Functional vesicles formed by anticancer drug assembly

In this Letter, a new type of nitrogen mustard conjugate vesicles is developed to improve the stability and efficiency of anticancer drug. Benzoic acid nitrogen mustard-peptide (AAAK) conjugate was designed and synthesized, which was found to self-assemble into vesicles in water. The formation of the vesicles was confirmed by dynamic light scattering (DLS), transmission electron microscopy (TEM) and circular dichroism (CD). The degradation data revealed that the benzoic acid nitrogen mustard peptide (AAAK) conjugate vesicles are more stable than the parent drug in aqueous solution. Furthermore, MTT assay revealed that the free drug conjugate has similar antitumor activity against MCF-7, Hela, HepG-2 cell lines compared with the parent drug. The benzoic acid nitrogen mustard-peptide conjugate vesicles may have potential in the treatment of cancers.

Efficient drug delivery and induction of apoptosis in colorectal tumors using a death receptor 5-targeted nanomedicine

Death Receptor 5 (DR5) is a pro-apoptotic cell-surface receptor that is a potential therapeutic target in cancer. Despite the potency of DR5-targeting agents in preclinical models, the translation of these effects into the clinic remains disappointing. Herein, we report an alternative approach to exploiting DR5 tumor expression using antibody-targeted, chemotherapy-loaded nanoparticles. We describe the development of an optimized polymer-based nanotherapeutic incorporating both a functionalized polyethylene glycol (PEG) layer and targeting antibodies to limit premature phagocytic clearance whilst enabling targeting of DR5-expressing tumor cells. Using the HCT116 colorectal cancer model, we show that following binding to DR5, the nanoparticles activate caspase 8, enhancing the anti-tumor activity of the camptothecin payload both in vitro and in vivo. Importantly, the combination of nanoparticle-induced DR5 clustering with camptothecin delivery overcomes resistance to DR5-induced apoptosis caused by loss of BAX or overexpression of anti-apoptotic FLIP. This novel approach may improve the clinical activity of DR5-targeted therapeutics while increasing tumor-specific delivery of systemically toxic chemotherapeutics.

The role of philosophy of science in Responsible Research and Innovation (RRI): the case of nanomedicine

Research on ethical, legal and social aspects (ELSA) of life sciences and new technologies has mainly been focused on impacts and consequences, while the emerging framework of Responsible Research and Innovation (RRI) focuses rather on increased involvement and reflexivity in research processes to foster science and technology that better answers the needs of society. I argue that philosophy of science should be a central feature of RRI and demonstrate how the philosophy of science can contribute in this sense. I show how investigating basic assumptions in research, here exemplified by reductive assumptions in causal modeling, can have important ethical and societal implications.

Targeting multiple types of tumors using NKG2D-coated iron oxide nanoparticles

Iron oxide nanoparticles (IONPs) hold great potential for cancer therapy. Actively targeting IONPs to tumor cells can further increase therapeutic efficacy and decrease off-target side effects. To target tumor cells, a natural killer (NK) cell activating receptor, NKG2D, was utilized to develop pan-tumor targeting IONPs. NKG2D ligands are expressed on many tumor types and its ligands are not found on most normal tissues under steady state conditions. The data showed that mouse and human fragment crystallizable (Fc)-fusion NKG2D (Fc-NKG2D) coated IONPs (NKG2D/NPs) can target multiple NKG2D ligand positive tumor types in vitro in a dose dependent manner by magnetic cell sorting. Tumor targeting effect was robust even under a very low tumor cell to normal cell ratio and targeting efficiency correlated with NKG2D ligand expression level on tumor cells. Furthermore, the magnetic separation platform utilized to test NKG2D/NP specificity has the potential to be developed into high throughput screening strategies to identify ideal fusion proteins or antibodies for targeting IONPs. In conclusion, NKG2D/NPs can be used to target multiple tumor types and magnetic separation platform can facilitate the proof-of-concept phase of tumor targeting IONP development.

NCI investment in nanotechnology: achievements and challenges for the future

Nanotechnology offers an exceptional and unique opportunity for developing a new generation of tools addressing persistent challenges to progress in cancer research and clinical care. The National Cancer Institute (NCI) recognizes this potential, which is why it invests roughly $150 M per year in nanobiotechnology training, research and development. By exploiting the various capacities of nanomaterials, the range of nanoscale vectors and probes potentially available suggests much is possible for precisely investigating, manipulating, and targeting the mechanisms of cancer across the full spectrum of research and clinical care. NCI has played a key role among federal R&D agencies in recognizing early the value of nanobiotechnology in medicine and committing to its development as well as providing training support for new investigators in the field. These investments have allowed many in the research community to pursue breakthrough capabilities that have already yielded broad benefits. Presented here is an overview of how NCI has made these investments with some consideration of how it will continue to work with this research community to pursue paradigm-changing innovations that offer relief from the burdens of cancer.

