A novel aqueous two phase assisted platform for efficient removal of process related impurities associated with E. coli based biotherapeutic protein products

This article presents a variant of aqueous two phase system (ATPS) as a tool for selective removal of process related impurities associated with Escherichia coli, namely host cell proteins and nucleic acids. Granulocyte colony stimulating factor (GCSF) expressed in E. coli has been selected as a model protein for the study. While achieving effective removal of host cell impurities as per the regulatory requirement for recombinant therapeutics, high product recovery has been achieved by adopting a novel strategy involving resolubilization of interfacial GCSF precipitate. This has been done such that the structural and biological activity of the product is retained. Exhaustive analysis of structural as well as functional integrity of resolubilized GCSF has been carried out using advanced analytical and in vitro bioassay tools. Product recovery of 99.5% has been achieved with the concentration of host cell proteins less than 100 ppm and of nucleic acids below 10 ng/ml. We think that the proposed platform can enable use of ATPS as a more economical alternative to process chromatography in industrial biopharmaceutical manufacturing processes.