Cluster assembled nanostructured TiO2 film mediates efficient and safe retroviral gene transduction in primary adult human melanocytes for ex-vivo gene therapy

Primary human melanocytes represent the precursor cells to melanoma and also specific targets of inherited and acquired pigmentation disorders (1,3). The possibility to genetically manipulate these cells for biological studies or therapy has not been fully exploited for the lack of efficient and safe stable gene transfer techniques (4). We have developed a new gene transfer technology on primary adult human melanocytes by means of retroviral infection in absence of any toxic polycations currently employed to improve infection efficency (i.e. polybrene). We demonstrate that this polycation induce apoptosis and DNA damage through ATM phosphorylation, causing a further genetic perturbation to cells. We have cultured primary human melanocytes on a biocompatible nanostructured TiO2 film, obtained by the deposition of a supersonic beam of titania clusters (5, 7), coated by retroviral vectors expressing GFP. By means of a “reverse infection “ mechanism we achieved 80% of infection in absence of any toxic effect. This high efficiency is related to the interaction of retroviral vectors and cells with the nanoparticle-assembled substrates. We expect that such technology based on nanostructured surfaces will allow efficient and safe genetic manipulation of primary cells for ex-vivo gene therapy.