Targeted multifunctional redox-sensitive micelle co-delivery of DNA and doxorubicin for the treatment of breast cancer

Polymeric-Micelle-Based Delivery Systems for Nucleic Acids

Nucleic acids can modulate gene expression specifically. They are increasingly being utilized and show huge potential for the prevention or treatment of various diseases. However, the clinical translation of nucleic acids faces many challenges due to their rapid clearance after administration, low stability in physiological fluids and limited cellular uptake, which is associated with an inability to reach the intracellular target site and poor efficacy. For many years, tremendous efforts have been made to design appropriate delivery systems that enable the safe and effective delivery of nucleic acids at the target site to achieve high therapeutic outcomes. Among the different delivery platforms investigated, polymeric micelles have emerged as suitable delivery vehicles due to the versatility of their structures and the possibility to tailor their composition for overcoming extracellular and intracellular barriers, thus enhancing therapeutic efficacy. Many strategies, such as the addition of stimuli-sensitive groups or specific ligands, can be used to facilitate the delivery of various nucleic acids and improve targeting and accumulation at the site of action while protecting nucleic acids from degradation and promoting their cellular uptake. Furthermore, polymeric micelles can be used to deliver both chemotherapeutic drugs and nucleic acid therapeutics simultaneously to achieve synergistic combination treatment. This review focuses on the design approaches and current developments in polymeric micelles for the delivery of nucleic acids. The different preparation methods and characteristic features of polymeric micelles are covered. The current state of the art of polymeric micelles as carriers for nucleic acids is discussed while highlighting the delivery challenges of nucleic acids and how to overcome them and how to improve the safety and efficacy of nucleic acids after local or systemic administration.

A multi-bioresponsive self-assembled nano drug delivery system based on hyaluronic acid and geraniol against liver cancer

Herein, a multi-bioresponsive self-assembled nano-drug delivery system (HSSG) was constructed by conjugating the anticancer drug Geraniol (GER) to hyaluronic acid (HA) via a disulfide bond. The HSSG NPs displayed a uniform spherical shape with an average diameter of ∼110 nm, maintained high stability, and realized controlled drug release in the tumor microenvironment (pH/glutathione/hyaluronidase). Results of fluorescence microscopy and flow cytometry verified that HSSG NPs were selectively uptaken by human hepatocellular carcinoma cell lines HepG2 and Huh7 via CD44 receptor-mediated internalization. Studies on H22 tumor-bearing mice demonstrate that HSSG NPs could effectively accumulate at the tumor site for a long period. In vitro and in vivo studies show that HSSG NPs significantly promoted the death of cancer cells while reducing the toxicity as compared to GER. Therefore, the HSSG NPs have great potential in the treatment of tumors.

Multifunctional nanoparticle for cancer therapy

Cancer is a complex disease associated with a combination of abnormal physiological process and exhibiting dysfunctions in multiple systems. To provide effective treatment and diagnosis for cancer, current treatment strategies simultaneously focus on various tumor targets. Based on the rapid development of nanotechnology, nanocarriers have been shown to exhibit excellent potential for cancer therapy. Compared with nanoparticles with single functions, multifunctional nanoparticles are believed to be more aggressive and potent in the context of tumor targeting. However, the development of multifunctional nanoparticles is not simply an upgraded version of the original function, but involves a sophisticated system with a proper backbone, optimized modification sites, simple preparation method, and efficient function integration. Despite this, many well-designed multifunctional nanoparticles with promising therapeutic potential have emerged recently. Here, to give a detailed understanding and analyzation of the currently developed multifunctional nanoparticles, their platform structures with organic or inorganic backbones were systemically generalized. We emphasized on the functionalization and modification strategies, which provide additional functions to the nanoparticle. We also discussed the application combination strategies that were involved in the development of nanoformulations with functional crosstalk. This review thus provides an overview of the construction strategies and application advances of multifunctional nanoparticles.

