[Show abstract][Hide abstract] ABSTRACT: Cancer stem cells (CSCs) are a small subset of cancer cells responsible for maintenance and progression of several types of cancer. Isolation, propagation, and the differentiation of CSCs in the proper stem niches expose the intrinsic difficulties for further studies. Here we show that induced cancer like stem cells (iCLSCs) can be generated by in vitro oncogenic manipulation of mouse embryonic stem cells (mESCs) with well-defined oncogenic elements; SV40 LTg and HrasV12 by using a mouse stem virus long terminal repeat (MSCV-LTR)-based retroviral system. The reprogrammed mESCs using both oncogenes were characterized through their oncogenic gene expression, the enhancement of proliferation, and unhampered maintenance of stem properties in vitro and in vivo. In addition, these transformed cells resulted in the formation of malignant, immature ovarian teratomas in vivo. To successfully further expand these properties to other organs and species, more research needs to be done to fully understand the role of a tumor- favorable microenvironment. Our current study has provided a novel approach to generate induced cancer like stem cells through in vitro oncogenic reprogramming and successfully initiated organ-specific malignant tumor formation in an orthotopic small animal cancer model.
PLoS ONE 10/2015; 10(10):e0141172. DOI:10.1371/journal.pone.0141172 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Thermogenic program (also known as browning) is a promising and attractive anti-obesity approach. Islet amyloid polypeptide (IAPP) and irisin have emerged as potential browning hormones that hold high potential to treat obesity. Here, we have constructed a dual browning gene system containing both IAPP and irisin (derived from fibronectin type III domain containing 5; FNDC5) combined with 2A and furin self-cleavage sites. Intraperitoneal administration of the construct complexed with a linear polyethylenimine into diet-induced obese mice demonstrated the elevation of anti-obesogenic effects characterized as the decreased body weight, adiposity, and levels of glucose and insulin. In addition, the construct delivery increased energy expenditure and the expression of core molecular determinants associated with browning. The additional advantages of the dual browning gene construct delivery compared to both single gene construct delivery and dual peptide delivery can be emphasized on efficacy and practicability. Hence, we have concluded that dual browning gene delivery makes it therapeutically attractive for diet-induced obesity treatment.
[Show abstract][Hide abstract] ABSTRACT: Oncolytic adenovirus (Ad) holds great promise as a potential gene therapy for cancer. However, intravenously administered Ad may encounter difficulties due to unfavorable host responses, non-specific interactions, and the heterogeneity of the tumor cell population. As an approach to combine the advantages of oncolytic Ad and synthetic polymers and to address the associated difficulties, Ad was physically complexed with a pH-sensitive block copolymer, methoxy poly(ethylene glycol)-b-poly(L-histidine) (mPEG-b-pHis). The in vitro transduction efficiency at an acidic extracellular pH was remarkably enhanced in cancer cells when treated with the Ad expressing green fluorescent protein (GFP) coated with mPEG-b-pHis (c-dE1/GFP) as compared to that of naked Ad (n-dE1/GFP). Time-lapse total internal reflection fluorescence microscopic imaging revealed a significantly enhanced cellular uptake rate of c-dE1/GFP at acidic tumor pH when compared with that at neutral pH or naked cognate Ad (n-dE1/GFP). In addition, c-dE1/GFP remained relatively stable in human serum-containing media, and considerably reduced both the innate and adaptive immune response against Ad. Moreover, the therapeutic efficacy and survival benefit of mPEG-b-pHis-complexed oncolytic Ad (c-H5mT/Luc) by systemic treatment was significantly enhanced compared to that with naked oncolytic Ad (n-H5mT/Luc) in both coxsackie and adenovirus receptor-positive and -negative tumors. Whole-body bioluminescence imaging showed 7.3-fold higher luciferase expression at the tumor site and 23.0-fold less luciferase expression in liver tissue for c-H5mT/Luc relative to that for naked oncolytic Ad (n-H5mT/Luc). Considering the heterogeneity of tumor tissue, these results are important for guiding the development of more potent and specific treatment of devastating metastatic cancers using this viral system.
