Multifunctional Microparticles Incorporating Gold Compound Inhibit Human Lung Cancer Xenograft.

PURPOSE: Gold porphyrin (AuP) is a complex that has been shown to be potent against various tumors. A biocompatible interpenetrating network (IPN) system comprised of polyethyleneglycol diacrylate (PEGdA) and chemically-modified gelatin has been shown to be an effective implantable drug depot to deliver AuP locally. Here we designed IPN microparticles complexed with AuP to facilitate intravenous administration and to diminish systemic toxicity. METHODS: We have synthesized and optimized an IPN microparticle formulation complexed with AuP. Tumor cell cytotoxicity, antitumor activity, and survival rate in lung cancer bearing nude mice were analyzed. RESULTS: IPN microparticles maintained AuP bioactivity against lung cancer cells (NCI-H460). In vivo study showed no observable systemic toxicity in nude mice bearing NCI-H460 xenografts after intravenous injection of 6 mg/kg AuP formulated with IPN microparticles. An anti-tumor activity level comparable to free AuP was maintained. Mice treated with 6 mg/kg AuP in IPN microparticles showed 100% survival rate while the survival rate of mice treated with free AuP was much less. Furthermore, microparticle-formulated AuP significantly reduced the intratumoral microvasculature when compared with the control. CONCLUSION: AuP in IPN microparticles can reduce the systemic toxicity of AuP without compromising its antitumor activity. This work highlighted the potential application of AuP in IPN microparticles for anticancer chemotherapy.

An Antitumor Bis(N-Heterocyclic Carbene)Platinum(II) Complex That Engages Asparagine Synthetase as an Anticancer Target.

New anticancer platinum(II) compounds with distinctive modes of action are appealing alternatives to combat the drug resistance and improve the efficacy of clinically used platinum chemotherapy. Herein, we describe a rare example of an antitumor PtII complex targeting a tumor-associated protein, rather than DNA, under cellular conditions. Complex [(bis-NHC)Pt(bt)]PF6 (1 a; Hbt=1-(3-hydroxybenzo[b]thiophen-2-yl)ethanone) overcomes cisplatin resistance in cancer cells and displays significant tumor growth inhibition in mice with higher tolerable doses compared to cisplatin. The cellular Pt species shows little association with DNA, and localizes in the cytoplasm as revealed by nanoscale secondary ion mass spectrometry. An unbiased thermal proteome profiling experiment identified asparagine synthetase (ASNS) as a molecular target of 1 a. Accordingly, 1 a treatment reduced the cellular asparagine levels and inhibited cancer cell proliferation, which could be reversed by asparagine supplementation. A bis-NHC-ligated Pt species generated from the hydrolysis of 1 a forms adducts with thiols and appears to target an active-site cysteine of ASNS.

Cyclometalated Gold(III) Complexes Containing N-Heterocyclic Carbene Ligands Engage Multiple Anti-Cancer Molecular Targets.

Metal N-heterocyclic carbene (NHC) complexes are a promising class of anti-cancer agents displaying potent in vitro and in vivo activities. Taking a multi-faceted approach employing two clickable photoaffinity probes, herein we report the identification of multiple molecular targets for anti-cancer active pincer gold(III) NHC complexes. These complexes display potent and selective cytotoxicity against cultured cancer cells and in vivo anti-tumor activities in mice bearing xenografts of human cervical and lung cancers. Our experiments revealed the specific engagement of the gold(III) complexes with multiple cellular targets, including HSP60, vimentin, nucleophosmin, and YB-1, accompanied by expected downstream mechanisms of action. Additionally, PtII and PdII analogues can also bind the cellular proteins targeted by the gold(III) complexes, uncovering a distinct pincer cyclometalated metal-NHC scaffold in the design of anti-cancer metal medicines with multiple molecular targets.

A Macrocyclic Ruthenium(III) Complex Inhibits Angiogenesis with Down-Regulation of Vascular Endothelial Growth Factor Receptor-2 and Suppresses Tumor Growth In Vivo.

A macrocyclic ruthenium(III) complex [RuIII (N2 O2 )Cl2 ]Cl (Ru-1) is reported as an inhibitor of angiogenesis and an anti-tumor compound. The complex is relatively non-cytotoxic towards endothelial and cancer cell lines in vitro, but specifically inhibited the processes of angiogenic endothelial cell tube formation and cancer cell invasion. Moreover, compared with known anti-cancer ruthenium complexes, Ru-1 is distinct in that it suppressed the expression of vascular endothelial growth factor receptor-2 (VEGFR2), and the associated downstream signaling that is crucial to tumor angiogenesis. In addition, in vivo studies showed that Ru-1 inhibited angiogenesis in a zebrafish model and suppressed tumor growth in nude mice bearing cancer xenografts.

