Genetic alteration of SJ293TS cells and modification of serum-free media enhances lentiviral vector production

Abstract

Successful cell and gene therapy clinical trials have resulted in the United States Food and Drug Administration and European Medicines Agency approving their use for treatment of patients with certain types of cancers and monogenetic diseases. These novel therapies, which rely heavily on lentiviral vectors to deliver therapeutic transgenes to patient cells, have driven additional investigations, increasing demand for both pre-clinical and current Good Manufacturing Practices-grade viral vectors. To better support novel studies by improving current production methods, we report the development of a genetically modified HEK293T-based cell line that is null for expression of both Protein Kinase R and Beta-2 microglobulin and grows in suspension using serum-free media, SJ293TS-DPB. Absence of Protein Kinase R increased anti-sense lentiviral vector titers by more than 7-fold, while absence of Beta-2 microglobulin, a key component of Major Histocompatibility Complex class I molecules, has been reported to reduce the immunogenicity of lentiviral particles. Furthermore, we describe an improved methodology for culturing SJ293TS-DPB which facilitates expansion, reduces handling, and increases titers by 2-fold compared to previous methods. SJ293TS-DPB stably produced lentiviral vectors for over four months and generated lentiviral vectors that efficiently transduce healthy human donor T cells and CD34+ hematopoietic stem cells.