Mitochondria transfection by oligonucleotides containing a signal peptide and vectorized by cationic liposomes

The progress of research in gene therapy allows hope for treatment of mitoc hondrial genetic disorders provided that efficient methods for gene transfe r into mitochondria can be found. In this work, we have used an oligonucleo tide coupled covalently to a mitochondria-targeted peptide at one end and a cationic liposome prepared from trimethyl aminoethane carbamoyl cholestero l iodide (TMAEC-Chol) to carry it in living cells. With a fluorescent probe to label the oligonucleotide at the other end and by means of confocal mic roscopy, we show that such modified oligonucleotides complexed to liposomes enter into the cytoplasm of human fibroblasts in primary culture, and then , after dissociation from the complexes, they penetrate into the mitochondr ia, The fluorescence was still observed after 8 days, suggesting the contin ued presence of oligonucleotides, At the concentrations used for this study , the cationic liposomes have practically no effect on cell growth, as reve aled by the MTT assay.