A pH- and Bioreducible Cationic Copolymer with Amino Acids and Piperazines for Adenovirus Delivery

Adenoviruses (Ads) are attractive nonviral vectors and show great potential in cancer gene therapy. However, inherent properties of Ads, including immunogenicity, nonspecific toxicity, and coxsackie and adenovirus receptor (CAR)-dependent cell uptake, limit their clinical use. To surmount these issues, we developed a pH- and glutathione-responsive poly(ethylene glycol)-poly(ꞵ-aminoester)-polyethyleneimine (PPA) for conjugation with Ad. The pH sensitivity of the PPA copolymer was elegantly tuned by substitution with different amino acids (arginine, histidine, and tryptophan), piperazines (Pip1, Pip2, and Pip3), and guanidine residues in the backbone of the PPA conjugate. PPA copolymer was further functionalized with short-chain cross-linker succinimidyl 3-(2-pyridyldithio)propionate) (SPDP) to obtain PPA-SPDP for facile conjugation with Ad. The PPA-conjugated Ad (PPA-Ad) conjugate was obtained by reacting PPA-SPDP conjugate with thiolated Ad (Ad-SH). Ad-SH was prepared by reacting Ad with 2-iminothiolane. The size distribution and zeta potential results of PPA-Ad conjugate showed an increasing trend with an increase in copolymer dose. From in vitro test, it was found that the transduction efficiency of PPA-Ad conjugate in CAR-positive cells (A549 and H460 cells) was remarkably increased at the acidic pH condition (pH 6.2) when compared with PPA-Ad conjugate incubated under the physiological condition (pH 7.4). Interestingly, the increase in transduction efficiency was evidenced in CAR-negative cells (MDA-MB-231 and T24 cells). These results demonstrated that biocompatible and biodegradable PPA copolymers can efficiently cover the surface of Ad and can increase the transduction efficiency, and hence PPA copolymers can be a useful nanomaterial for viral vector delivery in cancer therapy

Gene Regulations upon Hydrogel-Mediated Drug Delivery Systems in Skin Cancers—An Overview

The incidence of skin cancer has increased dramatically in recent years, particularly in Caucasian populations. Specifically, the metastatic melanoma is one of the most aggressive cancers and is responsible for more than 80% of skin cancer deaths around the globe. Though there are many treatment techniques, and drugs have been used to cure this belligerent skin cancer, the side effects and reduced bioavailability of drug in the targeted area makes it difficult to eradicate. In addition, cellular metabolic pathways are controlled by the skin cancer driver genes, and mutations in these genes promote tumor progression. Consequently, the MAPK (RAS–RAF–MEK–ERK pathway), WNT and PI3K signaling pathways are found to be important molecular regulators in melanoma development. Even though hydrogels have turned out to be a promising drug delivery system in skin cancer treatment, the regulations at the molecular level have not been reported. Thus, we aimed to decipher the molecular pathways of hydrogel drug delivery systems for skin cancer in this review. Special attention has been paid to the hydrogel systems that deliver drugs to regulate MAPK, PI3K–AKT–mTOR, JAK–STAT and cGAS-STING pathways. These signaling pathways can be molecular drivers of skin cancers and possible potential targets for the further research on treatment of skin cancers

Biostable and bioreducible polymersomes for intracellular delivery of doxorubicin

To minimize the premature drug release of nanocarriers, we have developed chemically cross-linked bioreducible polymersomes (CLPMs) that can specifically release the drug inside cancer cells. Polymersomes were prepared using poly(ethylene glycol)-b-poly(lysine)-b-poly(caprolactone), a biocompatible triblock copolymer. To chemically cross-link the polymersomes, the primary amine of the triblock copolymer was reacted with a disulfide-containing cross-linker. Doxorubicin (DOX) was chosen as a model anti-cancer drug, and was effectively encapsulated into the CLPMs. The drug-loaded polymersomes greatly retarded the release of DOX under physiological conditions (pH 7.4), whereas the release rate of DOX increased remarkably in the presence of 10 mM glutathione, mimicking an intracellular environment. Microscopic observation showed that DOX-loaded CLPMs could effectively deliver the drug into an intracellular level of SCC7 cancer cells, leading to high cytotoxicity. These observations suggest that CLPMs are promising nanocarriers for intracellular DOX delivery

Production of Minor Ginsenoside CK from Major Ginsenosides by Biotransformation and Its Advances in Targeted Delivery to Tumor Tissues Using Nanoformulations