[Show abstract][Hide abstract] ABSTRACT: Double helix nucleic acids were used as a combination drug carrier for doxorubicin (DOX), which physically intercalates with DNA double helices, and cisplatin (CDDP), which binds to DNA without an alkylation reaction. DNA interacting with DOX, CDDP, or both was complexed with positively charged, endosomolytic polymers. Compared with the free drug, the polyplexes (100 ~ 170 nm in size) delivered more drug into the cytosol and the nucleus and demonstrated similar or superior (up to a 7-fold increase) in vitro cell-killing activity. Additionally, the gene expression activities of most of the chemical drug-loaded plasmid DNA (pDNA) polyplexes were not impaired by the physical interactions between the nucleic acid and DOX/CDDP. When a model reporter pDNA (luciferase) was employed, it expressed luciferase protein at 0.7- ~ 1.4-fold the amount expressed by the polyplex with no bound drugs (a control), which indicated the fast translocation of the intercalated or bound drugs from the "carrier DNA" to the "nuclear DNA" of target cells. The proposed concept may offer the possibility of versatile combination therapies of genetic materials and small molecule drugs that bind to nucleic acids to treat various diseases.
[Show abstract][Hide abstract] ABSTRACT: In recent years, advances in biotechnology and protein engineering have enabled the production of large quantities of proteins and peptides as important therapeutic agents. Various researchers have used biocompatible functional polymers to prepare oral dosage forms of proteins and peptides for chronic use and for easier administration to enhance patient compliance. However, there is a need to enhance their safety and effectiveness further. Most macromolecules undergo severe denaturation at low pH and enzymatic degradation in the gastrointestinal tract. The macromolecules' large molecular size and low lipophilicity cause low permeation through the intestinal membrane. The major strategies that have been used to overcome these challenges (in oral drug carrier systems) can be classified as follows: enteric coating or encapsulation with pH-sensitive polymers or mucoadhesive polymers, co-administration of protease inhibitors, incorporation of absorption enhancers, modification of the physicochemical properties of the macromolecules, and site-specific delivery to the colon. This review attempts to summarize the various advanced oral delivery carriers, including nanoparticles, lipid carriers, such as liposomes, nano-aggregates using amphiphilic polymers, complex coacervation of oppositely charged polyelectrolytes, and inorganic porous particles. The particles were formulated and/or surface modified with functional polysaccharides or synthetic polymers to improve oral bioavailability of proteins and peptides. We also discuss formulation strategies to overcome barriers, therapeutic efficacies in vivo, and potential benefits and issues for successful oral dosage forms of the proteins and peptides.
Current pharmaceutical design 05/2015; 21(22). DOI:10.2174/1381612821666150531163944 · 3.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this study, a series of amphiphilic AB2-type 3-miktoarm copolymers consisting of hydrophilic poly(ethylene glycol) (PEG) as the A arm and hydrophobic poly(ε-caprolactone) (PCL) as the two B arms were synthesized through the ring-opening polymerization of ε-caprolactone (CL) using a PEG macroinitiator with a bi-arm structure. The self-assembly behaviors, drug-loading capacities, and controlled drug release features of the PEG-PCL2 miktoarm copolymers were compared with those of their linear diblock counterparts (PEG-PCL). The PEG-PCL2 miktoarm copolymer with a relatively short PCL arm length (PEG volume fraction, fPEG = 0.55) self-assembled in aqueous solution to form a spherical micelle structure. However, cylindrical micelles were observed for the miktoarm copolymers with long PCL arms (fPEG = 0.15–0.32), whereas the corresponding linear counterparts consistently formed spherical micelle structures regardless of the PCL arm lengths. Drug-loading using doxorubicin (DOX) as the model drug indicated that the PEG-PCL2 cylindrical micelles possessed superior drug-loading capacities compared with the spherical micelles of the corresponding diblock copolymers. Furthermore, although the DOX-loaded cylindrical micelles exhibited a slower release rate than the DOX-loaded spherical micelles, the former exhibited higher cellular uptake and improved cytotoxic effects than the latter. These findings demonstrate the useful morphological versatility of miktoarm-structured PEG-PCL block copolymers in comparison to the conventionally used linear diblock copolymers in the design of self-assembled nanocarriers for efficient drug delivery.
