Abstract
A new therapeutic approach is to modulate the expression of a gene by targeting mRNA by oligonucleotides (i.e antisense or siRNA). We studied formulations based on cationic lipids, forming particule complexes with nucleic acids (lipoplexes) making possible oligonucleotide protection and delivery. In our laboratory, we have the unique ability to formulate oligonucleotides within lipoplexes, globally charged either positively or negatively. We showed that they protect and efficently vectorize nucleic acids in cells in vitro as well as in vivo. These syntetic vectors have various advantages : homogeneous particles and with small sized, reproductibility, poor toxicity, stability in time and efficiency in the presence of serum. We applied these vectors to the delivery of antisense oligonucleotides and siRNA in vitro, respectively in a model of splicing correction containing the aberrant intro of B-thalassemia and in a model of breast cancer. Our results showed that our lipidic vectors provide a good efficiency in delivering oligonucleotides with using these 2 models, either at low concentration or in the presence of serum. Finally, we studied the cell uptake mechanism in cell culture and evaluated the proportion of active transport (principally endocytose), of passive transport (principally fusion) and of membrane fixation of lipoplexes : these seemed to depend on the incubation time, on the transfection medium, on the formulation, and on the global net charge as well as on the size of complexes. In vivo studies must be carried out to evaluate the efficiency and the respective properties of the different developed formulations, in splicing correction and brest cancer experimenal animal models.