Dawn of advanced molecular medicine: nanotechnological advancements in cancer imaging and therapy

Nanotechnology plays an increasingly important role not only in our everyday life (with all its benefits and dangers) but also in medicine. Nanoparticles are to date the most intriguing option to deliver high concentrations of agents specifically and directly to cancer cells; therefore, a wide variety of these nanomaterials has been developed and explored. These span the range from simple nanoagents to sophisticated smart devices for drug delivery or imaging. Nanomaterials usually provide a large surface area, allowing for decoration with a large amount of moieties on the surface for either additional functionalities or targeting. Besides using particles solely for imaging purposes, they can also carry as a payload a therapeutic agent. If both are combined within the same particle, a theranostic agent is created. The sophistication of highly developed nanotechnology targeting approaches provides a promising means for many clinical implementations and can provide improved applications for otherwise suboptimal formulations. In this review we will explore nanotechnology both for imaging and therapy to provide a general overview of the field and its impact on cancer imaging and therapy.

PSMA ligand conjugated PCL-PEG polymeric micelles targeted to prostate cancer cells

In this content, a small molecular ligand of prostate specific membrane antigen (SMLP) conjugated poly (caprolactone) (PCL)-b-poly (ethylene glycol) (PEG) copolymers with different block lengths were synthesized to construct a satisfactory drug delivery system. Four different docetaxel-loaded polymeric micelles (DTX-PMs) were prepared by dialysis with particle sizes less than 60 nm as characterized by dynamic light scattering (DLS) and transmission electron microscope (TEM). Optimization of the prepared micelles was conducted based on short-term stability and drug-loading content. The results showed that optimized systems were able to remain stable over 7 days. Compared with Taxotere, DTX-PMs with the same ratio of hydrophilic/hydrophobic chain length displayed similar sustained release behaviors. The cytotoxicity of the optimized targeted DTX-PCL_12K-PEG_5K-SMLP micelles (DTX-PMs2) and non-targeted DTX-PCL_12K-mPEG_5K micelles (DTX-PMs1) were evaluated by MTT assays using prostate specific membrane antigen (PSMA) positive prostate adenocarcinoma cells (LNCaP). The results showed that the targeted micelles had a much lower IC50 than their non-targeted counterparts (48 h: 0.87±0.27 vs 13.48±1.03 µg/ml; 72 h: 0.02±0.008 vs 1.35±0.54 µg/ml). In vitro cellular uptake of PMs2 showed 5-fold higher fluorescence intensity than that of PMs1 after 4 h incubation. According to these results, the novel nano-sized drug delivery system based on DTX-PCL-PEG-SMLP offers great promise for the treatment of prostatic cancer.

Micellization of antineoplastic agent to significantly upregulate efficacy and security

The amphiphilic diblock copolymer composed of methoxy poly(ethylene glycol) and racemic oligoleucine was synthesized which formed into micelle with uniform size in aqueous environment. Doxorubicin (DOX) was loaded into micelle aided by noncovalent interactions with high drug loading efficiency. The DOX-loaded micelle (referred as M-DOX) demonstrated the sustained drug release in vitro and excellent antiproliferative capability toward both MG63 and Saos-2 cells. Furthermore, for both MG63 and Saos-2-xenografted BALB/c nude mouse models, M-DOX exhibited enhanced intratumoral distribution, improved antitumor efficacy, and reduced side effects compared with free DOX. Therefore, the polypeptide micelle showed a bright prospect for controlled delivery of antitumor drugs in vivo.

N-acetyl-L-aspartyl-L-glutamate peptidase-like 2 is overexpressed in cancer and promotes a pro-migratory and pro-metastatic phenotype

N-acetyl-L-aspartyl-L-glutamate peptidase-like 2 (NAALADL2) is a member of the glutamate carboxypeptidase II family, best characterized by prostate-specific membrane antigen (PSMA/NAALAD1). Using immunohistochemistry (IHC), we have shown overexpression of NAALADL2 in colon and prostate tumours when compared with benign tissue. In prostate cancer, NAALADL2 expression was associated with stage and Grade, as well as circulating mRNA levels of the NAALADL2 gene. Overexpression of NAALADL2 was shown to predict poor survival following radical prostatectomy. In contrast to PSMA/NAALAD1, NAALADL2 was localized at the basal cell surface where it promotes adhesion to extracellular matrix proteins. Using stable knockdown and overexpression cell lines, we have demonstrated NAALADL2-dependent changes in cell migration, invasion and colony-forming potential. Expression arrays of the knockdown and overexpression cell lines have identified nine genes that co-expressed with NAALADL2, which included membrane proteins and genes known to be androgen regulated, including the prostate cancer biomarkers AGR2 and SPON2. Androgen regulation was confirmed in a number of these genes, although NAALADL2 itself was not found to be androgen regulated. NAALADL2 was also found to regulate levels of Ser133 phosphorylated C-AMP-binding protein (CREB), a master regulator of a number of cellular processes involved in cancer development and progression. In combination, these data suggest that changes in expression of NAALADL2 can impact upon a number of pro-oncogenic pathways and processes, making it a useful biomarker for both diagnosis and prognosis.

Nanomedical engineering: shaping future nanomedicines

Preclinical research in the field of nanomedicine continues to produce a steady stream of new nanoparticles with unique capabilities and complex properties. With improvements come promising treatments for diseases, with the ultimate goal of clinical translation and better patient outcomes compared with current standards of care. Here, we outline engineering considerations for nanomedicines, with respect to design criteria, targeting, and stimuli-triggered drug release strategies. General properties, clinical relevance, and current research advances of various nanomedicines are discussed in light of how these will realize their potential and shape the future of the field.

