Bioinformatics and Molecular Insights to Anti-Metastasis Activity of Triethylene Glycol Derivatives.

The anti-metastatic and anti-angiogenic activities of triethylene glycol derivatives have been reported. In this study, we investigated their molecular mechanism(s) using bioinformatics and experimental tools. By molecular dynamics analysis, we found that (i) triethylene glycol dimethacrylate (TD-10) and tetraethylene glycol dimethacrylate (TD-11) can act as inhibitors of the catalytic domain of matrix metalloproteinases (MMP-2, MMP-7 and MMP-9) by binding to the S1' pocket of MMP-2 and MMP-9 and the catalytic Zn ion binding site of MMP-7, and that (ii) TD-11 can cause local disruption of the secondary structure of vascular endothelial growth factor A (VEGFA) dimer and exhibit stable interaction at the binding interface of VEGFA receptor R1 complex. Cell-culture-based in vitro experiments showed anti-metastatic phenotypes as seen in migration and invasion assays in cancer cells by both TD-10 and TD-11. Underlying biochemical evidence revealed downregulation of VEGF and MMPs at the protein level; MMP-9 was also downregulated at the transcriptional level. By molecular analyses, we demonstrate that TD-10 and TD-11 target stress chaperone mortalin at the transcription and translational level, yielding decreased expression of vimentin, fibronectin and hnRNP-K, and increase in extracellular matrix (ECM) proteins (collagen IV and E-cadherin) endorsing reversal of epithelial-mesenchymal transition (EMT) signaling.

Mathematical Modelling of the Interaction Between Cancer Cells and an Oncolytic Virus: Insights into the Effects of Treatment Protocols.

Oncolytic virotherapy is an experimental cancer treatment that uses genetically engineered viruses to target and kill cancer cells. One major limitation of this treatment is that virus particles are rapidly cleared by the immune system, preventing them from arriving at the tumour site. To improve virus survival and infectivity Kim et al. (Biomaterials 32(9):2314-2326, 2011) modified virus particles with the polymer polyethylene glycol (PEG) and the monoclonal antibody herceptin. Whilst PEG modification appeared to improve plasma retention and initial infectivity, it also increased the virus particle arrival time. We derive a mathematical model that describes the interaction between tumour cells and an oncolytic virus. We tune our model to represent the experimental data by Kim et al. (2011) and obtain optimised parameters. Our model provides a platform from which predictions may be made about the response of cancer growth to other treatment protocols beyond those in the experiments. Through model simulations, we find that the treatment protocol affects the outcome dramatically. We quantify the effects of dosage strategy as a function of tumour cell replication and tumour carrying capacity on the outcome of oncolytic virotherapy as a treatment. The relative significance of the modification of the virus and the crucial role it plays in optimising treatment efficacy are explored.

Biodegradable Inorganic Nanovector: Passive versus Active Tumor Targeting in siRNA Transportation.

The biodegradable inorganic nanovector based on a layered double hydroxide (LDH) holds great promise for gene and drug delivery systems. However, in vivo targeted delivery of genes through LDH still remains a key challenge in the development of RNA interference therapeutics. Here, we describe in vivo and in vitro delivery system for Survivin siRNA (siSurvivin) assembled with passive LDH with a particle size of 100 nm or active LDH conjugated with a cancer overexpressing receptor targeting ligand, folic acid (LDHFA), conferring them an ability to target the tumor by either EPR-based clathrin-mediated or folate receptor-mediated endocytosis. When not only transfected into KB cells but also injected into xenograft mice, LDHFA/siSurvivin induced potent gene silencing at mRNA and protein levels in vitro, and consequently achieved a 3.0-fold higher suppression of tumor volume than LDH/siSurvivin in vivo. This anti-tumor effect was attributed to a selectively 1.2-fold higher accumulation of siSurvivin in tumor tissue compared with other organs. Targeting to the tumor with inorganic nanovector can guide and accelerate an evolution of next-generation theranosis system.

Tuning Surface Charge and PEGylation of Biocompatible Polymers for Efficient Delivery of Nucleic Acid or Adenoviral Vector.

