Amphoteric hyaluronic acid derivative for targeting gene delivery

A gene delivery system with autophagy blockade for enhanced anti-angiogenic therapy against Fusobacterium nucleatum-associated colorectal cancer

Anti-angiogenesis has emerged a promising strategy against colorectal cancer (CRC). However, the efficacy of anti-angiogenic therapy is greatly compromised by the up-regulated autophagy levels resulting from the evolutionary resistance mechanism and the presence of Fusobacterium nucleatum (F. nucleatum) in CRC. Herein, we report a cationic polymer capable of blocking autophagic flux to deliver plasmid DNA (pDNA) encoding soluble FMS-like tyrosine kinase-1 (sFlt-1) for enhanced anti-angiogenic therapy against F. nucleatum-associated CRC. The autophagy-inhibiting cationic polymer, referred to as PNHCQ, is synthesized by conjugating hydroxychloroquine (HCQ) into 3,3'-diaminodipropylamine-pendant poly(β-benzyl-L-aspartate) (PAsp(Nors)), which can be assembled and electrostatically interacted with sFlt-1 plasmid to form PNHCQ/sFlt-1 polyplexes. Hydrophobic HCQ modification not only boosts transfection efficiency but confers autophagy inhibition activity to the polymer. Hyaluronic acid (HA) coating is further introduced to afford PNHCQ/sFlt-1@HA for improved tumor targeting without compromising on transfection. Consequently, PNHCQ/sFlt-1@HA demonstrates significant anti-tumor efficacy in F. nucleatum-colocalized HT29 mouse xenograft model by simultaneously exerting anti-angiogenic effects through sFlt-1 expression and down-regulating autophagy levels exacerbated by F. nucleatum challenge. The combination of anti-angiogenic gene delivery and overall autophagy blockade effectively sensitizes CRC tumors to anti-angiogenesis, providing an innovative approach for enhanced anti-angiogenic therapy against F. nucleatum-resident CRC. STATEMENT OF SIGNIFICANCE: Up-regulated autophagy level within tumors is considered responsible for the impaired efficacy of clinic antiangiogenic therapy against CRC colonized with pathogenic F. nucleatum. To tackle this problem, an autophagy-inhibiting cationic polymer is developed to enable efficient intracellular delivery of plasmid DNA encoding soluble FMS-like tyrosine kinase-1 (sFlt-1) and enhance anti-angiogenic therapy against F. nucleatum-associated CRC. HA coating that can be degraded by tumor-enriching hyaluronidase is further introduced for improved tumor targeting without compromising transfection efficiency. The well-orchestrated polyplexes achieve considerable tumor accumulation, efficient in vivo transfection, and effectively reinforce the sensitivity of CRC to the sFlt-1-derived anti-angiogenic effects by significantly blocking overall autophagy flux exacerbated by F. nucleatum challenge, thus harvesting robust antitumor outcomes against F. nucleatum-resident CRC.

Tapping on the Potential of Hyaluronic Acid: from Production to Application

The manufacture, purification, and applications of hyaluronic acid (HA) are discussed in this article. Concerning the growing need for affordable, high-quality HA, it is essential to consider diverse production techniques using renewable resources that pose little risk of cross-contamination. Many microorganisms can now be used to produce HA without limiting the availability of raw materials and in an environmentally friendly manner. The production of HA has been associated with Streptococci A and C, explicitly S. zooepidemicus and S. equi. Different fermentation techniques, including the continuous, batch, fed-batch, and repeated batch culture, have been explored to increase the formation of HA, particularly from S. zooepidemicus. The topic of current interest also involves a complex broth rich in metabolites and residual substrates, intensifying downstream processes to achieve high recovery rates and purity. Although there are already established methods for commercial HA production, the anticipated growth in trade and the diversification of application opportunities necessitate the development of new procedures to produce HA with escalated productivity, specified molecular weights, and purity. In this report, we have enacted the advancement of HA technical research by analyzing bacterial biomanufacturing elements, upstream and downstream methodologies, and commercial-scale HA scenarios.

