1-2-dielaidoylphosphatidylethanolamine and Ascites

Delivery of small interfering RNA (siRNA) is recently gaining tremendous attention for the treatment of ovarian cancer. The present study investigated the potential of different liposomal formulations composed of (2,3-dioleoyloxy-propyl)-trimethylammonium (DOTAP) and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) encapsulating siRNA (hydration method) for their ability to knockdown luciferase (Luc) activity in human ovarian cancer SKOV-3 cells. Fluorescence single particle tracking (fSPT) and fluorescence correlation spectroscopy (FCS) in human-undiluted ascites fluid obtained from a peritoneal carcinomatosis patient revealed that cationic hydra-lipoplexes (HYDRA-LPXs) and HYDRA-LPXs decorated with stable DSPE-PEG (DSPE HYDRA-LPXs) showed high stability during at least 24 h. HYDRA-LPXs decorated with sheddable C8 and C16 PEG-Ceramides (Cer HYDRA-LPXs) resulted in rapid and premature release of siRNA already in the first hours. Despite their role in preventing aggregation in vivo, liposomes decorated with stable PEG residues resulted in a poor transfection compared to the ones decorated with sheddable PEG residues in reduced serum conditions. Yet, the transfection efficiency of both Cer HYDRA-LPXs significantly decreased following 1 h of incubation in ascites fluid due to a drastic drop in the cellular uptake, while DSPE HYDRA-LPXs are still taken up by cells, but too stable to induce efficient gene silencing.

Topics: Ascites; Cell Line, Tumor; Cell Survival; Fatty Acids, Monounsaturated; Humans; Liposomes; Luciferases; Phosphatidylethanolamines; Polyethylene Glycols; Quaternary Ammonium Compounds; RNA, Small Interfering

Viral vector systems are the most commonly used gene transfer tools for clinical gene therapy. However, lipofection systems are potential alternatives because of lower immunogenicity and easier cGMP production, but in vivo stability and transduction efficacy need to be improved. Therefore, we investigated gene transduction efficiency of our novel cGMP cationic lipids, CCQ22 and CCQ32, by FACS analysis. Toxicity analysis was performed to determine the cytotoxic side effects of the novel lipids. To evaluate the stability of the compounds in the context of local delivery to patients with intraperitoneally metastatic ovarian cancer, gene transfer was also tested in the presence of malignant ascites. Our novel cGMP standard lipids mediated gene transfer rates of more than 50%. However, for most cell lines cytotoxic side effects were similar to our reference lipofection system. In general, ascites had no major influence on gene transduction rates with the novel lipids. Our results suggest that CCQs may compare favorably with commercially available lipofection systems. These promising results facilitate further analysis of the compounds.

Topics: Ascites; Breast Neoplasms; Cell Line, Tumor; Cholesterol Esters; Female; Genetic Vectors; Humans; Lipids; Liposomes; Ovarian Neoplasms; Phosphatidylethanolamines; Plasmids; Transduction, Genetic