Applications and safety of gold nanoparticles as therapeutic devices in clinical trials

Use of gold nanoparticles (GNPs) in medicine is an emerging field of translational research with vast clinical implications and exciting therapeutic potential. However, the safety of using GNPs in human subjects is an important question that remains unanswered. This study reviews over 20 clinical trials focused on GNP safety and aims to summarize all the clinical studies, completed and ongoing, to identify whether GNPs are safe to use in humans as a therapeutic platform. In these studies, GNPs were implemented as drug delivery devices, for photothermal therapy, and utilized for their intrinsic therapeutic effects by various routes of delivery. These studies revealed no major safety concerns with the use of GNPs; however, the number of trials and total patient number remains limited. Multi-dose, multi-center blinded trials are required to deepen our understanding of the use of GNPs in clinical settings to facilitate translation of this novel, multifaceted therapeutic device. Expanding clinical trials will require collaboration between clinicians, scientists, and biotechnology companies.

Application of aptamer-drug delivery system in the therapy of breast cancer

Despite significant treatment advances, breast cancer remains the leading cause of cancer death in women. From the current treatment situation, in addition to developing chemoresistant tumours, distant organ metastasis, and recurrences, patients with breast cancer often have a poor prognosis. Aptamers as "chemical antibodies" may be a way to resolve this dilemma. Aptamers are single-stranded, non-coding oligonucleotides (DNA or RNA), resulting their many advantages, including stability for long-term storage, simplicity of synthesis and function, and low immunogenicity, a high degree of specificity and antidote. Aptamers have gained popularity as a method for diagnosing and treating specific tumors in recent years. This article introduces the application of ten different aptamer delivery systems in the treatment and diagnosis of breast cancer, and systematically reviews their latest research progress in breast cancer treatment and diagnosis. It provides a new direction for the clinical treatment of breast cancer.

PD-L1 siRNA-hyaluronic acid conjugate for dual-targeted cancer immunotherapy

"Foreignization" of tumor cells via delivery of a non-self foreign antigen (Ag) into tumors is an appealing strategy to initiate anti-tumor immunity that can facilitate tumor rejection by pre-existing foreign-Ag-reactive T cells. However, the immune-suppressive factors in the tumor microenvironment (TME) limit the durable and potent immune response of these cells against tumor antigens, stressing the need for improved tumor-foreignization strategies. Here, we demonstrate that blockade of programmed cell death ligand 1 (PD-L1) on both tumor cells and dendritic cells (DCs) can markedly potentiate the induction of tumor-reactive T cells, thereby strengthening the anti-tumor immunity ignited by tumor-foreignization. Specifically, we developed a polymeric nanoconjugate (PEG-HA-OVA/PPLs), consisting of siPD-L1-based polyplexes, PEGylated hyaluronic acid as the CD44-targeting moiety, and ovalbumin (OVA) as a model foreign antigen. Notably, PEG-HA-OVA/PPLs were simultaneously delivered into CD44^high tumor cells and CD44^high DCs, leading to efficient cross-presentation of OVA and downregulation of PD-L1 in both cell types. Importantly, the nanoconjugate not only allowed OVA-specific T cells to vigorously reject the foreignized tumor cells but also reprogrammed the TME to elicit robust T-cell responses specific to the endogenous tumor Ags, eventually generating long-lasting protective immunity. Thus, our combination strategy represents an innovative approach for the induction of potent tumor immunity via a two-step consecutive immune boost against exogenous and endogenous tumor Ags.

Radiosensitization of breast cancer cells using AS1411 aptamer-conjugated gold nanoparticles

BACKGROUND

Gold nanoparticles (GNPs) have been used to sensitize cancer cells and enhance the absorbed dose delivered to such cells. Active targeting can provide specific effect and higher uptake of the GNPs in the tumor cells, while having small effect on healthy cells. The aim of this study was to assess the possible radiosensitiazation effect of GNPs conjugated with AS1411 aptamer (AS1411/GNPs) on cancer cells treated with 4 MeV electron beams.

