Publications by authors named "Zachary R Stephen"

24 Publications

  • Page 1 of 1

In vivo Serum Enabled Production of Ultrafine Nanotherapeutics for Cancer Treatment.

Mater Today (Kidlington) 2020 Sep 4;38:10-23. Epub 2020 May 4.

Department of Materials Science and Engineering, University of Washington, Seattle, Washington, 98195, USA.

Systemic delivery of hydrophobic anti-cancer drugs with nanocarriers, particularly for drug-resistant and metastatic cancer, remain a challenge because of the difficulty to achieve high drug loading, while maintaining a small hydrodynamic size and colloid stability in blood to ensure delivery of an efficacious amount of drug to tumor cells. Here we introduce a new approach to address this challenge. In this approach, nanofibers of larger size with good drug loading capacity are first constructed by a self-assembly process, and upon intravascular injection and interacting with serum proteins in vivo, these nanofibers break down into ultra-fine nanoparticles of smaller size that inherit the drug loading property from their parent nanofibers. We demonstrate the efficacy of this approach with a clinically available anti-cancer drug: paclitaxel (PTX). In vitro, the PTX-loaded nanoparticles enter cancer cells and induce cellular apoptosis. In vivo, they demonstrate prolonged circulation in blood, induce no systemic toxicity, and show high potency in inhibiting tumor growth and metastasis in both mouse models of aggressive, drug-resistant breast cancer and melanoma. This study points to a new strategy toward improved anti-cancer drug delivery and therapy.
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http://dx.doi.org/10.1016/j.mattod.2020.03.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7944405PMC
September 2020

siRNA nanoparticle suppresses drug-resistant gene and prolongs survival in an orthotopic glioblastoma xenograft mouse model.

Adv Funct Mater 2021 Feb 6;31(6). Epub 2020 Nov 6.

Department of Materials Science and Engineering, University of Washington, Seattle, WA 98195, United States; Department of Neurological Surgery, University of Washington, Seattle, WA 98195, United States.

Temozolomide (TMZ) is the standard of care chemotherapy drug for treating glioblastomas (GBMs), the most aggressive cancer that affects people of all ages. However, its therapeutic efficacy is limited by the drug resistance mediated by a DNA repair protein, O-methylguanine-DNA methyltransferase (MGMT), which eliminates the TMZ-induced DNA lesions. Here we report the development of an iron oxide nanoparticle (NP) system for targeted delivery of siRNAs to suppress the TMZ-resistance gene (MGMT). We show that our NP is able to overcome biological barriers, bind specifically to tumor cells, and reduce MGMT expression in tumors of mice bearing orthotopic GBM serially-passaged patient-derived xenografts. The treatment with sequential administration of this NP and TMZ resulted in increased apoptosis of GBM stem-like cells, reduced tumor growth, and significantly-prolonged survival as compared to mice treated with TMZ alone. This study introduces an approach that holds great promise to improve the outcomes of GBM patients.
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http://dx.doi.org/10.1002/adfm.202007166DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7942690PMC
February 2021

Recent Progress in the Synergistic Combination of Nanoparticle-Mediated Hyperthermia and Immunotherapy for Treatment of Cancer.

Adv Healthc Mater 2021 01 25;10(2):e2001415. Epub 2020 Nov 25.

Department of Materials Science and Engineering, Department of Neurological Surgery, University of Washington, Seattle, WA, 98195, USA.

Immunotherapy has demonstrated great clinical success in certain cancers, driven primarily by immune checkpoint blockade and adoptive cell therapies. Immunotherapy can elicit strong, durable responses in some patients, but others do not respond, and to date immunotherapy has demonstrated success in only a limited number of cancers. To address this limitation, combinatorial approaches with chemo- and radiotherapy have been applied in the clinic. Extensive preclinical evidence suggests that hyperthermia therapy (HT) has considerable potential to augment immunotherapy with minimal toxicity. This progress report will provide a brief overview of immunotherapy and HT approaches and highlight recent progress in the application of nanoparticle (NP)-based HT in combination with immunotherapy. NPs allow for tumor-specific targeting of deep tissue tumors while potentially providing more even heating. NP-based HT increases tumor immunogenicity and tumor permeability, which improves immune cell infiltration and creates an environment more responsive to immunotherapy, particularly in solid tumors.
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http://dx.doi.org/10.1002/adhm.202001415DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8034553PMC
January 2021

Cocaine analogue conjugated magnetic nanoparticles for labeling and imaging dopaminergic neurons.

Biomater Sci 2020 Aug 9;8(15):4166-4175. Epub 2020 Jun 9.

Department of Material Sciences and Engineering, University of Washington, Seattle, WA 98195, USA.