As an effective and safe strategy to overcome the limits of therapeutic nucleic acid or adenovirus (Ad) vectors for in vivo application, various technologies to modify the surface of vectors with nonimmunogenic/biocompatible polymers have been emerging in the field of gene therapy. However, the transfection efficacy of the polymer to transfer genetic materials is still relatively weak. To develop more advanced and effective polymers to deliver not only Ad vectors, but also nucleic acids, 6 biocompatible polymers were newly designed and synthesized to different sizes (2k, 3.4k, or 5k) of poly(ethylene) glycol (PEG) and different numbers of amine groups (2 or 5) based on methoxy poly(ethylene glycol)-b-poly{N-[N-(2-aminoethyl)-2-aminoethyl]-l-glutamate (PNLG). We characterized size distribution and surface charge of 6 PNLGs after complexation with either nucleic acid or Ad. Among all 6 PNLGs, the 5 amine group PNLG showed the strongest efficacy in delivering nucleic acid as well as Ad vectors. Interestingly, cellular uptake results showed higher uptake ability in Ad complexed with 2 amine group PNLG than Ad/5 amine group PNLG, suggesting that the size of Ad/PNLGs is more essential than the surface charge for cellular uptake in polymers with charges greater than 30 mV. Moreover, the endosome escape ability of Ad/PNLGs increased depending on the number of amine groups, but decreased by PEG size. Cancer cell killing efficacy and immune response studies of oncolytic Ad/PNLGs showed 5 amine group PNLG to be a more effective and safe carrier for delivering Ad. Overall, these studies provide new insights into the functional mechanism of polymer-based approaches to either nucleic acid or Ad/nanocomplex. Furthermore, the identified ideal biocompatible PNLG polymer formulation (5 amine/2k PEG for nucleic acid, 5 amine/5k PEG for Ad) demonstrated high transduction efficiency as well as therapeutic value (efficacy and safety) and thus has strong potential for in vivo therapeutic use in the future.

Oncolytic Adenovirus Coated with Multidegradable Bioreducible Core-Cross-Linked Polyethylenimine for Cancer Gene Therapy.

Recently, adenovirus (Ad) has been utilized as a viral vector for efficient gene delivery. However, substantial immunogenicity and toxicity have obstructed oncolytic Ad's transition into clinical studies. The goal of this study is to generate an adenoviral vector complexed with multidegradable bioreducible core-cross-linked polyethylenimine (rPEI) polymer that has low immunogenicity and toxicity while having higher transduction efficacy and stability. We have synthesized different molecular weight rPEIs and complexed with Ad at varying molar ratios to optimize delivery of the Ad/polymer complex. The size and surface charge of Ad/rPEIs were characterized. Of note, Ad/rPEIs showed significantly enhanced transduction efficiency compared to either naked Ad or Ad/25 kDa PEI in both coxsackievirus and adenovirus receptor (CAR) positive and negative cancer cells. The cellular uptake result demonstrated that the relatively small size of Ad/16 kDa rPEIs (below 200 nm) was more critical to the complex's internalization than its surface charge. Cancer cell killing effect and viral production were significantly increased when oncolytic Ad (RdB/shMet, or oAd) was complexed with 16 kDa rPEI in comparison to naked oAd-, oAd/25 kDa PEI-, or oAd/32 kDa rPEI-treated cells. This increased anticancer cytotoxicity was more readily apparent in CAR-negative MCF7 cells, implying that it can be used to treat a broad range of cancer cells. Furthermore, A549 and HT1080 cancer cells treated with oAd/16 kDa rPEI had significantly decreased Met and VEGF expression compared to either naked oAd or oAd/25 kDa PEI. Overall, these results demonstrate that shMet expressing oncolytic Ad complexed with multidegradable bioreducible core-cross-linked PEI could be used as efficient and safe cancer gene therapy.

Safety profiles and antitumor efficacy of oncolytic adenovirus coated with bioreducible polymer in the treatment of a CAR negative tumor model.

