Novel human renal proximal tubular cell line for the production of complex proteins

Human host cell lines for the production of biopharmaceutical proteins are of interest due to differences in the glycosylation patterns of human and animal cell lines. Specifically, sialylation, which has a major impact on half-life and immunogenicity of recombinant biopharmaceuticals, differs markedly. Here, we established and characterized an immortalized well documented and serum-free host cell line, RS, from primary human renal proximal tubular epithelial cells (RPTEC). In order to test its capacity to produce complex glycosylated proteins, stable recombinant human erythropoietin (rhEpo) producing clones were generated. The clone with highest productivity, RS-1C9 was further characterized and showed stable productivity. Biological activity was observed in in vitro assays and 28% of rhEpo glyco-isoforms produced by RS-1C9 were in range and distribution of the biological reference standard (BRP) isoform, as compared to 11.5% of a CHO based rhEpo. Additionally, cellular α-2,6 sialylation, Galactose-alpha-1,3-galactose (alpha-Gal) and N-glycolylneuraminic acid (NeuGc) patterns compare favourably to CHO cells. While productivity of RS still needs optimization, its amenability to upscaling in bioreactors, its production of glyco-isoforms that will increase yields after down-stream processing of about 2.5 fold, presence of sialylation and lack of Neu5Gc recommend RS as alternative human host cell line for production of biopharmaceuticals.