Polymeric Nanovectors Research Articles

Coumarin-poly(2-oxazoline)s as synergetic and protein-undetected nanovectors for photodynamic therapy

Because of the difficult challenges of nanopharmaceutics, the development of a variety of nanovectors is still highly desired. Photodynamic therapy, which uses a photosensitizer to locally produce reactive oxygen species to kill the undesired cells, is a typical example for which encapsulation has been shown to be beneficial. The present work describes the use of coumarin-functionalized polymeric nanovectors based on the self-assembly of amphiphilic poly(2-oxazoline)s. Encapsulation of pheophorbide a, a known PDT photosensitizer, is shown to lead to an increased efficiency compared to the un-encapsulated version. Interestingly, the presence of coumarin both enhances the desired photocytotoxicity and enables the crosslinking of the vectors. Various nanovectors are examined, differing by their size, shape and hydrophilicity. Their behaviour in PDT protocols on HCT-116 cells monolayers is described, the influence of their crosslinking commented. Furthermore, the formation of a protein corona is assessed.

Optimizing TDP-43 silencing with siRNA-loaded polymeric nanovectors in neuronal cells for therapeutic applications: balancing knockdown and function.

TAR DNA-binding protein 43 (TDP-43) is a ubiquitously expressed DNA/RNA binding protein critical for regulating gene expression, including transcription, splicing, mRNA stability, and protein translation. Aggregation of pathological TDP-43 proteins in the cytoplasm of neurons and glial cells appears to be a common feature of amyotrophic lateral sclerosis (ALS) and other neurodegenerative diseases such as frontotemporal dementia (FTD), contributing to motor neuron degeneration and clinical symptoms. Downregulation of TDP-43 expression to prevent or reduce the formation of pathological aggregates is a potential therapeutic approach for treating TDP-43-related diseases. However, therapeutic strategies to reduce TDP-43 aggregation face significant challenges, as the downregulation of TDP-43 must balance the need to maintain its normal functions, which are essential for RNA metabolism and cellular homeostasis. In this study, we developed novel polymeric nanovectors for the delivery of TDP-43 siRNAs in neuronal cells. These nanovectors were designed to provide adequate TDP-43 silencing to achieve the desired functional reduction of TDP-43 levels, thereby optimizing its impact on cellular functions. Our results demonstrate that the polymeric nanovector formulations effectively reduced TDP-43 mRNA and protein levels to an extent comparable to those observed with traditional lipid-based systems. Concurrently, the polymeric nanovectors exhibited an enhanced capacity to reduce stress granules (SG) formation and facilitate TDP-43-containing SG disassembly, while preserving its essential cellular functions. This study provides the first evidence that polymeric nanovectors may be a valuable tool for developing therapeutic strategies to treat TDP-43 protein diseases, such as ALS and FTD, by directly silencing TDP-43 to reduce its aggregation.

Dendritic peptide-conjugated polymeric nanovectors for non-toxic delivery of plasmid DNA and enhanced non-viral transfection of immune cells

SummaryPlasmid DNA (pDNA) transfection is advantageous for gene therapies requiring larger genetic elements, including “all-in-one” CRISPR/Cas9 plasmids, but is limited by toxicity as well as poor intracellular release and transfection efficiency in immune cell populations. Here, we developed a synthetic non-viral gene delivery platform composed of poly(ethylene glycol)-b-poly(propylene sulfide) copolymers linked to a cationic dendritic peptide (DP) via a reduceable bond, PEG-b-PPS-ss-DP (PPDP). A library of self-assembling PPDP polymers was synthesized and screened to identify optimal constructs capable of transfecting macrophages with small (pCMV-DsRed, 4.6 kb) and large (pL-CRISPR.EFS.tRFP, 11.7 kb) plasmids. The optimized PPDP construct transfected macrophages, fibroblasts, dendritic cells, and T cells more efficiently and with less toxicity than a commercial Lipo2K reagent, regardless of pDNA size and under standard culture conditions in the presence of serum. The PPDP technology described herein is a stimuli-responsive polymeric nanovector that can be leveraged to meet diverse challenges in gene delivery.