Adenovirus (Ad) vectors show promise as cancer gene therapy delivery vehicles, but immunogenic safety concerns and coxsackie and adenovirus receptor (CAR)-dependency have limited their use. Alternately, biocompatible and bioreducible nonviral vectors, including arginine-grafted cationic polymers, have been shown to deliver nucleic acids through a cell penetration peptide (CPP) and protein transduction domain (PTD) effect. We utilized the advantages of both viral and nonviral vectors to develop a hybrid gene delivery vehicle by coating Ad with mPEG-PEI-g-Arg-S-S-Arg-g-PEI-mPEG (Ad/PPSA). Characterization of Ad/PPSA particle size and zeta potential showed an overall size and cationic charge increase in a polymer concentration-dependent manner. Ad/PPSA also showed a marked transduction efficiency increase in both CAR-negative and -positive cells compared to naked Ad. Competition assays demonstrated that Ad/PPSA produced higher transgene expression levels than naked Ad and achieved CAR-independent transduction. Oncolytic Ad (DWP418)/PPSA was able to overcome the nonspecificity of polymer-only therapies by demonstrating cancer-specific killing effects. Furthermore, the DWP418/PPSA nanocomplex elicited a 2.24-fold greater antitumor efficacy than naked Ad in vivo. This was supported by immunohistochemical confirmation of Ad E1As accumulation in MCF7 xenografted tumors. Lastly, intravenous injection of DWP418/PPSA elicited less innate immune response compared to naked Ad, evaluated by interleukin-6 cytokine release into the serum. The increased antitumor effect and improved vector targeting to both CAR-negative and -positive cells make DWP418/PPSA a promising tool for cancer gene therapy.

Sustained local delivery of oncolytic short hairpin RNA adenoviruses for treatment of head and neck cancer.

BACKGROUND: Oncolytic adenovirus (Ad)-mediated gene therapy is a promising approach for suppression of primary tumors. Therapeutic efficacy of Ad-mediated gene therapy has been limited by immunogenicity, rapid dissemination of viral progenies into systemic circulation and short duration of biological activity. Polymeric sustained local delivery can overcome many of these challenges to produce a viable therapy with improved outcomes. METHODS: Silk-elastinlike protein polymer (SELP) hydrogels were used for matrix-mediated delivery of oncolytic Ad, containing short hairpin RNA (shRNA) targeted to C-Met (sh-C-Met), to solid tumors in a nude mouse model of human head and neck cancer. The biological activity of Ad released from SELP hydrogels was examined as a function of time to investigate protective effects on viral activity. Antitumor efficacy and viral distribution were investigated for 3 weeks in tumor-bearing mice. RESULTS: The encapsulation of Ad with SELP hydrogels sustained biological activity longer than Ad alone. Ad in SELP matrix showed 1.5-fold greater antitumor efficacy compared to that of naked Ad in human xenograft tumor models. Histological analysis demonstrated that treatment with Ad in a SELP matrix resulted in apoptosis in a wider area of tumor tissue and higher density of Ad infection compared to Ad administered alone. CONCLUSIONS: Matrix-mediated delivery of Ad-containing shRNA with SELP hydrogels enhances therapeutic efficacy by tumor-selective infection, spatiotemporal control and preservation of biologic activity.

Challenges and progress toward tumor-targeted therapy by systemic delivery of polymer-complexed oncolytic adenoviruses.

Oncolytic adenovirus (oAd) elicits antitumor activity by preferential viral replication in cancer cells. However, poor systemic administrability or suboptimal intratumoral retainment of the virus remains a major challenge toward maximizing the antitumor activity of oAd in a clinical environment. To surmount these issues, a variety of non-immunogenic polymers has been used to modify the surface of oAds chemically or physically. Complexation of oAd with polymers can effectively evade the host immune response and reduces nonspecific liver sequestration. The tumor-specific delivery of these complexes can be further improved upon by inclusion of tumor-targeting moieties on the surface. Therefore, modification of the Ad surface using polymers is viewed as a potential strategy to enhance the delivery of Ad via systemic administration. This review aims to provide a comprehensive overview of polymer-complexed Ads, their progress, and future challenges in cancer treatment.

Bioreducible polymer-mediated delivery of oncolytic adenovirus can attenuate antiviral immune response and concurrently enhance the induction of antitumor immune response to effectively prevent metastasis.