Molecular imaging of the dopamine transporter (DAT) with Positron Emission Tomography (PET) or Single Photon Emission Computed Tomography (SPECT) has been widely used in studies of neurological and psychiatric disorders. Nevertheless, there is a great interest in expanding molecular imaging to include magnetic resonance technology, because of the superior spatial resolution this technology may provide. Here we present a magnetic nanoparticle (NP) that specifically targets dopaminergic neurons and allows DAT imaging with magnetic resonance imaging (MRI). The nanoparticle (namely, NP-DN) is composed of an iron oxide core and a polyethylene glycol (PEG) coating to which a DAT specific dopaminergic neurolabeler (DN) is conjugated. NP-DN displayed long-term stability with favorable hydrodynamic size and surface charge suitable for in vivo application. In vitro studies showed NP-DN was non-toxic, displayed specificity towards DAT-expressing neurons, and demonstrated a 3-fold increase in DAT labeling over non-targeted NP. Our study shows NP-DN provides excellent contrast enhancement for MRI and demonstrates great potential for neuroimaging.
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http://dx.doi.org/10.1039/d0bm00546kDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7390663PMC
August 2020

Iron Oxide Nanoparticles as T Contrast Agents for Magnetic Resonance Imaging: Fundamentals, Challenges, Applications, and Prospectives.

Adv Mater 2021 Jun 4;33(23):e1906539. Epub 2020 Jun 4.

Department of Materials Science & Engineering, University of Washington, Seattle, WA, 98195, USA.

Gadolinium-based chelates are a mainstay of contrast agents for magnetic resonance imaging (MRI) in the clinic. However, their toxicity elicits severe side effects and the Food and Drug Administration has issued many warnings about their potential retention in patients' bodies, which causes safety concerns. Iron oxide nanoparticles (IONPs) are a potentially attractive alternative, because of their nontoxic and biodegradable nature. Studies in developing IONPs as T contrast agents have generated promising results, but the complex, interrelated parameters influencing contrast enhancement make the development difficult, and IONPs suitable for T contrast enhancement have yet to make their way to clinical use. Here, the fundamental principles of MRI contrast agents are discussed, and the current status of MRI contrast agents is reviewed with a focus on the advantages and limitations of current T contrast agents and the potential of IONPs to serve as safe and improved alternative to gadolinium-based chelates. The past advances and current challenges in developing IONPs as a T contrast agent from a materials science perspective are presented, and how each of the key material properties and environment variables affects the performance of IONPs is assessed. Finally, some potential approaches to develop high-performance and clinically relevant T contrast agents are discussed.
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http://dx.doi.org/10.1002/adma.201906539DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8022883PMC
June 2021

Catalase-Functionalized Iron Oxide Nanoparticles Reverse Hypoxia-Induced Chemotherapeutic Resistance.

Adv Healthc Mater 2019 10 26;8(20):e1900826. Epub 2019 Sep 26.

Department of Material Sciences and Engineering, University of Washington, Seattle, WA, 98195, USA.

Intratumoral hypoxia is a major contributor to multiple drug resistance (MDR) in cancer, and can lead to poor prognosis of patients receiving chemotherapy. Development of an MDR-inhibitor that mitigates the hypoxic environment is crucial for cancer management and treatment. Reported is a biocompatible and biodegradable catalase-conjugated iron oxide nanoparticle (Cat-IONP) capable of converting reactive oxygen species to molecular oxygen to supply an oxygen source for the hypoxic tumor microenvironment. Cat-IONP demonstrates initial enzymatic activity comparable to free catalase while providing a nearly threefold increase in long-term enzymatic activity. It is demonstrated that Cat-IONP significantly reduces the in vitro expression of hypoxia-inducible factors at the transcription level in a breast cancer cell line. Co-treatment of Cat-IONP and paclitaxel (PTX) significantly increases the drug sensitivity of hypoxic-cultured cells, demonstrating greater than twofold and fivefold reduction in cell viability in comparison to cells treated only with 80 and 120 × 10 m PTX, respectively. These findings demonstrate the ability of Cat-IONP to act as an MDR-inhibitor at different biological levels, suggesting a promising strategy to combat cancer-MDR and to optimize cancer management and treatment outcomes.
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http://dx.doi.org/10.1002/adhm.201900826DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6919328PMC
October 2019

Time-Resolved MRI Assessment of Convection-Enhanced Delivery by Targeted and Nontargeted Nanoparticles in a Human Glioblastoma Mouse Model.

Cancer Res 2019 09 22;79(18):4776-4786. Epub 2019 Jul 22.

Department of Materials Science and Engineering, University of Washington, Seattle, Washington.

Convection-enhanced delivery (CED) provides direct access of infusates to brain tumors; however, clinical translation of this technology has not been realized because of the inability to accurately visualize infusates in real-time and lack of targeting modalities against diffuse cancer cells. In this study, we use time-resolved MRI to reveal the kinetics of CED processes in a glioblastoma (GBM) model using iron oxide nanoparticles (NP) modified with a glioma-targeting ligand, chlorotoxin (CTX). Mice bearing orthotopic human GBM tumors were administered a single dose of targeted CTX-conjugated NP (NPCP-CTX) or nontargeted NP (NPCP) via CED. High-resolution T2-weighted, T2*-weighted, and quantitative T2 MRI were utilized to image NP delivery in real time and determined the volume of distribution (V) of NPs at multiple time points over the first 48 hours post-CED. GBM-specific targeting was evaluated by flow cytometry and intracellular NP localization by histologic assessment. NPCP-CTX produced a V of 121 ± 39 mm at 24 hours, a significant increase compared with NPCP, while exhibiting GBM specificity and localization to cell nuclei. Notably, CED of NPCP-CTX resulted in a sustained expansion of V well after infusion, suggesting a possible active transport mechanism, which was further supported by the presence of NPs in endothelial and red blood cells. In summary, we show that time-resolved MRI is a suitable modality to study CED kinetics, and CTX-mediated CED facilitates extensive distribution of infusate and specific targeting of tumor cells. SIGNIFICANCE: MRI is used to monitor convection-enhanced delivery in real time using a nanoparticle-based contrast agent, and glioma-specific targeting significantly improves the volume of distribution in tumors.
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http://dx.doi.org/10.1158/0008-5472.CAN-18-2998DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6744959PMC
September 2019

