Utilizing the macroporous packed bed for insect cell/baculovirus expression

Due to their high porosity and biocompatibility, polyurethane foam (PUF) and cellulose foam were adopted for insect cell immobilization and baculovirus expression. Spodoptera frugiperda (SF-21) cells were grown within the macroporous matrix and then infected by Autographa californica nuclear polyhedrosis virus (AcNPV) which was encoded with human interleukin-5 (hIL-5) gene. An appropriate initial cell loading density and medium circulation velocity determined from the previous study were applied in this actual cell cultivation experiments to obtain a uniform initial and final axial cell distribution. The growth of insect cells and the expression of baculovirus were successful in the macroporous packed bed systems used. The final average cell density in cellulose foam achieved was 5.2×10⁷?cells/cm³ and 4.3×10⁷?cells/cm³ in PUF. Under the conditions of sufficient nutrition and oxygen supplement, the average productivity of hIL-5 in cellulose foam packed bed bioreactor reached 7.2×10⁷ unit/l-day. With 50% fresh medium replacement after viral infection, the average productivity of hIL-5 in PUF packed bed reached 8.4×10⁷ unit/l-day, about two fold than that without any fresh medium replacement at infection.