Patent ID: 6458565
Filing Date: 2002-10-01
Classification: C07K,C12N

Abstract:
In a method for producing a heterologous secreted protein from Chinese Hamster Ovary (CHO) cells grown on microcarriers, comprising:inoculating a cell bioreactor, containing microcarriers as a solid support for adherent cell growth and serum-containing cell culture medium, with an inoculum of CHO host cells transformed to express a heterologous secreted protein, wherein the inoculum was prepared by growing the transformed CHO host cells in serum-containing cell culture medium; and culturing the inoculated CHO host cells in adherent cell culture without perfusion of cell culture medium for a period of about one to three days prior to the initiation of feed; the improvement, comprising: initiating a feed of serum-free cell culture medium supplemented with insulin, ferric citrate, selenium and trace elements to the cell bioreactor via continuous perfusion; increasing the feed flow rate of serum-free cell culture medium supplemented with trace elements in stages until a final feed flow rate in a range of about 1 to 3.5 volume/volume/day is reached to produce and secrete a heterologous protein from the CHO host cells into the serum-free cell culture medium, wherein initiating feed and increasing the feed flow rate are performed together over a six to ten day period; and culturing the CHO host cells in adherent cell culture at the final feed flow rate.