Theranostic Nanoparticles for RNA-Based Cancer Treatment.

Acc Chem Res 2019 06 28;52(6):1496-1506. Epub 2019 May 28.

Department of Materials Science and Engineering , University of Washington , Seattle , Washington 98195 , United States.

Certain genetic mutations lead to the development of cancer through unchecked cell growth and division. Cancer is typically treated through surgical resection, radiotherapy, and small-molecule chemotherapy. A relatively recent approach to cancer therapy involves the use of a natural process wherein small RNA molecules regulate gene expression in a pathway known as RNA interference (RNAi). RNA oligomers pair with a network of proteins to form an RNA-induced silencing complex, which inhibits the translation of mRNA into proteins, thereby controlling the expression of gene products. Synthetically produced RNA oligomers may be designed to target and silence specific oncogenes to provide cancer therapy. The primary challenges facing the use of the RNAi pathway for cancer therapy are the safe and efficacious delivery of RNA payloads and their release at pertinent sites within disease-causing cells. Nucleases are abundant in the bloodstream and intracellular environment, and therapeutic RNA sequences often require a suitable carrier to provide protection from degradation prior to reaching their site of action in the body. The use of metal core nanoparticles (NPs) serving as targeted delivery vehicles able to shield and direct RNA payloads to their intended destinations have recently gained favor. Biological barriers present in the body establish a size prerequisite for drug delivery vehicles; to overcome recognition by the body's immune system and to gain access to intracellular environments, drug carriers must be small (< 100 nm). Iron oxide and gold core NPs can be synthesized with a high degree of control to create uniform ultrasmall drug delivery vehicles capable of bypassing key biological barriers. While progress is being made in size control of liposomal and polymer NPs, such advances still lag in comparison to the exquisite tunability and time stability of size engineering achievable with metal core NPs at bulk scales. Further, unlike lipid- and viral-based transfection agents, the biodistribution of metal core NPs can be traced using noninvasive imaging techniques that capitalize on the interaction of electromagnetic radiation and the inorganic atoms at the core of the NPs. Finally, metal core NPs have been shown to match the transfection efficiency of conventional RNA-delivery vehicles while also providing less immunogenicity and minimal side effects through the addition of tumor-targeting ligands on their surface. This Account reviews recent advances in the use of iron oxide and gold NPs for RNAi therapy. An overview of the different types of RNA-based therapies is provided along with a discussion of the advantages and current limitations of the technique. We highlight design considerations for the use of iron oxide and gold NP carriers in RNAi, including a discussion of the importance of size and its role in traversing biological barriers, NP surface modifications required for targeted delivery and RNA payload release, and auxiliary properties supporting imaging functionality for treatment monitoring. Applications of NPs for combination therapies including the pairing of RNAi with chemotherapy, photothermal therapy, immunotherapy, and radiotherapy are explored through examples. Finally, future perspectives are provided with a focus on the current limitations and the potential for clinical translation of iron oxide and gold NPs in RNAi therapy.
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http://dx.doi.org/10.1021/acs.accounts.9b00101DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6701180PMC
June 2019

Biconcave Carbon Nanodisks for Enhanced Drug Accumulation and Chemo-Photothermal Tumor Therapy.

Adv Healthc Mater 2019 04 11;8(8):e1801505. Epub 2019 Mar 11.

Department of Materials Science and Engineering, University of Washington, Seattle, Washington, DC, 98195, USA.

It is considered a significant challenge to construct nanocarriers that have high drug loading capacity and can overcome physiological barriers to deliver efficacious amounts of drugs to solid tumors. Here, the development of a safe, biconcave carbon nanodisk to address this challenge for treating breast cancer is reported. The nanodisk demonstrates fluorescent imaging capability, an exceedingly high loading capacity (947.8 mg g , 94.78 wt%) for doxorubicin (DOX), and pH-responsive drug release. It exhibits a higher uptake rate by tumor cells and greater accumulation in tumors in a mouse model than its carbon nanosphere counterpart. In addition, the nanodisk absorbs and transforms near-infrared (NIR) light to heat, which enables simultaneous NIR-responsive drug release for chemotherapy and generation of thermal energy for tumor cell destruction. Notably, this NIR-activated dual therapy demonstrates a near complete suppression of tumor growth in a mouse model of triple-negative breast cancer when DOX-loaded nanodisks are administered systemically.
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http://dx.doi.org/10.1002/adhm.201801505DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6483846PMC
April 2019

Nanoparticle Biokinetics in Mice and Nonhuman Primates.

