Fuente: WIPO "tomato" The invention relates to a particular modified camelid single chain antibody called VHHNPX and uses of VHHNPX in new methods for the efficient delivery of molecular cargos inside target cells (in particular neurons and eye retina cells). The invention further relates to a Neurovita short interfering peptide suitable for neuroprotection and neuroregeneration and uses thereof, in particular a Neurovita peptide short fragment encoding a PDZ-binding motif (PBM) inhibiting the PDZ domain of the human MAST2 & MAST1 enzymes. The invention also relates to polypeptides comprising this Neurovita short peptide, notably peptides further comprising a cell-penetrating molecule (CPM), and uses thereof.