[Show abstract][Hide abstract] ABSTRACT: Limited drug distribution is partially responsible for the efficacy gap between preclinical and clinical studies of nano-sized drug carriers for cancer therapy. In this study, we examined the transport behavior of cationic micelles formed from a triblock copolymer of poly(D,L-lactide-co-glycolide)-block-branched polyethyleneimine-block-poly(D,L-lactide-co-glycolide) using a unique in vitro tumor model composed of a multilayered cell culture (MCC) and an Ussing chamber system. The Cy3-labeled cationic micelles showed remarkable Cy3 distribution in the MCC whereas charge-shielded micelles with a poly(ethylene glycol) surface accumulated on the surface of the MCC. Penetration occurred against convectional flow caused by a hydraulic pressure gradient. The study using fluorescence resonance energy transfer (FRET) showed that the cationic micelles dissociate at the interface between the culture media and the MCC or possibly inside of the first-layer cells and penetrates into the MCC as unimers. The penetration and distribution were energy-dependent and suppressed by various endocytic inhibitors. These suggest that cationic unimers mainly utilized clathrin-mediated endocytosis and macropinocytosis for cellular entry and a significant fraction were exocytosed by an unknown mechanism.
[Show abstract][Hide abstract] ABSTRACT: A potent synthetic methodology is introduced to generate a useful intermediate for the preparation of ‘smart’ polymeric pro-drugs. Herein, living anionic block polymerization of ethylene oxide (EO) and N-phenylmaleimide (N-PMI), as well as the Gabriel process, are introduced. Hydrazinolysis of the resulting poly(ethylene oxide)-block-poly(N-PMI) (PEO-b-PN-PMI) using hydrazine under acidic conditions leads to the production of PEO-based frameworks with hydrazide (HZ) groups. The HZ groups are found to effect the formation of an acid-sensitive bond in reactions with medicines or drugs under neutral conditions (pH 7.2). The PEO-HZ intermediate, which shows a strong triplet splitting patterned chemical shift in the range δ = 6.5–8.5 ppm, represents the most powerful material employed for mass production of smart polymeric pro-drugs while controlling the drug-loading yield. Water-soluble “smart” polymeric pro-drugs, such as poly(ethylene oxide)-doxorubicin (PEO-HZ-Dox), poly(ethylene oxide)-methotrexate (PEO-HZ-MTX), and poly(ethylene oxide)-folate (PEO-HZ-FA) conjugates, show excellent acid-sensitive release profiles in water or alcohol at pH 4.5.
[Show abstract][Hide abstract] ABSTRACT: Branched-type hydrophilic polyethyleneimine derivatives (i.e., bPEI derivatives) are developed polymeric carriers for photodynamic therapy. Their chemical structures which contain pH-tunable hydrophobic/hydrophilic cavities enable efficient loading of hydrophobic drugs in basic pH environments. Intracellular stimuli trigger the release of the loaded drugs in bPEI derivatives. As expected, the hydrophobic photosensitizer known as pheophorbide A (PheoA) is solubilized by physical loading in the inner hydrophobic spaces of bPEI derivatives in environments with basic pH values. Interestingly, acidic pH environments induce aggregation, resulting in poor release of the loaded PheoA as well as in quenched photo-activity of the PheoA-loaded polymers. However, when reducible polycation derivatives of bPEI are used (i.e., RPC-bPEI), intracellular thiols degrade the disulfide linkages in the polymers, resulting in rapid PheoA release. Particularly, a RPC-bPEI containing 6 wt% PheoA (i.e., RPC-bPEI0.8kDa-PheoA6%) respond remarkably well to light exposure and display large differences between dark toxicity and light-induced toxicity. Cellular uptake of RPC-bPEI0.8kDa-PheoA6% is approximately sevenfold to ninefold lower than that of free PheoA. Nevertheless, the photo-toxicity of RPC-bPEI0.8kDa-PheoA6% was only two- to sixfold less potent than that of free PheoA. These results suggest that reducible bPEI materials may act as potential solubilizers and carriers for low-molecular-weight hydrophobic anti-cancer drugs.
[Show abstract][Hide abstract] ABSTRACT: To celebrate the success of the Journal of Controlled Release and the research covered in the journal, here we highlight some of the most cited research articles in the history of the journal. Based on the literature search in Google Scholar in July 2013, we identified ~30 research articles that have received most number of citations. Authors of these articles were invited to provide a commentary on these articles. This compilation of commentaries gives a historical perspective and current status of research covered in these articles.
