drug to penetrate through the vascular barrier to reach the cancer cells. This increase in the doxorubicin penetration subsequently led to an increase in the cancer killing effect. Overall, tuning the vascular barrier leakiness through ND surface group functionalization could provide an alternative strategy for the cancer nanomedicine to traverse across the vascular barrier.

Decoupling the Direct and Indirect Biological Effects of ZnO Nanoparticles Using a Communicative Dual Cell-Type Tissue Construct.

While matter at the nanoscale can be manipulated, the knowledge of the interactions between these nanoproducts and the biological systems remained relatively laggard. Current nanobiology study is rooted on in vitro study using conventional 2D cell culture model. A typical study employs monolayer cell culture that simplifies the real context of which to measure any nanomaterial effect; unfortunately, this simplification also demonstrated the limitations of 2D cell culture in predicting the actual biological response of some tissues. In fact, some of the characteristics of tissue such as spatial arrangement of cells and cell-cell interaction, which are simplified in 2D cell culture model, play important roles in how cells respond to a stimulus. To more accurately recapitulate the features and microenvironment of tissue for nanotoxicity assessments, an improved organotypic-like in vitro multicell culture system to mimic the kidney endoepithelial bilayer is introduced. Results showed that important nano-related parameters such as the diffusion, direct and indirect toxic effects of ZnO nanoparticles can be studied by combining this endoepithelial bilayer tissue model and traditional monolayer culture setting.

Mechanistic Investigation of the Biological Effects of SiO2, TiO2, and ZnO Nanoparticles on Intestinal Cells.

Silicon dioxide (SiO2), titanium dioxide (TiO2), and zinc oxide (ZnO) are currently among the most widely used nanoparticles (NPs) in the food industry. This could potentially lead to unintended exposure of the gastrointestinal tract to these NPs. This study aims to investigate the potential side-effects of these food-borne NPs on intestinal cells and to mechanistically understand the observed biological responses. Among the panel of tested NPs, ZnO NPs are the most toxic. Consistently in all three tested intestinal cell models, ZnO NPs invoke the most inflammatory responses from the cells and induce the highest intracellular production of reactive oxygen species (ROS). The elevated ROS levels induce significant damage to the DNA of the cells, resulting in cell-cycle arrest and subsequently cell death. In contrast, both SiO2 and TiO2 NPs elicit minimum biological responses from the intestinal cells. Overall, the study showcases the varying capability of the food-borne NPs to induce a cellular response in the intestinal cells. In addition to physicochemical differences in the NPs, the genetic landscape of the intestinal cell models governs the toxicology profile of these food-borne NPs.

Biomimicry 3D gastrointestinal spheroid platform for the assessment of toxicity and inflammatory effects of zinc oxide nanoparticles.

Our current mechanistic understanding on the effects of engineered nanoparticles (NPs) on cellular physiology is derived mainly from 2D cell culture studies. However, conventional monolayer cell culture may not accurately model the mass transfer gradient that is expected in 3D tissue physiology and thus may lead to artifactual experimental conclusions. Herein, using a micropatterned agarose hydrogel platform, the effects of ZnO NPs (25 nm) on 3D colon cell spheroids of well-defined sizes are examined. The findings show that cell dimensionality plays a critical role in governing the spatiotemporal cellular outcomes like inflammatory response and cytotoxicity in response to ZnO NPs treatment. More importantly, ZnO NPs can induce different modes of cell death in 2D and 3D cell culture systems. Interestingly, the outer few layers of cells in 3D model could only protect the inner core of cells for a limited time and periodically slough off from the spheroids surface. These findings suggest that toxicological conclusions made from 2D cell models might overestimate the toxicity of ZnO NPs. This 3D cell spheroid model can serve as a reproducible platform to better reflect the actual cell response to NPs and to study a more realistic mechanism of nanoparticle-induced toxicity.

Probing the relevance of 3D cancer models in nanomedicine research.

