High‐density continuous cultures of hybridoma cells in a depth filter perfusion system

A depth filter perfusion system (DFPS) for animal cell culture was developed and its use in continuous highdensity cultures of hybridoma cells was investigated. In the DFPS, based on cell immobilization in a cylindrical depth filter matrix, cells were easily immobilized and cultivated by simple medium recirculation. The cell density in the 20-mum pore size filter matrix reached up to 3 x 10(7) cells/mLin less than 10 days. This resulted in a high monoclonal antibody productivity of 744 mg/L/day, which was 25-35 times higher than that of continuous-suspension cultures using the same cell line. The 20-mum pore filter retained more cells than the 30-mum filterin a shorter period. The DFPS provides advantages of low-cost set-up, easy operation, and scale-up in the cultures of anchorage-independent cells. It also has a high potential for anchorage-dependent cell cultures because of its unusually high surface-to-volume ratio of 450-600 cm(2)/cm(3).