Magnetic Resonance Imaging and RNA Interference of Tumor with a Reducible Poly(urethane-amine) Nanocomposite System

Gadolinium-based small-molecule contrast agents are commonly utilized in clinics. However, these agents have a short retention time in vivo and possess a certain level of cytotoxicity. The reducible polymer poly­(urethane-amine) can increase the relaxation rate and blood circulation time of small-molecule gadolinium chelates. Moreover, the polymer can be used as a gene carrier to bind small interfering RNAs (siRNAs). We synthesized an active targeting integrated diagnosis and treatment nanocomposite system with reducible poly­(urethane-amine) as the carrier. This system incorporated functional units such as magnetic resonance imaging contrast agents Gd-diethylenetriamine pentaacetate and siRNA-vascular endothelial growth factor (siRNA-VEGF) and folic acid modified onto the surface of the polymer directed it to actively target tumor cells, thus improving the imaging effect of magnetic resonance imaging. Meanwhile, siRNA-VEGF carried by the system could reduce the expression of VEGF in tumor cells and inhibit tumor growth. The system showed good biocompatibility and was an integrated system of tumor diagnosis and treatment

Near-infrared in vivo fluorescence imaging of heterotopically transplanted pancreatic adenocarcinoma in nude mice.

<p>(a) Western blot shows the overexpression of CTSE in PANC-1-CTSE cells, which was much higher than that in PANC-1 and HEK293 cells (negative). (b) Four groups of nude mice (G1-G4) were all subcutaneously injected with PANC-1-CTSE and PANC-1 cell suspensions in the right thigh root (◊) and right axilla (☆), respectively. One group of nude mice (G1) was injected with probe a (4 mg/kg), while the others were injected with different doses of the probe A as follows: G2: 20 mg/kg; G3: 4 mg/kg; G4: 2 mg/kg. Abnormally high signals were observed in the right thigh root of the mice injected with probe A (G2-M4), with similar values observed in the G2 and G3. These were both significantly higher than that observed in G4. The signals were absent in the right thigh root of the mice injected with probe a (G1) and in the right axilla of all mice (G1–G4).</p

Genome-Wide Assessment in Escherichia coli Reveals Time-Dependent Nanotoxicity Paradigms

The use of engineered nanomaterials (eNM) in consumer and industrial products is increasing exponentially. Our ability to rapidly assess their potential effects on human and environmental health is limited by our understanding of nanomediated toxicity. High-throughput screening (HTS) enables the investigation of nanomediated toxicity on a genome-wide level, thus uncovering their novel mechanisms and paradigms. Herein, we investigate the toxicity of zinc-containing nanomaterials (Zn-eNMs) using a time-resolved HTS methodology in an arrayed Escherichia coli genome-wide knockout (KO) library. The library was screened against nanoscale zerovalent zinc (nZn), nanoscale zinc oxide (nZnO), and zinc chloride (ZnCl₂) salt as reference. Through sequential screening over 24 h, our method identified 173 sensitive clones from diverse biological pathways, which fell into two general groups: early and late responders. The overlap between these groups was small. Our results suggest that bacterial toxicity mechanisms change from pathways related to general metabolic function, transport, signaling, and metal ion homeostasis to membrane synthesis pathways over time. While all zinc sources shared pathways relating to membrane damage and metal ion homeostasis, Zn-eNMs and ZnCl₂ displayed differences in their sensitivity profiles. For example, ZnCl₂ and nZnO elicited unique responses in pathways related to two-component signaling and monosaccharide biosynthesis, respectively. Single isolated measurements, such as MIC or IC₅₀, are inadequate, and time-resolved approaches utilizing genome-wide assays are therefore needed to capture this crucial dimension and illuminate the dynamic interplay at the nano-bio interface

Assessment of two researchers on the CLE images, including the average sensitivity, specificity, positive predictive value, negative predictive value and accuracy.

<p>Abbreviations: CLE, confocal laser endomicroscopy; PPV, positive predictive value; NPV, negative predictive value.</p><p>Assessment of two researchers on the CLE images, including the average sensitivity, specificity, positive predictive value, negative predictive value and accuracy.</p

The probe chemical structure and action mechanism.

<p>(a) Chemical structures of optical probes. (b) Action mechanism of CTSE optical probe.</p

<i>In vitro</i> imaging and quantitative determination of PDAC and PanINs in DMBA-induced rats injected with probe A.

