US Patent 7619073 Method for purifying erythropoietin

The invention relates to a method for producing recombined erythropoietin having a particularly high degree of purity (≧98%). The method consists of at least 5 chromatographic purification steps, i.e. at least two anion exchange chromatographs, at least one hydrophobic interaction chromatography, at least one affinity chromatography and at least one hydroxyapatite chromatography. In preferred embodiments, the method does not require any exclusion chromatography and any reversed-phase chromatography. The invention relates to, in particular, a method wherein the following chromatographic purification steps have the following order; i) a first anion exchange chromatography, ii) an affinity chromatography, which relates, preferably, to a dye affinity chromatography, iii) a hydrophobic interaction chromatography, iv) an hydroxyapatite chromatography and v) a second anion exchange chromatography.