Dose response in rodents and nonhuman primates after hydrodynamic limb vein delivery of naked plasmid DNA.

The efficacy of gene therapy mediated by plasmid DNA (pDNA) depends on the selection of suitable vectors and doses. Using hydrodynamic limb vein (HLV) injection to deliver naked pDNA to skeletal muscles of the limbs, we evaluated key parameters that affect expression in muscle from genes encoded in pDNA. Short-term and long-term promoter comparisons demonstrated that kinetics of expression differed between cytomegalovirus (CMV), muscle creatine kinase, and desmin promoters, but all gave stable expression from 2 to 49 weeks after delivery to mouse muscle.

Evaluation of hydrodynamic limb vein injections in nonhuman primates.

The administration route is emerging as a critical aspect of nonviral and viral vector delivery to muscle, so as to enable gene therapy for disorders such as muscular dystrophy. Although direct intramuscular routes were used initially, intravascular routes are garnering interest because of their ability to target multiple muscles at once and to increase the efficiency of delivery and expression. For the delivery of naked plasmid DNA, our group has developed a hydrodynamic, limb vein procedure that entails placing a tourniquet over the proximal part of the target limb to block all blood flow and injecting the gene vector rapidly in a large volume so as to enable the gene vector to be extravasated and to access the myofibers.

Dynamic PolyConjugates for targeted in vivo delivery of siRNA to hepatocytes.

Achieving efficient in vivo delivery of siRNA to the appropriate target cell would be a major advance in the use of RNAi in gene function studies and as a therapeutic modality. Hepatocytes, the key parenchymal cells of the liver, are a particularly attractive target cell type for siRNA delivery given their central role in several infectious and metabolic disorders. We have developed a vehicle for the delivery of siRNA to hepatocytes both in vitro and in vivo, which we have named siRNA Dynamic PolyConjugates.

Transcriptional and phenotypic comparisons of Ppara knockout and siRNA knockdown mice.

RNA interference (RNAi) has great potential as a tool for studying gene function in mammals. However, the specificity and magnitude of the in vivo response to RNAi remains to be fully characterized. A molecular and phenotypic comparison of a genetic knockout mouse and the corresponding knockdown version would help clarify the utility of the RNAi approach.

Mechanism of plasmid delivery by hydrodynamic tail vein injection. I. Hepatocyte uptake of various molecules.

Background: The hydrodynamic tail vein (HTV) injection of naked plasmid DNA is a simple yet effective in vivo gene delivery method into hepatocytes. It is increasingly being used as a research tool to elucidate mechanisms of gene expression and the role of genes and their cognate proteins in the pathogenesis of disease in animal models. A greater understanding of its mechanism will aid these efforts and has relevance to macromolecular and nucleic acid delivery in general.

Rapid intravascular injection into limb skeletal muscle: a damage assessment study.

We have recently developed a simple and highly efficient methodology for delivering plasmid DNA (pDNA) to skeletal muscle cells of mammalian limbs. The procedure involves the rapid intravascular injection of a large volume of saline (containing pDNA) into the vasculature of the distal limb. As a result of the robust delivery methodology involved, it is important to understand the effects of the injection procedure on the skeletal muscle tissue in the targeted limb.

Delivery of small interfering RNA to mammalian cells in culture by using cationic lipid/polymer-based transfection reagents.

RNA interference (RNAi) has become a powerful tool for the knockdown of target gene expression and subsequent phenotypic analysis of gene function in mammalian cells in culture. Critical to the success of any small inhibitory RNA (siRNA)-mediated RNAi knockdown in mammalian cells is the efficient delivery of the siRNA to those cells. This chapter describes the use of popular cationic lipid?polymer-based transfection reagents for in vitro siRNA delivery and includes a general protocol with special emphasis on key transfection parameters important to the success of siRNA delivery.

A facile nonviral method for delivering genes and siRNAs to skeletal muscle of mammalian limbs.

Delivery is increasingly being recognized as the critical hurdle holding back the tremendous promise of nucleic acid-based therapies that include gene therapy and more recently siRNA-based therapeutics. While numerous candidate genes (and siRNA sequences) with therapeutic potential have been identified, their utility has not yet been realized because of inefficient and/or unsafe delivery technologies. We now describe an intravascular, nonviral methodology that enables efficient and repeatable delivery of nucleic acids to muscle cells (myofibers) throughout the limb muscles of mammals.

Plasmid-based gene delivery to target tissues in vivo: the intravascular approach.

Over the past several years, significant progress has been made in the development of non-viral methodologies that can effectively deliver genes to target tissues in vivo. One of the most surprising successes has been the discovery that naked plasmid DNA (pDNA) can be delivered into tissues such as liver and muscle with high efficiency using the vascular system. The key breakthrough involved the realization that pDNA could be injected rapidly into blood vessels (using increased volumes) in a manner that facilitates extravasation of the DNA solution outside the blood vessel wall.

Efficient in vitro and in vivo expression of covalently modified plasmid DNA.

The tracking of plasmid DNA (pDNA) movement within cells requires the attachment of labels to the DNA in a manner such that: (a) the pDNA remains intact during the labeling process and (b) the labels remain stably attached to the DNA. Keeping these two criteria in mind, we have recently developed a series of alkylating reagents that facilitate the one-step, covalent attachment of compounds directly onto nucleic acids in a nondestructive manner. Using these DNA-alkylating reagents, we have attached a wide range of both fluorescent and nonfluorescent reporter molecules onto pDNAs.

Efficient delivery of siRNA for inhibition of gene expression in postnatal mice.

It has recently been shown that RNA interference can be induced in cultured mammalian cells by delivery of short interfering RNAs (siRNAs). Here we describe a method for efficient in vivo delivery of siRNAs to organs of postnatal mice and demonstrate effective and specific inhibition of transgene expression in a variety of organs.

Self-quenched covalent fluorescent dye-nucleic acid conjugates as polymeric substrates for enzymatic nuclease assays.

A fluorescent method is described for assessing nuclease activity. The technique is based on the preparation of quenched fluorophore-nucleic acid covalent conjugates and their subsequent dequenching due to degradation by nucleases. The resulting fluorescence increase can be measured by a spectrofluorometer and exhibits subpicogram per milliliter sensitivity level for RNase A and low picogram per milliliter level for DNase I.