Multi-Targeted and On-Demand Non-Coding RNA Regulation Nanoplatform against Metastasis and Recurrence of Triple-Negative Breast Cancer

Dysregulation of microRNAs (miRs) is the hallmark of triple-negative breast cancer (TNBC), which is closely involved with its growth, metastasis, and recurrence. Dysregulated miRs are promising targets for TNBC therapy, however, targeted and accurate regulation of multiple disordered miRs in tumors is still a great challenge. Here, a multi-targeting and on-demand non-coding RNA regulation nanoplatform (MTOR) is reported to precisely regulate disordered miRs, leading to dramatical suppression of TNBC growth, metastasis, and recurrence. With the assistance of long blood circulation, ligands of urokinase-type plasminogen activator peptide and hyaluronan located in multi-functional shells enable MTOR to actively target TNBC cells and breast cancer stem cell-like cells (BrCSCs). After entering TNBC cells and BrCSCs, MTOR is subjected to lysosomal hyaluronidase-induced shell detachment, leading to an explosion of the TAT-enriched core, thereby enhancing nuclear targeting. Subsequently, MTOR could precisely and simultaneously downregulate microRNA-21 expression and upregulate microRNA-205 expression in TNBC. In subcutaneous xenograft, orthotopic xenograft, pulmonary metastasis, and recurrence TNBC mouse models, MTOR shows remarkably synergetic effects on the inhibition of tumor growth, metastasis, and recurrence due to its on-demand regulation of disordered miRs. This MTOR system opens a new avenue for on-demand regulation of disordered miRs against growth, metastasis, and recurrence of TNBC.

Enhancing the antitumor immunosurveillance of PD-L1-targeted gene therapy for metastatic melanoma using cationized Panax Notoginseng polysaccharide

Improved curative effects with reduced toxicity has always been the ultimate goal of gene delivery vectors for tumor immunotherapy. Panax notoginseng polysaccharide (PNP), a natural plant-derived macromolecule, not only has antitumor immune activity but also has the typical structural characteristics useful for gene delivery. In this work, positively charged polyethyleneimine (PEI) was directly grafted to the backbone of PNP to induced its charge reversal and generate a functional gene vector (PNP-PEI). Moreover, a short hairpin RNA targeting the programmed death-ligand 1 (PD-L1) was loaded into PNP-PEI to generate a potentially therapeutic nanoparticle (PNP-PEI/shPD-L1). In vitro and in vivo experiments demonstrated that PNP-PEI could efficiently carry the therapeutic shPD-L1 into tumor cells and that PNP-PEI/shPD-L1 could significantly inhibit the expression of PD-L1 and growth of B16-F10 cells. Noteworthily, treatment with PNP-PEI reversed the phenotype of macrophages from M2 to M1 subtype and promoted dendritic cell maturation, which encouraged the host immunity and enhanced the therapeutic antitumor effects. In summary, this study describes a PNP-based gene delivery vector and highlights the beneficial immunopotentiating therapeutic outcomes of PNP-PEI for tumor immunotherapy.

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.

miRNA Delivery by Nanosystems: State of the Art and Perspectives

MicroRNAs (miRNAs) are short (~21-23 nucleotides), non-coding endogenous RNA molecules that modulate gene expression at the post-transcriptional level via the endogenous RNA interference machinery of the cell. They have emerged as potential biopharmaceuticals candidates for the treatment of various diseases, including cancer, cardiovascular and metabolic diseases. However, in order to advance miRNAs therapeutics into clinical settings, their delivery remains a major challenge. Different types of vectors have been investigated to allow the delivery of miRNA in the diseased tissue. In particular, non-viral delivery systems have shown important advantages such as versatility, low cost, easy fabrication and low immunogenicity. Here, we present a general overview of the main types of non-viral vectors developed for miRNA delivery, with their advantages, limitations and future perspectives.

Non-viral transfection vectors: are hybrid materials the way forward?

