title: Measurement of sialic acid content is insufficient to assess bioactivity of recombinant human erythropoietin.
abstract: Assessment of biological potency and its comparison with clinical effects are important in the quality control of therapeutic glycoproteins. Animal models are usually used for evaluating bioactivity of these compounds. However, alternative methods are required to simplify the bioassay and avoid ethical issues associated with animal studies. Negatively charged sialic acid residues are known to be critical for in vivo bioactivity of recombinant human erythropoietin (rhEPO). In this study, we used capillary zone electrophoresis, a charge-based separation method, to estimate the sialic acid content for predicting in vivo bioactivity of rhEPO. In vivo bioactivities of rhEPO subfractions were measured and compared with sialylation levels. The results obtained indicated that in vivo bioactivity of rhEPO is not simply correlated with the sialylation level, which suggests that it is difficult to predict biological potency from the sialic acid content alone. N-Glycan moieties as well as sialic acid residues may have a significant impact on in vivo bioactivity of rhEPO.
authors.affiliation: Bio Process Research and Development Laboratories, Production Division, Kyowa Hakko Kirin Co., Ltd., Gunma, Japan. shigehiro.yanagihara@kyowa-kirin.co.jp
authors.forename: Shigehiro
authors.initials: S
authors.lastname: Yanagihara
authors.forename: Yuya
authors.initials: Y
authors.lastname: Taniguchi
authors.forename: Mareto
authors.initials: M
authors.lastname: Hosono
authors.forename: Eiji
authors.initials: E
authors.lastname: Yoshioka
authors.forename: Rika
authors.initials: R
authors.lastname: Ishikawa
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Shimada
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Kadoya
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kutsukake
mesh_terms: D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D019075:Electrophoresis, Capillary; D004921:Erythropoietin / Q000032:analysis* / Q000378:metabolism*; D006031:Glycosylation; D006801:Humans; D019158:N-Acetylneuraminic Acid / Q000032:analysis* / Q000378:metabolism*; D011994:Recombinant Proteins
chemical_list: D011994:Recombinant Proteins; D004921:Erythropoietin; D019158:N-Acetylneuraminic Acid