Lipofection

Lipofection describes the transfection with liposomes, vesicles or micelles.

Properties

Through a lipofection nucleic acids (eg, a vector) by binding to or inclusion are introduced into liposomes into cells usually. The liposomes fuse with the endosomal membrane after endocytosis.

In liposomes, vesicles or micelles with cationic lipids complexation with the anionic nucleic acids can be carried out ( nucleic acid adsorption), with uncharged lipids and membrane lipids, the nucleic acids must be enclosed by an entrapment in liposomes or vesicles. Entrapment in the liposomes and their preparation requires a greater expenditure of time than adsorption, but may also be liquids and thus molecules with a less negatively charged surface (see zeta potential ) into cells.

Entrapment

The entrapment used, for example, ether lipid infusion, a syringe having a membrane filter or ultrasound to produce the liposomes.

Less common methods include, for example, the preparation of erythrocyte ghosts (English for ghosts '). This erythrocytes are lysed in a hypotonic solution. Upon exit of the cell contents, there is a spontaneous re- seal the remaining empty cell membranes, including the surrounding medium, to which the nucleic acids have been added previously. Transfection is carried out analogously by fusion of cell membranes for cell fusion. The method is relatively time-consuming, but can accommodate relatively large volumes and leave in the target cell.

Adsorption

The adsorption of nucleic acids is achieved by adding to a suspension of nucleic acids with the cationic lipids. Here, cationic lipids such as DOTMA (N- [1 - (2,3- dioleyloxy ) propyl ]-N, N, N-trimethylammonium chloride ), DOTAP (1,2- dioleoyl -3- trimethylammonium -propane ), DDA ( dimethyldioctadecylammonium ), DC - chol ( 3 b -N- (dimethylaminoethyl ) carbamate -cholesterol ) or DOSPER ( 1,3-di- oleoyloxy -2-( 6 -carboxy- spermyl ) - propylamide ), in conjunction with membrane lipids such as phosphatidyl ethanolamine phosphatidylcholine and cholesterol used. Due to the toxicity of cationic lipids for each type of cell optimal ratios and amounts of lipids and nucleic acids have to be tested. The cationic lipids can trigger pro-apoptotic and pro-inflammatory effects. After an intravenous injection, a large part of the DNA -lipid complexes accumulate in the lungs. There are in the DNA vaccines is no direct correlation between the efficiency of in vitro lipofection and a triggered by lipofection in vivo immune response.