GMP-translatable culture vessels improve manufacturing outcomes
The SNBTS second-generation EBV-specific T cell bank was manufactured in
standard culture flasks, and we determined whether transfer to more
GMP-compliant G-Rex culture flasks would affect T cell phenotype or
functional markers. Sero-positive apheresis material from healthy
EBV-positive donors (n=6) were used to establish fresh EBV-specific T
cell cultures, and each donor culture was split to directly compare
culture in closable G-Rex flasks (G-Rex100) versus standard tissue
culture flasks (Corning) through an optimized three-round stimulation
process. The G-Rex flasks used had a standard research cap, but are
identical to GMP-compliant flasks which have a closed-process cap, so
can be considered GMP-translatable. At day 30 (9 days after the third
LCL stimulation), cells were harvested from both culture vessels and
analyzed by surface and intracellular cytokine phenotyping. The mean
percentage of CD8+ T cells was significantly higher (p=0.012) in G-Rex
flask than in standard flask (90.2 ± 3.49% versus 78.4 ± 2.11%
respectively, Figure 2A). However, T cell surface marker phenotype did
not differ significantly between culture flasks (Figure 2B).
Intracellular cytokine analysis after PMA/ionomycin stimulation
demonstrated that there was no significant difference in either quantity
of cytokine expression (measured by cMFI, Figure 2C) or cytokine
co-expression subpopulations in CD8+ T cells between flasks (Figure 2D).
These results demonstrate using manufacturing-scale G-Rex culture flasks
not only allows increased cell expansion (data not shown), but also
develops a more consistent T cell phenotype in a shorter period of time
than culture in conventional Corning flasks. This process is then
readily transferable to G-Rex closed-system flasks to allow a fully
closed manufacturing process via use of the Gatherex cell harvester
(Wilson Wolf Ltd).