Optimization of a peptide/non-cationic lipid gene delivery system for effective microinjection into chicken embryo in vivo

Bait-and-Switch Supramolecular Strategy To Generate Noncationic RNA-Polymer Complexes for RNA Delivery

RNA interference (RNAi) requires the intracellular delivery of RNA molecules to initiate the neutralization of targeted mRNA molecules, inhibiting the expression or translation of the targeted gene. Current polymers and lipids that are used to deliver RNA molecules are generally required to be positively charged, to achieve complexation with RNA and the cellular internalization. However, positive surface charge has been implicated as the reason for toxicity in many of these systems. Herein, we report a novel strategy to generate noncationic RNA-polymer complexes for RNA delivery with low cytotoxicity. We use an in situ electrostatic complexation using a methylated pyridinium group, which is simultaneously removed during the RNA binding step. The resultant complexes demonstrate successful knockdown in preimplantation mammalian embryos, thus providing a new approach for nucleic acid delivery.

Recent trends of polymer mediated liposomal gene delivery system

Advancement in the gene delivery system have resulted in clinical successes in gene therapy for patients with several genetic diseases, such as immunodeficiency diseases, X-linked adrenoleukodystrophy (X-ALD) blindness, thalassemia, and many more. Among various delivery systems, liposomal mediated gene delivery route is offering great promises for gene therapy. This review is an attempt to depict a portrait about the polymer based liposomal gene delivery systems and their future applications. Herein, we have discussed in detail the characteristics of liposome, importance of polymer for liposome formulation, gene delivery, and future direction of liposome based gene delivery as a whole.

The characteristics and performance of a multifunctional nanoassembly system for the co-delivery of docetaxel and iSur-pDNA in a mouse hepatocellular carcinoma model

Human hepatocellular carcinoma (HCC) is one of the most causes of cancer-related death and is well known because of resistant to chemotherapeutic drug. Co-delivery of antitumor agent docetaxel and iSur-pDNA, a suppressor of metastatic and resistance-related protein survivin, was postulated to achieve synergistic/combined effect of antitumor drug and gene therapeutics. To valid this hypothesis, a folate-modified multifunctional nanoassembly (FNA) loading both docetaxel and iSur-pDNA was constructed and evaluated as a therapeutic approach for HCC. The FNAs were prepared with folate-modified lipid FA-PEG-DSPE as the target to tumor, protamine sulfate (PS) as the condenser to protect and enhance the nuclear transfer of iSur-pDNA, and DOPE-based lipid envelope as the carrier of doctaxel and PS/DNA complex to achieve their co-delivery and enhance internalization into hepatoma cells. FNAs showed the particle size about 200nm with encapsulation efficiency >90%. Blank nanoassemblies (BNAs) loading only reporter gene revealed higher transfection efficiency with neglectable cytotoxicity compared with Lipofectamine 2000, which could result from enhanced cellular uptake via ligand-receptor recognition and efficient nuclear delivery mediated by PS. Cytotoxicity of FNAs against hepatocellular carcinoma cell line BEL 7402 was much higher than either docetaxel or non-docetaxel FNAs (nFNAs) loading only iSur-pDNA, and was also superior to the combined treatment with free docetaxel and nFNAs. Better antitumor efficacy of FNAs with low systemic toxicity was also observed on mouse hepatocellular carcinoma xenograft model. These results suggested that co-delivery of docetaxel and iSur-pDNA with FNAs could be a safer and more efficient strategy for the treatment of locally advanced and metastatic HCC.

Nonviral gene delivery: what we know and what is next

Gene delivery using nonviral approaches has been extensively studied as a basic tool for intracellular gene transfer and gene therapy. In the past, the primary focus has been on application of physical, chemical, and biological principles to development of a safe and efficient method that delivers a transgene into target cells for appropriate expression. This review summarizes the current status of the most commonly used nonviral methods, with an emphasis on their mechanism of action for gene delivery, and their advantages and limitations for gene therapy applications. The technical aspects of each delivery system are also reviewed, with a focus on how to achieve optimal delivery efficiency. A brief discussion of future development and further improvement of the current systems is intended to stimulate new ideas and encourage rapid advancement in this new and promising field.