MATERIALS AND METHODS

Cytotoxicity studies of the GNPs and AS1411/GNPs were carried out with MTT and MTS assay in different cancer cell lines of MCF-7, MDA-MB-231 and mammospheres of MCF-7 cells. Atomic absorption spectroscopy confirmed the cellular uptake of the gold particles. Radiosensitizing effect of the GNPs and AS1411/GNPs on the cancer cells was assessed by clonogenic assay.

RESULT

AS1411 aptamer increased the Au uptake in MCF-7 and MDA-MB-231 cells. Clonogenic survival data revealed that AS1411/GNPs at 12.5 mg/L could result in radiosensitization of the breast cancer cells and lead to a sensitizer enhancement ratio of 1.35 and 1.66 and 1.91 for MCf-7, MDA-MB-231 and mammosphere cells.

CONCLUSION

Gold nanoparticles delivery to the cancer cells was enhanced by AS1411 aptamer and led to enhanced radiation induced cancer cells death. The combination of our clonogenic assay and Au cell uptake results suggested that AS1411 aptamer has enhanced the radiation-induced cell death by increasing Au uptake. This enhanced sensitization contributed to cancer stem cell-like cells to 4 MeV electron beams. This is particularly important for future preclinical testing to open a new insight for the treatment of cancers.

Construction of a tumor microenvironment pH-responsive cleavable PEGylated hyaluronic acid nano-drug delivery system for colorectal cancer treatment

In order to improve active tumor targeting, tumor cell uptake efficiency and circulation time of doxorubicin (DOX) in vivo, we constructed a cleavable PEGylated hyaluronic acid nano-drug delivery system (HA-mPEG2k-DOX) based on a tumor microenvironment pH-responsive imine bond. In this study, HA-mPEG2k-DOX can self-assemble into stable nanoparticles (HA-mPEG2k-DOX NPs) with a particle size of 50 nm. And the NPs can efficiently target CD44 positive CT26 cells and the pH-responsive cleavable PEG shell can be detached under weakly acidic environments and effectively promote the cellular uptake of HA-DOX NPs. Compared with DOX·HCl, the HA-mPEG2k-DOX NPs can significantly increase the DOX circulation time by 12.5 times, efficiently target the tumor tissues of CT26 tumor-bearing mice and remain for 72 hours. Therefore, the antitumor results in vivo indicated that the HA-mPEG2k-DOX NPs have the best anti-tumor effect while reducing the toxicity of the DOX. Overall, the cleavable PEGylated HA-mPEG2k-DOX NPs responding to pH-sensitive imine bonds, while actively targeting CD44-positive tumor cells, improve the dilemma of cellular uptake and delivery by the PEGylated nano delivery system.

Hyaluronic Acid-Based Activatable Nanomaterials for Stimuli-Responsive Imaging and Therapeutics: Beyond CD44-Mediated Drug Delivery

There is a rapidly increasing interest in developing stimuli-responsive nanomaterials for treating a variety of diseases. By enabling the activation of function locally at the sites of interest, it is possible to increase therapeutic efficacy significantly while simultaneously reducing adverse side effects. While there are many sophisticated nanomaterials available, they are often highly complex and not easily transferrable to industrial scales and clinical settings. However, nanomaterials based on hyaluronic acid offer a compelling strategy for reducing their complexity while retaining several desirable benefits such as active targeting and stimuli-responsive degradation. Herein, the basic properties of hyaluronic acid, its binding partners, and natural routes for degradation by hyaluronidases-hyaluronic-acid-degrading enzymes-and oxidative stresses are discussed. Recent advances in designing hyaluronic acid-based, actively targeted, hyaluronidase- or reactive-oxygen-species-responsive nanomaterials for both diagnostic imaging and therapeutic delivery, which go beyond merely the classical targeting of CD44, are summarized.