Transfection is a process by which oligonucleotides (DNA or RNA) are delivered into living cells. This allows the synthesis of target proteins as well as their inhibition (gene silencing). However, oligonucleotides cannot cross the plasma membrane by themselves; therefore, efficient carriers are needed for successful gene delivery. Recombinant viruses are among the earliest described vectors. Unfortunately, they have severe drawbacks such as toxicity and immunogenicity. In this regard, the development of non-viral transfection vectors has attracted increasing interests, and has become an important field of research. In the first part of this review we start with a tutorial introduction into the biological backgrounds of gene transfection followed by the classical non-viral vectors (cationic organic carriers and inorganic nanoparticles). In the second part we highlight selected recent reports, which demonstrate that hybrid vectors that combine key features of classical carriers are a remarkable strategy to address the current challenges in gene delivery.

Hyaluronan as tunable drug delivery system

The hyaluronan (HA) polymer is an important macromolecule of extracellular matrix with remarkable structure and functions: it is a linear and unbranched polymer without sulphate or phosphate groups and has key role in several biological processes in mammals. It is ubiquitous in mammalian tissues with several and specific functions, influencing cell proliferation and migration as well as angiogenesis and inflammation. To exert these important functions in tissues HA modifies the concentration and size. Considering this HA content in tissues is carefully controlled by different mechanisms including covalent modification of the synthetic enzymes and epigenetic control of their gene expression. The function of HA is also critical in several pathologies including cancer, diabetes and chronic inflammation. Among these biological roles, the structural properties of HA allow to use this polymer in regenerative medicine including cosmetics and drug delivery. HA takes advantage from its capacity to form gels even at concentration of 1% producing scaffolds with very intriguing mechanical properties. These hydrogels are useful in regenerative medicine as biocompatible material for advanced therapeutic uses. In this review we highlight the biological aspects of HA addressing the mechanisms controlling the HA content in tissues and its role as drug delivery system.

Application of hyaluronic acid as carriers in drug delivery

Hyaluronic acid has good biocompatibility, biodegradability, and nonimmunogenicity. In addition, it has the ability to recognize specific receptors that are overexpressed on the surface of tumor cells, and cancer drugs can be targeted to the tumor cells to better kill them. Therefore, hyaluronic acid has attracted much attention as drug delivery vehicle. Herein, the application of hyaluronic acid as carrier in drug delivery was analyzed and summarized in detail. It showed that hyaluronic acid would have broad prospects for drug delivery.

Novel polyethyleneimine-R8-heparin nanogel for high-efficiency gene delivery in vitro and in vivo

Gene therapy is an efficient and promising approach to treat malignant tumors. However, protecting the nucleic acid from degradation in vivo and efficient delivering it into tumor cells remain challenges that require to be addressed before gene therapy could be applied in clinic. In this study, we prepared novel polyethyleneimine-RRRRRRRR(R8)-heparin (HPR) nanogel as an efficient gene delivery system, which consists of heparin and cell penetrating peptide R8 grafted low-molecule-weight polyethyleneimine (PEI). Due to the shielding effect of heparin, crosslinking PEI-R8 with heparin was designed to diminish the toxicity of the gene delivery system. Meanwhile, a partial of R8 peptide which located on the surface of HPR nanogel could significantly enhance the cellular uptake. The formed HPR/pDNA complex exhibited effective endolysosomal escape, resulting in a high-efficiency transfection. Furthermore, the HPR could deliver the plasmid which could transcribe human TNF-related apoptosis inducing ligand (phTRAIL), into HCT-116 cells and induce significant cell apoptosis. In addition, HPR/phTRAIL complex showed satisfactory antitumor activity in abdominal metastatic colon carcinoma model. Finally, the antitumor mechanism of HPR/phTRAIL was also explored by western blot and histological analysis. The above results suggested that the HPR nanogel could serve as a promising gene delivery system.

Hyaluronic acid-based biopharmaceutical delivery and tumor-targeted drug delivery system

Hyaluronic acid (HA) is a natural polysaccharide with good biocompatibility and degradability. HA and its derivatives can be used as sustained-release carriers for drugs, which can delay the release of drugs and have a long-acting effect. They can be used for the delivery of various drugs such as proteins, nucleic acids and anti-tumor drugs. HA and its derivatives can specifically bind to multiple receptors on the cell surface and can be used for targeted drug delivery, especially for the delivery of anti-tumor drugs. Thus, there are different forms of tumor-targeted drug delivery systems based on HA.