Nanomedicine: a new frontier in cancer therapeutics.

Nanotechnology is a cutting edge and rapidly evolving technology in medicine. The potential of nanomedicine in cancer therapy is infinitely promising due to the fact that novel developments are constantly being explored. This is particularly the case in the use of nanoparticles in both tumor diagnosis, as well as treatment. This article will attempt to describe some recent advances using nanoparticle drug delivery system in cancer therapy. The evolution history, the challenges and the role of nanoparticles in cancer drug delivery will briefly be discussed together with additional opportunities in cancer therapy. An overall understanding of these issues will help with further advancement of designing better drug delivery system that can be applied clinically.

Silver nanoparticles mediate differential responses in keratinocytes and fibroblasts during skin wound healing.

With advances in nanotechnology, pure silver has been recently engineered into nanometer-sized particles (diameter <100 nm) for use in the treatment of wounds. In conjunction with other studies, we previously demonstrated that the topical application of silver nanoparticles (AgNPs) can promote wound healing through the modulation of cytokines. Nonetheless, the question as to whether AgNPs can affect various skin cell types--keratinocytes and fibroblasts--during the wound-healing process still remains. Therefore, the aim of this study was to focus on the cellular response and events of dermal contraction and epidermal re-epithelialization during wound healing under the influence of AgNPs; for this we used a full-thickness excisional wound model in mice. The wounds were treated with either AgNPs or control with silver sulfadiazine, and the proliferation and biological events of keratinocytes and fibroblasts during healing were studied. Our results confirm that AgNPs can increase the rate of wound closure. On one hand, this was achieved through the promotion of proliferation and migration of keratinocytes. On the other hand, AgNPs can drive the differentiation of fibroblasts into myofibroblasts, thereby promoting wound contraction. These findings further extend our current knowledge of AgNPs in biological and cellular events and also have significant implications for the treatment of wounds in the clinical setting.

Thermosensitive hydrogel PEG-PLGA-PEG enhances engraftment of muscle-derived stem cells and promotes healing in diabetic wound.

Regenerating new tissue using cell transplantation has relied on successful cell engraftment in the host; however, cell engraftment into the diabetic skin wound is not as successful as in many other tissues. We used a biodegradable and biocompatible triblock co-polymer poly(ethylene glycol-b-[DL-lactic acid-co-glycolic acid]-b-ethylene glycol) (PEG-PLGA-PEG), which forms a thermosensitive hydrogel, as a wound dressing and scaffold. We found that the thermosensitive hydrogel increased the engraftment of muscle-derived stem cells (MDSCs) by 20- to 30-fold until day 20, when the wound was completely closed in a db/db genetically diabetic mouse model. At day 9, 30% of the transplanted MDSCs were found to remain, and 15% remained at day 20 after transplantation. The increased engraftment resulted in enhanced wound healing, as indicated by the wound closure rate, epithelium migration, and collagen deposition. Using MDSCs stably expressing beta-gal and immunofluorescence, we found that 25% of MDSCs differentiated into fibroblasts, 10% into myofibroblasts, and 10% into endothelial cells. We conclude that using the thermosensitive hydrogel as a scaffold increased the engraftment of MDSCs, which leads to improved diabetic wound healing, possibly by retaining the cells at the wound site for longer.

Electroporatic delivery of TGF-beta1 gene works synergistically with electric therapy to enhance diabetic wound healing in db/db mice.

Electrical stimulation (ES) is a therapeutic treatment for wound healing. Electroporation, a type of ES, is a well-established method for gene delivery. We hypothesize that proper conditions can be found with which both electrical and gene therapies can be additively applied to treat diabetic wound healing. For the studies of transforming growth factor-beta1 (TGF-beta1) local expression and therapeutic effects, full thickness excisional wound model of db/db mice was used, we measured TGF-beta1 cytokine level at 24 h postwounding and examined wounds histologically. Furthermore, wound closure was evaluated by wound-area measurements at each day for 14 d. We found that syringe electrodes are more effective than the conventional caliper electrodes. Furthermore, diabetic skin was more sensitive to the electroporative damage than the normal skin. The optimal condition for diabetic skin was six pulses of 100 V per cm for 20 ms. Under such condition, the healing rate of electrically treated wound was significantly accelerated. Furthermore, when TGF-beta1 gene was delivered by electric pulses, the healing rate was further enhanced. Five to seven days postapplication of intradermal injection of plasmid TGF-beta1 followed by electroporation, the wound bed showed an increased reepithelialization rate, collagen synthesis, and angiogenesis. The data indicates that indeed the electric effect and gene effect work synergistic in the genetically diabetic model.

