Characterization of metalloprotease and serine protease activities in batch CHO cell cultures: control of human recombinant IFN-γ proteolysis by addition of iron citrate

Abstract

Background During the production of any recombinant proteins, an evaluation of the product quality is crucial. Proteolytic events may occur during the process and could influence the product quality. Indeed, proteolysis is an unpredictable process and relatively little is know regarding the proteolytic enzymes produced and released by mammalian cells. In fact, proteases originating from the host cell line cannot be avoided in cell culture. Due to regulatory and safety prospects, the addition of serum, fetuin or albumin that usually limit protease activities, is not desirable. Thus, in serum-free cultures of mammalian cells, control of protease activity constitutes a major challenge. In the present work, the presence of proteases and their effect on quality of IFN-g produced by a recombinant CHO cell line cultivated in a stirred-tank bioreactor were studied. Whereas the quality of IFN-g remained constant during the CHO cell cultures performed in BDM medium, IFN-g proteolysis was observed when cultures were carried out in RPMI medium with serum [1,2].