Packaging biological cargoes in mesoporous materials: opportunities for drug delivery

INTRODUCTION

Confinement of biomolecules in structured nanoporous materials offers several desirable features ranging from chemical and thermal stability, to resistance to degradation from the external environment. A new generation of mesoporous materials presents exciting new possibilities for the formulation and controlled release of biological agents. Such materials address niche applications in enteral and parenteral delivery of biologics, such as peptides, polypeptides, enzymes and proteins for use as therapeutics, imaging agents, biosensors, and adjuvants.

AREAS COVERED

Mesoporous silica Santa Barbara Amorphous-15 (SBA-15), with its unique, tunable pore diameter, and easily functionalized surface, provides a representative example of this new generation of materials. Here, we review recent advances in the design and synthesis of nanostructured mesoporous materials, focusing on SBA-15, and highlight opportunities for the delivery of biological agents to various organ and tissue compartments.

EXPERT OPINION

The SBA-15 platform provides a delivery carrier that is inherently separated from the active biologic due to distinct intra and extra-particle environments. This permits the SBA-15 platform to not require direct modification of the active biological therapeutic. Additionally, this makes the platform universal and allows for its application independent of the desired methods of discovery and development. The SBA-15 platform also directly addresses issues of targeted delivery and controlled release, although future challenges in the implementation of this platform reside in particle design, biocompatibility, and the tunability of the internal and external material properties. Examples illustrating the flexibility in the application of the SBA-15 platform are also discussed.

Three-dimensional flash flow microreactor for scale-up production of monodisperse PEG-PLGA nanoparticles

We present a pressure-tolerant 3D parallel polyimide (PI) film microreactor operating at up to ~160 bars with direct 3D flow focusing geometry for mass production of PEG-PLGA nanoparticles in a ~10(1) gram-scale (g h(-1)).

Structure-based rational design of prodrugs to enable their combination with polymeric nanoparticle delivery platforms for enhanced antitumor efficacy

Drug-loaded nanoparticles (NPs) are of particular interest for efficient cancer therapy due to their improved drug delivery and therapeutic index in various types of cancer. However, the encapsulation of many chemotherapeutics into delivery NPs is often hampered by their unfavorable physicochemical properties. Here, we employed a drug reform strategy to construct a small library of SN-38 (7-ethyl-10-hydroxycamptothecin)-derived prodrugs, in which the phenolate group was modified with a variety of hydrophobic moieties. This esterification fine-tuned the polarity of the SN-38 molecule and enhanced the lipophilicity of the formed prodrugs, thereby inducing their self-assembly into biodegradable poly(ethylene glycol)-block-poly(d,l-lactic acid) (PEG-PLA) nanoparticulate structures. Our strategy combining the rational engineering of prodrugs with the pre-eminent features of conventionally used polymeric materials should open new avenues for designing more potent drug delivery systems as a therapeutic modality.

Non-spherical micro- and nanoparticles: fabrication, characterization and drug delivery applications

INTRODUCTION

Micro- and nanoparticles in drug and vaccine delivery have opened up new possibilities in pharmaceutics. In the past, researchers focused mainly on particle size, surface chemistry and the use of various materials to control particle characteristics and functions. Lately, shape has been acknowledged as an important design parameter having an impact on the interaction with biological systems.

AREAS COVERED

In this review, we report on the latest developments in fabrication methods to tailor particle geometry, summarize analytical techniques for non-spherical particles and highlight the most important findings regarding their interaction with biological systems and their potential applications in drug delivery.

EXPERT OPINION

The impact of shape on particle internalization into different cell types and particle biodistribution has been extensively studied in the past. Current research focuses on shape-dependent uptake mechanisms and applications for tumour therapy and vaccination. Different fabrication methods can be used to produce a variety of different particle types and shapes. Key challenges will be the transfer of new non-spherical particle fabrication methods from lab-scale to industrial large-scale production. Not all techniques may be scalable for the production of high quantities of particles. It will also be challenging to transfer the promising in vitro findings to suitable in vivo models.

Engineered nanoparticles for drug delivery in cancer therapy

In medicine, nanotechnology has sparked a rapidly growing interest as it promises to solve a number of issues associated with conventional therapeutic agents, including their poor water solubility (at least, for most anticancer drugs), lack of targeting capability, nonspecific distribution, systemic toxicity, and low therapeutic index. Over the past several decades, remarkable progress has been made in the development and application of engineered nanoparticles to treat cancer more effectively. For example, therapeutic agents have been integrated with nanoparticles engineered with optimal sizes, shapes, and surface properties to increase their solubility, prolong their circulation half-life, improve their biodistribution, and reduce their immunogenicity. Nanoparticles and their payloads have also been favorably delivered into tumors by taking advantage of the pathophysiological conditions, such as the enhanced permeability and retention effect, and the spatial variations in the pH value. Additionally, targeting ligands (e.g., small organic molecules, peptides, antibodies, and nucleic acids) have been added to the surface of nanoparticles to specifically target cancerous cells through selective binding to the receptors overexpressed on their surface. Furthermore, it has been demonstrated that multiple types of therapeutic drugs and/or diagnostic agents (e.g., contrast agents) could be delivered through the same carrier to enable combination therapy with a potential to overcome multidrug resistance, and real-time readout on the treatment efficacy. It is anticipated that precisely engineered nanoparticles will emerge as the next-generation platform for cancer therapy and many other biomedical applications.