ACS Nano 2017 09 18;11(9):9514-9524. Epub 2017 Sep 18.

Clinical Research Division, Fred Hutchinson Cancer Research Center , Seattle, Washington 98109, United States.

Despite the preponderance of iron oxide nanoparticles (NPs) designed for theranostic applications, widespread clinical translation of these NPs lags behind. A better understanding of how NP pharmacokinetics vary between small and large animal models is needed to rapidly customize NPs for optimal performance in humans. Here we use noninvasive magnetic resonance imaging (MRI) to track iron oxide NPs through a large number of organ systems in vivo to investigate NP biokinetics in both mice and nonhuman primates. We demonstrate that pharmacokinetics are similar between mice and macaques in the blood, liver, spleen, and muscle, but differ in the kidneys, brain, and bone marrow. Our study also demonstrates that full-body MRI is practical, rapid, and cost-effective for tracking NPs noninvasively with high spatiotemporal resolution. Our techniques using a nonhuman primate model may provide a platform for testing a range of NP formulations.
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http://dx.doi.org/10.1021/acsnano.7b05377DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6002853PMC
September 2017

Mesoporous carbon nanoshells for high hydrophobic drug loading, multimodal optical imaging, controlled drug release, and synergistic therapy.

Nanoscale 2017 Jan;9(4):1434-1442

Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, United States.

Loading and controlled release of sufficient hydrophobic drugs to tumor cells has been the bottleneck in chemotherapy for decades. Herein we report the development of a fluorescent and mesoporous carbon nanoshell (FMP-CNS) that exhibits a loading capacity for the hydrophobic drug paclitaxel (PTX) as high as ∼80 wt% and releases the drug in a controllable fashion under NIR irradiation (825 nm) at an intensity of 1.5 W cm. The high drug loading is primarily attributed to its mesoporous structure and to the supramolecular π-stacking between FMP-CNSs and PTX molecules. The FMP-CNS also exhibits wavelength-tunable and upconverted fluorescence properties and thus can serve as an optical marker for confocal, two-photon, and near infrared (NIR) fluorescence imaging. Furthermore, our in vitro results indicate that FMP-CNSs demonstrate high therapeutic efficacy through the synergistic effect of combined chemo-photothermal treatment. In vivo studies demonstrate marked suppression of tumor growth in mice bearing rat C6 glioblastoma after administration with a single intratumoral injection of PTX-loaded FMP-CNS.
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http://dx.doi.org/10.1039/c6nr07894jDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5334464PMC
January 2017

pH-Sensitive O6-Benzylguanosine Polymer Modified Magnetic Nanoparticles for Treatment of Glioblastomas.

Bioconjug Chem 2017 01 12;28(1):194-202. Epub 2016 Dec 12.

Department of Materials Science and Engineering, ‡Department of Chemistry, §Department of Biochemistry, ∥Department of Neurological Surgery, and ⊥Department of Radiology, University of Washington , Seattle, Washington 98195, United States.

Nanoparticle-mediated delivery of chemotherapeutics has demonstrated potential in improving anticancer efficacy by increasing serum half-life and providing tissue specificity and controlled drug release to improve biodistribution of hydrophobic chemotherapeutics. However, suboptimal drug loading, particularly for solid core nanoparticles (NPs), remains a challenge that limits their clinical application. In this study we formulated a NP coated with a pH-sensitive polymer of O-methylguanine-DNA methyltransferase (MGMT) inhibitor analog, dialdehyde modified O-benzylguanosine (DABGS) to achieve high drug loading, and polyethylene glycol (PEG) to ameliorate water solubility and maintain NP stability. The base nanovector consists of an iron oxide core (9 nm) coated with hydrazide functionalized PEG (IOPH). DABGS and PEG-dihydrazide were polymerized on the iron oxide nanoparticle surface (IOPH-pBGS) through acid-labile hydrazone bonds utilizing a rapid, freeze-thaw catalysis approach. DABGS polymerization was confirmed by FTIR and quantitated by UV-vis spectroscopy. IOPH-pBGS demonstrated excellent drug loading of 33.4 ± 5.1% by weight while maintaining small size (36.5 ± 1.8 nm). Drug release was monitored at biologically relevant pHs and demonstrated pH dependent release with maximum release at pH 5.5 (intracellular conditions), and minimal release at physiological pH (7.4). IOPH-pBGS significantly suppressed activity of MGMT and potentiated Temozolomide (TMZ) toxicity in vitro, demonstrating potential as a new treatment option for glioblastomas (GBMs).
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http://dx.doi.org/10.1021/acs.bioconjchem.6b00545DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5510587PMC
January 2017

Hexanoyl-Chitosan-PEG Copolymer Coated Iron Oxide Nanoparticles for Hydrophobic Drug Delivery.

ACS Macro Lett 2015 Apr 23;4(4):403-407. Epub 2015 Mar 23.

Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, USA.