Poly(γ-glutamic acid)-coated lipoplexes loaded with Doxorubicin for enhancing the antitumor activity against liver tumors

The study was to develop poly-γ-glutamic acid (γ-PGA)-coated Doxorubicin (Dox) lipoplexes that enhance the antitumor activity against liver tumors. γ-PGA-coated lipoplexes were performed by electrostatistically attracting to the surface of cationic charge liposomes with anionic γ-PGA. With the increasing of γ-PGA concentration, the particle size of γ-PGA-coated Dox lipoplexes slightly increased, the zeta potential from positive shifted to negative, and the entrapment efficiency (EE) were no significant change. The release rate of γ-PGA-coated Dox lipoplexes slightly increased at acidic pH, the accelerated Dox release might be attributed to greater drug delivery to tumor cells, resulting in a higher antitumor activity. Especially, γ-PGA-coated Dox lipoplexes exhibited higher cellular uptake, significant in vitro cytotoxicity in HepG2 cells, and improved in vivo antitumor efficacy toward HepG2 hepatoma-xenografted nude models in comparison with Dox liposomes and free Dox solution. In addition, the analysis results via flow cytometry showed that γ-PGA-coated Dox lipoplexes induce S phase cell cycle arrest and significantly increased apoptosis rate of HepG2 cells. In conclusion, the presence of γ-PGA on the surface of Dox lipoplexes enhanced antitumor effects of liver tumors.

Nonviral cancer gene therapy: Delivery cascade and vector nanoproperty integration

Gene therapy represents a promising cancer treatment featuring high efficacy and limited side effects, but it is stymied by a lack of safe and efficient gene-delivery vectors. Cationic polymers and lipid-based nonviral gene vectors have many advantages and have been extensively explored for cancer gene delivery, but their low gene-expression efficiencies relative to viral vectors limit their clinical translations. Great efforts have thus been devoted to developing new carrier materials and fabricating functional vectors aimed at improving gene expression, but the overall efficiencies are still more or less at the same level. This review analyzes the cancer gene-delivery cascade and the barriers, the needed nanoproperties and the current strategies for overcoming these barriers, and outlines PEGylation, surface-charge, size, and stability dilemmas in vector nanoproperties to efficiently accomplish the cancer gene-delivery cascade. Stability, surface, and size transitions (3S Transitions) are proposed to resolve those dilemmas and strategies to realize these transitions are comprehensively summarized. The review concludes with a discussion of the future research directions to design high-performance nonviral gene vectors.

Fabrication of HA/PEI-functionalized carbon dots for tumor targeting, intracellular imaging and gene delivery

Carbon quantum dots (CDs) as emerging carbon nano-materials have attracted tremendous attention in biomedical fields due to unique properties.

Multi-Responsive "Turn-On" Nanocarriers for Efficient Site-Specific Gene Delivery In Vitro and In Vivo

Systemic gene delivery is a complicated and multistep process that confronts numerous biological barriers. It remains a formidable challenge to exploit a single gene carrier with multiple features to combat all obstacles collectively. Herein, a multi-responsive "turn-on" polyelectrolyte complex (DNA/OEI-SS_x /HA-SS-COOH, DSS) delivery system is demonstrated with a sequential self-assembly of disulfide-conjugated oligoethylenimine (OEI-SS_x ) and disulfide bond-modified hyaluronic acid envelope (HA-SS-COOH) that can combat multiple biological barriers collectively when administered intravenously. DSS is designed to effectively accumulate at the tumor tissue and to be internalized into tumor cells by recognizing CD44. The multi-responsive "turn-on" DSS can respond to the alterations of hyaluronidases and glutathione at both the tumor site and at the intracellular milieu. Sequential degradation and detachment of the HA-SS-COOH envelope followed by the dissociation of the OEI-SSx/DNA inner core contributes to the activation of the endosomal escape and gene release functions, thus greatly enhancing nuclear gene delivery. A systematic investigation of DSS has revealed that the tumor accumulation ability, internalization, and endosome escape of the DSS nanocarriers, DNA unpacking and nuclear transportation are all remarkably improved by the multi-responsive "turn-on" design resulting in highly efficient gene transfection in vitro and in vivo.