For decades, 2D cell culture format on plastic has been the main workhorse in cancer research. Though many important understandings of cancer cell biology were derived using this platform, it is not a fair representation of the in vivo scenario. In this review, both established and new 3D cell culture systems are discussed with specific references to anti-cancer drug and nanomedicine applications. 3D culture systems exploit more realistic spatial, biochemical and cellular heterogeneity parameters to bridge the experimental gap between in vivo and in vitro settings when studying the performance and efficacy of novel nanomedicine strategies to manage cancer. However, the complexities associated with 3D culture systems also necessitate greater technical expertise in handling and characterizing in order to arrive at meaningful experimental conclusions. Finally, we have also provided future perspectives where cutting edge 3D culture technologies may be combined with under-explored technologies to build better in vitro cancer platforms.

Novel theranostic DNA nanoscaffolds for the simultaneous detection and killing of Escherichia coli and Staphylococcus aureus.

A novel theranostic platform is made by utilizing a self-assembled DNA nanopyramid (DP) as scaffold for incorporation of both detection and therapeutic moieties to combat bacterial infection. Red-emissive glutathione-protected gold nanoclusters (GSH-Au NCs) were used for bacterial detection. Actinomycin D (AMD) that was intercalated on the DP scaffold was used as therapeutic agent. This results in the formation of theranostic DPAu/AMD. Model bacteria Escherichia coli and Staphylococcus aureus were found to be readily taken in the DPAu/AMD and be susceptible to its killing effect. In addition, DPAu/AMD was observed to outperform the free AMD in killing infectious bacteria. The degradation of the DP structure by DNase was found to be responsible for the release of AMD and the effective killing effect of the infectious bacteria. This novel strategy presents a basic platform for future improvements to detect infectious bacteria and treatment.

The reduction of anti-cancer drug antagonism by the spatial protection of drugs with PLA-TPGS nanoparticles.

Docetaxel (DCL) and tamoxifen (TAM) individually are potent drugs in the fight against breast cancer. However when used in combination, they become antagonistic because of differential metabolism of both drugs. We reasoned that by spatially protecting them from metabolizing enzymes with poly (lactide)-D-α-tocopheryl polyethylene glycol succinate (PLA-TPGS) nanoparticles (NPs), we might reduce this drug antagonism. We now report that the drug antagonism between DCL and TAM in MCF7 cell line, was significantly reduced when co-delivered in PLA-TPGS NPs. In addition, this effect of NPs attenuated at high drug concentrations. To investigate the role of NPs in the reduction of drug antagonism, we quantified cellular uptake of the fluorescent model drug coumarin 6 (C6) encapsulated in a rigorous permutation of drugs-nanoparticles ratios. NPs carrying C6 exhibited enhanced cellular uptake over their free C6 counterparts at correspondingly low drug concentrations. This led us to conclude that the reduction of drug antagonism by NPs is correlated to cellular uptake and being in NPs therefore protects both drugs until they are released intracellular for therapeutic anti-cancer effect.

Phage based green chemistry for gold ion reduction and gold retrieval.

The gold mining industry has taken its toll on the environment, triggering the development of more environmentally benign processes to alleviate the waste load release. Here, we demonstrate the use of bacteriophages (phages) for biosorption and bioreduction of gold ions from aqueous solution, which potentially can be applied to remediate gold ions from gold mining waste effluent. Phage has shown a remarkably efficient sorption of gold ions with a maximum gold adsorption capacity of 571 mg gold/g dry weight phage. The product of this phage mediated process is gold nanocrystals with the size of 30-630 nm. Biosorption and bioreduction processes are mediated by the ionic and covalent interaction between gold ions and the reducing groups on the phage protein coat. The strategy offers a simple, ecofriendly and feasible option to recover of gold ions to form readily recoverable products of gold nanoparticles within 24 h.

Effect of zinc oxide nanomaterials-induced oxidative stress on the p53 pathway.