Nanoparticle (NP) formulations may be used to improve efficacy of hydrophobic drugs by circumventing solubility issues and providing targeted delivery. In this study, we developed a hexanoyl-chitosan-PEG (CP6C) copolymer coated, paclitaxel (PTX)-loaded, and chlorotoxin (CTX) conjugated iron oxide NP (CTX-PTX-NP) for targeted delivery of PTX to human glioblastoma (GBM) cells. We modified chitosan with polyethylene glycol (PEG) and hexanoyl groups to obtain the amphiphilic CP6C. The resultant copolymer was then coated onto oleic acid-stabilized iron oxide NPs (OA-IONP) hydrophobic interactions. PTX, a model hydrophobic drug, was loaded into the hydrophobic region of IONPs. CTX-PTX-NP showed high drug loading efficiency (>30%), slow drug release in PBS and the CTX-conjugated NP was shown to successfully target GBM cells. Importantly, the NPs showed great therapeutic efficacy when evaluated in GBM cell line U-118 MG. Our results indicate that this nanoparticle platform could be used for loading and targeted delivery of hydrophobic drugs.
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http://dx.doi.org/10.1021/acsmacrolett.5b00091DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4755322PMC
April 2015

Approach to Rapid Synthesis and Functionalization of Iron Oxide Nanoparticles for High Gene Transfection.

ACS Appl Mater Interfaces 2016 Mar 4;8(10):6320-8. Epub 2016 Mar 4.

Department of Materials Science and Engineering, University of Washington , Seattle, Washington 98195, United States.

Surface functionalization of theranostic nanoparticles (NPs) typically relies on lengthy, aqueous postsynthesis labeling chemistries that have limited ability to fine-tune surface properties and can lead to NP heterogeneity. The need for a rapid, simple synthesis approach that can provide great control over the display of functional moieties on NP surfaces has led to increased use of highly selective bioorthoganol chemistries including metal-affinity coordination. Here we report a simple approach for rapid production of a superparamagnetic iron oxide NPs (SPIONs) with tunable functionality and high reproducibility under aqueous conditions. We utilize the high affinity complex formed between catechol and Fe((III)) as a means to dock well-defined catechol modified polymer modules on the surface of SPIONs during sonochemical coprecipitation synthesis. Polymer modules consisted of chitosan and poly(ethylene glycol) (PEG) copolymer (CP) modified with catechol (CCP), and CCP functionalized with cationic polyethylenimine (CCP-PEI) to facilitate binding and delivery of DNA for gene therapy. This rapid synthesis/functionalization approach provided excellent control over the extent of PEI labeling, improved SPION magnetic resonance imaging (MRI) contrast enhancement and produced an efficient transfection agent.
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http://dx.doi.org/10.1021/acsami.5b10883DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4829641PMC
March 2016

Iron-Oxide-Based Nanovector for Tumor Targeted siRNA Delivery in an Orthotopic Hepatocellular Carcinoma Xenograft Mouse Model.

Small 2016 Jan 7;12(4):477-87. Epub 2015 Dec 7.

Department of Materials Science and Engineering, University of Washington, Seattle, WA, 98195, USA.

Hepatocellular carcinoma (HCC) is one of the deadliest cancers worldwide. Small interfering RNA (siRNA) holds promise as a new class of therapeutics for HCC, as it can achieve sequence-specific gene knockdown with low cytotoxicity. However, the main challenge in the clinical application of siRNA lies in the lack of effective delivery approaches that need to be highly specific and thus incur low or no systemic toxicity. Here, a nonviral nanoparticle-based gene carrier is presented that can specifically deliver siRNA to HCC. The nanovector (NP-siRNA-GPC3 Ab) is made of an iron oxide core coated with chitosan-polyethylene glycol (PEG) grafted polyethyleneimine copolymer, which is further functionalized with siRNA and conjugated with a monoclonal antibody (Ab) against human glypican-3 (GPC3) receptor highly expressed in HCC. A rat RH7777 HCC cell line that coexpresses human GPC3 and firefly luciferase (Luc) is established to evaluate the nanovector. The nanoparticle-mediated delivery of siRNA against Luc effectively suppresses Luc expression in vitro without notable cytotoxicity. Significantly, NP-siLuc-GPC3 Ab administered intravenously in an orthotopic model of HCC is able to specifically bound to tumor and induce remarkable inhibition of Luc expression. The findings demonstrate the potential of using this nanovector for targeted delivery of therapeutic siRNA to HCC.
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http://dx.doi.org/10.1002/smll.201501985DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4829640PMC
January 2016

3D Porous Chitosan-Alginate Scaffolds as an In Vitro Model for Evaluating Nanoparticle-Mediated Tumor Targeting and Gene Delivery to Prostate Cancer.

Biomacromolecules 2015 Oct 16;16(10):3362-72. Epub 2015 Sep 16.

Department of Materials Science and Engineering and ‡Department of Neurological Surgery, University of Washington , Seattle, Washington 98195, United States.

