Efficientin vivogene transfection by stable DNA/PEI complexes coated by hyaluronic acid

Interaction of γ-Polyglutamic Acid/Polyethyleneimine/Plasmid DNA Ternary Complexes with Serum Components Plays a Crucial Role in Transfection in Mice

Typical examples of non-viral vectors are binary complexes of plasmid DNA with cationic polymers such as polyethyleneimine (PEI). However, problems such as cytotoxicity and hemagglutination, owing to their positively charged surfaces, hinder their in vivo use. Coating binary complexes with anionic polymers, such as γ-polyglutamic acid (γ-PGA), can prevent cytotoxicity and hemagglutination. However, the role of interactions between these complexes and serum components in in vivo gene transfer remains unclear. In this study, we analyzed the contribution of serum components to in vivo gene transfer using PEI/plasmid DNA binary complexes and γ-PGA/PEI/plasmid DNA ternary complexes. In binary complexes, heat-labile components in the serum greatly contribute to the hepatic and splenic gene expression of the luciferase gene. In contrast, serum albumin and salts affected the hepatic and splenic gene expression in the ternary complexes. Changes in physicochemical characteristics, such as increased particle size and decreased absolute values of ζ-potential, might be involved in the enhanced gene expression. These findings would contribute to a better understanding of in vivo non-viral gene transfer using polymers, such as PEI and γ-PGA.

Tuning the Potency of Farnesol-Modified Polyethylenimine with Polyanionic Trans-Booster to Enhance DNA Delivery

Low molecular weight polyethylenimine (PEI) based lipopolymers become an attractive strategy to construct nonviral therapeutic carriers with promising transfection efficiency and minimal toxicity. Herein, this paper presents the design and synthesis of novel farnesol (Far) conjugated PEI, namely PEI1.2k-SA-Far7. The polymers had quick DNA complexation, effective DNA unpacking (dissociation), and cellular uptake abilities when complexed with plasmid DNA. However, they were unable to provide robust transfection in culture, indicating inability of Far grafting to improve the transfection efficacy significantly. To overcome this limitation, the commercially available polyanionic Trans-Booster additive, which is capable of displaying electrostatic interaction with PEI1.2k-SA-Far7, has been used to enhance the uptake of pDNA polyplexes and transgene expression. pDNA condensation was successfully achieved in the presence of the Trans-Booster with more stable polyplexes, and in vitro transfection efficacy of the polyplexes was improved to be comparable to that obtained with an established reference reagent. The PEI1.2k-SA-Far7/pDNA/Trans-Booster ternary complex exhibited good compatibility with cells and minimal hemolysis activity. This work demonstrates the exemplary potency of using additives in polyplexes and the potential of resultant ternary complexes for effective pDNA delivery.

Tailoring Gene Transfer Efficacy through the Arrangement of Cationic and Anionic Blocks in Triblock Copolymer Micelles

The arrangement of charged segments in triblock copolymer micelles affects the gene delivery potential of polymeric micelles and can increase the level of gene expression when an anionic segment is incorporated in the outer shell. Triblock copolymers were synthesized by RAFT polymerzation with narrow molar mass distributions and assembled into micelles with a hydrophobic core from poly(n-butyl acrylate). The ionic shell contained either (i) an anionic segment followed by a cationic segment (HAC micelles) or (ii) a cationic block followed by an anionic block (HCA micelles). The pH-responsive anionic block contained 2-carboxyethyl acrylamide (CEAm), while the cationic block comprised 3-guanidinopropyl acrylamide (GPAm). Increasing the molar content of CEAm in HAC and HCA micelles from 6 to 13 mol % improved cytocompatibility and the endosomal escape property, while the HCA micelle with the highest mol % of anionic charges in the outer shell exhibited the highest gene expression. It became evident that improved membrane interaction of the best performing HCA micelle contributed to achieving high gene expression.