Folate-decorated and reduction-sensitive micelles assembled from amphiphilic polymer-camptothecin conjugates for intracellular drug delivery

It is one of the challenges for a wide clinical application of polymer micelles to address the structure disintegration and premature drug release before reaching a pathological site. In the current study, folic acid (FA)-decorated polymer-drug conjugates (FSC) were synthesized with disulfide linkages between camptothecin (CPT) and amphiphilic poly(ethylene glycol)-b-poly(ε-caprolactone) (PECL) copolymers. FSC conjugates were proposed to assemble into micelles with a hydrophobic core of PCL segments and CPT and a hydrophilic corona of PEG segments. The addition of hexadecanol during micelle formation (FSC-16) was proposed to modulate the interactions of hydrophobic segments in micelles and enhance the reductive sensitivity. FSC-16 micelles were obtained with critical micelle concentration of around 2 μg/mL and an average size of around 200 nm, and the conjugated CPT was rapidly released out in response to glutathione. The reductive sensitivity was also demonstrated with respect to the changes of micelle size and morphologies as well as the fluorescent intensity of pyrene loaded in micelles. Benefiting from the FA receptor-mediated uptake and the reduction-sensitive release of CPT, significant cytotoxicity and cell apoptosis were identified for FSC-16 micelles against SKOV-3 cells with strong expressions of FA receptors. Flow cytometry and confocal laser scanning microscopy analyses demonstrated that CPT was distributed into nuclei after cellular uptake and intracellular release from FSC-16 micelles. Thus, the FA-decorated and reduction-sensitive micelles assembled from polymer-drug conjugates show advantages in inhibiting premature release during circulation, enhancing cellular uptake at the tumor tissues, and promoting intracellular release and nuclei location of the active moieties.

NIH workshop on clinical translation of molecular imaging probes and technology--meeting report

A workshop on "Clinical Translation of Molecular Imaging Probes and Technology" was held August 2, 2013 in Bethesda, Maryland, organized and supported by the National Institute of Biomedical Imaging and Bioengineering (NIBIB). This workshop brought together researchers, clinicians, representatives from pharmaceutical companies, molecular probe developers, and regulatory science experts. Attendees met to talk over current challenges in the discovery, validation, and translation of molecular imaging (MI) probes for key clinical applications. Participants also discussed potential strategies to address these challenges. The workshop consisted of 4 sessions, with 14 presentations and 2 panel discussions. Topics of discussion included (1) challenges and opportunities for clinical research and patient care, (2) advances in molecular probe design, (3) current approaches used by industry and pharmaceutical companies, and (4) clinical translation of MI probes. In the presentations and discussions, there were general agreement that while the barriers for validation and translation of MI probes remain high, there are pressing clinical needs and development opportunities for targets in cardiovascular, cancer, endocrine, neurological, and inflammatory diseases. The strengths of different imaging modalities, and the synergy of multimodality imaging, were highlighted. Participants also underscored the continuing need for close interactions and collaborations between academic and industrial partners, and federal agencies in the imaging probe development process.

Polymeric nanoparticle technologies for oral drug delivery

Biologics increasingly are being used for the treatment of many diseases. These treatments typically require repeated doses administered by injection. Alternate routes of administration, particularly oral, are considered favorable because of improved convenience and compliance by patients, but physiological barriers such as extreme pH level, enzyme degradation, and poor intestinal epithelium permeability limit absorption. Encapsulating biologics in drug delivery systems such as polymeric nanoparticles prevents inactivation and degradation caused by low pH and enzymes of the gastrointestinal tract. However, transport across the intestinal epithelium remains the most critical barrier to overcome for efficient oral delivery. This review focuses on recent advances in polymeric nanoparticles being developed to overcome transport barriers and their potential for translation into clinical use.

Insight into nanoparticle cellular uptake and intracellular targeting

Collaborative efforts from the fields of biology, materials science, and engineering are leading to exciting progress in the development of nanomedicines. Since the targets of many therapeutic agents are localized in subcellular compartments, modulation of nanoparticle-cell interactions for efficient cellular uptake through the plasma membrane and the development of nanomedicines for precise delivery to subcellular compartments remain formidable challenges. Cellular internalization routes determine the post-internalization fate and intracellular localization of nanoparticles. This review highlights the cellular uptake routes most relevant to the field of non-targeted nanomedicine and presents an account of ligand-targeted nanoparticles for receptor-mediated cellular internalization as a strategy for modulating the cellular uptake of nanoparticles. Ligand-targeted nanoparticles have been the main impetus behind the progress of nanomedicines towards the clinic. This strategy has already resulted in remarkable progress towards effective oral delivery of nanomedicines that can overcome the intestinal epithelial barrier. A detailed overview of the recent developments in subcellular targeting as a novel platform for next-generation organelle-specific nanomedicines is also provided. Each section of the review includes prospects, potential, and concrete expectations from the field of targeted nanomedicines and strategies to meet those expectations.

