Production of glycoproteins using manganese

Abstract

Culture media comprising manganese and methods of culturing cells to improve sialylation and glycosylation of glycoproteins are provided.

What is claimed is: 
     
         1 . A method for producing an erythropoietic composition comprising sialylated erythropoiesis-stimulating molecules, comprising the steps of:
 growing a manganese-responsive host cell in a culture medium containing an amount of manganese effective to increase the sialylation of said erythropoietic composition,   wherein the concentration of manganese in said culture medium ranges from about 0.01 to about 40 μM.   
     
     
         2 . The method of  claim 1  further comprising the step of recovering an erythropoietic composition wherein less than about 5% of the erythropoiesis-stimulating molecules are lower sialylated. 
     
     
         3 . The method of  claim 1  in which the amount of manganese is effective to increase the percentage of highly sialylated erythropoiesis-stimulating molecules. 
     
     
         4 . The method of  claim 1  wherein the amount of manganese is effective to increase the percentage of erythropoiesis-stimulating molecules which are glycosylated at potential O-linked glycosylation sites. 
     
     
         5 . The method of  claim 1  wherein the amount of manganese is effective to increase the percentage of galactose among the sugars attached to erythropoiesis-stimulating molecules. 
     
     
         6 . The method of anyone of  claims 1 - 5  wherein the culture medium is essentially serum-free. 
     
     
         7 . The method of any of  claims 1 - 6  wherein the erythropoiesis-stimulating molecules comprise the amino acid sequence of SEQ ID NO: 3 (erythropoietin) or erythropoietic fragments thereof. 
     
     
         8 . The method of any of  claims 1 - 7  wherein the erythropoiesis-stimulating molecules comprise the amino acid sequence of SEQ ID NO: 2 {darbepoetin) or erythropoietic fragments thereof. 
     
     
         9 . The method of any of  claims 1 - 8  wherein the host cell is a mammalian cell. 
     
     
         10 . The method of any of  claims 1 - 9  wherein the host cell is a CHO cell. 
     
     
         11 . The method of any of  claims 1 - 10  wherein the manganese is at a concentration of from about 0.1 to about 10 μM. 
     
     
         12 . The method of any of  claims 1 - 10  wherein the manganese is at a concentration of from about 0.4 to about 4 μM. 
     
     
         13 . The method of any of  claims 1 - 12  wherein the culture medium further comprises one or more supplementary amino acids selected from the group consisting of asparagine, aspartic acid, cysteine, cystine, isoleucine, leucine, tryptophan, or valine. 
     
     
         14 . The method of any of  claims 1 - 13  wherein the host cells are grown in roller bottles. 
     
     
         15 . The method of any of  claims 1 - 14  wherein the manganese is added after a rapid cell growth phase. 
     
     
         16 . The method of  claim 15  wherein the rapid cell growth phase lasts. for a period ranging between about 2 and 20 days. 
     
     
         17 . The method of  claim 16  wherein the manganese is added after two harvest cycles. 
     
     
         18 . The method of  claim 17  wherein the first harvest cycle is about 8 days and the second harvest cycle is about 7 days long. 
     
     
         19 . A culture medium comprising host cells and a non-toxic amount of manganese effective to increase the sialylation of a glycoprotein composition. 
     
     
         20 . The culture medium of  claim 19  wherein the host cells secrete an erythropoietic composition. 
     
     
         21 . The culture medium of  claim 19  or  20  wherein the manganese is at a concentration of from about 0.01 to about 40 μM. 
     
     
         22 . The culture medium of  claim 21  wherein the manganese is at a concentration of from about 0.1 to about 10 μM.