Lipid transfection profile

Figure 4 Standard transfection profile of the cationic lipid 10-(cholesteryloxycarbo-nyl-methyl)-l,4,10-triazadecane acetate (CholAc43) (64) on COS-7-cells is shown. A standard transfection experiment comprised eight different lipid/DNA-charge ratios from 1 1 to 1 15 (x-axis). TE (luciferase activity) is expressed in relation to the TE of a standard lipid (DOTAP), determined in the same experiment (DOTAP = 100%, left bar). As a measure of toxicity, the protein content after the transfection experiment is shown in the same diagram (left y-axis). Abbreviation DOTAP, N-[l-2,3-dioleoyloxy)propyl-N,N,N-trimethyl-ammoniumchloride.

The transfection profiles of the most effective lipids of this group are similar, showing a peak (highest TE) at lipid/DNA ratios from 2 to 5. For the most effective lipids, the viability of the cells at maximum TE usually decreased to roughly 50%o. An exception is the lipid 14, which shows the highest TE as well as only a minor toxicity of about 70%o viability. We chose lipid KL-1-14 for further development of a versatile transfection reagent. 

TE of KL-1-14 without helper lipids was very low and reached only about twice the TE, which was found for the standard lipid DOTAP. Independent of the amount of DOPE incorporated in the lipoplexes (ratio of DOPE/KL-1-14 0.3, 0.5, 0.6, 0.7, 0.8, 0.8, 1.0, and 1.2), transfection behaviors (maximum transfection efficiencies and transfection profiles) of all mixtures were similar and comparable to the profile of KL-1-14/DOPE (1 1) as shown in Figure 2 (individual data for all mixtures are not shown). 

Figure 6 Lipofection results (lipofection profiles) of lipoplexes from the R-configu-rated cationic lipids KL-1-1 to KL-1-17 (Table 1) in a mixture with equimolar amounts of l,2-dioleoyl-sn-glycero-3-phosphatidylethanolamine (DOPE) (counterion chloride) and the pCMVluc-plasmid. Each bar represents the mean ( S.D.) of three wells of a 96-well microtiter plate. T-axis (left) represents the transfection efficiencies expressed in relative light units (RLU) (lu/pg protein). X-axis (right) represents the viability of the cells compared to nontreated control cells. F-axis represents the different cationic lipid/plasmid DNA-charge ratios from 1 to 15.

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