Excessive production of reactive oxygen species (ROS) is a hallmark feature in nanomaterials (NMs) induced cellular toxicity. However, the inter-relationship between NMs induced ROS generation and the cells innate ability to regulate intracellular ROS level in effecting a particular cellular outcome is currently underexplored. Here, using a BJ fibroblast p53 knockdown system, we showed that p53 may be implicated in playing a dual regulatory role to determine cell survivability in response to oxidative stress induced by ZnO NMs. At low level of ZnO NMs induced ROS, p53 triggers expression of antioxidant genes such as SOD2, GPX1, SESN1, SESN2 and ALDH4A1 to restore oxidative homeostasis while at high concentration of ZnO NMs, the elevated level of intracellular ROS activated the apoptotic pathway through p53. The implication of our finding that p53 can function as an important regulator in determining ZnO induced cytotoxicity is highlighted by the differential action of ZnO on p53 deficient and proficient colorectal cell lines. p53 deficient cells cancer cells such as DLD-1 and SW480 are more susceptible to ZnO induced cell death compared to p53 proficient cells such as colon epithelial cells NCM460 and HCT116 cells in a ROS dependent manner. Collectively, our findings showcased a role p53 plays in the context of nanotoxicity and highlights the need to consider the interplay of physicochemical properties of NMs and cell biology.

MicroRNA-34c inversely couples the biological functions of the runt-related transcription factor RUNX2 and the tumor suppressor p53 in osteosarcoma.

Osteosarcoma (OS) is a primary bone tumor that is most prevalent during adolescence. RUNX2, which stimulates differentiation and suppresses proliferation of osteoblasts, is deregulated in OS. Here, we define pathological roles of RUNX2 in the etiology of OS and mechanisms by which RUNX2 expression is stimulated. RUNX2 is often highly expressed in human OS biopsies and cell lines. Small interference RNA-mediated depletion of RUNX2 inhibits growth of U2OS OS cells. RUNX2 levels are inversely linked to loss of p53 (which predisposes to OS) in distinct OS cell lines and osteoblasts. RUNX2 protein levels decrease upon stabilization of p53 with the MDM2 inhibitor Nutlin-3. Elevated RUNX2 protein expression is post-transcriptionally regulated and directly linked to diminished expression of several validated RUNX2 targeting microRNAs in human OS cells compared with mesenchymal progenitor cells. The p53-dependent miR-34c is the most significantly down-regulated RUNX2 targeting microRNAs in OS. Exogenous supplementation of miR-34c markedly decreases RUNX2 protein levels, whereas 3'-UTR reporter assays establish RUNX2 as a direct target of miR-34c in OS cells. Importantly, Nutlin-3-mediated stabilization of p53 increases expression of miR-34c and decreases RUNX2. Thus, a novel p53-miR-34c-RUNX2 network controls cell growth of osseous cells and is compromised in OS.

Intramuscular nerve damage in lacerated skeletal muscles may direct the inflammatory cytokine response during recovery.

The expression of inflammatory cytokines and growth factors in surgically repaired lacerated muscles over a 12-week recovery phase was investigated. We hypothesized that these expression levels are influenced by both neural and muscular damage within lacerated muscles. Microarrays were confirmed with reverse transcription-polymerase chain reaction assays and histology of biopsies at the lesion of three simulated lacerated muscle models in 130 adult rats. The lacerated medial gastrocnemius with the main intramuscular nerve branch either cut (DN), crushed but leaving an intact nerve sheath (RN); or preserved intact (PN) were compared. At 4 weeks, DN had a higher number of interleukins up-regulated. DN and RN also had a set of Bmp genes significantly expressed between 2 and 8 weeks (P ≤ 0.05). By 12 weeks, DN had a poorer and slower myogenic recovery and greater fibrosis formation correlating with an up-regulation of the Tgf-ß gene family. DN also showed poorer re-innervation with higher mRNA expression levels of nerve growth factor (Ngf) and brain-derived neurotrophin growth factor (Bdnf) over RN and PN. This study demonstrates that the inflammatory response over 12 weeks in lacerated muscles may be directed by the type of intramuscular nerve damage, which can influence the recovery at the lesion site. Inflammatory-related genes associated to the type of intramuscular nerve damage include Gas-6, Artemin, Fgf10, Gdf8, Cntf, Lif, and Igf-2. qPCR also found up-regulation of Bdnf (1-week), neurotrophin-3 (2w), Lif (4w), and Ngf (4w, 8w) mRNA expressions in DN, making them possible candidates for therapeutic treatment to arrest the poor recovery in muscle lacerations (250).

The role of the tumor suppressor p53 pathway in the cellular DNA damage response to zinc oxide nanoparticles.