Cationic nanoparticles (NPs) for targeted gene delivery are conventionally evaluated using 2D in vitro cultures. However, this does not translate well to corresponding in vivo studies because of the marked difference in NP behavior in the presence of the tumor microenvironment. In this study, we investigated whether prostate cancer (PCa) cells cultured in three-dimensional (3D) chitosan-alginate (CA) porous scaffolds could model cationic NP-mediated gene targeted delivery to tumors in vitro. We assessed in vitro tumor cell proliferation, formation of tumor spheroids, and expression of marker genes that promote tumor malignancy in CA scaffolds. The efficacy of NP-targeted gene delivery was evaluated in PCa cells in 2D cultures, PCa tumor spheroids grown in CA scaffolds, and PCa tumors in a mouse TRAMP-C2 flank tumor model. PCa cells cultured in CA scaffolds grew into tumor spheroids and displayed characteristics of higher malignancy as compared to those in 2D cultures. Significantly, targeted gene delivery was only observed in cells cultured in CA scaffolds, whereas cells cultured on 2D plates showed no difference in gene delivery between targeted and nontarget control NPs. In vivo NP evaluation confirmed targeted gene delivery, indicating that only CA scaffolds correctly modeled NP-mediated targeted delivery in vivo. These findings suggest that CA scaffolds serve as a better in vitro platform than 2D cultures for evaluation of NP-mediated targeted gene delivery to PCa.
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http://dx.doi.org/10.1021/acs.biomac.5b01032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4831622PMC
October 2015

Temozolomide nanoparticles for targeted glioblastoma therapy.

ACS Appl Mater Interfaces 2015 Apr 18;7(12):6674-82. Epub 2015 Mar 18.

‡Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, United States.

Glioblastoma (GBM) is a deadly and debilitating brain tumor with an abysmal prognosis. The standard therapy for GBM is surgery followed by radiation and chemotherapy with Temozolomide (TMZ). Treatment of GBMs remains a challenge, largely because of the fast degradation of TMZ, the inability to deliver an effective dose of TMZ to tumors, and a lack of target specificity that may cause systemic toxicity. Here, we present a simple method for synthesizing a nanoparticle-based carrier that can protect TMZ from rapid degradation in physiological solutions and can specifically deliver them to GBM cells through the mediation of a tumor-targeting peptide chlorotoxin (CTX). Our nanoparticle, namely NP-TMZ-CTX, had a hydrodynamic size of <100 nm, exhibited sustained stability in cell culture media for up to 2 weeks, and could accommodate stable drug loading. TMZ bound to nanoparticles showed a much higher stability at physiological pH, with a half-life 7-fold greater than that of free TMZ. NP-TMZ-CTX was able to target GBM cells and achieved 2-6-fold higher uptake and a 50-90% reduction of IC50 72 h post-treatment as compared to nontargeted NP-TMZ. NP-TMZ-CTX showed great promise in its ability to deliver a large therapeutic dose of TMZ to GBM cells and could serve as a template for targeted delivery of other therapeutics.
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http://dx.doi.org/10.1021/am5092165DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4637162PMC
April 2015

Nanoparticle mediated silencing of DNA repair sensitizes pediatric brain tumor cells to γ-irradiation.

Mol Oncol 2015 Jun 29;9(6):1071-80. Epub 2015 Jan 29.

Department of Neurological Surgery, University of Washington, Seattle, WA 98195, USA; Department of Materials Science and Engineering, University of Washington, Seattle, WA 98195, USA; Department of Radiology, University of Washington, Seattle, WA 98195, USA. Electronic address:

Medulloblastoma (MB) and ependymoma (EP) are the most common pediatric brain tumors, afflicting 3000 children annually. Radiotherapy (RT) is an integral component in the treatment of these tumors; however, the improvement in survival is often accompanied by radiation-induced adverse developmental and psychosocial sequelae. Therefore, there is an urgent need to develop strategies that can increase the sensitivity of brain tumors cells to RT while sparing adjacent healthy brain tissue. Apurinic endonuclease 1 (Ape1), an enzyme in the base excision repair pathway, has been implicated in radiation resistance in cancer. Pharmacological and specificity limitations inherent to small molecule inhibitors of Ape1 have hindered their clinical development. Here we report on a nanoparticle (NP) based siRNA delivery vehicle for knocking down Ape1 expression and sensitizing pediatric brain tumor cells to RT. The NP comprises a superparamagnetic iron oxide core coated with a biocompatible, biodegradable coating of chitosan, polyethylene glycol (PEG), and polyethyleneimine (PEI) that is able to bind and protect siRNA from degradation and to deliver siRNA to the perinuclear region of target cells. NPs loaded with siRNA against Ape1 (NP:siApe1) knocked down Ape1 expression over 75% in MB and EP cells, and reduced Ape1 activity by 80%. This reduction in Ape1 activity correlated with increased DNA damage post-irradiation, which resulted in decreased cell survival in clonogenic assays. The sensitization was specific to therapies generating abasic lesions as evidenced by NP:siRNA not increasing sensitivity to paclitaxel, a microtubule disrupting agent. Our results indicate NP-mediated delivery of siApe1 is a promising strategy for circumventing pediatric brain tumor resistance to RT.
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http://dx.doi.org/10.1016/j.molonc.2015.01.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4439369PMC
June 2015

Redox-responsive magnetic nanoparticle for targeted convection-enhanced delivery of O6-benzylguanine to brain tumors.

ACS Nano 2014 Oct 29;8(10):10383-95. Epub 2014 Sep 29.

