Synthesis and Characterization of Long Chain Alkyl Acyl Carnitine Esters. Potentially Biodegradable Cationic Lipids for Use in Gene Delivery

Abstract

A series of alkyl acyl carnitine esters (alkyl 3-acyloxy-4-trimethylammonium butyrate chloride) were synthesized as potential biocompatible cationic lipids for use in gene transfer. The physicochemical properties of the lipids, liposomes prepared from them, and their complexes with DNA were characterized by differential scanning calorimetry (DSC), particle size, zeta potential, and surface monolayer measurements. The transition temperatures and behavior at an air-water interface for this series are similar to phosphatidylcholines with the same hydrocarbon chain length. The physical properties of the l derivatives were not significantly different from the dl derivatives. At 70 degrees C, the acyl chains were readily hydrolyzed at pH 7. The influence of the aliphatic chain length (n = 12-18) on transfection efficiency in vitro was determined using cationic liposomes prepared from these lipids or their mixtures with the helper lipids, dioleoylphosphatidylethanolamine (DOPE), dioleoylphosphatidylcholine, monooleoylglycerol, and cholesterol (Chol). The mixture of myristyl 3-myristoyloxy-4-trimethylammonium butyrate chloride (MMCE, 4d) with DOPE at a 1:1 molar ratio mediated the highest transfection efficiency in cell culture. The mixture of oleyl 3-oleoyloxy-4-trimethylammonium butyrate chloride (OOCE, 4f) with Chol at a 1:1 molar ratio gave the highest transfection efficiency after intravenous administration in mice. In vivo gene expression using 4f was comparable to values obtained with the best cationic lipids reported to date.

Novel cationic cardiolipin analogue-based liposome for efficient DNA and small interfering RNA delivery in vitro and in vivo

“…Transfection efficiency of the CCLA-based liposome with reporter genes It has been reported that different helper lipids 23 and the charge ratio of the positively charged lipid versus negatively charged DNA 24 can contribute to the variable transfection efficiency. To determine the optimal combination for the CCLA-based liposome transfection, two most commonly used helper lipids, cholesterol and DOPE, were formulated with CCLA at different molar ratio and screened for their transfection efficiency in vitro using b-gal reporter gene assay.…”

“…Gene transfection has also been demonstrated with several monovalent cationic liposomes with molar ratio of cationic lipid to helper lipid close to 1:1. 1,23,25 CCLA has four hydrophobic chains and two positive charges, a structure resembling to two singly charged cationic lipids conjugated together. Therefore, the optimal molar ratio of CCLA to DOPE (1:2) is comparable to the ratio of 1:1 for other cationic and helper lipids.…”

“…28 The size of the CCLA-based liposome (B110 nm) is within a similar range as shown for other cationic liposome. 23 Therefore, a similar pattern of CCLA-based liposome may have resulted in higher expression in the lung than in the heart. Based on the tissue distribution study conducted on a liposome formulation containing CCLA, cholesterol and dioleoylphosphatidylcholine (DOPC) to deliver antisense oligonucleotide, the highest level of the liposome was also detected in the lung, and the level of expression was in the order of lung4spleen4liver4kidney4heart (unpublished results).…”

Designer Materials for Nucleic Acid Delivery

“…Other viral types have revealed toxicity or caused devastating immune and inflammatory responses, resulting in patient death. [7][8][9] Because of these problems, alternative methods involving the development of synthetic materials are currently being studied for the delivery of nucleic acids. [10][11][12][13][14][15] Systems that mimic the positive features of viral delivery vehicles yet circumvent the negative aspects of these systems are highly sought-after.…”

Targeted Delivery of Nucleic Acid-Based Therapeutics to the Pulmonary Circulation

“…We and others have previously shown that lungs can be preferentially and efficiently transfected following i.v. administration of a transgene expression plasmid complexed with cationic liposomes (28)(29)(30)(31)(32). Pulmonary gene transfer via cationic lipids is largely mediated by a passive mechanism of serum-induced aggregation of lipid vectors, although the nonspecific interaction of cationic lipid vectors with the negatively charged endothelium may also play a role (33).…”