Polyphosphoester-based nanoparticles with viscous flow core enhanced therapeutic efficacy by improved intracellular drug release

The intracellular drug release rate from the hydrophobic core of self-assembled nanoparticles can significantly affect the therapeutic efficacy. Currently, the hydrophobic core of many polymeric nanoparticles which are usually composed of poly(ε-caprolactone) (PCL), polylactide (PLA), or poly(D, L-lactide-co-glycolide) (PLGA) may hinder the diffusion of drug from the core because of their glassy state at room temperature. To investigate the effect of the hydrophobic core state on therapeutic efficacy, we synthesized an amphiphilic diblock copolymers of hydrophilic poly(ethylene glycol) (PEG) and hydrophobic polyphosphoester, which were in a viscous flow state at room temperature. The obtained copolymers self-assembled into core-shell nanoparticles, which efficiently encapsulate doxorubicin (DOX) in the hydrophobic polyphosphoester core (NP(PPE)/DOX). As speculated, compared with the nanoparticles bearing glassy core (hydrophobic PLA core, NP(PLA)/DOX), the encapsulated DOX was more rapidly released from NP(PPE)/DOX with viscous flow core, resulting in significantly increased cytotoxicity. Accordingly, the improved intracellular drug release from viscous flow core enhances the inhibition of tumor growth, suggesting the nanoparticles bearing viscous flow core show great potential in cancer therapy.

Ceramic nanoparticles: Recompense, cellular uptake and toxicity concerns

Over the past few years, nanoparticles and their role in drug delivery have been the centre of attraction as new drug delivery systems. Various forms of nanosystems have been designed, such as nanoclays, scaffolds and nanotubes, having numerous applications in areas such as drug loading, target cell uptake, bioassay and imaging. The present study discusses various types of nanoparticles, with special emphasis on ceramic nanocarriers. Ceramic materials have high mechanical strength, good body response and low or non-existing biodegradability. In this article, the various aspects concerning ceramic nanoparticles, such as their advantages over other systems, their cellular uptake and toxicity concerns are discussed in detail.

Multivalent polymers for drug delivery and imaging: the challenges of conjugation

Multivalent polymers offer a powerful opportunity to develop theranostic materials on the size scale of proteins that can provide targeting, imaging, and therapeutic functionality. Achieving this goal requires the presence of multiple targeting molecules, dyes, and/or drugs on the polymer scaffold. This critical review examines the synthetic, analytical, and functional challenges associated with the heterogeneity introduced by conjugation reactions as well as polymer scaffold design. First, approaches to making multivalent polymer conjugations are discussed followed by an analysis of materials that have shown particular promise biologically. Challenges in characterizing the mixed ligand distributions and the impact of these distributions on biological applications are then discussed. Where possible, molecular-level interpretations are provided for the structures that give rise to the functional ligand and molecular weight distributions present in the polymer scaffolds. Lastly, recent strategies employed for overcoming or minimizing the presence of ligand distributions are discussed. This review focuses on multivalent polymer scaffolds where average stoichiometry and/or the distribution of products have been characterized by at least one experimental technique. Key illustrative examples are provided for scaffolds that have been carried forward to in vitro and in vivo testing with significant biological results.

Overcoming the challenges in administering biopharmaceuticals: formulation and delivery strategies

The formulation and delivery of biopharmaceutical drugs, such as monoclonal antibodies and recombinant proteins, poses substantial challenges owing to their large size and susceptibility to degradation. In this Review we highlight recent advances in formulation and delivery strategies--such as the use of microsphere-based controlled-release technologies, protein modification methods that make use of polyethylene glycol and other polymers, and genetic manipulation of biopharmaceutical drugs--and discuss their advantages and limitations. We also highlight current and emerging delivery routes that provide an alternative to injection, including transdermal, oral and pulmonary delivery routes. In addition, the potential of targeted and intracellular protein delivery is discussed.

Development of therapeutic polymeric nanoparticles for the resolution of inflammation

Liver X receptors (LXRs) attenuate inflammation by modulating the expression of key inflammatory genes, making LXRs and their ligands particularly attractive candidates for therapeutic intervention in cardiovascular, metabolic, and/or inflammatory diseases. Herein, enhanced proresolving activity of polymeric nanoparticles (NPs) containing the synthetic LXR agonist GW3965 (LXR-NPs) is demonstrated, developed from a combinatorial library of more than 70 formulations with variations in critical physicochemical parameters. In vitro studies on peritoneal macrophages confirm that LXR-NPs are significantly more effective than the free agonist at downregulating pro-inflammatory mediators (MCP-1 and TNFα), as well as inducing the expression of LXR target genes (ABCA1 and SREBP1c). Through a zymosan-induced acute peritonitis in vivo model, LXR-NPs are found to be more efficient than free GW3965 at limiting the recruitment of polymononuclear neutrophils (50% vs 17%), suppressing the gene expression and secretion of pro-inflammatory factors MCP-1 and TNFα in peritoneal macrophages, and decreasing the resolution interval up to 4 h. Furthermore, LXR-NPs suppress the secretion of MCP-1 and TNFα by monocytes and macrophages more efficiently than the commercial drug dexamethasone. Overall, these findings demonstrate that LXR-NPs are capable of promoting resolution of inflammation and highlight the prospect of LXR-based nanotherapeutics for inflammatory diseases.

