The present invention relates to a lipid nanoparticle system comprising a lipid component, a cationic surfactant, a non-ionic surfactant, a polysaccharide and, optionally, a positively charged peptide, useful for the release of pharmacologically active molecules, and especially for transfecting genetic material into cells and/or tissues. It also relates to methods for obtaining nanoparticles, to pharmaceutical compositions comprising it, as well as to the use thereof in gene therapy.