CXCR4-Receptor-Targeted Liposomes for the Treatment of Peritoneal Fibrosis

Peritoneal fibrosis (PF) is a common complication of long-term peritoneal dialysis (PD). It is considered as the main reason for dialysis inadequacy and PD withdrawal. Transforming growth factor beta (TGF-β) regulates the expression of stromal cell-derived factor 1 (SDF-1α) and its receptor C-X-C chemokine receptor type 4 (CXCR4) on human peritoneal mesothelial cells (HPMCs), resulting in an increased migratory potential of HPMCs and extracellular matrix (ECM) deposition in the scar tissue and eventually fibrosis. Because SDF-1α/CXCR4 activation has a vital role in the pathogenesis of PF, codelivery of a CXCR4-receptor targeting agent with an antifibrotic agent in a single nanocarrier can be a promising strategy for treating PF. Here, for the first time, AMD3100 (AMD), a CXCR4-receptor antagonist, was coformulated with sulfotanshinone IIA sodium (STS IIA) into a liposome (STS-AMD-Lips) to develop a CXCR4 receptor targeting form of combination therapy for PF. CXCR4 targeting increased the ability of liposomes to target fibrotic peritoneal mesothelial cells overexpressing CXCR4 and facilitated the ability of STS IIA treatment at the fibrotic site. The liposome had an average diameter of 103 nm with encapsulated efficiencies of above 50%. The in vivo studies confirmed the reversal of PD solution-induced epithelial-to-mesenchymal transition by STS-AMD-Lips in HPMCs. The in vivo studies also revealed the precise biodistribution of the liposomes to peritoneum. Significant reduction of the morphological lesions and decreased level of ECM proteins were observed in rats treated with STS-AMD-Lips, proving that the liposomal nanocarrier has excellent ability to reverse PF. It has been concluded that the STS-AMD-Lips exhibit specific peritoneal targeting ability and could be used to improve STS-AMD combination delivery for the treatment of PF.

Hyaluronan-based delivery of therapeutic oligonucleotides for treatment of human diseases

INTRODUCTION

Oligonucleotide therapeutics such as antisense oligonucleotides and siRNA requires chemical modifications and nano-sized carriers to circumvent stability problems in vivo, to reach target tissues, and to overcome tissue and cellular barriers. Hyaluronic acid (HA), already utilized in drug delivery and tissue engineering, possess properties that are useful to solve these problems and achieve full potential of oligonucleotide therapeutics.

AREAS COVERED

Complexes of oligonucleotide therapeutics with HA are discussed in terms of interactions providing the complexes formation and genes targeted by the therapeutics to cure diseases such as cancer, atherosclerosis, liver cirrhosis, and inflammation. The achieved therapeutic effects are rationalized as consequences of biodistribution, cell internalization and endosomal escape provided by HA.

EXPERT OPINION

Design of electrostatic, coordination, and hydrophobic interactions as well as covalent conjugation between oligonucleotide drugs, HA macromolecules and intermediate ligands are crucial for carrier-cargo association and dissociation under different conditions to impart oligonucleotides stability in vivo, their accumulation in diseased organs, cellular uptake, and dissociation in cytoplasm intact. These are the delivery factors that provides eventual complex formation of oligonucleotide therapeutics with their mRNA, microRNA, or protein targets. Elucidation of the impact of structural parameters of oligonucleotide/HA complexes on their therapeutic effect in vivo is important for the future rational design of the delivery agents.

Current status and future perspectives of gold nanoparticle vectors for siRNA delivery

Discovering the vast therapeutic potential of siRNA opened up new clinical research areas focussing on a number of diseases and applications; however significant problems with siRNA stability and delivery have hindered its clinical applicability. As a result, interest in the development of practical siRNA delivery systems has grown in recent years. Of the numerous siRNA delivery strategies currently on offer, gold nanoparticles (AuNPs) stand out thanks to their biocompatibility and capacity to protect siRNA against degradation; not to mention the versatility offered by their tuneable shape, size and optical properties. Herein this review provides a complete summary of the methodologies for functionalizing AuNPs with siRNA, paying singular attention to the AuNP shape, size and surface coating, since these key factors heavily influence cellular interaction, internalization and, ultimately, the efficacy of the hybrid particle. The most noteworthy hybridization strategies have been highlighted along with the most innovative and outstanding in vivo studies with a view to increasing clinical interest in the use of AuNPs as siRNA nanocarriers.