Dendritic Peptide-Conjugated Polymeric Nanovectors for Nontoxic Delivery of Plasmid DNA and Enhanced Non-Viral Transfection of Immune Cells

Dendritic Peptide-Conjugated Polymeric Nanovectors for Nontoxic Delivery of Plasmid DNA and Enhanced Non-Viral Transfection of Immune Cells

Optimizing cisplatin delivery to triple-negative breast cancer through novel EGFR aptamer-conjugated polymeric nanovectors

BackgroundManagement of triple-negative breast cancer (TNBC) is still challenging because of its aggressive clinical behavior and limited targeted treatment options. Cisplatin represents a promising chemotherapeutic compound in neoadjuvant approaches and in the metastatic setting, but its use is limited by scarce bioavailability, severe systemic side effects and drug resistance. Novel site-directed aptamer-based nanotherapeutics have the potential to overcome obstacles of chemotherapy. In this study we investigated the tumor targeting and the anti-tumorigenic effectiveness of novel cisplatin-loaded and aptamer-decorated nanosystems in TNBC.MethodsNanotechnological procedures were applied to entrap cisplatin at high efficacy into polymeric nanoparticles (PNPs) that were conjugated on their surface with the epidermal growth factor receptor (EGFR) selective and cell-internalizing CL4 aptamer to improve targeted therapy. Internalization into TNBC MDA-MB-231 and BT-549 cells of aptamer-decorated PNPs, loaded with BODIPY505-515, was monitored by confocal microscopy using EGFR-depleted cells as negative control. Tumor targeting and biodistribution was evaluated by fluorescence reflectance imaging upon intravenously injection of Cyanine7-labeled nanovectors in nude mice bearing subcutaneous MDA-MB-231 tumors. Cytotoxicity of cisplatin-loaded PNPs toward TNBC cells was evaluated by MTT assay and the antitumor effect was assessed by tumor growth experiments in vivo and ex vivo analyses.ResultsWe demonstrate specific, high and rapid uptake into EGFR-positive TNBC cells of CL4-conjugated fluorescent PNPs which, when loaded with cisplatin, resulted considerably more cytotoxic than the free drug and nanovectors either unconjugated or conjugated with a scrambled aptamer. Importantly, animal studies showed that the CL4-equipped PNPs achieve significantly higher tumor targeting efficiency and enhanced therapeutic effects, without any signs of systemic toxicity, compared with free cisplatin and untargeted PNPs.ConclusionsOur study proposes novel and safe drug-loaded targeted nanosystems for EGFR-positive TNBC with excellent potential for the application in cancer diagnosis and therapy.

Polymeric Nanovectors Incorporated with Ganciclovir and HSV-tk Encoding Plasmid for Gene-Directed Enzyme Prodrug Therapy.

In the area of gene-directed enzyme prodrug therapy (GDEPT), using herpes simplex virus thymidine kinase (HSV-tk) paired with prodrug ganciclovir (GCV) for cancer treatment has been extensively studied. It is a process involved with two steps whereby the gene (HSV-tk) is first delivered to malignant cells. Afterward, non-toxic GCV is administered to that site and activated to cytotoxic ganciclovir triphosphate by HSV-tk enzyme expressed exogenously. In this study, we presented a one-step approach that both gene and prodrug were delivered at the same time by incorporating them with polymeric micellar nanovectors. GCV was employed as an initiator in the ring-opening polymerization of ε-caprolactone (ε-CL) to synthesize hydrophobic GCV-poly(caprolactone) (GCV–PCL), which was furthered grafted with hydrophilic chitosan to obtain amphiphilic polymer (GCV–PCL–chitosan) for the fabrication of self-assembled micellar nanoparticles. The synthesized amphiphilic polymer was characterized using Fourier transform infrared spectroscopy and proton nuclear magnetic resonance. Micellar prodrug nanoparticles were analyzed by dynamic light scattering, zeta potential, critical micelle concentration, and transmission electron microscopy. Polymeric prodrug micelles with optimal features incorporated with HSV-tk encoding plasmids were cultivated with HT29 colorectal cancer cells and anticancer effectiveness was determined. Our results showed that prodrug GCV and HSV-tk cDNA encoded plasmid incorporated in GCV–PCL–chitosan polymeric nanocarriers could be delivered in a one-step manner to HT-29 cells and triggered high cytotoxicity.

Fabrication of smart polymeric nanovectors to amplify intracellular oxidative stress for chemodynamic therapy

<p indent=0mm>Cellular homeostasis is of crucial importance for cell functions and the imbalance of cellular homeostasis is closely correlated to cell dysfunctions and diseases. For instance, the elevation of oxidative stress is recognized as a hallmark of cancer cells. Recently, it is of increasing interest to develop polymeric nanovectors responsive to endogenous oxidative stress. However, these nanovectors suffer from insufficient sensitivity. Since cancer cells can be directly killed by a high level of oxidative stress, the development of polymeric nanovectors to upregulate intracellular oxidative stress for cancer treatment has emerged as chemodynamic therapy (CDT), which could be accomplished by either boosting reactive oxygen species (ROS) generation or suppressing intracellular antioxidative systems. In this article, we summarize the different methodologies to amplify intracellular oxidative stress with selective examples. This new therapeutic strategy not only can be directly used for cancer therapy but also can be readily integrated with other therapeutic approaches such as chemotherapy to achieve improved therapeutic outcomes.