<p>(a) <i>In vitro</i> imaging of tissue from tumors (R1 = PanIN-I; R2 = PanIN-II; R3 = PanIN-III; R4 = PDAC), kidney, liver, spleen, muscle and normal pancreas of four rats. (b) Quantitative analysis of near-infrared fluorescence imaging of tumor tissue and normal pancreatic tissue from four rats. (c-g) Routine pathological HE staining of (c) normal pancreas; (d) PanIN-I (R1); (e) PanIN-II (R2); (f) PanIN-III (R3); and (g) PDAC (R4). M = muscle; T = tumor; L = liver; S = spleen; K = kidney; P = pancreas. Scale bar, 100 µm.</p

Genome-Wide Assessment in Escherichia coli Reveals Time-Dependent Nanotoxicity Paradigms

The use of engineered nanomaterials (eNM) in consumer and industrial products is increasing exponentially. Our ability to rapidly assess their potential effects on human and environmental health is limited by our understanding of nanomediated toxicity. High-throughput screening (HTS) enables the investigation of nanomediated toxicity on a genome-wide level, thus uncovering their novel mechanisms and paradigms. Herein, we investigate the toxicity of zinc-containing nanomaterials (Zn-eNMs) using a time-resolved HTS methodology in an arrayed Escherichia coli genome-wide knockout (KO) library. The library was screened against nanoscale zerovalent zinc (nZn), nanoscale zinc oxide (nZnO), and zinc chloride (ZnCl2) salt as reference. Through sequential screening over 24 h, our method identified 173 sensitive clones from diverse biological pathways, which fell into two general groups: early and late responders. The overlap between these groups was small. Our results suggest that bacterial toxicity mechanisms change from pathways related to general metabolic function, transport, signaling, and metal ion homeostasis to membrane synthesis pathways over time. While all zinc sources shared pathways relating to membrane damage and metal ion homeostasis, Zn-eNMs and ZnCl2 displayed differences in their sensitivity profiles. For example, ZnCl2 and nZnO elicited unique responses in pathways related to two-component signaling and monosaccharide biosynthesis, respectively. Single isolated measurements, such as MIC or IC50, are inadequate, and time-resolved approaches utilizing genome-wide assays are therefore needed to capture this crucial dimension and illuminate the dynamic interplay at the nano-bio interface

Process of <i>in situ</i> DMBA-induced pancreatic adenocarcinoma in rats.

<p>Abbreviations: DMBA, 7,12-dimethyl-1,2-benzanthracene; PanIN, pancreatic intraepithelial neoplasia; PDAC, pancreatic ductal adenocarcinoma.</p><p>Process of <i>in situ</i> DMBA-induced pancreatic adenocarcinoma in rats.</p

Comparison between pathological and CLE results.

<p>The results for CLE-1 and CLE-2 were the assessments of two researchers, respectively. Mistaken assessments are shown in brackets; ^* false negative; ^*^* false positive.</p><p>Abbreviations: CLE, confocal laser endomicroscopy; PanIN, pancreatic intraepithelial neoplasia; PDAC, pancreatic ductal adenocarcinoma.</p><p>Comparison between pathological and CLE results.</p

Monitoring Pancreatic Carcinogenesis by the Molecular Imaging of Cathepsin E <i>In Vivo</i> Using Confocal Laser Endomicroscopy

<div><p>The monitoring of pancreatic ductal adenocarcinoma (PDAC) in high-risk populations is essential. Cathepsin E (CTSE) is specifically and highly expressed in PDAC and pancreatic intraepithelial neoplasias (PanINs), and its expression gradually increases along with disease progression. In this study, we first established an <i>in situ</i> 7,12-dimethyl-1,2-benzanthracene (DMBA)-induced rat model for PanINs and PDAC and then confirmed that tumorigenesis properties in this model were consistent with those of human PDAC in that CTSE expression gradually increased with tumor development using histology and immunohistochemistry. Then, using <i>in vivo</i> imaging of heterotopically implanted tumors generated from CTSE- overexpressing cells (PANC-1-CTSE) in nude mice and <i>in vitro</i> imaging of PanINs and PDAC in DMBA-induced rats, the specificity of the synthesized CTSE-activatable probe was verified. Quantitative determination identified that the fluorescence signal ratio of pancreatic tumor to normal pancreas gradually increased in association with progressive pathological grades, with the exception of no significant difference between PanIN-II and PanIN-III grades. Finally, we monitored pancreatic carcinogenesis <i>in vivo</i> using confocal laser endomicroscopy (CLE) in combination with the CTSE-activatable probe. A prospective double-blind control study was performed to evaluate the accuracy of this method in diagnosing PDAC and PanINs of all grades (>82.7%). This allowed us to establish effective diagnostic criteria for CLE in PDAC and PanINs to facilitate the monitoring of PDAC in high-risk populations.</p></div