Cationic microRNA-delivering nanocarriers for efficient treatment of colon carcinoma in xenograft model

Manipulation of tumor microRNAs (miRNAs) may offer novel avenues for treatment of cancer. However, development of safe, robust, non-viral delivery methods remains a main challenge to obtain the promise of gene therapy. The miR-145 is dysregulated in many cancers, including colon carcer, and further in vitro investigation established antiproliferative and proapoptotic roles of miR-145. Herein, we study a PLGA/PEI (poly (d, l-lactide-co-glycolide)/polyethylenimine)-mediated miRNA vector delivery system; the validation of the method was carried out using a colon cancer xenograft model with miR-145 vector encoding for the expression of miR-145 (pDNA). First, high-molecular-weight PEI (25000 Da) was conjugated with cetyl to formulate reducible cetylated PEI (PEI-cet), and then PEI-cet was introduced to PLGA suspension. Next, PLGA/PEI-cet was crosslinked with hyaluronic acid (HA) to facilitate cellular uptake of miRNA plasmid vector via HA receptor-mediated endocytosis. After local administration of PLGA/PEI/HA complexes, intact miRNA plasmid vectors were delivered into HCT-116 colon cancer cells and xenograft tumor-bearing mice, and significant antitumor effects were achieved. The results show that the HA-based miR-145 nanocarrier could efficiently facilitate cellular uptake and significantly enhance miR-145 expression in HCT-116 cells. Consequently, the increased miR-145 induced G1 cell cycle arrest, reduced tumor proliferation and increased apoptosis, inhibited HCT-116 cell migration and suppressed c-MYC expressions, a regulatory target of miR-145. Of particular importance is the significant decrease in tumor growth in the mice model of colon cancer with the targeting miR-145 delivery system. The results in this work show that miR-145 has been effectively delivered to colon carcinomas through a PLGA/PEI/HA vehicle, indicating a promising miRNA replacement therapy strategy.

Hyaluronic acid grafted PLGA copolymer nanoparticles enhance the targeted delivery of Bromelain in Ehrlich's Ascites Carcinoma

Rapidly increasing malignant neoplastic disease demands immediate attention. Several dietary compounds have recently emerged as strong anti-cancerous agents. Among, Bromelain (BL), a protease from pineapple plant, was used to enhance its anti-cancerous efficacy using nanotechnology. In lieu of this, hyaluronic acid (HA) grafted PLGA copolymer, having tumor targeting ability, was developed. BL was encapsulated in copolymer to obtain BL-copolymer nanoparticles (NPs) that ranged between 140 to 281nm in size. NPs exhibited higher cellular uptake and cytotoxicity in cells with high CD44 expression as compared with non-targeted NPs. In vivo results on tumor bearing mice showed that NPs were efficient in suppressing the tumor growth. Hence, the formulation could be used as a self-targeting drug delivery cargo for the remission of cancer.

Hyaluronic acid reagent functional chitosan-PEI conjugate with AQP2-siRNA suppressed endometriotic lesion formation

To identify a new drug candidate for treating endometriosis which has fewer side effects, a new polymeric nanoparticle gene delivery system consisting of polyethylenimine-grafted chitosan oligosaccharide (CSO-PEI) with hyaluronic acid (HA) and small interfering RNA (siRNA) was designed. There was no obvious difference in sizes observed between (CSO-PEI/siRNA)HA and CSO-PEI/siRNA, but the fluorescence accumulation in the endometriotic lesion was more significant for (CSO-PEI/siRNA)HA compared with CSO-PEI/siRNA due to the specific binding of HA to CD44. In addition, the (CSO-PEI/siRNA)HA nanoparticle gene therapy significantly decreased the endometriotic lesion sizes with atrophy and degeneration of the ectopic endometrium. The epithelial cells of ectopic endometrium from rat models of endometriosis showed a significantly lower CD44 expression than control after treatment with (CSO-PEI/siRNA)HA. Furthermore, observation under an electron microscope showed no obvious toxic effect on the reproductive organs. Therefore, (CSO-PEI/siRNA)HA gene delivery system can be used as an effective method for the treatment of endometriosis.