In this paper, we explored how ZnO nanoparticles cross-interact with a critical tumor suppressive pathway centered around p53, which is one of the most important known tumor suppressors that protects cells from developing cancer phenotypes through its control over major pathways like apoptosis, senescence and cell cycle progression. We showed that the p53 pathway was activated in BJ cells (skin fibroblasts) upon ZnO nanoparticles treatment with a concomitant decrease in cell numbers. This suggests that cellular responses like apoptosis in the presence of ZnO nanoparticles require p53 as the molecular master switch towards programmed cell death. This also suggests that in cells without robust p53, protective response can be tipped towards carcinogenesis when stimulated by DNA damage inducing agents like ZnO nanoparticles. We observed this precarious tendency in the same BJ cells with p53 knocked down using endogeneous expressing shRNA. These p53 knocked down BJ cells became more resistant to ZnO nanoparticles induced cell death and increased cell progression. Collectively, our results suggest that cellular response towards specific nanoparticle induced cell toxicity and carcinogenesis is not only dependent on specific nanoparticle properties but also (perhaps more importantly) the endogenous genetic, transcriptomic and proteomic landscape of the target cells.

Cancer-related ectopic expression of the bone-related transcription factor RUNX2 in non-osseous metastatic tumor cells is linked to cell proliferation and motility.

INTRODUCTION: Metastatic breast cancer cells frequently and ectopically express the transcription factor RUNX2, which normally attenuates proliferation and promotes maturation of osteoblasts. RUNX2 expression is inversely regulated with respect to cell growth in osteoblasts and deregulated in osteosarcoma cells. METHODS: Here, we addressed whether the functional relationship between cell growth and RUNX2 gene expression is maintained in breast cancer cells. We also investigated whether the aberrant expression of RUNX2 is linked to phenotypic parameters that could provide a selective advantage to cells during breast cancer progression. RESULTS: We find that, similar to its regulation in osteoblasts, RUNX2 expression in MDA-MB-231 breast adenocarcinoma cells is enhanced upon growth factor deprivation, as well as upon deactivation of the mitogen-dependent MEK-Erk pathway or EGFR signaling. Reduction of RUNX2 levels by RNAi has only marginal effects on cell growth and expression of proliferation markers in MDA-MB-231 breast cancer cells. Thus, RUNX2 is not a critical regulator of cell proliferation in this cell type. However, siRNA depletion of RUNX2 in MDA-MB-231 cells reduces cell motility, while forced exogenous expression of RUNX2 in MCF7 cells increases cell motility. CONCLUSIONS: Our results support the emerging concept that the osteogenic transcription factor RUNX2 functions as a metastasis-related oncoprotein in non-osseous cancer cells.

Sphingosine-1-phosphate mediates proliferation maintaining the multipotency of human adult bone marrow and adipose tissue-derived stem cells.

High renewal and maintenance of multipotency of human adult stem cells (hSCs), are a prerequisite for experimental analysis as well as for potential clinical usages. The most widely used strategy for hSC culture and proliferation is using serum. However, serum is poorly defined and has a considerable degree of inter-batch variation, which makes it difficult for large-scale mesenchymal stem cells (MSCs) expansion in homogeneous culture conditions. Moreover, it is often observed that cells grown in serum-containing media spontaneously differentiate into unknown and/or undesired phenotypes. Another way of maintaining hSC development is using cytokines and/or tissue-specific growth factors; this is a very expensive approach and can lead to early unwanted differentiation. In order to circumvent these issues, we investigated the role of sphingosine-1-phosphate (S1P), in the growth and multipotency maintenance of human bone marrow and adipose tissue-derived MSCs. We show that S1P induces growth, and in combination with reduced serum, or with the growth factors FGF and platelet-derived growth factor-AB, S1P has an enhancing effect on growth. We also show that the MSCs cultured in S1P-supplemented media are able to maintain their differentiation potential for at least as long as that for cells grown in the usual serum-containing media. This is shown by the ability of cells grown in S1P-containing media to be able to undergo osteogenic as well as adipogenic differentiation. This is of interest, since S1P is a relatively inexpensive natural product, which can be obtained in homogeneous high-purity batches: this will minimize costs and potentially reduce the unwanted side effects observed with serum. Taken together, S1P is able to induce proliferation while maintaining the multipotency of different human stem cells, suggesting a potential for S1P in developing serum-free or serum-reduced defined medium for adult stem cell cultures.