High-throughput analysis of intraclonal variability of glycoprotein sialylation

Development of recombinant Chinese Hamster Ovary (CHO) cells producing therapeutic proteins requires analyzing the quality, such as sialic acid content, of proteins produced by many cell clones. In order to perform these analyses, high-throughput methods are required. Conventional methods for quantifying sialic acid, however, require protein purification, which is time consuming and cannot be used for high-throughput analysis. Here we used a high-throughput method (HTM) that we recently developed to analyze the intraclonal variability of 24 CHO cell subclones. The sialic acid content varied significantly from 1 to 70 mg sialic acid/g protein, and the concentration of total proteins secreted by the cells varied from 41 to 214 mg/L. In addition, the sialic acid content was negatively correlated with total protein concentration. This trend agrees with previous theoretical and experimental studies. Overall, the HTM can finish these analyses in 15 minutes, while conventional methods used in previous studies will require at least 24 days. Thus, the HTM can significantly accelerate the analyses of clonal and intraclonal variability in cell line development