Potential roles of hyaluronic acid in in vivo CAR T cell reprogramming for cancer immunotherapy

Chimeric antigen receptor (CAR) T cell therapy has recently shown unprecedented clinical efficacy for cancer treatment, particularly of hematological malignancies. However, the complex manufacturing processes that involve ex vivo genetic modification of autologous T cells limits its therapeutic application. CAR T cells generated in vivo provide a valid alternative immunotherapy, "off-the-shelf", for cancer treatment. This approach requires carriers for the delivery of CAR-encoding constructs, which are plasmid DNA or messenger RNA, to T cells for CAR expression to help eradicate the tumor. As such, there are a growing number of studies reporting gene delivery systems for in vivo CAR T cell therapy based on viral vectors and polymeric nanoparticles. Hyaluronic acid (HA) is a natural biopolymer that can serve for gene delivery, because of its inherent properties of cell recognition and internalization, as well as its biodegradability, biocompatibility, and presence of functional groups for the chemical conjugation of targeting ligands. In this review, the potential of HA in the delivery of CAR constructs is discussed on the basis of previous experience of HA-based nanoparticles for gene therapy. Furthermore, current studies on CAR carriers for in vivo-generated CAR T cells are included, giving an idea of a rational design of HA-based systems for the more efficient delivery of CAR to circulating T cells.

Modified hyaluronic acid-collagen matrices trigger efficient gene transfer and prohealing behavior in fibroblasts for improved wound repair

Growth factor therapy has demonstrated great promise for chronic wound repair, but controlling growth factor activity and cell phenotype over desired time frames remains a critical challenge. In this study, we developed a gene-activated hyaluronic acid-collagen matrix (GAHCM) comprising DNA/polyethylenimine (PEI) polyplexes retained on hyaluronic acid (HA)-collagen hydrogels using collagen mimetic peptides (CMPs). We hypothesized that manipulating both the number of CMP-collagen tethers and the ECM composition would provide a powerful strategy to control growth factor gene transfer kinetics while regulating cell behavior, resulting in enhanced growth factor activity for wound repair. We observed that polyplexes with 50% CMP-modified PEI (50 CP) showed enhanced retention of polyplexes in HCM hydrogels by 2.7-fold as compared to non-CMP modified polyplexes. Moreover, the incorporation of HA in the hydrogel promoted a significant increase in gene transfection efficiency based upon analysis of Gaussia luciferase (GLuc) reporter gene expression, and gene expression could be attenuated by blocking HA-CD44 signaling. Furthermore, when fibroblasts were exposed to vascular endothelial growth factor-A (VEGF-A)-GAHCM, the 50 CP matrix facilitated sustained VEGF-A production for up to 7 days, with maximal expression at day 5. Application of these VEGF-A-50 CP samples stimulated prolonged pro-healing responses, including the TGF-β1-induced myofibroblast-like phenotypes and enhanced closure of murine splinted wounds. Overall, these findings demonstrate the use of ECM-based materials to stimulate efficient gene transfer and regulate cellular phenotype, resulting in improved control of growth factor activity for wound repair. GAHCM have significant potential to overcome key challenges in growth factor therapy for regenerative medicine. STATEMENT OF SIGNIFICANCE: Despite great promise for growth factor therapies in wound treatment, controlling growth factor activity and providing a microenvironment for cells that maximizes growth factor signaling have continued to limit the success of existing formulations. Our GAHCM strategy, combining CMP gene delivery and hyaluronic acid-collagen matrix, enabled enhanced wound healing efficacy via the combination of controlled and localized growth factor expression and matrix-mediated regulation of cell behavior. Incorporation of CMPs and HA in the same matrix synergistically enhanced VEGF activity as compared with simpler matrices. Accordingly, GAHCM will advance our ability to leverage growth factor signaling for wound healing, resulting in new long-term treatments for recalcitrant wounds.

