Correct glycosylation of proteins is essential for production of therapeutic proteins as glycosylation is important for protein solubility, stability, half-life and immunogenicity. The heavily... Show moreCorrect glycosylation of proteins is essential for production of therapeutic proteins as glycosylation is important for protein solubility, stability, half-life and immunogenicity. The heavily glycosylated plasma protein C1-inhibitor (C1-INH) is used in treatment of hereditary angioedema attacks. In this study, we used C1-INH as a model protein to propose an approach to develop recombinant glycoproteins with the desired glycosylation. We produced fully functional recombinant C1-INH in Chinese hamster ovary (CHO) cells. In vivo we observed a biphasic clearance, indicating different glycosylation forms. N-glycan analysis with mass spectrometry indeed demonstrated heterogeneous glycosylation for recombinant C1-INH containing terminal galactose and terminal sialic acid. Using a Ricinus Communis Agglutinin I (RCA(120)) column, we could reduce the relative abundance of terminal galactose and increase the relative abundance of terminal sialic acid. This resulted in a fully active protein with a similar in vivo clearance rate to plasmaderived C1-INH. In summary, we describe the development of a recombinant human glycoprotein using simple screening tools to obtain a product that is similar in function and in vivo clearance rate to its plasma-derived counterpart. The approach used here is of potential use in the development of other therapeutic recombinant human glycoproteins. Show less
Replacement therapy with recombinant drugs is the main therapeutic strategy for hemophilia B patients. To reduce the production costs of recombinant coagulation factors, improvement of their... Show moreReplacement therapy with recombinant drugs is the main therapeutic strategy for hemophilia B patients. To reduce the production costs of recombinant coagulation factors, improvement of their expression and activity by enhancement of gamma-carboxylation might be of interest. The expression and functional activity of vitamin K-dependent (VKD) coagulation proteins rely, in part, on the VKD process of gamma-carboxylation that is mediated by the enzymes gamma-carboxylase and vitamin K epoxide reductase (VKOR). Since the recombinant production of VKD proteins is hampered by the inefficiency of this enzymatic process, we specifically have examined the stable expression of functional blood coagulation factor IX (FIX) in HEK293 cells following transient overexpression of VKORC1 as an important part of VKOR component. Recombinant hFIX-producing human embryonic kidney (HEK) cells were transfected to overexpress VKORC1. Following reverse transcription polymerase chain reaction (RT-PCR) analysis, expression efficiency of the active hFIX was analyzed by performing enzyme-linked immunosorbent assay and coagulation test. In addition, to quantify gamma-carboxylated recombinant FIX, the barium citrate method was used. Overexpression of VKORC1 in FIX-producing HEK cells, resulting in a 3.2-fold higher expression of functional FIX, which displayed a 1.4-fold enhanced specific activity. Moreover, a 3.9-fold enhanced recovery of fully gamma-carboxylated FIX following barium citrate adsorption was achieved. Collectively, these findings indicate that the overexpression of VKORC1 results in the production of higher levels of functional hFIX in HEK293 cells. The increase of the VKORC1 as a supplier of gamma-carboxylase seems to play a significant role in increasing the amount and efficiency of recombinant FIX production, thereby reducing the production costs. Show less
Shirzad-Wasei, N.; Oostrum, J. van; Bovee-Geurts, P.H.M.; Kusters, L.J.A.; Bosman, G.J.C.G.M.; Grip, W.J. de 2015
