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.

Endosomolysis by masking of a membrane-active agent (EMMA) for cytoplasmic release of macromolecules.

Endosomolysis, a critical barrier to efficient delivery of macromolecules such as nucleic acids, has been breached using a novel approach: endosomolysis by masking of a membrane-active agent (EMMA). To demonstrate the concept of EMMA, a cationic membrane-active peptide, melittin, was reversibly inhibited using a maleic anhydride derivative. At neutral pH, the lysines of melittin are covalently acylated with the anhydride, thereby inhibiting melittin's membrane disruption activity.

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.