Synthesis of self-assembled hyaluronan based nanoparticles and their applications in targeted imaging and therapy

Hyaluronan (HA) is a polysaccharide consisting of repeating disaccharides of N-acetyl-d-glucosamine and d-glucuronic acid. There are increasing interests in utilizing self-assembled HA nanoparticles (HA-NPs) for targeted imaging and therapy. The principal endogenous receptor of HA, cluster of differentiation 44 (CD44), is overexpressed on many types of tumor cells as well as inflammatory cells in human bodies. Active targeting from HA-CD44 mediated interaction and passive targeting due to the enhanced permeability retention (EPR) effect could lead to selective accumulation of HA-NPs at targeted disease sites. This review focuses on the synthesis strategies of self-assembled HA-NPs, as well as their applications in therapy and biomedical imaging.

pH-Sensitive Polymers as Dynamic Mediators of Barriers to Nucleic Acid Delivery

The nonviral delivery of exogenous nucleic acids (NA) into cells for therapeutic purposes has rapidly matured into tangible clinical impact. Synthetic polymers are particularly attractive vectors for NA delivery due to their relatively inexpensive production compared to viral alternatives and their highly tailorable chemical properties; indeed, many preclinical investigations have revealed the primary biological barriers to nonviral NA delivery by systematically varying polymeric material properties. This review focuses on applications of pH-sensitive chemistries that enable polymeric vectors to serially address multiple biological barriers to NA delivery. In particular, we focus on recent innovations with in vivo evaluation that dynamically enable colloidal stability, cellular uptake, endosomal escape, and nucleic acid release. We conclude with a summary of successes to date and projected areas for impactful future research.

In vitro and in vivo gene delivery using chitosan/hyaluronic acid nanoparticles: Influences of molecular mass of hyaluronic acid and lyophilization on transfection efficiency

BACKGROUND

Lyophilization is an effective method for preserving nonviral gene vectors. To improve the stability and transgene expression of lyophilized plasmid DNA (pDNA) complexes, we coated the surfaces of pDNA/chitosan complexes with hyaluronic acid (HA) of varying molecular masses. The transgene expression of pDNA/chitosan/HA ternary complexes was characterized in vitro and in vivo.

METHODS

pDNA complexes were lyophilized overnight and the resultant products with spongy, porous consistencies were stored at -30, 4 or 25°C for 2 weeks. Rehydrated complexes were characterized using gel retardation assays, aiming to confirm complex formation, measure particle size and evaluate zeta potential, as well as conduct luciferase gene reporter assays. The anti-tumor effects of pDNA ternary complexes were evaluated using suicide gene (pTK) coding thymidine kinase in Huh7-implanted mice.

RESULTS

Transfection efficiencies of pDNA/chitosan/HA ternary complexes were dependent on the average molecular masses of HA. The coating of pDNA/chitosan complexes with HA maintained the cellular transfection efficiencies of lyophilized pDNA ternary complexes. Furthermore, intratumoral injection of lyophilized, rehydrated pDNA ternary complexes into tumor-bearing mice showed a significant suppression of tumor growth.

CONCLUSIONS

The coating of pDNA/chitosan complexes with high-molecular-weight HA augmented the stability and cellular transfection ability of the complexes after lyophilization-rehydration.

Indocyanine Green-Conjugated Magnetic Prussian Blue Nanoparticles for Synchronous Photothermal/Photodynamic Tumor Therapy

Indocyanine green (ICG) is capable of inducing a photothermal effect and the production of cytotoxic reactive oxygen species for cancer therapy. However, the major challenge in applying ICG molecules for antitumor therapy is associated with their instability in aqueous conditions and rapid clearance from blood circulation, which causes insufficient bioavailability at the tumor site. Herein, we conjugated ICG molecules with Prussian blue nanoparticles enclosing a Fe₃O₄ nanocore, which was facilitated by cationic polyethyleneimine via electrostatic adsorption. The nanocarrier-loaded ICG formed stable aggregates that enhanced cellular uptake and prevented fluorescence quenching. Moreover, the strong superparamagnetism of the Fe₃O₄ core in the obtained nanocomposites further improved cellular internalization of the drugs guided by a localized magnetic field. The therapeutic efficacy of this nanoplatform was evaluated using tumor models established in nude mice, which demonstrated remarkable tumor ablation in vivo due to strong photothermal/photodynamic effects. This study provides promising evidence that this multifunctional nanoagent might function as an efficient mediator for combining photothermal and photodynamic cancer therapy.