The synthesis and comparison of chondroitin sulfate-modified PDMAEMA with chondroitin sulfate-modified PEI as a potential gene delivery vector

CS-PDMAEMA obtained by reacting HS-PDMAEMA with CSMA via Michael addition, shows lower cytotoxicity and better transfection efficiency than PDMAEMA. The transfection efficiency is higher in 3T3 cells than in U87 cells owing to higher expression of ASGP-R.

Improved gene transfection efficacy and cytocompatibility of multifunctional polyamidoamine-cross-linked hyaluronan particles

We describe a multi-functional, cationic hyaluronic acid (HA)-based gene carrier with improved transfection over non-cross-linked HA, and negligible cytotoxicity. Cationized particles are developed by cross-linking HA chain carboxyl groups with polyamidoamine amine termini to produce well segregated particles of 350-400 nm with a surface charge density of +2 mV, compared with -35 mV for non-cationized particles. A tethered antibody fragment retains ligand binding for cell targeting. Cationized and antibody-linked particles complex plasmid DNA efficiently and the cationized particles successfully deliver reporter genes to bovine intervertebral disk cells as an intervertebral disk regeneration model.

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.

Hyaluronic acid conjugates as vectors for the active targeting of drugs, genes and nanocomposites in cancer treatment

Hyaluronic acid (HA) is a naturally-occurring glycosaminoglycan and a major component of the extracellular matrix. Low levels of the hyaluronic acid receptor CD44 are found on the surface of epithelial, hematopoietic, and neuronal cells; it is overexpressed in many cancer cells, and in particular in tumor-initiating cells. HA has recently attracted considerable interest in the field of developing drug delivery systems, having been used, as such or encapsulated in different types of nanoassembly, as ligand to prepare nano-platforms for actively targeting drugs, genes, and diagnostic agents. This review describes recent progress made with the several chemical strategies adopted to synthesize conjugates and prepare novel delivery systems with improved behaviors.

Design of magnetic polyplexes taken up efficiently by dendritic cell for enhanced DNA vaccine delivery

Dendritic cells (DC) targeting vaccines require high efficiency for uptake, followed by DC activation and maturation. We used magnetic vectors comprising polyethylenimine (PEI)-coated superparamagnetic iron oxide nanoparticles, with hyaluronic acid (HA) of different molecular weights (<10 and 900 kDa) to reduce cytotoxicity and to facilitate endocytosis of particles into DCs via specific surface receptors. DNA encoding Plasmodium yoelii merozoite surface protein 1-19 and a plasmid encoding yellow fluorescent gene were added to the magnetic complexes with various % charge ratios of HA: PEI. The presence of magnetic fields significantly enhanced DC transfection and maturation. Vectors containing a high-molecular-weight HA with 100% charge ratio of HA: PEI yielded a better transfection efficiency than others. This phenomenon was attributed to their longer molecular chains and higher mucoadhesive properties aiding DNA condensation and stability. Insights gained should improve the design of more effective DNA vaccine delivery systems.

A photo-degradable gene delivery system for enhanced nuclear gene transcription

There currently exists a significant gap in our understanding of how the detailed chemical characteristics of polycation gene carriers influence their delivery performances in overcoming an important cellular-level transport barrier, i.e., intranuclear gene transcription. In this study, a UV-degradable gene carrier material (ENE4-1) was synthesized by crosslinking low molecular weight branched polyethylenimine (bPEI-2k) molecules using UV-cleavable o-nitrobenzyl urethane (NBU) as the linker molecule. NBU degrades upon exposure to mild UV irradiation. Therefore, this UV-degradable carrier allows us to control the chemical characteristics of the polymer/DNA complex (polyplex) particles at desired locations within the intracellular environment. By using this photolytic DNA carrier, we found that the exact timing of the UV degradation significantly influences the gene transfection efficiencies of ENE4-1/DNA(pGL2) polyplexes in HeLa cells. Interestingly, even if the polyplexes were UV-degraded at different intracellular locations/times, their nuclear entry efficiency was not influenced by the location/timing of UV degradation. The UV treatment did not influence the size or binding strength of the polyplexes. However, we confirmed that the degradation of the carrier molecules impacts the chemical characteristics of the polyplexes (it produces carbamic acid and nitrosobenzyl aldehyde groups on ENE4-1). We believe that these anionic acid groups enhance the interaction of the polyplexes with nuclear transcription proteins and thus the final gene expression levels; this effect was found to occur, even though UV irradiation itself has a general effect of reducing transfection efficiencies. Excess (uncomplexed) ENE4-1 polymers appear to not play any role in the UV-enhanced gene transcription phenomenon.