Oncolytic virotherapy is a highly promising and novel treatment modality for cancer. Several clinical trials with oncolytic viruses have illustrated that the potent antitumor efficacy of these viruses may rely on the efficient induction of antitumor immune response. In contrast, antiviral immune response is attributed to adverse side defects and diminishing therapeutic efficacy. In the present report, we generated a nanohybrid complex incorporating immune stimulatory oncolytic adenovirus (oAd) co-expressing decorin (DCN) and interleukin (IL)-12 with a bioreducible nanomaterial composed of PEI-Arg-mPEG-S-S-mPEG-Arg-PEI blocks (PAPS), ultimately aiming to modulate both antitumor and antiviral immune responses to be favorable toward oncolytic virotherapy. The transduction efficacy of the PAPS-incorporated nanohybrid vector (Ad/PAPS) was significantly higher than that of a complex using our previously reported polymer PPSA (Ad/PPSA) regardless of the cellular coxsackievirus and adenovirus receptor expression level of cancer cells. oAd complexed with PAPS (oAd/PAPS) also elicited a more potent cancer cell killing effect, antitumor efficacy, and metastasis inhibition than naked oAd or oAd complexed with PPSA (oAd/PPSA) through a higher level of therapeutic transgenes (DCN and IL-12), viral replication, and more efficient infiltration of T cells into tumor tissues. Notably, oAd/PAPS induced the highest level of antitumor immune response while the antiviral immune response was mediated at a significantly lower level than those of naked oAd. Adaptive immune response against the virus was also significantly attenuated in the oAd/PAPS group. oAd/PAPS treatment also led to the highest level of antitumor central memory T cells and the lowest level of immunosuppressive regulatory T cells in the spleen. Collectively, our findings illustrate that oAd/PAPS can simultaneously regulate both antitumor and antiviral immune responses to be more favorable to oncolytic virotherapy, leading to improved gene expression, viral replication, and growth inhibition of both primary and metastatic tumors.

Polymeric delivery systems for nucleic acid therapeutics: Approaching the clinic.

Gene therapy using nucleic acids has many clinical applications for the treatment of diseases with a genetic origin as well as for the development of innovative vaccine formulations. Since nucleic acids in their free form are rapidly degraded by nucleases present in extracellular matrices, have poor pharmacokinetics and hardly pass cellular membranes, carrier systems are required. Suitable carriers that protect the nucleic acid payload against enzymatic attack, prolong circulation time after systemic administration and assist in cellular binding and internalization are needed to develop nucleic acid based drug products. Viral vectors have been investigated and are also clinically used as delivery vehicles. However, some major drawbacks are associated with their use. Therefore there has been substantial attention on the use of non-viral carrier systems based on cationic lipids and polymers. This review focuses on the properties of polymer-based nucleic acid formulations, also referred as polyplexes. Different polymeric systems are summarized, and the cellular barriers polyplexes encounter and ways to tackle these are discussed. Finally attention is given to the clinical status of non-viral nucleic acid formulations.

Optimizing Active Tumor Targeting Biocompatible Polymers for Efficient Systemic Delivery of Adenovirus.

Adenovirus (Ad) has risen to be a promising alternative to conventional cancer therapy. However, systemic delivery of Ad, which is necessary for the treatment of metastatic cancer, remains a major challenge within the field, owing to poor tumor tropism and nonspecific hepatic tropism of the virus. To address this limitation of Ad, we have synthesized two variants of folic acid (FA)-conjugated methoxy poly(ethylene glycol)-b-poly{N-[N-(2-aminoethyl)-2-aminoethyl]-L-glutamate (P5N2LG-FA and P5N5LG-FA) using 5 kDa poly(ethylene glycol) (PEG) with a different level of protonation (N2 < N5 in terms of charge), along with a P5N5LG control polymer without FA. Our findings demonstrate that P5N5LG, P5N2LG-FA, and P5N5LG-FA exert a lower level of cytotoxicity compared to 25 kDa polyethyleneimine. Furthermore, green fluorescent protein (GFP)-expressing Ad complexed with P5N2LG-FA and P5N5LG-FA (Ad/P5N2LG-FA and Ad/P5N5LG-FA, respectively) exerted superior transduction efficiency compared to naked Ad or Ad complexed with P5N5LG (Ad/P5N5LG) in folate receptor (FR)-overexpressing cancer cells (KB and MCF7). All three nanocomplexes (Ad/P5N5LG, Ad/P5N2LG-FA, and Ad/P5N5LG-FA) internalized into cancer cells through coxsackie adenovirus receptor-independent endocytic mechanism and the cell uptake was more efficient than naked Ad. Importantly, the cell uptake of the two FA functionalized nanocomplexes (Ad/P5N2LG-FA and Ad/P5N5LG-FA) was dependent on the complementary interaction of FA-FR. Systemically administered Ad/P5N5LG, Ad/P5N2LG-FA, and Ad/P5N5LG-FA showed exponentially higher retainment of the virus in blood circulation up to 24 h post-administration compared with naked Ad. Both tumor-targeted nanocomplexes (Ad/P5N2LG-FA and Ad/P5N5LG-FA) showed significantly higher intratumoral accumulation than naked Ad or Ad/P5N5LG via systemic administration. Both tumor-targeted nanocomplexes accumulated at a lower level in liver tissues compared to naked Ad. Notably, the nonspecific accumulation of Ad/P5N2LG-FA was significantly lower than Ad/P5N5LG-FA in several normal organs, while exhibiting a significantly higher intratumoral accumulation level, showing that careful optimization of polyplex surface charge is critical to successful tumor-targeted systemic delivery of Ad nanocomplexes.