Exosomes derived from tumor cells genetically modified to express Mycobacterium tuberculosis antigen: a novel vaccine for cancer therapy

OBJECTIVES

To examine the potential of exosomes derived from the tumor cells, which had been genetically modified to express a Mycobacterium tuberculosis antigen, as a cancer vaccine aimed at overcoming the weak immunogenicity of tumor antigens.

RESULTS

We transfected B16 melanoma cells with a plasmid encoding the M. tuberculosis antigen, early secretory antigenic target-6 (ESAT-6). The secreted exosomes bearing both tumor-associated antigens and the pathogenic antigen (or their epitopes) were collected. When the exosomes were injected into foot pads of mice, they significantly (p < 0.05) evoked cellular immunity against both ESAT-6, and B16 tumor cells. Intra-tumoral injection of the exosomes significantly suppressed (p < 0.001) tumor growth in syngeneic B16 tumor-bearing mice, while the exosomes derived from the non-transfected B16 cells showed no effect on tumor growth, although both exosomes should have similar tumor antigens.

CONCLUSIONS

Exosomes bearing both tumor antigens and the M. tuberculosis antigen (or their epitopes) have a high potential as a candidate for cancer vaccine to overcome the immune escape by tumor cells.

Activated Charge-Reversal Polymeric Nano-System: The Promising Strategy in Drug Delivery for Cancer Therapy

Various polymeric nanoparticles (NPs) with optimal size, tumor-targeting functionalization, or microenvironment sensitive characteristics have been designed to solve several limitations of conventional chemotherapy. Nano-sized polymeric drug carrier systems have remarkably great advantages in drug delivery and cancer therapy, which are still plagued with severe deficiencies, especially insufficient cellular uptake. Recently, surface charge of medical NPs has been demonstrated to play an important role in cellular uptake. NPs with positive charge show higher affinity to anionic cell membranes such that with more efficient cellular internalization, but otherwise cause severe aggregation and fast clearance in circulation. Thus, surface charge-reversal NPs, specifically activated at the tumor site, have shown to elegantly resolve the enhanced cellular uptake in cancer cells vs. non-specific protein adsorption dilemma. Herein, this review mainly focuses on the effect of tumor-site activated surface charge reversal NPs on tumor treatment, including the activated mechanisms and various applications in suppressing cancer cells, killing cancer stem cell and overcoming multidrug resistance, with the emphasis on recent research in these fields. With the comprehensive and in-depth understanding of the activated surface charge reversal NPs, this approach might arouse great interest of scientific research on enhanced efficient polymeric nano-carriers in cancer therapy.

Biomedical Biopolymers, their Origin and Evolution in Biomedical Sciences: A Systematic Review

Biopolymers provide a plethora of applications in the pharmaceutical and medical applications. A material that can be used for biomedical applications like wound healing, drug delivery and tissue engineering should possess certain properties like biocompatibility, biodegradation to non-toxic products, low antigenicity, high bio-activity, processability to complicated shapes with appropriate porosity, ability to support cell growth and proliferation and appropriate mechanical properties, as well as maintaining mechanical strength. This paper reviews biodegradable biopolymers focusing on their potential in biomedical applications. Biopolymers most commonly used and most abundantly available have been described with focus on the properties relevant to biomedical importance.

Highly Effective Non-Viral Antitumor Gene Therapy System Comprised of Biocompatible Small Plasmid Complex Particles Consisting of pDNA, Anionic Polysaccharide, and Fully Deprotected Linear Polyethylenimine

We have reported that ternary complexes of plasmid DNA with conventional linear polyethylenimine (l-PEI) and certain polyanions were very stably dispersed, and, with no cryoprotectant, they could be freeze-dried and re-hydrated without the loss of transfection ability. These properties enabled the preparation of a concentrated suspension of very small pDNA complex, by preparing the complexes at highly diluted conditions, followed by condensation via lyophilization-and-rehydration procedure. Recently, a high potency linear polyethylenimine having no residual protective groups, i.e., Polyethylenimine “Max” (PEI “Max”), is available, which has been reported to induce much higher gene expression than conventional l-PEI. We tried to prepare the small DNA/PEI “Max”/polyanion complexes by a similar freeze-drying method. Small complex particles could be obtained without apparent aggregation, but transfection activity of the rehydrated complexes was severely reduced. Complex-preparation conditions were investigated in details to achieve the freeze-dried DNA/PEI “Max”/polyanion small ternary complexes with high transfection efficiency. DNA/PEI “Max”/polyanion complexes containing cytokine-coding plasmids were then prepared, and their anti-tumor therapeutic efficacy was examined in tumor-bearing mice.

