Short peptide sequences that are able to transport molecules across the cell membrane have been developed as tools for intracellular delivery of therapeutic molecules. This work describes a novel family of cell-penetrating peptides named Vectocell peptides [also termed DPVs (Diatos peptide vectors)]. These peptides, originating from human heparin binding proteins and/or anti-DNA antibodies, once conjugated to a therapeutic molecule, can deliver the molecule to either the cytoplasm or the nucleus of mammalian cells. Vectocell peptides can drive intracellular delivery of molecules of varying molecular mass, including full-length active immunoglobulins, with efficiency often greater than that of the well-characterized cell-penetrating peptide Tat. The internalization of Vectocell peptides has been demonstrated to occur in both adherent and suspension cell lines as well as in primary cells through an energy-dependent endocytosis process, involving cell-membrane lipid rafts. This endocytosis occurs after binding of the cell-penetrating peptides to extracellular heparan sulphate proteoglycans, except for one particular peptide (DPV1047) that partially originates from an anti-DNA antibody and is internalized in a caveolar independent manner. These new therapeutic tools are currently being developed for intracellular delivery of a number of active molecules and their potentiality for in vivo transduction investigated.