The application of hyaluronic acid-derivatized carbon nanotubes in hematoporphyrin monomethyl ether-based photodynamic therapy for in vivo and in vitro cancer treatment

Carbon nanotubes (CNTs) have shown great potential in both photothermal therapy and drug delivery. In this study, a CNT derivative, hyaluronic acid-derivatized CNTs (HA-CNTs) with high aqueous solubility, neutral pH, and tumor-targeting activity, were synthesized and characterized, and then a new photodynamic therapy agent, hematoporphyrin monomethyl ether (HMME), was adsorbed onto the functionalized CNTs to develop HMME-HA-CNTs. Tumor growth inhibition was investigated both in vivo and in vitro by a combination of photothermal therapy and photodynamic therapy using HMME-HA-CNTs. The ability of HMME-HA-CNT nanoparticles to combine local specific photodynamic therapy with external near-infrared photothermal therapy significantly improved the therapeutic efficacy of cancer treatment. Compared with photodynamic therapy or photothermal therapy alone, the combined treatment demonstrated a synergistic effect, resulting in higher therapeutic efficacy without obvious toxic effects to normal organs. Overall, it was demonstrated that HMME-HA-CNTs could be successfully applied to photodynamic therapy and photothermal therapy simultaneously in future tumor therapy.

Nanoparticles for gene delivery

Nanocarriers are a new type of nonviral gene carriers, many of which have demonstrated a broad range of pharmacological and biological properties, such as being biodegradable in the body, stimulus-responsive towards the surrounding environment, and an ability to specifically targeting certain disease sites. By summarizing some main types of nanocarriers, this Concept considers the current status and possible future directions of the potential clinical applications of multifunctional nanocarriers, with primary attention on the combination of such properties as biodegradability, targetability, transfection ability, and stimuli sensitivity.

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.

Polysaccharide gene transfection agents

Gene delivery is a promising technique that involves in vitro or in vivo introduction of exogenous genes into cells for experimental and therapeutic purposes. Successful gene delivery depends on the development of effective and safe delivery vectors. Two main delivery systems, viral and non-viral gene carriers, are currently deployed for gene therapy. While most current gene therapy clinical trials are based on viral approaches, non-viral gene medicines have also emerged as potentially safe and effective for the treatment of a wide variety of genetic and acquired diseases. Non-viral technologies consist of plasmid-based expression systems containing a gene associated with the synthetic gene delivery vector. Polysaccharides compile a large family of heterogenic sequences of monomers with various applications and several advantages as gene delivery agents. This chapter, compiles the recent progress in polysaccharide based gene delivery, it also provides an overview and recent developments of polysaccharide employed for in vitro and in vivo delivery of therapeutically important nucleotides, e.g. plasmid DNA and small interfering RNA.

Targeted therapy of gastrointestinal tumors using hyaluronic acid drug carriers

Hyaluronic acid (HA) is a natural, linear, high molecular weight mucopolysaccharide with good biocompatibility and biodegradability. Recently, HA receptor has been found on the surface of tumor cells. Therefore, sustained-release and tumor-targeting drug carriers with hyaluronic acid and its derivatives have been fabricated, because they can bind specifically to the HA receptor on the surface of tumor cells and are biodegradable. Now, the research on targeted therapy using hyaluronic acid drug carriers is focused on the therapy of prostatic cancer, pulmonary cancer and head and neck neoplasms. Colon tumors are the only type of gastrointestinal tumors in which hyaluronic acid drug carriers were studied. In this paper, we introduce the design and characteristics of hyaluronic acid drug carriers and review recent progress and future prospects of targeted treatment of gastrointestinal tumors using hyaluronic acid drug carriers.