Polymeric Micelles for Breast Cancer Therapy: Recent Updates, Clinical Translation and Regulatory Considerations

With the growing burden of cancer, parallel advancements in anticancer nanotechnological solutions have been witnessed. Among the different types of cancers, breast cancer accounts for approximately 25% and leads to 15% of deaths. Nanomedicine and its allied fields of material science have revolutionized the science of medicine in the 21st century. Novel treatments have paved the way for improved drug delivery systems that have better efficacy and reduced adverse effects. A variety of nanoformulations using lipids, polymers, inorganic, and peptide-based nanomedicines with various functionalities are being synthesized. Thus, elaborate knowledge of these intelligent nanomedicines for highly promising drug delivery systems is of prime importance. Polymeric micelles (PMs) are generally easy to prepare with good solubilization properties; hence, they appear to be an attractive alternative over the other nanosystems. Although an overall perspective of PM systems has been presented in recent reviews, a brief discussion has been provided on PMs for breast cancer. This review provides a discussion of the state-of-the-art PMs together with the most recent advances in this field. Furthermore, special emphasis is placed on regulatory guidelines, clinical translation potential, and future aspects of the use of PMs in breast cancer treatment. The recent developments in micelle formulations look promising, with regulatory guidelines that are now more clearly defined; hence, we anticipate early clinical translation in the near future.

Safe magnetic resonance imaging on biocompatible nanoformulations

Magnetic resonance imaging (MRI) holds promise for the early clinical diagnosis of various diseases, but most clinical MR techniques require the use of a contrast medium. Several nanomaterial (NM) mediated contrast agents (CAs) are widely used as T1- and T2-based MR contrast agents for clinical and non-clinical applications. Unfortunately, most NM-based CAs are toxic or non-biocompatible, restricting their practical/clinical applications. Therefore, the development of nontoxic and biocompatible CAs for clinical MRI diagnosis is highly desired. To this end, several biocompatible and biomimetic strategies have been developed to offer long blood circulation time, significant biocompatibility, in vivo biodistribution and high contrast ability for efficient imaging. However, detailed review reports on biocompatible NMs, specifically for MR imaging have not yet been summarized. Thus, in the present review we summarize  various surface coating strategies (such as polymers, proteins, cell membranes, etc.) to achieve biocompatible NPs, providing a detailed discussion of advances and future prospects for safe MRI imaging.

Polyethyleneimine (PEI) as a Polymer-Based Co-Delivery System for Breast Cancer Therapy

Cancer has become one of the leading causes of morbidity and mortality worldwide. This disease is classified broadly by tissue, organ, and system; different cancer types and subtypes require different treatments. Drug bioavailability, selectivity, and high dosage, as well as extended treatment, are significantly associated with the development of resistance – a complex problem in cancer therapy. It is expected that the combination of anticancer drugs and drug delivery systems, using polymers to increase the access of such agents to their site of action, will improve the efficacy of therapy. Polyethyleneimine (PEI) is a polymer used as a co-delivery system for anticancer drugs and gene therapy. PEI is also useful for other purposes, such as transfection and bio-adsorbent agents. In co-delivery, PEI can promote drug internalization. However, PEI with a high molecular weight is linked to higher cytotoxicity, thus requiring further evaluation of clinical safety. This review focuses on the utilization of PEI as a co-delivery system for anticancer therapy, as well as its potential to overcome resistance, particularly in the treatment of specific subtypes (eg, breast cancer). In conclusion, PEI has promising applications and is improvable for the development of anticancer drugs.

Construction of GSH-triggered cationic fluoropolymer as two-in-one nanoplatform for combined chemo/gene therapy

The combined chemo-gene therapy has become a promising approach for enhanced anti-cancer treatment. However, effective co-delivery of therapeutic gene and drug into target cells and tissues remains a major obstacle....

