Development of a laboratory scalable process for enhancing lentivirus production by transient transfection of HEK293 adherent cultures.

Transfection of surface adherent cells remain as a standard methodology for lentiviral production for early phase clinical studies and research purposes. Production today is based on transient co-transfection of three or four plasmids, where the viral elements are encoded separately for safety reasons. Assembly of functional lentiviral particles requires all plasmids to be efficiently transfected into each cell, a notable challenge with many currently available methods for transient transfection. We have previously demonstrated the significant improvement of cationic polymer-based transfection in various cell types using a combination of fusogenic lipids and histone deacetylase 6 inhibitor (Enhancers). In this report, we focused on the transfection step and the feasibility of improving lentiviral production using the Enhancers. After optimization of DNA amount and N/P ratio, transfection using seven commercial gene carriers showed comparable maximal efficiency of production with high cell viability. In the presence of Enhancers, the production of functional lentivirus using LPEI was increased by as much as tenfold and outperformed lentiviral production using Lipofectamine 3000. We demonstrate a scalable and optimized workflow where the use of the Enhancers significantly improved the lentiviral particle production in various HEK293 cell lines.