Patent ID: 8524477

Claim:
A method for obtaining a composition comprising one or more isoforms of an erythropoietin (EPO) comprising glycans linked thereto wherein the glycans comprise, on average, at least six (6) sialic acids per EPO molecule and from zero (0) to two (2) Lewis x structures, the method comprising: providing a eukaryotic cell comprising a nucleic acid sequence encoding an adenoviral E1A protein in expressible format and a nucleic acid encoding an EPO in expressible format, wherein the eukaryotic cell further contains a nucleic acid sequence encoding a sialyltransferase under control of a heterologous promoter; culturing the eukaryotic cell in a serum-free culture medium, thus allowing expression of an EPO, the adenoviral E1A protein, and the sialyltransferase in the eukaryotic cell; harvesting the expressed EPO from the eukaryotic cell and/or from the culture medium; and purifying and fractionating the EPO to obtain a composition comprising one or more isoforms of an EPO comprising glycans linked thereto wherein the glycans comprise, on average, at least six (6) sialic acids per EPO molecule and from zero (0) to two (2) Lewis x structures.