[Show abstract][Hide abstract] ABSTRACT: Endosomal entrapment is one of the main barriers that must be overcome for efficient gene expression along with cell internalization, DNA release and nuclear import. Introducing pH-sensitive ionizable groups into the polycationic polymers to increase gene transfer efficiency has proven to be a useful method; however, effective methods of introducing equal numbers of ionizable groups in both polymer and monomer forms, has not been reported. In this paper, we prepared two types of histidine grafted Poly(L-lysine) (PLL), a stacking form of Poly(L-histidine) (PLL-g-PHis) and a mono- L-histidine (PLL-g-mHis) with same number of imidazole groups. These two types showed profound differences in hemolytic activity, cellular uptake, internalization and transfection efficiency. Cy3-labeled PLL-g-PHis showed strong fluorescence in the nucleus after internalization, and high hemolytic activity upon pH changes was also observed from PLL-g-PHis. The arrangement of imidazole groups from PHis also provided higher gene expression than mHis due to its ability to escape the endosome. mHis or PHis grafting reduced the cytotoxicity of PLL and changed the cellular uptake by changing the quantity of free ɛ-amines available for gene condensation. The sub-cellular localization of PLL-g-PHis/pDNA measured by YOYO1-pDNA intensity was highest inside the nucleus, and the lysotracker which stains the acidic compartments was lowest among polymers. Thus, the polymeric histidine arrangement demonstrate the ability to escape the endosome and trigger rapid release of polyplexes into the cytosol resulting in a greater amount of genes available for translocation to the nucleus and enhanced gene expression.
[Show abstract][Hide abstract] ABSTRACT: Nontoxic endogenous nucleotides such as adenosine triphosphate and guanosine triphosphate have secondary phosphate groups, causing proton-buffering capacity and/or hemolytic activity in endolysosomal pH ranges. Nucleotides co-delivered in single polymeric pDNA nanocarrier induce highly enhanced transfection efficiency with negligible cytotoxicity due to their endosomolytic functions.
[Show abstract][Hide abstract] ABSTRACT: This study investigates the potential of dexamethasone (Dex) to enhance the nuclear accumulation and subsequent gene expression of plasmid DNA (pDNA) delivered using a charged polymeric micelle-based gene delivery system. (PLGA)n -b-bPEI25kDa block copolymers are synthesized and used to prepare Dex-loaded cationic micelles (DexCM). After preparing DexCM/pDNA complexes, bPEI1.8kDa is coated on the complexes using a Layer-by-Layer (LbL) technique to construct DexCM/pDNA/bPEI1.8kDa complexes (i.e., LbL-DexCM polyplexes) that are 100-180 nm in diameter and have a zeta potential of 30-40 mV. In MCF7 cells, LbL-DexCM polyplexes cause 3-13-fold higher transfection efficiencies compared to LbL-CM polyplexes and show negligible cytotoxicity. LbL-DexCM3 polyplexes induce much higher nuclear delivery of pDNA compared to LbL-CM3 polyplexes. These results suggest that Dex-loaded polyplexes could be used in gene and drug delivery applications to increase nuclear accumulation of therapeutic payloads, further leading to a decrease in the dose of the drug and gene necessary to achieve equivalent therapeutic effects.
[Show abstract][Hide abstract] ABSTRACT: The enhanced permeability and retention (EPR) of nanoparticles in tumors has long stood as one of the fundamental principles of cancer drug delivery, holding the promise of safe, simple and effective therapy. By allowing particles preferential access to tumors by virtue of size and longevity in circulation, EPR provided a neat rationale for the trend toward nano-sized drug carriers. Following the discovery of the phenomenon by Maeda in the mid-1980s, this rationale appeared to be well justified by the flood of evidence from preclinical studies and by the clinical success of Doxil®. Clinical outcomes from nano-sized drug delivery systems, however, have indicated that EPR is not as reliable as previously thought. Drug carriers generally fail to provide superior efficacy to free drug systems when tested in clinical trials. A closer look reveals that EPR-dependent drug delivery is complicated by high tumor interstitial fluid pressure (IFP), irregular vascular distribution, and poor blood flow inside tumors. Furthermore, the animal tumor models used to study EPR differ from clinical tumors in several key aspects that seem to make EPR more pronounced than in human patients. On the basis of this evidence, we believe that EPR should only be invoked on a case-by-case basis, when clinical evidence suggests the tumor type is susceptible.