Evaluation of biocompatible alginate- and deferoxamine-coated ternary composites for magnetic resonance imaging and gene delivery into glioblastoma cells

BACKGROUND

This paper describes comparative studies in cytotoxicities, magnetic resonance imaging (MRI), and gene delivery into glioblastoma U87MG or U138MG cells with ternary composites that are consist of superparamagnetic iron oxide (SPIO) nanoparticles (NPs) (size: 8-10 nm) with different surface coatings, circular plasmid DNA (pDNA) (~4 kb) equipped with fluorescent/luminescent probe, and branched polyethylenimine (25 kDa, PDI 2.5).

METHODS

Three types of SPIO-NPs were used, including: (I) naked iron oxide NPs with Fe-OH surface group (Bare-NP); (II) iron oxide NPs with a coating of alginate (Alg-NPs); and (III) iron oxide NPs with a coating of deferoxamine (Def-NPs). By tuning the polyethylenimine (PEI)/NP ratios and with a fixed DNA amount, different ternary composites were employed for NP/gene transfection into glioblastoma U87MG or U138MG cells, which were then characterized by Prussian blue staining, in vitro MRI, green fluorescence protein (GFP) fluorescence and luciferase assay.

RESULTS

Among the composites prepared, 0.2 ng PEI/0.5 µg DNA/1.0 µg Bare-NP ternary composite possessed the best cellular uptake efficiency of NP to the cytoplasm, following the trend Bare-NP > Alg-NP > Def-NP. This observation was consistent to the MRI assessments with in vitro T 2 relaxivity (r 2) values of 46.0, 35.5, and 23.7 s(-1)·µM(-1)·Fe, respectively. For cellular uptake efficiency of the pDNA, all variations of PEI/NP ratios of the composites did not yield significant differences. However, cellular uptake efficiencies of pDNA in the ternary composites in U138MG cells were generally higher than that of U87MG cells by an order of magnitude. Exceptionally, the ternary composite 0.2 ng PEI/0.5 µg DNA/1.0 µg Bare-NP possessed a lowered luciferase activity RLU for gene expression in U138MG cells. A total of 0.2 ng PEI/0.5 µg DNA/0.1 µg Bare-NP would be uptaken to the cell nucleus with the highest luciferase activity. A working concentration range of PEI with at least 15% higher cell viabilities than lipofectamine was 0.1 to 0.2 ng/well. The cytotoxicities became significant when 0.5 ng/well PEI was present in the ternary composites.

CONCLUSIONS

The as-prepared composites offer potential biomedical applications in simultaneous gene delivery, imaging contrast enhancement, and metabolism study.

Reversibly cross-linked polyplexes enable cancer-targeted gene delivery via self-promoted DNA release and self-diminished toxicity

Polycations often suffer from the irreconcilable inconsistency between transfection efficiency and toxicity. Polymers with high molecular weight (MW) and cationic charge feature potent gene delivery capabilities, while in the meantime suffer from strong chemotoxicity, restricted intracellular DNA release, and low stability in vivo. To address these critical challenges, we herein developed pH-responsive, reversibly cross-linked, polyetheleneimine (PEI)-based polyplexes coated with hyaluronic acid (HA) for the effective and targeted gene delivery to cancer cells. Low-MW PEI was cross-linked with the ketal-containing linker, and the obtained high-MW analogue afforded potent gene delivery capabilities during transfection, while rapidly degraded into low-MW segments upon acid treatment in the endosomes, which promoted intracellular DNA release and reduced material toxicity. HA coating of the polyplexes shielded the surface positive charges to enhance their stability under physiological condition and simultaneously reduced the toxicity. Additionally, HA coating allowed active targeting to cancer cells to potentiate the transfection efficiencies in cancer cells in vitro and in vivo. This study therefore provides an effective approach to overcome the efficiency-toxicity inconsistence of nonviral vectors, which contributes insights into the design strategy of effective and safe vectors for cancer gene therapy.

