Synthesis and Transfection Activity of New Cationic Phosphoramidate Lipids: High Efficiency of an Imidazolium Derivative

Abstract

In an effort to enhance the gene-transfer efficiencies of cationic lipids and to decrease their toxicities, a series of new phosphoramidate lipids with chemical similarity to cell membrane phospholipids was synthesised. These lipids contained various cationic headgroups, such as arginine methyl ester, lysine methyl ester, homoarginine methyl ester, ethylenediamine, diaminopropane, guanidinium and imidazolium. Their transfection abilities, either alone or with the co-lipid DOPE, were evaluated in HEK293-T7 cells. We found that imidazolium lipophosphoramidate 7 a/DOPE lipoplexes gave the most efficient transfection with low toxicity (15 %). The luciferase activity was 100 times higher than that obtained with DOTAP/DOPE lipoplexes. The size, zeta potential, pDNA-liposome interactions and cellular uptakes of the lipoplexes were determined. No definitive correlation between the zeta potential values and the transfection efficiencies could be established, but the uptake of lipoplexes by the cells was correlated with their final transfection efficiencies. Our results show that imidazolium phosphoramidate lipids constitute a potential new class of cationic lipids for gene transfer.

Enhancement of dendritic cells transfection in vivo and of vaccination against B16F10 melanoma with mannosylated histidylated lipopolyplexes loaded with tumor antigen messenger RNA

“…16,21 O,O-dioleyl-N-[3N-(N-methylimidazolium iodide)propylene] phosphoramidate (lipid 1) and O,Odioleyl-N-histamine phosphoramidate (lipid 2) were synthesized as described (Supplementary Figure S1). 18,19 β-Dmannopyranosyl-N-dodecylhexadecanamide (Man-lipid) was synthesized as described. 22 Plasmids pTG11033 [pCMV-Luc; 9514 base pairs (bp), a gift from Transgène S.A., Strasbourg, France] and pCMV-EGFP (5310 bp) were pDNA encoding the luciferase gene of Photinus pyralis (firefly luciferase, FLuc) and the EGFP under control of a cytomegalovirus promoter, respectively.…”

“…16 Recently, we have designed new imidazole/imidazolium binary liposomes (termed Lip100) made with a cationic [O,O-dioleyl-N-(3N-(N-methylimidazolium iodide)propylene) phosphoramidate)], lipid 1, and a neutral [O, O-dioleyl-N-histamine phosphoramidate], co-lipid 2, in a molar ratio of 1:1 (Supplementary Figure S1, found in the online version of this article). 18,19 Lipid 1 possesses an N-methylimidazolium polar head conferring a permanent positive charge used for nucleic acid DNA condensation. The imidazole group of co-lipid 2 is not alkylated on the nitrogen atoms and can acquire a cationic charge when the pH of the medium drops below pH 6 favoring the endosome destabilization and nucleic acids delivery in the cytosol.…”

Synthetic vectors for gene delivery: An overview of their evolution depending on routes of administration.

“…Replacement of oleic or linoleic aliphatic chains (KLN47 and BSV4, respectively) by phytanyl chains permitted the formation of more fusogenic type structures identified as inversed hexagonal phases without the addition of DOPE, significantly improving in vivo transfection efficiency [25]. Neutral lipophosphoramides (colipids) bearing an imidazole motif have also been synthesized, their association with various cationic lipids (DOTAP and phosphoguanidines) resulted in transfection efficiencies up to 100 times higher than the same compounds formulated with DOPE [26].…”

Enhanced Achilles tendon healing by fibromodulin gene transfer

“…The detailed structure of those carriers has been previously described 23 . The chosen vector/pDNA weight ratios were those that permitted to get a good balance between efficacy and toxicity in previous studies 20,24 . PTG1/pDNA polyplexes at ratio of 6:1 (µg:µg) were slightly positive with a (ζ potential of +11±1.6 mV.…”