Comparison of growth and recombinant protein expression in two different insect cell lines in attached and suspension culture

Culture conditions required for obtaining maximum recombinant protein conce ntrations from two cell lines, Spodoptera frugiperda (IPLB-Sf2l-AE) and Tri choplusia ni (Tn 5B--4), were determined in this work. Conditions studied i nclude mode of culture (suspended vs attached), agitation rates, inoculum s izes, cell concentration at the time of infection, and various serum-free m edia (SFM). Results were compared with the performance of attached cultures in TnM-FH with 10% fetal bovine serum. Growth rates in the different cultu re media tested were similar, but the cell numbers achieved (i.e., yield) i mproved 2 to 2.7-fold in SFM over cultures in TnM-FH. Agitation rates of 15 0-160 rpm were necessary for maximum growth of suspended Tn 5B-1-4 cells co mpared to 125-150 rpm for Sf-21 cells. An inoculum size of 5 x 10(5) cells/ mL gave good growth rates and optimum biomass yields for both cell lines. C ultures of both cell lines were infected with viruses encoding for beta -ga lactosidase or human secreted alkaline phosphatase (seAP). Protein expressi on in TnM-FH in attached culture showed that Tn 5B-1-4 cells are 2-4.5 time s more productive on a per cell basis than Sf-21 cells grown under similar conditions. Production of beta -galactosidase in Sf-21 cells increased 50% in suspension cultures with SFM compared to attached cultures in TnM-FH, bu t seAP expression was essentially unchanged by culture techniques. The Tn 5 B-1-4 cells produced 2.6-4.4 and 2.7-3 times more beta -galactosidase and s eAP, respectively, in SFM in suspension compared to Sf-21 cells. EX-CELL 40 1 and Sf900-II were formulated as optimized SFM for Sf cell lines. However, in Sf-21 cultures EX-CELL 400 performed better than the other two media, a s it increased the beta -galactosidase yield up to 25%. Surprisingly, EX-CE LL 401 was the best medium for the production of beta -galactosidase by Tn 5B-1-4 cells, resulting in 25% and 69% higher volumetric and specific yield s, respectively, compared to EX-CELL 405 which was formulated for this spec ific cell line. These results show that even when culture media are designe d for maximal growth of a specific cell line, other media may provide the b est conditions for protein production.