O‐ethylphosphatidylcholine: A metabolizable cationic phospholipid which is a serum‐compatible DNA transfection agent

Abstract

1,2-dioleoyl-sn-glycero-3-ethylphosphocholine was prepared in a one-step reaction from phosphatidylcholine by reaction with ethyl trifluoromethanesulfonate. This and related O-alkyl phosphatidylcholines constitute the first chemically stable triesters of biological lipid structures and the first cationic derivatives of phospholipids consisting entirely of biological metabolites linked with ester bonds. The complex of cationic phospholipid and plasmid DNA transfected cells with high efficiency. Maximum efficiency of transfection was obtained with complexes in which the positive charge was a few percent in excess over the negative charge. Modest stimulation of transfection of common cell lines was obtained by continuous culture in the presence of 10% serum. Incubation of the phospholipid complex for at least 2 h at 37 degrees C in nearly pure serum had no deleterious effects on transfection efficiency. The lipid has low toxicity; BHK cells tolerated amounts of 2 mg/2 x 10(6) cells at concentrations of 1 mg/mL. The lipid is biodegradable; it was hydrolyzed by phospholipase A(2) in vitro and was metabolized with a half-life of a few days in cells in culture. The synthetic route to cationic phospholipids is well suited to the preparation of derivatives that are tailor-made to have a wide variety of different properties.

Lipoplexes with alkylphospholipid as new helper lipid for efficient in vitro and in vivo gene transfer in tumor therapy

“…On the other hand, the highest transfection with APL-LPs were obtained in vitro with a slightly higher P/N between 1.5 and 2 (L9-LP: 1.69), whereas L9-LP with a P/N ratio of 3.2 was much more effective in vivo. This is consistent with the findings of several other groups [33][34][35][36][37][38] indicating that a slight positive charge (charge ratio between 1 and 2) supports the binding of the complex to the (negatively charged) cell membrane, whereas nucleic acid compaction rather than surface charge was critical for an efficient nuclear trafficking. 39 On the other hand, some reports describe other ratios for more efficient complexes, 10,38,[40][41][42] which indicated that the charge ratio is not the only factor responsible for the transfection efficacy.…”

Phase behavior of selected artificial lipids

“…1,2-Diacyl-P-O-ethylphosphatidylcholines are a novel class of cationic lipids, which are synthesized by esterification of phosphatidylcholines with ethyl-trifluoromethylsulfonates [19]. Some derivatives have already shown promising properties as liposomal DNA transfection agents.…”

New strategy for transfection: mixtures of medium-chain and long-chain cationic lipids synergistically enhance transfection

“…This is the first report, as far as we know, on the use of a combination of compounds with different chain lengths but the same head group to improve the gene delivery properties of lipoplexes. Figure 1 shows that combining EDLPC (Avanti Polar Lipids, Inc., Alabaster, AL, USA) with EDOPC (synthesized in our lab according to MacDonald et al 13 ) enhances by B30-fold the extent of transfection of HUAEC (BioWhitakker, Inc., Walkersville, MD, USA), compared with EDLPC or EDOPC alone. The ratio of EDLPC to EDOPC is important and different ratios are optimal, depending upon whether serum is present or absent.…”

“…The ratio of EDLPC to EDOPC is important and different ratios are optimal, depending upon whether serum is present or absent. The EDLPC/EDMPC (EDMPC was synthesized in our lab according to MacDonald et al 13 ) mixture exhibits a similar pattern to that of EDLPC/EDOPC, but the extent of transfection is lower than that of EDLPC/EDOPC.…”