cRGD-directed, NIR-responsive and robust AuNR/PEG-PCL hybrid nanoparticles for targeted chemotherapy of glioblastoma in vivo

cRGD-directed, NIR-responsive and robust AuNR/PEG-PCL hybrid nanoparticles (cRGD-HNs) were designed and developed for targeted chemotherapy of human glioma xenografts in mice. As expected, cRGD-HNs had excellent colloidal stability. The in vitro release studies showed that drug release from DOX-loaded cRGD-HNs (cRGD-HN-DOX) was minimal under physiological conditions but markedly accelerated upon NIR irradiation at a low power density of 0.2 W/cm2, due to photothermally induced phase transition of PCL regime. MTT assays showed that the antitumor activity of cRGD-HN-DOX in αvβ3 integrin over-expressed human glioblastoma U87MG cells was greatly boosted by mild NIR irradiation, which was significantly more potent than non-targeting HN-DOX counterpart under otherwise the same conditions and was comparable or superior to free DOX, supporting receptor-mediated endocytosis mechanism. The in vivo pharmacokinetics studies showed that cRGD-HN-DOX had much longer circulation time than free DOX. The in vivo imaging and biodistribution studies revealed that cRGD-HN-DOX could actively target human U87MG glioma xenograft in nude mice. The therapeutic studies in human U87MG glioma xenografts exhibited that cRGD-HN-DOX in combination with NIR irradiation completely inhibited tumor growth and possessed much lower side effects than free DOX. The Kaplan-Meier survival curves showed that all mice treated with cRGD-HN-DOX plus NIR irradiation survived over an experimental period of 48 days while control groups treated with PBS, cRGD-HN-DOX, cRGD-HNs with NIR irradiation, free DOX, or HN-DOX with NIR irradiation (non-targeting control) had short life spans of 15-40 days. Ligand-directed AuNR/PEG-PCL hybrid nanoparticles with evident tumor-targetability as well as superior spatiotemporal and rate control over drug release have emerged as an appealing platform for cancer chemotherapy in vivo.

Nanomedicine in the Management of Microbial Infection - Overview and Perspectives

For more than 2 billion years, microbes have reigned on our planet, evolving or outlasting many obstacles they have encountered. In the 20th century, this trend took a dramatic turn with the introduction of antibiotics and vaccines. Nevertheless, since then, microbes have progressively eroded the effectiveness of previously successful antibiotics by developing resistance, and many infections have eluded conventional vaccine design approaches. Moreover, the emergence of resistant and more virulent strains of bacteria has outpaced the development of new antibiotics over the last few decades. These trends have had major economic and health impacts at all levels of the socioeconomic spectrum - we need breakthrough innovations that could effectively manage microbial infections and deliver solutions that stand the test of time. The application of nanotechnologies to medicine, or nanomedicine, which has already demonstrated its tremendous impact on the pharmaceutical and biotechnology industries, is rapidly becoming a major driving force behind ongoing changes in the antimicrobial field. Here we provide an overview on the current progress of nanomedicine in the management of microbial infection, including diagnosis, antimicrobial therapy, drug delivery, medical devices, and vaccines, as well as perspectives on the opportunities and challenges in antimicrobial nanomedicine.

Quantitative comparison of tumor delivery for multiple targeted nanoparticles simultaneously by multiplex ICP-MS

Given the rapidly expanding library of disease biomarkers and targeting agents, the number of unique targeted nanoparticles is growing exponentially. The high variability and expense of animal testing often makes it unfeasible to examine this large number of nanoparticles in vivo. This often leads to the investigation of a single formulation that performed best in vitro. However, nanoparticle performance in vivo depends on many variables, many of which cannot be adequately assessed with cell-based assays. To address this issue, we developed a lanthanide-doped nanoparticle method that allows quantitative comparison of multiple targeted nanoparticles simultaneously. Specifically, superparamagnetic iron oxide (SPIO) nanoparticles with different targeting ligands were created, each with a unique lanthanide dopant. Following the simultaneous injection of the various SPIO compositions into tumor-bearing mice, inductively coupled plasma mass spectroscopy was used to quantitatively and orthogonally assess the concentration of each SPIO composition in serial blood and resected tumor samples.

Convergence of nanotechnology and cancer prevention: are we there yet?

Nanotechnology is emerging as a promising modality for cancer treatment; however, in the realm of cancer prevention, its full utility has yet to be determined. Here, we discuss the potential of integrating nanotechnology in cancer prevention to augment early diagnosis, precision targeting, and controlled release of chemopreventive agents, reduced toxicity, risk/response assessment, and personalized point-of-care monitoring. Cancer is a multistep, progressive disease; the functional and acquired characteristics of the early precancer phenotype are intrinsically different from those of a more advanced anaplastic or invasive malignancy. Therefore, applying nanotechnology to precancers is likely to be far more challenging than applying it to established disease. Frank cancers are more readily identifiable through imaging and biomarker and histopathologic assessment than their precancerous precursors. In addition, prevention subjects routinely have more rigorous intervention criteria than therapy subjects. Any nanopreventive agent developed to prevent sporadic cancers found in the general population must exhibit a very low risk of serious side effects. In contrast, a greater risk of side effects might be more acceptable in subjects at high risk for cancer. Using nanotechnology to prevent cancer is an aspirational goal, but clearly identifying the intermediate objectives and potential barriers is an essential first step in this exciting journey.