Efficient targeted gene delivery by a novel PAMAM/DNA dendriplex coated with hyaluronic acid

Aim: To design and develop a novel target-specific DNA-delivery system using hyaluronic acid (HA)–polyamidoamine (PAMAM) conjugates (P–HA). Materials & methods: The coupling of HA to the PAMAM dendrimer was analyzed by 1H-NMR and elemental analysis (CHN). Their properties were characterized in terms of size and zeta-potential and evaluated for in vitro and in vivo transfection efficiency. Results: The designed covalent HA-dendriplexes enhanced gene transfection of pCMV-Luc reporter gene in overexpressing CD44-receptor cancer cells. They were also more efficient in transfecting MDA-MB231 cells than conventional PEI-polyplexes. The cytotoxicity of the covalent HA-dendriplexes was lower than when using conventional polyethylenimine-polyplexes. In vivo studies showed that these targeted complexes were also efficient for delivering pCMVLuc in different organs of healthy mice, as well as in tumors of C57BL/6 animals. Conclusions: The HA-dendriplexes developed in this work may offer an advantageous alternative to conventional cationic polymer-based formulations for DNA delivery into cancer cells in an efficient and safe manner.

Nanoparticle delivery and combination therapy of gambogic acid and all-trans retinoic acid

In order to enhance the in vivo codelivery efficiency of gambogic acid (GA) and all-trans retinoic acid (ATRA), our strategy was to entrap GA in the self-assembled nanoparticles based on amphiphilic hyaluronic acid (HA)-ATRA (HRA) conjugate. In this way, GA and ATRA were loaded simultaneously in a nanocarrier and codelivered into the tumor cell through HA receptor-mediated endocytosis. GA-loaded HRA nanoparticles (GA-HRA) were prepared by a dialysis method, and their physicochemical characteristics were investigated as well. GA-HRA exhibited a high drug loading capacity (31.1%), had a particle size in the range of 100–150 nm, and good biocompatibility. HRA nanoparticles were effectively internalized by MCF-7 cells and translocated into the nucleus in a time-dependent manner. The in vivo imaging analysis demonstrated that the fluorescent signals in the tumor were markedly increased with DiR-loaded nanoparticles after intravenous administration compared to free DiR solution, suggesting it has excellent tumor targeting properties. More importantly, GA-HRA exhibited excellent in vivo efficacy with dramatically reduced toxicity. In conclusion, with the assistance of HRA nanoparticles, GA and ATRA can successfully realize an effective combination chemotherapy as well as tumor-targeted delivery.

Nanoparticle-DNA-polymer composites for hepatocellular carcinoma cell labeling, sensing, and magnetic resonance imaging

This paper describes comparative studies and protocols in (1) self-assembling of ultrasmall superparamagnetic iron oxide nanoparticle (NP), circular plasmid DNA, and branched polyethylenimine (PEI) composites; (2) magnetofection; (3) gene delivery, (4) magnetic resonance imaging (MRI), and (5) cytotoxicity of the composites toward hepatocellular carcinoma HepG2 cells.

Anionic polymer-coated lipoplex for safe gene delivery into tumor by systemic injection

In this study, we developed an anionic lipoplex by coating cationic lipoplex with anionic polymers such as hyaluronan (HA), chondroitin sulfate C (CS) and poly-l-glutamic acid (PLE) to deliver the plasmid DNA efficiently into the tumor by avoiding interaction with erythrocytes. The sizes of HA-, CS- and PLE-coated lipoplexes were ∼200 nm and the ζ-potentials were negative. CS- and PLE-coated lipoplexes did not induce agglutination after mixing with erythrocytes, but cationic and HA-coated lipoplexes exhibited agglutination. In terms of biodistribution and gene expression after intravenous administration, cationic and HA-coated lipoplexes largely accumulated and induced gene expression in the lung. In contrast, CS- and PLE-coated lipoplexes did not exhibit high gene expression in the lung and mainly accumulated in the liver. However, in tumor, differences in lipoplex accumulation and gene expression were not observed among the lipoplexes. In terms of toxicity after intravenous injection, CS- and PLE-coated lipoplexes did not increase tumor necrosis factor-α, aspartate aminotransferase and alanine aminotransferase concentrations in blood. From these findings, CS and PLE coatings for cationic lipoplex might produce safe systemic vectors, although they did not increase gene expression in tumor.