Chiral Supraparticles for Controllable Nanomedicine.

Chirality is ubiquitous in nature and hard-wired into every biological system. Despite the prevalence of chirality in biological systems, controlling biomaterial chirality to influence interactions with cells has only recently been explored. Chiral-engineered supraparticles (SPs) that interact differentially with cells and proteins depending on their handedness are presented. SPs coordinated with d-chirality demonstrate greater than threefold enhanced cell membrane penetration in breast, cervical, and multiple myeloma cancer cells. Quartz crystal microbalance with dissipation and isothermal titration calorimetry measurements reveal the mechanism of these chiral-specific interactions. Thermodynamically, d-SPs show more stable adhesion to lipid layers composed of phospholipids and cholesterol compared to l-SPs. In vivo, d-SPs exhibit superior stability and longer biological half-lives likely due to opposite chirality and thus protection from endogenous proteins including proteases. This work shows that incorporating d-chirality into nanosystems enhances uptake by cancer cells and prolonged in vivo stability in circulation, providing support for the importance of chirality in biomaterials. Thus, chiral nanosystems may have the potential to provide a new level of control for drug delivery systems, tumor detection markers, biosensors, and other biomaterial-based devices.

Physically crosslinked injectable hydrogels for long-term delivery of oncolytic adenoviruses for cancer treatment.

A dual pH- and temperature-responsive physically crosslinked and injectable hydrogel system was developed for efficient and long-term delivery of oncolytic adenoviruses (Ads). Three different types of physically crosslinked hydrogels with different chemical compositions and properties were prepared. These hydrogels with good biocompatibility can be injected at pH 9.0 and room temperature and rapidly form a gel under body or tumor microenvironment conditions. Ads encapsulated in hydrogels were released gradually without burst release. Moreover, these physically crosslinked hydrogels provided a protective environment for Ads and maintained their bioactivity for a long period of time. Compared to naked Ads, Ads protected by these physically crosslinked hydrogels showed strong cytotoxicity to cancer cells even after 11 days. The Ad-loaded hydrogel system also exhibited enhanced and long-term antitumor therapeutic effects in human xenograft tumor models. Due to these outstanding properties, Ad-loaded injectable hydrogels might have potential for long-term cancer treatment.

Systemic administration of human mesenchymal stromal cells infected with polymer-coated oncolytic adenovirus induces efficient pancreatic tumor homing and infiltration.

Oncolytic adenovirus (oAd)-mediated gene therapy is a promising approach for cancer treatment because of its cancer cell-restricted replication and therapeutic gene expression. However, systemic administration of oAd is severely restricted by their immunogenic nature and poor tumor homing ability, thus oAd cannot be utilized to treat disseminated metastases. In this study, human bone marrow-derived mesenchymal stromal cell (hMSCs) was used as a viral replication-permissive carrier for oAd with an aim to improve the systemic delivery of the virus to tumor tissues. To overcome the poor delivery of oAd into hMSCs, a relaxin (RLX)-expressing oncolytic Ad (oAd/RLX), which degrades dense tumor extracellular matrix of highly desmoplastic pancreatic cancer, was complexed with biodegradable polymer (poly (ethyleneimine)-conjugated poly(CBA-DAH); PCDP), generating oAd/RLX-PCDP complex. oAd/RLX-PCDP complex enhanced the internalization of oAd into hMSC, leading to superior viral production and release from hMSCs, along with high RLX expression. Furthermore, systemic administration of oAd/RLX-PCDP-treated hMSCs elicited more potent antitumor effect compared to naked oAd/RLX or oAd/RLX-treated hMSC in pancreatic tumor model. This potent antitumor effect of systemically administered oAd/RLX-PCDP-treated hMSCs was achieved by superior viral replication in tumor tissues than any other treatment group. In conclusion, these results demonstrate that hMSCs are effective carriers for the systemic delivery of oAd to tumor sites and treatment of pancreatic cancer.