H2O2-Responsive amphiphilic polymer with aggregation-induced emission (AIE) for DOX delivery and tumor therapy

Stimuli-responsive drug delivery systems (DDSs) based on amphiphilic polymers have attracted much attention. In this study, we reported an innovative H₂O₂-responsive amphiphilic polymer (TBP), bearing a H₂O₂-sensitive phenylboronic ester, AIE fluorophore tetraphenylethene (TPE) hydrophobic, and polyethylene glycol hydrophilic (PEG) moieties. TBP could self-assemble into micelles with an encapsulation efficiency as high as 74.9% for doxorubicin (DOX) in aqueous solution. In the presence of H₂O₂, TBP micelles was decomposed by oxidation, hydrolysis and rearrangement, leading to almost 80% DOX release from TBP@DOX micelles. TBP and the corresponding degradation products were biocompatible, while TBP@DOX micelles only displayed obvious toxicity toward cancer cells. Drug delivery process was clearly monitored by confocal laser scanning microscopic (CLSM) and flow cytometry (FCM) analysis. Moreover, in vivo anticancer study showed that TBP@DOX micelles were accumulated in tumor region of nude mice and effectively inhibited tumor growth. The results suggested that the reported H₂O₂-responsive amphiphilic polymer displayed great potential in drug delivery and tumor therapy.

Multi-functional polymeric micelles for chemotherapy-based combined cancer therapy

Currently, the therapeutic performance of traditional mono-chemotherapy on cancers remains unsatisfactory because of the tumor heterogeneity and multidrug resistance. In light of intricate tumor structures and distinct tumor microenvironments (TMEs), combinational therapeutic strategies with multiple anticancer drugs from different mechanisms can synergistically optimize the outcomes and concomitantly minimize the adverse effects during the therapy process. Extensive research on polymeric micelles (PMs) for biomedical applications has revealed the growing importance of nanomedicines for cancer therapy in the recent decade. Starting from traditional simple delivery systems, PMs have been extended to multi-faceted therapeutic strategies. Here we review and summarize the most recent advances in combinational therapy based on multifunctional PMs including a combination of multiple anticancer drugs, chemo-gene therapy, chemo-phototherapy and chemo-immunotherapy. The design approaches, action mechanisms and therapeutic applications of these nanodrugs are summarized. In addition, we highlight the opportunities and potential challenges associated with this promising field, which will provide new guidelines for advanced combinational cancer chemotherapy.

A four-in-one pure nanomedicine for synergistic multi-target therapy against breast cancer

Designing a multi-target nanomedicine without a carrier is pivotal for successful cancer nanotherapy. This study details a novel four-in-one RRX/BMS/CA4/PTX nanomedicine by simple nanoprecipitation. In this multi-target pure nanomedicine, paclitaxel (PTX) causes the immunogenic cell death of 4T1 tumour cells and the differentiation of marrow-derived suppressor cells (MDSCs) into dendritic cells (DCs) at low dose; repertaxin (RRX) selectively depletes cancer stem cells (CSCs) that are not killed by paclitaxel to inhibit lung metastasis from the breast; BMS-1 blocks the PD-1/PD-L1 pathway for proliferating effector T cells; and combretastatin A4 (CA4) targets tumour microvessels to cut off the blood supply in the tumour microenvironment. The synergy of multi-target therapies results in excellent antitumour effects. The tumour inhibition rate of 4T1 tumours is 92.5%, and the lung metastasis suppression rate exceeds 90%; no relapse is observed at 46 days after the treatment endpoint, and the survival of 50% of mice is prolonged by 95 days. Due to the low dose of PTX administration, the systemic toxicity of the RRX/BMS/CA4/PTX nanomedicine is not found. Our results suggest a strategy for designing multi-target pure nanomedicines with simple construction and efficacious therapeutic responses that present potential for clinical transformation.

CD147 Monoclonal Antibody Targeted Reduction-Responsive Camptothecin Polyphosphoester Nanomedicine for Drug Delivery in Hepatocellular Carcinoma Cells