Efficient simultaneous tumor targeting delivery of all-trans retinoid acid and Paclitaxel based on hyaluronic acid-based multifunctional nanocarrier

An amphiphilic hyaluronic acid (HA)-g-all-trans retinoid acid (HRA) conjugate was successfully developed as a tumor-targeting nanocarrier for potentially synergistic combination chemotherapy of all-trans retinoid acid (ATRA) and paclitaxel (PTX). The HRA conjugate was synthesized by an imine reaction between HA-COOH and ATRA-NH2. PTX-loaded HRA nanoparticles possessed a high loading capacity, nanoscale particle sizes, and good biocompatible characteristics. Cell viability assays indicated that PTX-loaded HRA nanoparticles exhibited concentration- and time-dependent cytotoxicity. Moreover, they displayed obvious superiority in inducing the apoptosis of tumor cells. Cellular uptake analysis suggested that HRA nanoparticles could be efficiently taken up by cells via endocytic pathway and transport into the nucleus, contributing to HA receptor-mediated endocytosis and ATRA-induced nuclear translocation, respectively. Moreover, in vivo imaging analysis indicated that the accumulation of DiR-loaded HRA nanoparticles in tumor was increased obviously after intravenous administration as compared to free DiR solution, which confirmed that the HRA nanoparticles could assist the drugs targeting to the tumor. Furthermore, PTX-loaded HRA nanoparticles exhibited greater tumor growth inhibition effect in vivo with reducing the toxicity. Therefore, HRA nanoparticles can be considered as a promising targeted codelivery system for combination cancer chemotherapy.

Polyethyleneimine/DNA polyplexes with reduction-sensitive hyaluronic acid derivatives shielding for targeted gene delivery

The natural anionic polysaccharide hyaluronic acid (HA) was modified by introducing reduction-sensitive disulfide bond between the carboxyl groups and the backbone of HA (HA-SS-COOH). HA-SS-COOH and its corresponding unmodified stable analog HA were used to shield DNA/PEI polyplexes (DP) to form ternary complexes (DPS and DPH complexes). The shielding/deshielding effect was tested along with size, zeta potential, cell viability and transfection. Both DPS and DPH complexes showed increase in size, decrease in zeta potential and low cytotoxicity in physiological conditions due to the anionic shielding. In the reductive environment, only HA-SS-COOH coated ternary complexes (DPS) demonstrated the size increase and recovered high positive zeta potential. DPS complexes showed an up to 14-fold higher transfection than the stable coated one, indicating the efficiency of the reduction-responsive deshielding design. Moreover, the presence of extra free HA inhibited the transfection of DPS on HepG2 and B16F10 cells with HA receptor expression, while displaying no effect on non-targeted NIH3T3 cells. More rapid cellular association of DPS with HepG2 was observed, thus confirming the targeting reservation of disulfide bond modified HA. Intratumoral injection of DPS complexes resulted in much higher accumulation and luciferase expression in the tumor bearing C57BL/6 mice. Both in vitro and in vivo results demonstrated the successful combination of deshielding and target functions in HA derivatives for gene delivery.