Recent advances in “bioartificial polymeric materials” based nanovectors

AbstractThis chapter analyzes the advantages of the use of bioartificial polymers as carriers and the main strategies used for their design. Despite the enormous progresses in this field, more studies are required for the fully evaluation of these nanovectors in complex organisms and for the characterization of the pharmacodynamic and pharmacokinetic of the loaded drugs. Moreover, progresses in polymer chemistry are introducing a wide range of functionalities in the bioartificial polymeric material (BPM) nanostructures leading to a second generation of bioartificial polymer therapeutics based on novel and heterogeneous architectures with higher molecular weight and predictable structures, in order to achieve greater multivalency and increased loading capacity. Therefore, research on bioartificial polymeric nanovectors is an “on-going” field capable of attracting medical interest.

Polymeric self-assemblies for photodynamic therapy: A critical approach

The work presented here suggests a new approach in the critical development of polymeric nanovectors for photodynamic therapy (PDT) against cancer. Whereas hundreds of studies quickly jump forward from formation of self-assemblies to biological application without having a thorough examination of the vector solution, we suggest having a parallel assessment of formation/characterization of the nanovectors and biological activity [1]. This is possible by first using a careful physical chemistry characterization of the vectors by both batch techniques (light and neutron scattering, electron microscopy, atomic force microscopy) and Asymmetrical Flow Field-Flow Fractionation (AsFlFFF) coupled to adequate detectors (refractometry, light scattering) [2]. This enables us to fully characterize the vectors regarding purity, size and zeta potential.

Design maps for cellular uptake of gene nanovectors by computer simulation

Understanding how nanovectors transport DNA molecules through cell membranes is of great importance in gene therapy. In this paper, we systematically investigate the mechanism of cellular uptake of cationic polymeric nanovectors containing DNA molecules through dissipative particle dynamics simulations. Our results show that the property of polyelectrolyte chains grafted to nanovector and DNA molecules can have important impacts on the endocytosis. Interestingly, it is found that the nanovector can be fully taken up with proper number of DNA molecules on its surface. On the contrary, in the absence of DNA it may become harder to be totally engulfed. Since the adsorption number of DNA is related to external pH, the cellular uptake could exhibit pH-responsive behavior. Further, we also provide insights into the comparison of uptake behaviors between cancer and normal cells, and importantly, we find that the enhanced uptake of gene nanovectors may be an inherent property of cancer cells. The present study may give some significant suggestions on future nanovector design for gene delivery.

Drug delivery by polymeric nanoparticles induces autophagy in macrophages

Drug delivery nanosystems are currently used in human therapy. In preliminary studies we have observed that Eudragit ® RS nanoparticles, prepared by nanoprecipitation or double emulsion techniques, are cytotoxic for NR8383 rat macrophages. In this study, we expand our previous analysis and suggest that unloaded Eudragit ® RS nanoparticles prepared by nanoprecipitation (NP/ERS) may induce important morphological and biochemical cellular modifications leading to cellular death. In NR8383 rat macrophages cell line exposed to doses varying from 15 to 100 μg/mL, NP/ERS nanoparticles are internalized inside the cells, reach the mitochondria and alter the structure of these organelles. In addition, the exposure to nanoparticles induces cellular autophagy as demonstrated by electron microscopy analysis, microchip array, qRT-PCR and Western blot assays. Although toxicity of nanoparticles has already been evidenced, it is the first time that results show clearly that the toxicity of polymeric nanovectors may be related to an activation of autophagy.

Intracellular pathways and nuclear localization signal peptide-mediated gene transfection by cationic polymeric nanovectors

Polyethylenimine (PEI) - based polymers are promising cationic nanovectors. A good understanding of the mechanism by which cationic polymers/DNA complexes are internalized and delivered to nuclei helps to identify which transport steps may be manipulated in order to improve the transfection efficiency. In this work, cell internalization and trafficking of PEI-CyD (PC) composed of β-cyclodextrin (β-CyD) and polyethylenimine (PEI, Mw 600) are studied. The results show that the PC transfected DNA is internalized by binding membrane-associated proteoglycans. The endocytic pathway of the PC particles is caveolae- and clathrin-dependent with both pathways converging to the lysosome. The intracellular fate of the PC provides visual evidence that it can escape from the lysosome. Lysosomal inhibition with chloroquine has no effect on PC mediated transfection implying that blocking the lysosomal traffic does not improve transfection. To improve the nuclear delivery of PC transfected DNA, nuclear localization signal (NLS) peptides are chosen to conjugate and combine with the PC. Compared to PC/pDNA, PC-NLS/pDNA, and PC/pDNA/NLS can effectively improve gene transfection in dividing and non-dividing cells.

