A novel EGFR-targeted gene delivery system based on complexes self-assembled by EGF, DNA, and activated PAMAM dendrimers.

Epidermal growth factor receptor (EGFR)-targeted gene delivery is a promising approach in gene therapy against EGFR-positive cancer. In addition, macromolecules, such as polyamidoamine (PAMAM) dendrimers, are potential nonviral gene carriers in this therapy because of their biocompatibility and modifiable features. To achieve the goal of selectively enhancing the transfection efficiency in EGFR-positive cancer cells, the researchers developed chemical approaches of EGF-dendrimer conjugate, which were effective but complicated. Studies on liposomes reveal that self-assembly is another effective but simpler approach in EGF modification. Moreover, properly activated PAMAM dendrimers exhibit higher transfection efficiency, but little research has been done on its ligand-modification. In this study, we developed and characterized a novel gene-delivery system based on activated EGF-dendriplexes, which is formed via self-assembly by EGF and complexes prepared by activated PAMAM dendrimer and plasmid DNA. Such complexes exhibit desired features compared to nonmodified or non-activated dendriplexes in vitro, including selective enhancement of transfection efficiency in EGFR-positive cells, decreased cytotoxicity, and low agonist effect. In vivo experimentation shows their EGFR-positive tumor targeted biodistribution and increased transfection efficiency at EGFR-positive tumors. Our results demonstrated that activated EGF-dendriplexes are safe and effective carriers for delivering gene drugs to EGFR-positive cells, which makes these complexes a promising targeted nonviral gene-delivery system for auxiliary cancer therapy.

A novel lipid-based nanomicelle of docetaxel: evaluation of antitumor activity and biodistribution.

PURPOSE: A lipid-based, nanomicelle-loaded docetaxel (M-DOC) was designed and characterized. Optical imaging was employed to evaluate the pharmacokinetics and antitumor efficacy of docetaxel in vivo. MATERIALS AND METHODS: The M-DOC was prepared using the emulsion-diffusion method. Transmission electron microscopy and dynamic light scattering were used to assess the morphology and particle size of the M-DOC. Critical micelle concentrations, their stability under physiological conditions, and their encapsulation efficiency - as measured by high-performance liquid chromatography - were assessed. Pharmacological features were evaluated in two different animal models by comparing M-DOC treatments with docetaxel injections (I-DOC). Bioluminescence imaging was used to assess antitumor activity and docetaxel distribution in vivo, using nude mice injected with luciferase-expressing MDA-MB-231 human breast tumor cells. In addition, animals injected with B16 melanoma cells were used to measure survival time and docetaxel distribution. RESULTS: The M-DOC was prepared as round, uniform spheres with an effective diameter of 20.8 nm. The critical micelle concentration of the original emulsion was 0.06%. Satisfactory encapsulation efficiency (87.6% ± 3.0%) and 12-hour stability were achieved. Xenograft results demonstrated that the M-DOC was more effective in inhibiting tumor growth, without significantly changing body weight. Survival was prolonged by 12.6% in the M-DOC group. Tumor growth inhibitory rates in the M-DOC and I-DOC groups were 91.2% and 57.8% in volume and 71.8% and 44.9% in weight, respectively. Optical bioluminescence imaging of tumor growths yielded similar results. Area under the curve((0-6 hour)) levels of docetaxel in blood and tumors were significantly higher in the M-DOC group (15.9 ± 3.2 µg/mL(-1), 601.1 ± 194.5 µg/g(-1)) than in the I-DOC group (7.2 ± 1.7 µg/mL(-1), 357.8 ± 86.2 µg/g(-1)). The fluorescent dye 1,1-dioctadecyl-3,3,3,3'-tetramethylindotricarbocyanine iodide mimicked M-DOC in optical imaging, and accumulated more in tumors in comparison with I-DOC. CONCLUSION: These results suggest that the lipid-based nanomicelle system was effective in inhibiting tumor growth, with little toxicity. Moreover, we have developed a noninvasive optical imaging method for antitumor drug evaluation, which merits further analysis for potential clinical applications.

Self-assembled human serum albumin-coated complexes for gene delivery with improved transfection.

The efficiency and safety of gene delivery vectors were important factors for gene therapy. To enhance gene transfection efficiency and to incorporate biocompatible components to the polyamidoamine (PAMAM) dendrimer mediated gene delivery systems, human serum albumin (HSA) was introduced to dendriplexes of PAMAM dendrimer and DNA via electrostatic interactions to form self-assembled PAMAM/DNA/HSA complexes (HSA-dendriplexes). The self-assembled complexes were characterized by gel retardation assay and particle size and zeta potential analysis. Meanwhile, the toxicity of HSA-dendriplexes was evaluated by the MTT assay and haemolysis test, which indicated that the complexes exhibited decreased cytotoxicity with the incorporation of HSA. As compared to dendriplexes, the ternary HSA-dendriplexes increased the enhanced green fluorescent protein gene (EGFP) expression in vitro by 1.7-fold. In addition, HSA-dendriplexes showed a significantly higher luciferase gene expression than dendriplexes or naked DNA in the liver, kidney, lungs and spleen of mice. Our results demonstrated that HSA-dendriplexes increases PAMAM mediated gene transfection efficiency and decreases the cytotoxicity and haemolysis, which made the ternary complexes a promising targeting gene delivery system.

Enhance the dissolution rate and oral bioavailability of pranlukast by preparing nanosuspensions with high-pressure homogenizing method.

PURPOSE: Pranlukast, one of the potential therapeutic tools in the treatment of asthma, has limited clinical applications due to its poor water solubility. The study is aimed to provide a platform for better utilizing pranlukast with enhancement of the dissolution rate and, thus, the oral bioavailability of pranluka'st by preparing nanosuspensions through high-pressure homogenization method. METHOD: Poloxamer407 and PEG200 were chosen as stabilizer and surfactant. The formulation was investigated systematically with the dissolution tests as predominant method. Nanosuspensions were prepared by programmed high-pressure homogenization method. The product was characterized by particle size analysis, TEM and XRD are evaluated by in vitro dissolution tests and in vivo absorption examination. In addition, nanosuspensions with only pranlukast were prepared and compared with formulated nanosuspensions. RESULTS: The optimal values of formulation were 0.5% (w/v) pranlukast with 0.375% (w/v) Poloxamer407, 0.375% (w/v) PEG200 and the screened programming homogenizing procedure parameters were 680 bar for the first 15 circles, 1048 bar for the next 9 circles and 1500 bar for the last 9 circles. Nanosuspensions of 318.2 ± 7.3 nm, -29.3 ± 0.8 mV were obtained. The XRD analysis indicated no change of crystalline occurred in the process of homogenization. The in vitro dissolution behavior of nanosuspensions exhibited complete release in 30 min with a remarkable fast dissolution rate. The in vivo bioavailability of formulated pranlukast nanosuspensions demonstrated its enhancement of fast onset of therapeutic drug effects with 4.38-fold improved compared to that of raw crystals. CONCLUSION: The study provides a feasible, practical thinking of industry development in the clinical use of pranlukast.