In the treatment of tumor-targeted small-molecule anti-cancer drugs, antibody-mediated therapies, especially for antibody-drug conjugates (ADCs), have revealed great latent force. However, the therapeutic drugs provided by ADCs possess limitation. Considering that the combination of antibodies and nano-drugs can broaden their applicability in the field of tumor treatment, herein, we developed an antibody conjugated polymeric prodrug nanoparticles SAE-PEG-b-PBYP-ss-CPT for targeted camptothecin (CPT) delivery to liver tumor cells. The diblock copolymer was composed of PEG and biodegradable polyphosphoester (PBYP) containing alkynyl groups in the side chain. A derivative of CPT (CPT-ss-N₃) was bonded to the PBYP via "click" reaction. The diethyl squarate (SAE) in the terminal of PEG chain was used as a functional group to bond with CD147 monoclonal antibody (CD147 mAb). The particle size and size distribution of the both nanoparticles, with antibody binding (namely CD147-CPT NPs) and without antibody (abbreviated as CPT-loaded NPs), were measured by dynamic light scattering (DLS). The morphologies of both two kinds of nanoparticles were observed by transmission electron microscope (TEM). The results of X-ray photoelectron spectroscopy (XPS) showed that CD147 mAb had been coupled to the surface of CPT-loaded NPs. Endocytosis test indicated that CD147-CPT NPs had higher uptake rate and accumulation in HepG2 cells than those of CPT-loaded NPs without antibodies, due to CD147 mAb can specifically bind to CD147 protein overexpressed in HepG2 cells. We establish a method to bond monoclonal antibodies to anti-cancer polymeric prodrugs, and endow biodegradable polymeric prodrugs with precise targeting functions to liver cancer cells.

Fabrication of aminated poly(glycidyl methacrylate)-based polymers for co-delivery of anticancer drugs and the p53 gene

Aminated poly(glycidyl methacrylate)s-based polymers for gene delivery not only can reduce toxicity and improve solubility, but can improve gene transfection efficiency and reduce protein aggregation. In this study, we first prepared poly(glycidyl methacrylate) (PGMA) via reversible addition-fragmentation chain transfer (RAFT) polymerization, and then the obtained PGMA homopolymer was post-modified with ethanol amine (EA), 1-amino-2-propanol (AP), 3-(dibutylamino)propylamine (DA) and N-(2-hydroxyethyl)ethylenediamine (HA), respectively, to yield four kinds of PGMA-based gene vectors containing hydroxyl groups (abbreviated as PGEA, PGAP, PGDA and PGHA). The effects of the different side chains and hydroxyl groups on the biological properties of these four cationic polymers were investigated. We found that the transfection efficiency of the PGHA/p53 complex was higher than those of the other three polymer/gene complexes through MTT assay and laser scanning confocal microscopy. Hence, we chose HA for further post-modification to fabricate a cationic copolymer, PCL-ss-P(PEGMA-co-GHA) (abbreviated as PGHAP), via a combination of ring opening polymerization (ROP) and RAFT copolymerization. The PCL-ss-P(PEGMA-co-GHA) amphiphilic copolymer could self-assemble into nanoparticles, which could be used to encapsulate anticancer drug doxorubicin (DOX) and compress the p53 gene to form the DOX-loaded PCL-ss-P(PEGMA-co-GHA)/p53 complex (abbreviated as DPGHAP/p53). The gel retardation assay showed that p53 gene could be well immobilized and remained stable under the electronegative conditions. MTT assay showed that the DPGHAP/p53 complex had a significant antitumor effect on A549 cells and H1299 cells compared with free DOX or/and p53 gene therapy alone. Furthermore, the test results from live cell imaging systems revealed that the DPGHAP/p53 complexes could effectively deliver DOX and the p53 gene into A549 cells. Therefore, the constructed cationic polymer PCL-ss-P(PEGMA-co-GHA) has potential application prospects as a co-vector of anticancer drugs and genes.

Targeting Delivery Nanocarriers for (+)-Terrein to Enhance Its Anticancer Effects

As a compound from marine fungi, (+)-terrein showed significant anticancer activity. In this study, (+)-terrein was extracted from the marine-derived fungus and showed significant cytotoxicity against cancer cells, especially in A549 cells. To enhance its anticancer effects, redox-responsive nanocarriers based on folic acid-chitosan decorating the mesoporous silica nanoparticles were designed to control (+)-terrein target delivery into cancer cells. (+)-Terrein was loaded in the holes, and folic acid-chitosan worked as a gatekeeper by disulfide linkage controlling (+)-terrein release in the tumor microenvironment. The (+)-terrein drug delivery systems exhibited cytotoxicity toward A549 cells through induction of apoptosis. The apoptosis effect was confirmed by the increase in the expression of cleaved caspase-3, caspase-9, and PARP. Taken together, this work evaluates for the first time the (+)-terrein delivery system and provides a promising nanomedicine platform for (+)-terrein.