Gene delivery to tumor cells by cationic polymeric nanovectors coupled to folic acid and the cell-penetrating peptide octaarginine

Target ligand folic acid (FA) and cell-penetrating peptide octaarginine (R8) were coupled with the gene vectors (PEI 600-CyD, PC) composed of β-cyclodextrin (β-CyD) and low-molecular-weight polyethylenimine (PEI, Mw 600) to form nanovectors for highly efficient gene delivery to tumor cells. The resultant ternary nanocomplexes of FA-PC/R8-PC/pDNA produced excellent gene transfaction abilities in the folate receptor (FR)-positive tumor cells in vitro and in vivo. The FR-mediated endocytosis and the R8-mediated transmembrane functionality together contributed to the high transfection levels. This study provides a promising means to produce gene nanovectors for in vivo applications.

Abstract 5488: Merging structure-activity relationship and nanotechnology to re-engineer cisplatin

Abstract The use of nanovectors holds the potential to revolutionize cancer chemotherapy by specifically targeting tumor. A number of polymeric nanovectors are currently in development or in clinics, and are dramatically altering the pharmacodynamics and pharmacokinetics profile of the active agent. However, most of these polymeric constructs decrease the potency of the conjugated active agent, relying on increased uptake into the tumor for the improved therapeutic index. Furthermore, the nanovector formulation of small molecules such as cisplatin, which is a first-line therapy for multiple cancers, has been a challenge. So there is an urgent need to design a nanoparticle which will release a drug at its target site without decreasing efficacy of cisplatin. In the present study, we synthesized cisplatin-poly-isobutylene-maleic acid modified with glucosamine conjugate, which self assembles into nanoparticles with unique size depending on cisplatin to polymer ratio. The poly-isobutylene-maleic acid modification with glucosamine, mimicking glycans, not only increases hydrophilicity but also gives unique structural facilitation to polymer backbone so it can hold cisplatin by caboxylato and coordinate bond. The release kinetics of these nanoparticles reveals that the cisplatin release is pH dependent, and is released faster in lower pH than neutral or basic condition. We found that the these nanoparticles were taken up by cancer cells within 6 hours and inhibited proliferation and induced apoptosis in lung and breast cancer cells in vitro. In an in vivo lung and breast cancer models, the nanoparticles reduce tumor growth significantly with reduced systemic toxicity as compared to free cisplatin. In conclusion we have demonstrated that rationally re-engineered cisplatin nanoparticles improved therapeutic index for lung, breast and transgenic ovarian murine cancer models, which can be harnessed in the clinical management of cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5488.

Peptide- and Aptamer-Functionalized Nanovectors for Targeted Delivery of Therapeutics

Targeted delivery of therapeutics is an area of vigorous research, and peptide- and aptamer-functionalized nanovectors are a promising class of targeted delivery vehicles. Both peptide- and aptamer-targeting ligands can be readily designed to bind a target selectively with high affinity, and more importantly are molecules accessible by chemical synthesis and relatively compact compared with antibodies and full proteins. The multitude of peptide ligands that have been used for targeted delivery are covered in this review, with discussion of binding selectivity and targeting performance for these peptide sequences where possible. Aptamers are RNA or DNA strands evolutionarily engineered to specifically bind a chosen target. Although use of aptamers in targeted delivery is a relatively new avenue of research, the current state of the field is covered and promises of future advances in this area are highlighted. Liposomes, the classic drug delivery vector, and polymeric nanovectors functionalized with peptide or aptamer binding ligands will be discussed in this review, with the exclusion of other drug delivery vehicles. Targeted delivery of therapeutics, from DNA to classic small molecule drugs to protein therapeutics, by these targeted nanovectors is reviewed with coverage of both in vitro and in vivo deliveries. This is an exciting and dynamic area of research and this review seeks to discuss its broad scope.

Long-Circulating Polymeric Nanovectors for Tumor-Selective Gene Delivery

Significant advances in the understanding of the genetic abnormalities that lead to the development, progression, and metastasis of neoplastic diseases has raised the promise of gene therapy as an approach to medical intervention. Most of the clinical protocols that have been approved in the United States for gene therapy have used the viral vectors because of the high efficiency of gene transfer. Conventional means of gene delivery using viral vectors, however, has undesirable side effects such as insertion of mutational viral gene into the host genome and development of replication competent viruses. Among non-viral gene delivery methods, polymeric nanoparticles are increasingly becoming popular as vectors of choice. The major limitation of these nanoparticles is poor transfection efficiency at the target site after systemic administration due to uptake by the cells of reticuloendothelial system (RES). In order to reduce the uptake by the cells of the RES and improve blood circulation time, these nanoparticles are coated with hydrophilic polymers such as poly(ethylene glycol) (PEG). This article reviews the use of such hydrophilic polymers employed for improving the circulation time of the nanocarriers. The mechanism of polymer coating and factors affecting the circulation time of these nanocarriers will be discussed. In addition to the long circulating property, modifications to improve the target specificity of the particles and the limitations of steric protection will be analyzed.