Anti-cancer activity of curcumin loaded nanoparticles in prostate cancer

Prostate cancer is the most commonly diagnosed cancer disease in men in the Unites States and its management remains a challenge in everyday oncology practice. Thus, advanced therapeutic strategies are required to treat prostate cancer patients. Curcumin (CUR) is a promising anticancer agent for various cancer types. The objective of this study was to evaluate therapeutic potential of novel poly(lactic-co-glycolic acid)- CUR nanoparticles (PLGA-CUR NPs) for prostate cancer treatment. Our results indicate that PLGA-CUR NPs efficiently internalize in prostate cancer cells and release biologically active CUR in cytosolic compartment of cells for effective therapeutic activity. Cell proliferation (MTS), clonogenic, and Western blot analyses reveal that PLGA-CUR NPs can effectively inhibit proliferation and colony formation ability of prostate cancer cells than free CUR. PLGA-CUR NPs showed superior tumor regression compared to CUR in xenograft mice. Further investigations reveal that PLGA-CUR NPs inhibit nuclear β-catenin and AR expression in cells and in tumor xenograft tissues. It also suppresses STAT3 and AKT phosphorylation and leads to apoptosis via inhibition of key anti-apoptotic proteins, Mcl-1, Bcl-xL and caused induction of PARP cleavage. Additionally, significant downregulation of oncogenic miR21 and up-regulation of miR-205 was observed with PLGA-CUR NPs treatment as determined by RT-PCR and in situ hybridization analyses. A superior anti-cancer potential was attained with PSMA antibody conjugated PLGA-CUR NPs in prostate cancer cells and a significant tumor targeting of (131)I labeled PSMA antibody was achieved with PLGA-CUR NPs in prostate cancer xenograft mice model. In conclusion, PLGA-CUR NPs can significantly accumulate and exhibit superior anticancer activity in prostate cancer.

Co-delivery of doxorubicin and siRNA with reduction and pH dually sensitive nanocarrier for synergistic cancer therapy

Drug resistance is the greatest challenge in clinical cancer chemotherapy. Co-delivery of chemotherapeutic drugs and siRNA to tumor cells is a vital means to silence drug resistant genes during the course of cancer chemotherapy for an improved chemotherapeutic effect. This study aims at effective co-delivery of siRNA and anticancer drugs to tumor cells. A ternary block copolymer PEG-PAsp(AED)-PDPA consisting of pH-sensitive poly(2-(diisopropyl amino)ethyl methacrylate) (PDPA), reduction-sensitive poly(N-(2,2'-dithiobis(ethylamine)) aspartamide) PAsp(AED), and poly(ethylene glycol) (PEG) is synthesized and assembled into a core-shell structural micelle which encapsulated doxorubicin (DOX) in its pH-sensitive core and the siRNA-targeting anti-apoptosis BCL-2 gene (BCL-2 siRNA) in a reduction-sensitive interlayer. At the optimized size and zeta potential, the nanocarriers loaded with DOX and BCL-2 siRNA may effectively accumulate in the tumor site via blood circulation. Moreover, the dual stimuli-responsive design of micellar carriers allows microenviroment-specific rapid release of both DOX and BCL-2 siRNA inside acidic lysosomes with enriched reducing agent, glutathione (GSH, up to 10 mM). Consequently, the expression of anti-apoptotic BCL-2 protein induced by DOX treatment is significantly down-regulated, which results in synergistically enhanced apoptosis of human ovarian cancer SKOV-3 cells and thus dramatically inhibited tumor growth.

Engineered nanomedicine for myeloma and bone microenvironment targeting

Bone is a favorable microenvironment for tumor growth and a frequent destination for metastatic cancer cells. Targeting cancers within the bone marrow remains a crucial oncologic challenge due to issues of drug availability and microenvironment-induced resistance. Herein, we engineered bone-homing polymeric nanoparticles (NPs) for spatiotemporally controlled delivery of therapeutics to bone, which diminish off-target effects and increase local drug concentrations. The NPs consist of poly(D,L-lactic-co-glycolic acid) (PLGA), polyethylene glycol (PEG), and bisphosphonate (or alendronate, a targeting ligand). The engineered NPs were formulated by blending varying ratios of the synthesized polymers: PLGA-b-PEG and alendronate-conjugated polymer PLGA-b-PEG-Ald, which ensured long circulation and targeting capabilities, respectively. The bone-binding ability of Ald-PEG-PLGA NPs was investigated by hydroxyapatite binding assays and ex vivo imaging of adherence to bone fragments. In vivo biodistribution of fluorescently labeled NPs showed higher retention, accumulation, and bone homing of targeted Ald-PEG-PLGA NPs, compared with nontargeted PEG-PLGA NPs. A library of bortezomib-loaded NPs (bone-targeted Ald-Bort-NPs and nontargeted Bort-NPs) were developed and screened for optimal physiochemical properties, drug loading, and release profiles. Ald-Bort-NPs were tested for efficacy in mouse models of multiple myeloma (MM). Results demonstrated significantly enhanced survival and decreased tumor burden in mice pretreated with Ald-Bort-NPs versus Ald-Empty-NPs (no drug) or the free drug. We also observed that bortezomib, as a pretreatment regimen, modified the bone microenvironment and enhanced bone strength and volume. Our findings suggest that NP-based anticancer therapies with bone-targeting specificity comprise a clinically relevant method of drug delivery that can inhibit tumor progression in MM.

