Stable Expression of Erythropoietin cDNA in Chinese Hamster Ovary Cells
红细胞生成素在中国仓鼠卵巢细胞中稳定表达

An plasmid for the expression of erythropoietin is costructed by insering erthropoietin cDNA in cloning site of eucaryotic expression vector. The expression plasmid is introduced into COS-7 cells and biologically active erythropoietin is expressed, which is indicated by ELISA and colony formation assays. The plasmid is then introduced into CHO cells by means of electroporation and the foreign gene is amplified by exposing the cells to gradually higher concentration of methetrexate. The expression level reaches 2-3ug/106 cells/24hrs when MTX concentration is 2x10-7 mol/L. The expression level of the cells remain stable after 3 months of cryopreservation. It is possible to obtain higher expression level by further amplification and selection.