Synergistic antitumor effect mediated by a paclitaxel-conjugated polymeric micelle-coated oncolytic adenovirus.

Combination treatment consisting of oncolytic adenovirus (Ad) and paclitaxel (PTX) is a promising strategy to achieve synergistic antitumor effect. However, a co-administration approach is subject to inherent limitations due to the poor solubility of PTX and chemoresistance of tumor cells. In order to overcome these limitations, an oncolytic Ad expressing a p53 variant (oAd-vp53) that is resistant to p53 inactivation in the tumor microenvironment was complexed with PEGylated and PTX-conjugated polymeric micelle (APP). This approach generated an oAd-vp53/APP complex (176.4 nm in diameter) that could concurrently deliver both oncolytic Ad and the nanoparticulate drug APP to tumors. APP-complexed replication-incompetent Ad (dAd/APP) exhibited 12-fold higher transduction efficiency than naked dAd in coxsackie adenovirus receptor (CAR)-negative cancer cells. This increased efficiency was attributed to more efficient cellular internalization mediated by charge interactions between APP and anionic cell membranes. Furthermore, oAd-vp53/APP elicited synergistically higher cancer cell killing than naked oAd-vp53, APP, or oAd-vp53 in combination with PTX (oAd-vp53 + PTX); this synergistic effect was shown to be due to superior induction of apoptosis and viral replication. Importantly, oAd-vp53/APP induced more potent and synergistic antitumor effect through both local and systemic administration by enhancing replication of oncolytic Ad and induction of apoptosis in tumor tissue. Further, the APP coating on the surface of Ad markedly attenuated the host immune response against Ad and decreased hepatic sequestration, resulting in minimal hepatotoxicity and a good safety profile. These attributes enabled oAd-vp53/APP to elicit potent antitumor effect over multiple treatment cycles. Altogether, we demonstrate that concurrent delivery of oncolytic Ad and APP as a single nanocomplex is a promising strategy for achieving synergistic antitumor effect.

Antitumor effect and safety profile of systemically delivered oncolytic adenovirus complexed with EGFR-targeted PAMAM-based dendrimer in orthotopic lung tumor model.

Adenovirus (Ad)-mediated cancer gene therapy has been proposed as a promising alternative to conventional therapy for cancer. However, success of systemically administered naked Ad has been limited due to the immunogenicity of Ad and the induction of hepatotoxicity caused by Ad's native tropism. In this study, we synthesized an epidermal growth factor receptor (EGFR)-specific therapeutic antibody (ErbB)-conjugated and PEGylated poly(amidoamine) (PAMAM) dendrimer (PPE) for complexation with Ad. Transduction of Ad was inhibited by complexation with PEGylated PAMAM (PP) dendrimer due to steric hindrance. However, PPE-complexed Ad selectively internalized into EGFR-positive cells with greater efficacy than either naked Ad or Ad complexed with PP. Systemically administered PPE-complexed oncolytic Ad elicited significantly reduced immunogenicity, nonspecific liver sequestration, and hepatotoxicity than naked Ad. Furthermore, PPE-complexed oncolytic Ad demonstrated prolonged blood retention time, enhanced intratumoral accumulation of Ad, and potent therapeutic efficacy in EGFR-positive orthotopic lung tumors in comparison with naked Ad. We conclude that ErbB-conjugated and PEGylated PAMAM dendrimer can efficiently mask Ad's capsid and retarget oncolytic Ad to be efficiently internalized into EGFR-positive tumor while attenuating toxicity induced by systemic administration of naked oncolytic Ad.

