Researchers demonstrated a three- to eightfold increase in titer, noting that timing and amount of caffeine is key.
Give caffeine to cells engineered to produce viruses used for gene therapy, and the cells can generate three to eight times more virus, according to researchers at the University of Texas Southwestern Medical Center, Dallas. They emphasize that the timing of caffeine addition to standard lentiviral production protocols is important for achieving higher virus titers. Caffeine concentration is also key, as too much caffeine was toxic to the cells and did not increase virus production.
Details are published in Human Gene Therapy in a paper titled “Creating Higher Titer Lentivirus with Caffeine.”
Lentiviral vectors are used for gene-delivery applications in basic research as well as gene therapy. They are useful for gene transfer because they have a large cloning capacity and a broad tropism. Although procedures for lentiviral vector production have been standardized, simple methods to create higher titer virus during production would have extensive and important applications for both research and clinical use, the University of Texas team notes.
In their research, the group achieved three- to eightfold increases in titers during standard lentiviral production by the addition of caffeine to a final concentration of 2–4 mM. They say that sodium butyrate, a histone deacetylase inhibitor shown previously to increase viral titer, works about 50% as well as caffeine.
They also show that the DNA-PKcs (DNA-dependent protein kinase catalytic subunit) inhibitor NU7026 can also increase viral titer, but that the combination of caffeine and NU7026 is not more effective than caffeine alone. Additionally, they demonstrated that the time course of caffeine treatment is important in achieving a higher titer virus and is most effective when caffeine is present from 17 to 41 hours post-transfection. Furthermore, the investigators revealed that although caffeine increases lentiviral vector titer, it has the opposite effect on the titer of adeno-associated virus type 2 vector.
The addition of caffeine “should significantly decrease the cost of lentiviral production for research and clinical uses,” conclude the authors.