Doxorubicin-loaded iron oxide nanoparticles for glioblastoma therapy: a combinational approach for enhanced delivery of nanoparticles

Although doxorubicin (DOX) is an effective anti-cancer drug with cytotoxicity in a variety of different tumors, its effectiveness in treating glioblastoma multiforme (GBM) is constrained by insufficient penetration across the blood–brain barrier (BBB). In this study, biocompatible magnetic iron oxide nanoparticles (IONPs) stabilized with trimethoxysilylpropyl-ethylenediamine triacetic acid (EDT) were developed as a carrier of DOX for GBM chemotherapy. The DOX-loaded EDT-IONPs (DOX-EDT-IONPs) released DOX within 4 days with the capability of an accelerated release in acidic microenvironments. The DOX-loaded EDT-IONPs (DOX-EDT-IONPs) demonstrated an efficient uptake in mouse brain-derived microvessel endothelial, bEnd.3, Madin–Darby canine kidney transfected with multi-drug resistant protein 1 (MDCK-MDR1), and human U251 GBM cells. The DOX-EDT-IONPs could augment DOX’s uptake in U251 cells by 2.8-fold and significantly inhibited U251 cell proliferation. Moreover, the DOX-EDT-IONPs were found to be effective in apoptotic-induced GBM cell death (over 90%) within 48 h of treatment. Gene expression studies revealed a significant downregulation of TOP II and Ku70, crucial enzymes for DNA repair and replication, as well as MiR-155 oncogene, concomitant with an upregulation of caspase 3 and tumor suppressors i.e., p53, MEG3 and GAS5, in U251 cells upon treatment with DOX-EDT-IONPs. An in vitro MDCK-MDR1-GBM co-culture model was used to assess the BBB permeability and anti-tumor activity of the DOX-EDT-IONPs and DOX treatments. While DOX-EDT-IONP showed improved permeability of DOX across MDCK-MDR1 monolayers compared to DOX alone, cytotoxicity in U251 cells was similar in both treatment groups. Using a cadherin binding peptide (ADTC5) to transiently open tight junctions, in combination with an external magnetic field, significantly enhanced both DOX-EDT-IONP permeability and cytotoxicity in the MDCK-MDR1-GBM co-culture model. Therefore, the combination of magnetic enhanced convective diffusion and the cadherin binding peptide for transiently opening the BBB tight junctions are expected to enhance the efficacy of GBM chemotherapy using the DOX-EDT-IONPs. In general, the developed approach enables the chemotherapeutic to overcome both BBB and multidrug resistance (MDR) glioma cells while providing site-specific magnetic targeting.

Polymer-mediated gene therapy: Recent advances and merging of delivery techniques

The ability to safely and precisely deliver genetic materials to target sites in complex biological environments is vital to the success of gene therapy. Numerous viral and nonviral vectors have been developed and evaluated for their safety and efficacy. This study will feature progress in synthetic polymers as nonviral vectors, which benefit from their chemical versatility, biocompatibility, and ability to carry both therapeutic cargo and targeting moieties. The combination of synthetic gene carrying constructs with advanced delivery techniques promises new therapeutic options for treating and curing genetic disorders. This article is characterized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Sgc8 aptamer targeted glutathione-responsive nanoassemblies containing Ara-C prodrug for the treatment of acute lymphoblastic leukemia