Evolving lessons on nanomaterial-coated viral vectors for local and systemic gene therapy.

Viral vectors are promising gene carriers for cancer therapy. However, virus-mediated gene therapies have demonstrated insufficient therapeutic efficacy in clinical trials due to rapid dissemination to nontarget tissues and to the immunogenicity of viral vectors, resulting in poor retention at the disease locus and induction of adverse inflammatory responses in patients. Further, the limited tropism of viral vectors prevents efficient gene delivery to target tissues. In this regard, modification of the viral surface with nanomaterials is a promising strategy to augment vector accumulation at the target tissue, circumvent the host immune response, and avoid nonspecific interactions with the reticuloendothelial system or serum complement. In the present review, we discuss various chemical modification strategies to enhance the therapeutic efficacy of viral vectors delivered either locally or systemically. We conclude by highlighting the salient features of various nanomaterial-coated viral vectors and their prospects and directions for future research.

Hepatoma targeting peptide conjugated bio-reducible polymer complexed with oncolytic adenovirus for cancer gene therapy.

Despite adenovirus (Ad) vector's numerous advantages for cancer gene therapy, such as high ability of endosomal escape, efficient nuclear entry mechanism, and high transduction, and therapeutic efficacy, tumor specific targeting and antiviral immune response still remain as a critical challenge in clinical setting. To overcome these obstacles and achieve cancer-specific targeting, we constructed tumor targeting bioreducible polymer, an arginine grafted bio-reducible polymer (ABP)-PEG-HCBP1, by conjugating PEGylated ABP with HCBP1 peptides which has high affinity and selectivity towards hepatoma. The ABP-PEG-HCBP1-conjugated replication incompetent GFP-expressing ad, (Ad/GFP)-ABP-PEG-HCBP1, showed a hepatoma cancer specific uptake and transduction compared to either naked Ad/GFP or Ad/GFP-ABP. Competition assays demonstrated that Ad/GFP-ABP-PEG-HCBP1-mediated transduction was specifically inhibited by HCBP1 peptide rather than coxsackie and adenovirus receptor specific antibody. In addition, ABP-PEG-HCBP1 can protect biological activity of Ad against serum, and considerably reduced both innate and adaptive immune response against Ad. shMet-expressing oncolytic Ad (oAd; RdB/shMet) complexed with ABP-PEG-HCBP1 delivered oAd efficiently into hepatoma cancer cells. The oAd/ABP-PEG-HCBP1 demonstrated enhanced cancer cell killing efficacy in comparison to oAd/ABP complex. Furthermore, Huh7 and HT1080 cancer cells treated with oAd/shMet-ABP-PEG-HCBP1 complex had significantly decreased Met and VEGF expression in hepatoma cancer, but not in non-hepatoma cancer. In sum, these results suggest that HCBP1-conjugated bioreducible polymer could be used to deliver oncolytic Ad safely and efficiently to treat hepatoma.

Targeting delivery of tocopherol and doxorubicin grafted-chitosan polymeric micelles for cancer therapy: In vitro and in vivo evaluation.

In this study, we report the development of a novel, redox-sensitive chitosan-based targeted drug delivery system, containing two drugs. We determined whether the synthesized polymeric micelles (HPTOC-DOX) were suitable as a drug carrier. The formation of HPTOC-DOX micelles was confirmed by (1)H NMR. HPTOC-DOX formed micelles of approximately 151.9-311.2nm in size in aqueous solution. Analysis of the drug release profile of HPTOC-DOX in different pH conditions (pH 5.2, 6.2, and 7.4) indicated that DOX was released from HPTOC-DOX micelles at acidic pH (5.2 or 6.2), while almost no DOX was released at pH 7.4. In vitro cell cytotoxicity and hemolysis assays indicated that HPTOC-DOX micelles safely deliver anti-cancer drugs and decrease the cytotoxicity of DOX. In vitro anti-cancer activity assays, confocal laser scanning microscopy analysis of SK-BR-3 cells, and in vivo anti-tumor activity in SK-BR-3-derived tumor-bearing mice were used to evaluate synergistic drug effects and the effect of the targeting peptide (anti-human epidermal growth factor receptor 2 [HER2] target peptide, epitope form; LTVSPWY) on receptor-mediated endocytosis.