Glycyrrhetinic acid-graft-hyaluronic acid conjugate as a carrier for synergistic targeted delivery of antitumor drugs

Glycyrrhetinic acid-graft-hyaluronic acid (HGA) conjugate was synthesized as a carrier for intravenous administration of paclitaxel (PTX), which combined hyaluronic acid (HA) and glycyrrhetinic acid (GA) as the active targeting ligands to liver tumor. In the present study, physicochemical characteristics, cellular uptake efficiency, and in vivo fates of HGA conjugates were investigated. HGA nanoparticles could readily load PTX with high efficiency up to 31.16 wt.% and entrapment efficiency to 92.02%. Moreover, PTX-loaded HGA nanoparticles exhibited more significant cytotoxicity to HepG2 cells than B16F10 cells due to simultaneously over-expressing HA and GA receptors. Meanwhile, the cellular uptake of nanoparticles was clearly enhanced in HepG2 and B16F10 cells compared to a normal fibroblast cell (HELF cells). In particular, more HGA nanoparticles were taken up by HepG2 cells than by B16F10 cells, which might be attributed to the affinity of multiple ligands of HA and GA to HepG2 cells. Furthermore, liver and tumor targeting activity of HGA nanoparticles was also confirmed by in vivo imaging analysis. The fluorescence signals of DiR-labeled HGA nanoparticles in tumor and liver were 2.88 and 1.83 folds stronger than that of the control, respectively. These results indicate HGA nanoparticles can be a potential drug carrier with "double target sites" for liver cancer therapy.

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.

A comparative study of three ternary complexes prepared in different mixing orders of siRNA/redox-responsive hyperbranched poly (amido amine)/hyaluronic acid

In this study, a novel redox-responsive hyperbranched poly(amido amine) (named PCD) was synthesized and used as a cationic polymer to form a ternary complex with small interfering RNA (siRNA) and hyaluronic acid (HA) for siRNA delivery. Here, it is hypothesized that different mixing orders result in different assembly structures, which may affect the siRNA delivery efficiency. To investigate the effects of mixing orders on siRNA delivery efficiency in two human breast cancer cell lines, three ternary complexes with different mixing orders of siRNA/PCD/HA were prepared and characterized: mixing order I (initially prepared siRNA/PCD binary complex further coated by negatively charged HA), mixing order II ( initially prepared HA/PCD binary complex further incubated with siRNA), and mixing order III ( initially prepared siRNA/HA mixture further electrostatically compacted by positively charged PCD). With an optimized siRNA/PCD/HA charge ratio of 1/20/16, the particle sizes and zeta potentials of these ternary complexes were 124.8 nm and 27.3 mV (mixing order I), 147.5 nm and 29.9 mV (mixing order II), and 128.8 nm and 19.4 mV (mixing order III). Also, the effects on stability, cellular uptake, and gene silencing efficiency of siRNA formulated in ternary complexes with different mixing orders were investigated. The results showed that mixing orders I and III displayed better siRNA transfection and protection than mixing order II in human breast cancer MCF-7 and MDA-MB-231 cells. More interesting, at the siRNA/PCD/HA charge ratio of 1/20/16, the gene silencing effects on vascular endothelial growth factor expression in MDA-MB- 231 cells were as follows: mixing order III > mixing order I > mixing order II. Based on these results, a likely explanation for the difference in functionality dependent on mixing orders is the formation of different assembly structures. These results may help future optimization of siRNA ternary complexes for achieving better delivery efficiencies, especially for target-specific siRNA delivery to cells with HA receptor overexpression.

Polypeptide grafted hyaluronan: A self-assembling comb-branched polymer constructed from biological components

Rheological evidence is provided demonstrating that covalent grafting of monodisperse isotactic poly(L-leucine) branches onto linear hyaluronan (HA) polysaccharide chains yields comb-branched HA chains that self-assemble into long-lived physical networks in aqueous solutions driven by hydrophobic interactions between poly(L-leucine) chains. This is in stark contrast to native (unmodified) HA solutions which exhibit no tendency to form long-lived physical networks.