Optimized cationic lipid-based gene delivery reagents for use in developing vertebrate embryos

We have used cationic lipid-based transfection reagents for ectopic gene expression experiments in developing vertebrate embryos. Lipofectamine, Lipofectamine 2000, and Lipofectamine enhanced with a disulfide linked pegylated lipid (mPEG-SS-DOPE) were initially tested and optimized in cell culture. Two reagent formulations, 1:4 (DNA:Lipofectamine 2000) Lipofectamine 2000, and 7.5% pegylated Lipofectamine, produced the highest levels of gene expression in vitro. Those formulations, containing the enhance green fluorescent protein reporter gene, were microinjected into intact vertebrate embryos -- systemically through the vasculature and locally into selected tissues -- to assess in vivo transfection efficiency. Whereas both formulations are capable of transfecting cells in developing embryos in vivo, greater transfection efficiencies in a broader range of tissue types were obtained with the pegylated Lipofectamine formulation. We conclude that in developing vertebrate embryos, optimized cationic lipid-based reagents are capable of producing significant levels of ectopic gene expression and can be used as alternatives to electroporation and viral-mediated gene delivery.

Widespread lipoplex-mediated gene transfer to vascular endothelial cells and hemangioblasts in the vertebrate embryo

We report here a method that allows fast, efficient, and low-cost screening for gene function in the vascular system of the vertebrate embryo. Through intracardiac delivery of nucleic acids optimally compacted by a specific cationic lipid, we are able to induce in vivo endothelial cell-specific gain-of-function during development of the vascular network in the chick embryo. When the nucleic acids are delivered during the period of intraembryonic hematopoiesis, aortic hemangioblasts, the forerunners of the hematopoietic stem cells known to derive from the aortic endothelium, are also labeled. Similarly, we show that siRNA could be used to induce loss-of-function in vascular endothelial cells. This gene transfer technique was also applied to the mouse embryo with a high efficiency. The present method allows large-scale analysis and may represent a new and versatile tool for functional genomics.

Multiphoton excitation spectra in biological samples

Multiphoton microscopy is becoming a popular mode of live and fixed cell imaging. This mode of imaging offers several advantages due to the fact that fluorochrome excitation is a nonlinear event resulting in excitation only at the plane of focus. Multiphoton excitation is enhanced by the use of ultrafast lasers emitting in the near IR, offering better depth penetration coupled with efficient excitation. Because these lasers, such as titanium:sapphire lasers, offer tunable output it is possible to use them to collect multiphoton excitation spectra. We use the software-tunable Coherent Chameleon laser coupled to the Zeiss LSM 510 META NLO to acquire x-y images of biological samples at multiple excitation wavelengths, creating excitation lambda stacks. The mean intensity of pixels within the image plotted versus excitation wavelength reveals the excitation spectra. Excitation lambda stacks can be separated into individual images corresponding to the signal from different dyes using linear unmixing algorithms in much the same way that emission fingerprinting can be used to generate crosstalk free channels from emission lambda stacks using the META detector. We show how this technique can be used to eliminate autofluorescence and to produce crosstalk-free images of dyes with very close overlap in their emission spectra that cannot be separated using emission fingerprinting. Moreover, excitation finger- printing can be performed using nondescanned detectors (NDDs), offering more flexibility for eliminating autofluorescence or crosstalk between fluorochromes when imaging deep within the sample. Thus, excitation fingerprinting complements and extends the functions offered by the META detector and emission fingerprinting. We correct biases in the laser and microscope transmission to acquire realistic multiphoton excitation spectra for fluorochromes within cells using the microscope, which enables the optimization of the excitation wavelength for single and multilabel experiments and provides a means for studying the influence of the biological environment on nonlinear excitation.

Using electroporation and lipid-mediated transfection of GFP-expressing plasmids to label embryonic avian cells for vital confocal and two-photon microscopy

Fluorescent proteins have emerged as an ideal fluorescent marker for studying cell morphologies in vital systems. These proteins were first applied in whole organisms with established germ-line transformation protocols, but now it is possible to label cells with fluorescent proteins in other organisms. Here we present two ways to introduce GFP expressing plasmids into avian embryos for vital confocal and two-photon imaging. First, electroporation is a powerful approach to introduce GFP into the developing neural tube, offering several advantages over dye labeling. Second, we introduce a new lipid-based transfection system for introducing plasmid DNA directly to a small group of injected cells within live, whole embryos. These complementary approaches make it possible to transfect a wide-range of cell types in the avian embryo and the bright, stable, uniform expression of GFP offers great advantages for vital fluorescence imaging.