The present invention provides a method for the generation of genetically modified T cells comprising the steps a) a sample provided comprising T cells, b) preparation of said sample by centrifugation, c) enrichment of the T cells, d) activation of the T cells using modulatory agents, e) genetic modification of the T cells by transduction with lentiviral vector particles, f) removal of said modulatory agents, thereby generating a sample of genetically modified T cells, wherein said method is performed in equal or less than 144 hours, less than 120 hours, less than 96 hours, less than 72 hours, less than 48 hours, or less than 24 hours. In one embodiment of the invention said enrichment of T cells is performed by magnetic cell separation using magnetic particles that are directly or indirectly coupled to antibodies or antigen binding fragments thereof specific for CD4 and/or CD8 wherein said magnetic particles can be removed from the cells after separation.

An object of the present invention is to provide a nucleic acid molecule, a vector, a recombinant cell, and a drug for treating a central nervous system disease, which easily migrate to the central nervous system. The nucleic acid molecule of the present invention contains a nucleotide sequence encoding a fusion protein, the fusion protein containing: an anti-transferrin receptor (TfR) antibody or an antigen-binding fragment thereof; and a protein to be brought into function in the central nervous system.