For over 2000 years, ginseng (roots of Panax ginseng C.A. Meyer) has been used as a traditional herbal medicine. Ginsenosides are bioactive compounds present in ginseng responsible for the pharmacological effects and curing various acute diseases as well as chronic diseases including cardiovascular disease, cancer and diabetes. Structurally, ginsenosides consist of a hydrophobic aglycone moiety fused with one to four hydrophilic glycoside moieties. Based on the position of sugar units and their abundance, ginsenosides are classified into major and minor ginsenosides. Despite the great potential of ginsenosides, major ginsenosides are poorly absorbed in the blood circulation, resulting in poor bioavailability. Interestingly, owing to their small molecular weight, minor ginsenosides exhibit good permeability across cell membranes and bioavailability. However, extremely small quantities of minor ginsenosides extracted from ginseng plants cannot fulfill the requirement of scientific and clinical studies. Therefore, the production of minor ginsenosides in mass production is a topic of interest. In addition, their poor solubility and lack of targetability to tumor tissues limits their application in cancer therapy. In this review, various methods used for the transformation of major ginsenosides to minor ginsenoside compound K (CK) are summarized. For the production of CK, various transformation methods apply to major ginsenosides. The challenges present in these transformations and future research directions for producing bulk quantities of minor ginsenosides are discussed. Furthermore, attention is also paid to the utilization of nanoformulation technology to improve the bioavailability of minor ginsenoside CK

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

Carboxymethyl dextran-based hypoxia-responsive nanoparticles for doxorubicin delivery

In an attempt to develop the hypoxia-responsive nanoparticles for cancer therapy, a polymer conjugate, consisting of carboxymethyl dextran (CMD) and black hole quencher 3 (BHQ3), was prepared. The polymer conjugate can self-assemble into nanoparticles (CMD-BHQ3 NPs) under aqueous conditions. The anticancer drug, doxorubicin (DOX), was loaded in CMD-BHQ3 NPs to prepare DOX@CMD-BHQ3 NPs. The CMD-BHQ3 NPs released DOX in a sustained manner under physiological conditions, whereas the release rate of DOX remarkably increased under hypoxic conditions throughout the cleavage of the azo bond in BHQ3. In vitro cytotoxicity study revealed that DOX@CMD-BHQ3 NPs showed higher toxicity under hypoxic conditions than normoxic conditions. Confocal microscopic images indicated oxygen-dependent intracellular release of DOX from DOX@CMD-BHQ3. In vivo biodistribution study demonstrated that CMD-BHQ3 NPs were preferentially accumulated in the tumor after systemic administration into tumor bearing mice. Overall, CMD-BHQ3 might be a promising carrier for selective drug release in the hypoxic tumor. (C) 2017 Elsevier B.V. All rights reserved

Bioinspired pH- and Temperature-Responsive Injectable Adhesive Hydrogels with Polyplexes Promotes Skin Wound Healing

Despite great potential, the delivery of genetic materials into cells or tissues of interest remains challenging owing to their susceptibility to nuclease degradation, lack of permeability to the cell membrane, and short in vivo half-life, which severely restrict their widespread use in therapeutics. To surmount these shortcomings, we developed a bioinspired in situ-forming pH- and temperature-sensitive injectable hydrogel depot that could control the delivery of DNA-bearing polyplexes for versatile biomedical applications. A series of multiblock copolymer, comprised of water-soluble poly­(ethylene glycol) (PEG) and pH- and temperature-responsive poly­(sulfamethazine ester urethane) (PSMEU), has been synthesized as in situ-forming injectable hydrogelators. The free-flowing PEG–PSMEU copolymer sols at high pH and room temperature (pH 8.5, 23 °C) were transformed to stable gel at the body condition (pH 7.4, 37 °C). Physical and mechanical properties of hydrogels, including their degradation rate and viscosity, are elegantly controlled by varying the composition of urethane ester units. Subcutaneous administration of free-flowing PEG–PSMEU copolymer sols to the dorsal region of Sprague–Dawley rats instantly formed hydrogel depot. The degradation of the hydrogel depot was slow at the beginning and found to be bioresorbable after two months. Cationic protein or DNA-bearing polyplex-loaded PEG–PSMEU copolymer sols formed stable gel and controlled its release over 10 days in vivo. Owing to the presence of urethane linkages, the PEG–PSMEU possesses excellent adhesion strength to wide range of surfaces including glass, plastic, and fresh organs. More importantly, the hydrogels effectively adhered on human skin and peeled easily without eliciting an inflammatory response. Subcutaneous implantation of PEG–PSMEU copolymer sols effectively sealed the ruptured skin, which accelerated the wound healing process as observed by the skin appendage morphogenesis. The bioinspired in situ-forming pH- and temperature-sensitive injectable adhesive hydrogel may provide a promising platform for myriad biomedical applications as controlled delivery vehicle, adhesive, and tissue regeneration