Department of Materials Science and Engineering, University of Washington , Seattle, Washington 98195, United States.

Resistance to temozolomide (TMZ) based chemotherapy in glioblastoma multiforme (GBM) has been attributed to the upregulation of the DNA repair protein O(6)-methylguanine-DNA methyltransferase (MGMT). Inhibition of MGMT using O(6)-benzylguanine (BG) has shown promise in these patients, but its clinical use is hindered by poor pharmacokinetics that leads to unacceptable toxicity. To improve BG biodistribution and efficacy, we developed superparamagnetic iron oxide nanoparticles (NP) for targeted convection-enhanced delivery (CED) of BG to GBM. The nanoparticles (NPCP-BG-CTX) consist of a magnetic core coated with a redox-responsive, cross-linked, biocompatible chitosan-PEG copolymer surface coating (NPCP). NPCP was modified through covalent attachment of BG and tumor targeting peptide chlorotoxin (CTX). Controlled, localized BG release was achieved under reductive intracellular conditions and NPCP-BG-CTX demonstrated proper trafficking of BG in human GBM cells in vitro. NPCP-BG-CTX treated cells showed a significant reduction in MGMT activity and the potentiation of TMZ toxicity. In vivo, CED of NPCP-BG-CTX produced an excellent volume of distribution (Vd) within the brain of mice bearing orthotopic human primary GBM xenografts. Significantly, concurrent treatment with NPCP-BG-CTX and TMZ showed a 3-fold increase in median overall survival in comparison to NPCP-CTX/TMZ treated and untreated animals. Furthermore, NPCP-BG-CTX mitigated the myelosuppression observed with free BG in wild-type mice when administered concurrently with TMZ. The combination of favorable physicochemical properties, tumor cell specific BG delivery, controlled BG release, and improved in vivo efficacy demonstrates the great potential of these NPs as a treatment option that could lead to improved clinical outcomes.
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http://dx.doi.org/10.1021/nn503735wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4212796PMC
October 2014

In vivo safety evaluation of polyarginine coated magnetic nanovectors.

Mol Pharm 2013 Nov 21;10(11):4099-106. Epub 2013 Oct 21.

Department of Materials Science and Engineering, University of Washington , Seattle, Washington 98195, United States.

Safety and efficacy are of critical importance to any nanomaterial-based diagnostic and therapy. The innocuity and functionality of a nanomaterial in vivo is largely dependent on the physicochemical properties of the material, particularly its surface coating. Here, we evaluated the influence of polycationic coating on the efficacy, clearance organ uptake, and safety of magnetic nanovectors designed for siRNA delivery. Polyethylene glycol (PEG) coated superparamagnetic iron oxide nanoparticles (NPs) of 12 nm in core diameter were modified with a polycationic coating of either poly-l-arginine (pArg) or polyethylenimine (PEI) and further covalently functionalized with siRNA oligonucleotides. The produced NP-pArg-siRNA and NP-PEI-siRNA nanovectors were similar in hydrodynamic size (21 and 22 nm, respectively) but significantly differed in zeta potentials (+2.1 mV and +29.8 mV, respectively). Fluorescence quantification assays revealed that the NP-pArg-siRNA nanovector was 3-fold more potent than NP-PEI-siRNA in delivering siRNA and 1.8-fold more effective in gene silencing when tested in rat C6 glioblastoma cells. In vivo, both nanovector formulations were similarly taken up by the spleen and liver as determined by histopathological and hemopathological assays. However, PEI coated nanovectors elicited severe hemoincompatibility and damage to the liver and spleen, while pArg coated nanovectors were found to be safe and tolerable. Combined, our findings suggest that polycationic coatings of pArg were more effective and safer than commonly used PEI coatings for preparation of nanovectors. The NP-pArg-siRNA nanovector formulation developed here shows great potential for in vivo based biomedical applications.
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http://dx.doi.org/10.1021/mp4005468DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3946456PMC
November 2013

Targeted cell uptake of a noninternalizing antibody through conjugation to iron oxide nanoparticles in primary central nervous system lymphoma.

World Neurosurg 2013 Jul-Aug;80(1-2):134-41. Epub 2013 Jan 5.

Department of Neurosurgery, The Fourth Affiliated Hospital of China Medical University, Shenyang, Liaoning, People's Republic of China.

Background: At present there is no standard of care for patients with primary central nervous system lymphoma (PCNSL) because of the difficulty in delivering therapeutically effective doses of drugs to the intracellular site of the target PCNSL. Here we report the use of an iron oxide nanoparticle to promote the internalization of a PCNSL targeting antibody by target cells.

Methods: Iron oxide nanoparticles coated with a copolymer of chitosan-grafted polyethylene glycol (NPs) were conjugated with an anti-CD20 single-chain variable fragment-streptavidin fusion protein (FP), and optically activated with Oregon Green 488. The ability of NP-FP to target PCNSL cells was assessed using flow cytometry and the ferrozine assay. Cell internalization of NP-FP was examined by confocal fluorescence microscopy.