Controlled gene delivery system based on thermosensitive biodegradable hydrogel.

PURPOSE: Currently, most pDNA delivery systems based on synthetic polymers are either nonbiodegradable or not sensitive to the release environment. The primary objective of this study was to develop and evaluate an aqueous-based, thermosensitive, biodegradable and biocompatible triblock copolymer to control pDNA delivery in vitro and in vivo. METHODS: The triblock copolymers, poly[ethylene glycol-b-(D, L-lactic acid-co-glycol acid)-b-ethylene glycol] (PEG-PLGA-PEG), were synthesized as previously described. The molecular weight and polydispersity of PEG-PLGA-PEG were monitored by gel permeation chromatography (GPC). The cytotoxicity of PEG-PLGA-PEG was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The release of 32P-labeled pDNA entrapped in aqueous dispersion of PEG-PLGA-PEG in 0.1 mol/L sodium phosphate buffer solution (pH 7.4) was studied at 37 degrees C under agitation. Gene transfection efficiency was evaluated in a skin wound model in CD-1 mice. RESULTS: The aqueous dispersion of PEG-PLGA-PEG flows freely at room temperature but form a gel at 37 degrees C body temperature. The in vitro degradation of PEG-PLGA-PEG lasted for more than 30 days. The cytotoxicity of PEG-PLGA-PEG evaluated in HEK 293 cells was significantly lower than that of poly-L-lysine hydrochloride. The release profile of supercoiled pDNA from the polymer followed the zero-order kinetics up to 12 days. Maximal gene expression of luciferase was at 24 h in the skin wound of CD-1 mice and by 72 h, the expression dropped by nearly 94%. CONCLUSION: These results suggest hydrogel formed by PEG-PLGA-PEG could be a promising platform for delivery of pDNA, which represents a novel strategy that may serve as a non-viral vector for gene therapy in wound healing.

Intradermal injection of transforming growth factor-beta1 gene enhances wound healing in genetically diabetic mice.

PURPOSE: To evaluate the biologic effect of direct cutaneous TGF-beta1 gene delivery on impaired wound healing models using genetically diabetic mice. METHODS: Diabetic mice (C57BKS.Cg-m +/+ Leprdb female mice) with 1 cm x 1 cm excisional wounds were intradermally injected with 60 microg of plasmid DNA encoding TGF-beta1 gene. The wound closure was measured up to 14 days postwounding. At days 7 and 14 postwounding, sections of skin were taken for hematoxylin and eosin and Masson's trichome staining to examine the morphology and collagen deposition. The cell proliferation and TGF-beta1 gene expression were studied using immunohistochemical stainings for 5-bromo-2-deoxyuridine and for TGF-beta1. RESULTS: A higher cell proliferation rate and a denser and more organized new extracellular matrix were observed in the treated wound site. Complete wound closure was detected as early as 7 days for TGF-beta1-treated group in comparison with 11-14 days for the untreated, control plasmid DNA- and PBS-treated groups. CONCLUSION: A single intradermal injection of TGF-beta1 plasmid DNA was sufficient to enhance wound healing. This approach represents a new strategy that may be applied to the treatment of excisional wounds in human diabetic patients.

Thermosensitive hydrogel as a Tgf-beta1 gene delivery vehicle enhances diabetic wound healing.

PURPOSE: To accelerate diabetic wound healing with TGF-beta1 gene delivery system using a thermosensitive hydrogel made of a triblock copolymer, PEG-PLGA-PEG. METHODS: Two 7 x 7 mm full thickness excisional wounds were created in parallel at the back of each genetically diabetic mouse. The hydrogel containing plasmid TGF-beta1 was administered to the wound and formed an adhesive film in situ. Controls were either untreated or treated with the hydrogel without DNA. We used a commercial wound dressing, Humatrix, either with or without DNA, to compare the therapeutic effect with the thermosensitive hydrogel. RESULTS: We found that thermosensitive hydrogel alone is slightly beneficial for reepithealization at early stage of healing (day 1-5), but significantly accelerated repithelializaion, increased cell proliferation, and organized collagen were observed in the wound bed treated with thermosensitive hydrogel containing plasmid TGF-beta1. The accelerated reepithelialization was accompanied with enhanced collagen synthesis and more organized extracellular matrix deposition. Humatrix alone or with plasmid TGF-beta1, had little effect. CONCLUSIONS: Thermosensitive hydrogel made of PEG-PLGA-PEG triblock copolymer provides excellent wound dressing activity and delivers plasmid TGF-beta1 to promote wound healing in a diabetic mouse model.