Cytarabine (Ara-C) is an essential medicine used in the clinical treatment of acute lymphoblastic leukemia. However, Ara-C suffers from high hydrophilicity, rapid plasma degradation and significant side effects. Thus, herein, to eliminate the limitations of Ara-C in the treatment of leukemia, Sgc8 aptamer targeting and glutathione (GSH)-responsive polymeric micelles (PCL-ss-Ara@Sgc8-BSA) were prepared. The prodrug was synthesized via covalent bond formation between acryloyl chloride-terminal PCL-ss-PCL and Ara-C, and surface decoration with Sgc8-bovine serum albumin (Sgc8-BSA). The obtained PCL-ss-Ara@Sgc8-BSA exhibited good GSH-responsive drug release behavior, obvious targetability and sufficient antitumor effect to acute lymphoblastic leukemia (ALL) cells (CCRF-CEM). A hemolysis test was further carried out to demonstrate that these polymeric micelles are safe to be administrated intravenously. Compared with free Ara-C, PCL-ss-Ara@Sgc8-BSA significantly enhanced tumor growth inhibition in mice bearing CCRF-CEM xenograft tumors, while causing little side effects, and improved the survival rate of CCRF-CEM tumor-bearing mice in vivo. Therefore, this new self-assembling small molecular prodrug equipped with Sgc8 targeting function is a potential treatment for the targeted therapy of acute lymphoblastic leukemia.

Stepwise pH-sensitive and biodegradable polypeptide hybrid micelles for enhanced cellular internalization and efficient nuclear drug delivery

The short blood circulation time, reduced cellular uptake, and uncontrollable drug release still hinder the polymer micelle as an efficient drug delivery vehicle in clinical applications. In this study, a series of stepwise pH-sensitive and biodegradable polypeptide hybrid terpolymers, poly (lysine-co-N,N-bis(acryloyl) cystamine-co-dimethylmaleic anhydride) (PLB-DMMA), were designed and synthesized to achieve prolonged circulation time, enhanced cellular uptake and controllable anti-cancer drug release. The synthesized terpolymers can self-assemble into spherical nano-micelles (NMs) with narrow distributions and exhibited stepwise responses to extracellular and intracellular pH condition of the tumor cell. The as prepared NMs showed a negative surface charge under normal physiological conditions exhibiting advantageous stability during blood circulation. By the first-step pH response, the surface charge of the NMs switched from negative to positive to enhance cellular uptake under the slightly acidic tumor extracellular environment. After internalization into tumor cells, the second-step pH response resulted in an endosome escape of the NMs via the "proton-sponge" effect in the acidic endo/lysosome environment. Additionally, a rapid drug release was triggered in response to the intracellular reductive environment of tumor cells via the destruction of disulfide-linked polymer chains to enhance the nucleus delivery of DOX. in vitro cell assays showed that the blank NMs showed negligible systemic toxicity against normal cells while the DOX-loaded NMs significantly inhibited growth of the tumor cells. In general, it was suggested that the as developed stepwise pH-sensitive and biodegradable PLB-DMMA based NMs would be a smart and promising drug delivery candidate for anti-cancer chemotherapy.

Multifunctional titanium phosphate nanoparticles for site-specific drug delivery and real-time therapeutic efficacy evaluation

Receptor-targeted delivery systems have been proposed as means of concentrating therapeutic agents to improve therapeutic effects on disease sites and reduce side effects on normal issues. Herein, we synthesized biocompatible folic acid (FA)-functionalized DHE-modified TiP (TiP-PAH-DHE-FA) nanoparticles as a drug delivery system that possessed high drug loading capability and enhanced folate-receptor-mediated cellular uptake. Moreover, it also allowed drug effect evaluation based on the real-time monitoring of the fluorescence intensity of HE molecules that are triggered by intercellular ROS. This acquired drug delivery system provided a novel platform to integrate efficient cell-specific drug delivery with real-time monitoring of therapeutic efficacy.

Biodegradable polyester unimolecular systems as emerging materials for therapeutic applications

Unimolecular micelles, as a class of single-molecular micelles, are structurally stable regardless of their concentrations or alterations of the outer environment such as pH, temperature, ion strength etc. in comparison with conventional polymeric micelles. Polyester unimolecular micelles are extensively applied in bio-medical fields because of their stability, biocompatibility, biodegradability, structural-controllabilty etc. In this review, the most recent developments in polyester unimolecular micelle designs in terms of Boltorn polymer H40 core, cyclodextrin, dendrimer or dendrimer-like polymer, or polyhedral oligomeric silsesquioxane (POSS) based polyester unimolecular micelles are presented. The significance and application in biomedical fields including drug delivery, bio-imaging and theranostics are also classified in this review. Finally, the remaining challenges and future perspectives for further development of unimolecular micelles as therapeutic materials are also discussed.