On designing stable magnetic vectors as carriers for malaria DNA vaccine

Superparamagnetic iron oxide nanoparticles (SPIONs) can be used as therapeutic and diagnostic agents due to their unique magnetic characteristics, provided that they are stable in physiological conditions. Here, the assembly of different magnetic vector configurations comprising SPIONs, polyethylenimine (PEI), and hyaluronic acid (HA), acting as carriers for malaria DNA vaccine encoding Plasmodium yoelii merozoite surface protein MSP1-19 (VR1020-PyMSP1-19), and their stability in different cell media were investigated. The order of assembly affected vector size, surface charge, stability, and ability to bind and release DNA. Generally, all vectors showed relatively small size of less than 200 nm in water, whereas higher degree of aggregation was observed immediately after transferring to high-ionic strength media such as 150 mM NaCl buffer and RPMI 1640 culture media (Roswell Park Memorial Institute medium). However, the pre-addition of HA to DNA effectively reduced the extent of aggregation in serum-free RPMI 1640 with sizes of almost all complexes remaining below 90 nm, particularly at HA:PEI charge ratio of 100%. The presence of fetal bovine serum (FBS) in RPMI 1640 culture media further converted the surface charge of vectors from positive to negative, decreasing the size to smaller than 50 nm. Partial disassembly of some vectors was observed in water, in RPMI, and in RPMI supplemented with 10% FBS after incubation for 1h, but not in NaCl buffer, indicating that incubation of complexes in NaCl buffer prior to transfection may limit the intracellular release of plasmid DNA. DNase sensitivity assay showed that plasmid DNA vaccine encoding the PyMSP1-19 in all configurations preserved their structural integrity without damage, even after DNase I treatment for 30 min. This study demonstrated that structurally well-defined magnetic gene carriers could be designed to improve malaria DNA vaccine delivery systems, particularly for in vivo applications.

Improvement in the colloidal stability of protein kinase-responsive polyplexes by PEG modification

We have reported a disease-cell specific gene expression system that is responsive to intracellular signaling proteins (e.g., protein kinases and proteases) hyperactivated in diseased cells. For this system, cationic peptide-grafted polymers were synthesized for polyplex formation with genes. Here, we modified poly(ethylene glycol) (PEG) to a protein kinase A (PKA)-responsive polymer to improve polyplex stability. PEG modification neutralized the surface charge of the polyplex and successfully increased polyplex stability at physiological conditions. However, PEG modification (PEG contents, 0.6 and 3.3 mol %) showed almost negligible effects on the reactivity of grafted peptides to PKA and the promotion of gene expression responding to PKA activity. Excessive modification of PEG (PEG contents, 6.8 mol %) inhibited polyplex formation. These results indicate that moderate modification of PEG to the enzyme-responsive polymer improves polyplex stability without inhibiting the reaction with enzymes.

Efficient gene delivery to mesenchymal stem cells by an ethylenediamine-modified polysaccharide from mulberry leaves

This study investigates the use of a natural polysaccharide isolated from mulberry leaves as a nonviral gene vector. Ethylenediamine is chemically grafted to the backbone of a polysaccharide from mulberry leaves (MPS) to acquire nucleic acid binding affinity. A particle-size observation indicates that the cationic mulberry leaf polysaccharide (CMPS) can efficiently combine with plasmid transforming growth factor β1 (TGF-β1) to form nanoscaled particles. In addition, the electrophoresis assay indicates a retarded plasmid migration when the CMPS/pTGF-β1 weight ratio is increased to 30:1. The in vitro cell transfection experiment is performed based on bone marrow mesenchymal stem cells (MSCs) derived from rat femurs and tibias, and the findings reveal that the complex with a CMPS/pTGF-β1 weight ratio of 50:1 exhibits the highest cell transfection effect, which is significantly higher than that of branched poly(ethyleneimine) (PEI) (25 kDa; p = 0.001, Student's t-test) and slightly higher than Lipofectamine 2000. Moreover, the cytotoxicity assay also demonstrates that all of these tested complexes and the plasmid TGF-β1 are nontoxic to mesenchymal stem cells (MSCs). The results of the living cell imaging confirm that more of the CMPS/plasmid TGF-β1 nanoparticles can be taken up and at a faster rate by the MSCs than by the positive control Lipofectamine 2000; these data are consistent with the transfection efficiency data. Together, these results suggest that the CMPS/pTGF-β1 nanoparticle can potentially be developed into a promising alternative for the transfer of therapeutic genes into cells.