Poly(N-isopropylacrylamide) derived nanogels demonstrated thermosensitive self-assembly and GSH-triggered drug release for efficient tumor Therapy

Recently, interest in stimuli-responsive core–shell nanogels as drug delivery systems for tumor therapy has increased.

CD44 targeting biocompatible and biodegradable hyaluronic acid cross-linked zein nanogels for curcumin delivery to cancer cells: In vitro and in vivo evaluation

In this study, we developed novel hyaluronic acid cross-linked zein nanogels (HA-Zein NGs) to deliver the potential anticancer agent curcumin (CRC), a naturally occurring phytochemical drug in cancer cells. In vitro studies showed that they are highly compatible with the tested cell lines. They showed CD44 specific uptake in CT26 cell line more than by the CD44 receptor pre-inhibited CT26 cells. The CRC encapsulated HA-Zein NGs (HA-Zein-CRC NGs) found to exert a specific toxicity against CT26 sparing healthy normal fibroblast cells in vitro. The apoptotic effects were further confirmed with flow cytometry showing that the HA-Zein-CRC NGs exhibited high anticancer activity against the CT26 cells. The in vivo bio-distribution with a CT26 tumor model showed their high tumor accumulation thereby improved antitumor efficacy with a low dosage of CRC, compared to the previous reports. Thus, the preclinical studies clearly showed that these novel HA-Zein NGs would be highly beneficial in encapsulating hydrophobic drugs with improved pharmacokinetics thereby enhancing the therapeutic outcomes.

One-step gene delivery into the cytoplasm in a fusion-dependent manner based on a new membrane fusogenic lipid

A new type of membrane fusogenic lipid was prepared to deliver DNA or siRNA into the cytoplasm directly in a fusion-dependent manner in order to bypass the cellular endocytosis to avoid the inefficient escape from the endosome and low transfection efficacy.

Bioreducible Cross-Linked Hyaluronic Acid/Calcium Phosphate Hybrid Nanoparticles for Specific Delivery of siRNA in Melanoma Tumor Therapy

This study introduces a novel cross-linking strategy capable of successfully stabilizing CaP nanoparticles and stimuli-responsive small interfering RNA (siRNA) release. We synthesized a polysaccharide derivative thiolated hyaluronic acid (HA-SH), which was slightly modified but multifunctional and developed a smart redox-responsive delivery system. siRNA was efficaciously condensed by calcium phosphate (CaP) via electrostatic interaction to form a positively charged inner "core". Disulfide cross-linked HA (HA-ss-HA) was formed and played a role as an anionic outer "shell" to stabilize the CaP core. We demonstrated that the nanoparticles were stable both in the storage milieu and systemic circulation, thus overcoming the most serious disadvantage of CaP nanoparticles for gene delivery. Meanwhile, this smart system could selectively release siRNA into the cytosol by both a GSH-triggered disassembly and successful endosomal escape. Therefore, the hybrid delivery system achieved an 80% gene-silencing efficiency in vitro for both luciferase and Bcl2. Silencing of Bcl2 resulted in dramatic apoptosis of B16F10 cells. Besides, equipped with the tumor-targeting component HA, the nanoparticles significantly suppressed the growth of B16F10 xenograft tumor in mice. The anionic HA-ss-HA-equipped nanoparticles showed no apparent toxicity in vitro or in vivo, as well as showed a high transfection efficiency. Taken together, this redox-responsive, tumor-targeting smart anionic nanoparticle holds great promise for exploitation in functionalized siRNA delivery and tumor therapy.

Gold-stabilized carboxymethyl dextran nanoparticles for image-guided photodynamic therapy of cancer

Photodynamic therapy (PDT) has been extensively investigated to treat cancer since it induces cell death through the activation of photosensitizers by light.