Ultra-high throughput synthesis of nanoparticles with homogeneous size distribution using a coaxial turbulent jet mixer

High-throughput production of nanoparticles (NPs) with controlled quality is critical for their clinical translation into effective nanomedicines for diagnostics and therapeutics. Here we report a simple and versatile coaxial turbulent jet mixer that can synthesize a variety of NPs at high throughput up to 3 kg/d, while maintaining the advantages of homogeneity, reproducibility, and tunability that are normally accessible only in specialized microscale mixing devices. The device fabrication does not require specialized machining and is easy to operate. As one example, we show reproducible, high-throughput formulation of siRNA-polyelectrolyte polyplex NPs that exhibit effective gene knockdown but exhibit significant dependence on batch size when formulated using conventional methods. The coaxial turbulent jet mixer can accelerate the development of nanomedicines by providing a robust and versatile platform for preparation of NPs at throughputs suitable for in vivo studies, clinical trials, and industrial-scale production.

Update on current and potential nanoparticle cancer therapies

PURPOSE OF REVIEW

To summarize the most recent preclinical and clinical advancements in therapeutic nano-oncology.

RECENT FINDINGS

First-generation nanotherapies are well tolerated in humans and evidence shows that they are efficacious, while at the same time reducing the burden of side-effects. Most of these therapies are not specifically targeted, but take advantage of enhanced passive accumulation within tumors to preferentially deliver chemotherapies that demonstrate off-target toxicities when administered as free drugs. Also, actively targeted nanotherapies are entering the clinical arena and preliminary data are encouraging. Finally, a number of exciting preclinical developments in nanotechnology provide clear evidence that nanotherapies will continue to enter the clinic and will have a significant impact in oncology.

SUMMARY

A number of intriguing nanoparticle therapies are being tested in preclinical and clinical trials. Nanoparticles with increasing molecular sophistication, specific targeting properties, and unique mechanisms of action will find their way to the clinic. Certainly, nanoparticle-based therapies will be increasingly represented in drug development pipelines, and will continue to provide efficacious and well tolerated drug options for patients with cancer.

Rational design of urea-based glutamate carboxypeptidase II (GCPII) inhibitors as versatile tools for specific drug targeting and delivery

Glutamate carboxypeptidase II (GCPII), also known as prostate specific membrane antigen (PSMA), is an established prostate cancer marker and is considered a promising target for specific anticancer drug delivery. Low-molecular-weight inhibitors of GCPII are advantageous specific ligands for this purpose. However, they must be modified with a linker to enable connection of the ligand with an imaging molecule, anticancer drug, and/or nanocarrier. Here, we describe a structure-activity relationship (SAR) study of GCPII inhibitors with linkers suitable for imaging and drug delivery. Structure-assisted inhibitor design and targeting of a specific GCPII exosite resulted in a 7-fold improvement in Ki value compared to the parent structure. X-ray structural analysis of the inhibitor series led to the identification of several inhibitor binding modes. We also optimized the length of the inhibitor linker for effective attachment to a biotin-binding molecule and showed that the optimized inhibitor could be used to target nanoparticles to cells expressing GCPII.

Copper-free click-chemistry platform to functionalize cisplatin prodrugs

The ability to rationally design and construct a platform technology to develop new platinum(IV) [Pt(IV)] prodrugs with functionalities for installation of targeting moieties, delivery systems, fluorescent reporters from a single precursor with the ability to release biologically active cisplatin by using well-defined chemistry is critical for discovering new platinum-based therapeutics. With limited numbers of possibilities considering the sensitivity of Pt(IV) centers, we used a strain-promoted azide-alkyne cycloaddition approach to provide a platform, in which new functionalities can easily be installed on cisplatin prodrugs from a single Pt(IV) precursor. The ability of this platform to be incorporated in nanodelivery vehicle and conjugation to fluorescent reporters were also investigated.

Cell-penetrating, guanidinium-rich molecular transporters for overcoming efflux-mediated multidrug resistance

Multidrug resistance (MDR) is a major cause of chemotherapy failure in the clinic. Drugs that were once effective against naïve disease subsequently prove ineffective against recurrent disease, which often exhibits an MDR phenotype. MDR can be attributed to many factors; often dominating among these is the ability of a cell to suppress or block drug entry through upregulation of membrane-bound drug efflux pumps. Efflux pumps exhibit polyspecificity, recognizing and exporting many different types of drugs, especially those whose lipophilic nature contributes to residence in the membrane. We have developed a general strategy to overcome efflux-based resistance. This strategy involves conjugating a known drug that succumbs to efflux-mediated resistance to a cell-penetrating molecular transporter, specifically, the cell-penetrating peptide (CPP), d-octaarginine. The resultant conjugates are discrete single entities (not particle mixtures) and highly water-soluble. They rapidly enter cells, are not substrates for efflux pumps, and release the free drug only after cellular entry at a rate controlled by linker design and favored by target cell chemistry. This general strategy can be applied to many classes of drugs and allows for an exceptionally rapid advance to clinical testing, especially of drugs that succumb to resistance. The efficacy of this strategy has been successfully demonstrated with Taxol in cellular and animal models of resistant cancer and with ex vivo samples from patients with ovarian cancer. Next generation efforts in this area will involve the extension of this strategy to other chemotherapeutics and other MDR-susceptible diseases.