Methods for enhanced protein production

Abstract

The present invention provides a method of increasing protein production in a cell culture by growing cells that produce the protein (e.g., the growth phase) in a perfusion cell culture to a high cell density (i.e., at least above about 40×10 6 cells/mL) and then switching to a protein production phase, wherein the cells are cultured in a fed-batch cell culture. The present invention further provides a method for clarifying a protein from a cell culture by adjusting the pH of the cell culture to below neutral pH (i.e., below a pH of 7) and settling the cell culture, such that the cell culture separates to form a supernatant layer and a cell-bed layer, wherein the protein is in the supernatant layer.

We claim: 
     
         1 . A method for clarifying a protein from a cell culture, comprising:
 (A) adjusting the pH of the cell culture to below neutral pH; and   (B) settling the cell culture, such that the cell culture separates to form a supernatant layer and a cell-bed layer, wherein the protein is in the supernatant layer.   
     
     
         2 . The method of  claim 1 , wherein the cell culture is settled for at least 30 minutes. 
     
     
         3 . The method of  claim 1 , wherein the cell culture is settled for between 30 and 120 minutes. 
     
     
         4 . The method of  claim 1 , wherein the pH is between 4 and 7. 
     
     
         5 . The method of  claim 4 , wherein the pH of the buffer is preferably at the same pH as that the cell settling was done. 
     
     
         6 . The method of  claim 1 , wherein the cell culture is an animal cell culture. 
     
     
         7 . The method of  claim 6 , wherein the cell culture is a Chinese Hamster Ovary (CHO) cell culture. 
     
     
         8 . The method of  claim 1 , wherein the protein is an antibody. 
     
     
         9 . The method of  claim 8 , wherein the antibody is a monoclonal antibody. 
     
     
         10 . The method of  claim 9 , wherein the monoclonal antibody is selected from the group consisting of a human, humanized and chimeric antibody. 
     
     
         11 . The method of  claim 1 , wherein the protein is selected from the group consisting of enzymes, receptors, fusion proteins, cytokines, regulatory factors, hormones, antigen-binding agents, therapeutic proteins, and diagnostic proteins.