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

To improve liposomal gene transfer we investigated the influence of membrane-interacting alkylphospholipids (APLs) on gene transfer efficiency in vitro and in vivo using the LacZ reporter gene and the cytosine deaminase (CD) suicide gene. Liposomes were first optimized concerning the kind and amount of APL and the additional liposome components. Thus, an up to 270% increase in the transfer efficiency of the LacZ gene into HCT15 and HCT116 human colon carcinoma cells could be obtained in vitro compared to lipofectin-mediated transfection by using a lipoplex consisting of tetradecylphosphocholine/dimethyldioctadecylamine/cholesterol/dioleylphosphoethanolamine-liposomes and the pSV40-betaGal-plasmid. The in vivo experiments revealed that alkylphospholipid-lipoplexes (APL-LPs) were similarly effective in the transfer of the LacZ gene into colon carcinoma as formulations consisting of lipofectin. Using the CD-gene in combination with APL-LPs resulted in a significantly stronger inhibition of C26 colon carcinoma growth compared to lipofectin-mediated gene transfer following treatment of mice with the prodrug 5-fluorocytosine. The results of this study demonstrate for the first time that the utilization of membrane-active APLs as component of the liposomal part of lipoplexes enhances the efficacy of gene therapy in vitro and in vivo.