Establishment of a cell line expressing recombinant factor VII and its subsequent conversion to active form FVIIa through hepsin by genetic engineering method

Abstract

Factor VII (FVII) is a plasma glycoprotein that participates in the coagulation process leading to generation of fibrin. It is converted to factor VIIa that plays an important role in the coagulation cascade. The aim of this study was isolating and cloning the genes of human factor VII and hepsin and subsequent co-transfection of the constructs to Chinese hamster ovary (CHO) cell line to obtain rFVIIa. Factor VII and hepsin cDNAs were isolated from HepG2 cell line and cloned into pcDNA3.1 (+) vector. The constructs were co-transfected to CHO cell line. A cell line that permanently expressed recombinant factor VII (rFVII) and hepsin was established. The expression of rFVII was confirmed by reverse transcriptase-polymerase chain reaction, enzyme-linked immunosorbent assay and Western blot analysis. Biological activity of rFVII was evaluated by prothrombin time assay. The results showed that the genes of FVII and hepsin were successfully cloned and expressed. Stable CHO cells co-transfected with pcNDA3.1-FVII and pcNDA3.1-hepsin expressed FVII and hepsin mRNA, but there was no expression in the CHO cells transfected with insert free pcDNA3.1. FVIIa protein was secreted to medium of CHO cells co-transfected with pcNDA3.1-FVII and pcNDA3.1-hepsin. The expected band of rFVII was detected in Western blot analysis. A three- to fourfold decrease in clotting time was observed when human FVII-depleted plasma was used in combination with human thromboplastin in the presence of rFVII, confirming the biological activity of rFVII. As we are aware, this is the first report of establishing a cell line expressing FVIIa using genetic engineering methods.