Results: The antibody-conjugated NPs had a near-neutral zeta potential and remained stable in biological media for more than 1 week, which may minimizes nonspecific cell uptake. The diameter of the NPs was about 70 nm, which is in an optimal range for maximizing cell uptake. The selective binding of these NPs was demonstrated with binding to PCNSL cells 3- to 4-fold higher than binding to control cells. Z-stack imaging by confocal microscopy revealed the NPs were internalized by PCNSL cells.

Conclusions: The high-degree specific binding and cell uptake of NP-FP in PCNSL suggests this NP formulation can be further developed to improve therapy of PCNSL.
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http://dx.doi.org/10.1016/j.wneu.2013.01.011DOI Listing
November 2013

Fabrication of magnetic nanoparticles with controllable drug loading and release through a simple assembly approach.

J Control Release 2012 Aug 24;162(1):233-41. Epub 2012 Jun 24.

Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, USA.

Nanoparticle-based cancer therapeutics promises to improve drug delivery safety and efficacy. However, fabrication of consistent theranostic nanoparticles with high and controllable drug loading remains a challenge, primarily due to the cumbersome, multi-step synthesis processes conventionally applied. Here, we present a simple and highly controllable method for assembly of theranostic nanoparticles, which may greatly reduce batch-to-batch variation. The major components of this nanoparticle system include a superparamagnetic iron oxide nanoparticle (SPION), a biodegradable and pH-sensitive poly (beta-amino ester) (PBAE) copolymer, a chemotherapeutic agent doxorubicin (DOX). Here the polymer pre-loaded with drug is directly assembled to the surface of SPIONs forming a drug loaded nanoparticle (NP-DOX). NP-DOX demonstrated a high drug loading efficiency of 679 μg DOX per mg iron, sustained stability in cell culture media up to 7 days, and a strong r(2) relaxivity of 146 mM(-1)•s(-1) for magnetic resonance imaging (MRI). The drug release analysis of NP-DOX showed fast DOX release at pH 5.5 and 6.4 (as in endosomal environment) and slow release at pH 7.4 (physiological condition), demonstrating pH-sensitive drug release kinetics. In vitro evaluation of NP-DOX efficacy using drug-resistant C6 glioma cells showed a 300% increase in cellular internalization at 24h post-treatment and 65% reduction of IC50 at 72 h post-treatment when compared to free DOX. These nanoparticles could serve as a foundation for building smart theranostic formulations for sensitive detection through MRI and effective treatment of cancer by controlled drug release.
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http://dx.doi.org/10.1016/j.jconrel.2012.06.028DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3422574PMC
August 2012

Magnetite Nanoparticles for Medical MR Imaging.

Mater Today (Kidlington) 2011 Jul;14(7-8):330-338

Department of Materials Science and Engineering, University of Washington Seattle, WA 98195 USA.

Nanotechnology has given scientists new tools for the development of advanced materials for the detection and diagnosis of disease. Iron oxide nanoparticles (SPIONs) in particular have been extensively investigated as novel magnetic resonance imaging (MRI) contrast agents due to a combination of favorable superparamagnetic properties, biodegradability, and surface properties of easy modification for improved in vivo kinetics and multifunctionality. This review discusses the basics of MR imaging, the origin of SPION's unique magnetic properties, recent developments in MRI acquisition methods for detection of SPIONs, synthesis and post-synthesis processes that improve SPION's imaging characteristics, and an outlook on the translational potential of SPIONs.
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http://dx.doi.org/10.1016/S1369-7021(11)70163-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3290401PMC
July 2011

Targeting of primary breast cancers and metastases in a transgenic mouse model using rationally designed multifunctional SPIONs.

ACS Nano 2012 Mar 22;6(3):2591-601. Epub 2012 Feb 22.

Department of Materials Science & Engineering, University of Washington, Seattle, Washington 98195, USA.

Breast cancer remains one of the most prevalent and lethal malignancies in women. The inability to diagnose small volume metastases early has limited effective treatment of stage 4 breast cancer. Here we report the rational development and use of a multifunctional superparamagnetic iron oxide nanoparticle (SPION) for targeting metastatic breast cancer in a transgenic mouse model and imaging with magnetic resonance (MR). SPIONs coated with a copolymer of chitosan and polyethylene glycol (PEG) were labeled with a fluorescent dye for optical detection and conjugated with a monoclonal antibody against the neu receptor (NP-neu). SPIONs labeled with mouse IgG were used as a nontargeting control (NP-IgG). These SPIONs had desirable physiochemical properties for in vivo applications such as near neutral zeta potential and hydrodynamic size around 40 nm and were highly stable in serum containing medium. Only NP-neu showed high uptake in neu expressing mouse mammary carcinoma (MMC) cells which was reversed by competing free neu antibody, indicating their specificity to the neu antigen. In vivo, NP-neu was able to tag primary breast tumors and significantly, only NP-neu bound to spontaneous liver, lung, and bone marrow metastases in a transgenic mouse model of metastatic breast cancer, highlighting the necessity of targeting for delivery to metastatic disease. The SPIONs provided significant contrast enhancement in MR images of primary breast tumors; thus, they have the potential for MRI detection of micrometastases and provide an excellent platform for further development of an efficient metastatic breast cancer therapy.
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http://dx.doi.org/10.1021/nn205070hDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3397248PMC
March 2012
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