Cationic facial amphiphiles: a promising class of transfection agents.

Abstract

A promising class of compounds for DNA transfection have been designed by conjugating various potyamines to bile-acid-based amphiphiles. Formulations containing these compounds were tested for their ability to facilitate the uptake of a 3-galactosidase reporter plasmid into COS-7 cells. Dioleoyl phosphatidyl ethanolamine (DOPE) formulations of some of the compounds were several times better than Lipofectin at promoting DNA uptake. The most active compounds contained the most hydrophilic bile acid components.The activity is clearly not related to affinity for DNA: the hydrophobic bile acid conjugates were found to form stable complexes with DNA at lower charge ratios than the hydrophilic conjugates. We suggest that the high activity of the best compounds is related to their facial amphiphilicity, which may confer an ability to destabilize membranes. The success of these unusual cationic transfection agents may inspire the design of even more effective gene delivery agents.Gene therapy is an exciting approach to the treatment of genetic defects, as well as diseases such as cancer and chronic viral infections (1-3). Unfortunately, the enthusiasm initially displayed for gene therapy has been tempered by the realization that there are no easy solutions to the problem of how to get genes into cells. The most efficient methods for transferring DNA across cell membranes involve the use of viral vectors (1, 4, 5); however, there are growing concerns about both the short-and long-term risks ofviral vectors. These concerns have prompted a search for other strategies for DNA delivery, and in the past few years, a variety of nonviral gene delivery systems have been investigated (6-9). Although some success in getting DNA into cells has been achieved, gene delivery with nonviral vectors remains an inefficient process. To make gene therapy a reality, more efficient DNA delivery systems are needed. In this paper, we report the design and preliminary evaluation of a promising class of DNA delivery agents. In designing these delivery agents, we started by considering the properties of existing nonviral delivery systems. Of all the nonviral DNA delivery systems that have been explored, cationic lipids have shown the most promise based on a combination of efficacy, stability, and toxicity. Lipofectin (Fig.

Design of compounds that increase the absorption of polar molecules

“…The positive charge sets 9 apart from the taurine conjugates and other negatively charged bile salts, and suggests that it is worth investigating whether positively charged groups are useful features to include in the design of other absorption promoters. Cationic lipids and other cationic polymers have been shown to increase the uptake of plasmid DNA and other negatively charged oligonucleotides in various cell types (22)(23)(24)(25)(26)(27)(28). The efficacy of cationic polymers in DNA delivery has been partly attributed to their attraction for negatively charged cell membranes.…”

Preorganized, Macromolecular, Gene‐Delivery Systems

“…In a seminal work, Kahne and co-workers [11] designed a new family of compounds based on the idea that facially amphiphilic components known to destabilize membranes might increase the fusiogenic potential of the transfecting particles and thereby enhance DNA uptake. After observing some abstract similarities between certain amphiphilic peptides that promote DNA uptake [12] and polyhydroxylated steroids, they designed several amphiphilic bile acid derivatives (e.g.…”

Antibacterial properties of cationic steroid antibiotics

“…Kahne et al ¢rst reported facial amphiphiles derived from cholic acid prepared for use as transfection agents [21]. These compounds, prepared from cholic acid with carbohydrates appended on one face of the molecule (1 in Fig.…”