SK-HEP cells and lentiviral vector for production of human recombinant factor VIII

Generation of hyperfunctional recombinant human factor IX variants expressed in human cell line SK-Hep-1

OBJECTIVE

To develop recombinant factor IX (FIX) variants with augmented clotting activity.

RESULTS

We generated three new variants, FIX-YKALW, FIX-ALL and FIX-LLW, expressed in SK-Hep-1 cells and characterized in vitro and in vivo. FIX-YKALW showed the highest antigen expression level among the variants (2.17 µg^-mL), followed by FIX-LLW (1.5 µg^-mL) and FIX-ALL (0.9 µg^-mL). The expression level of FIX variants was two-five fold lower than FIX-wild-type (FIX-WT) (4.37 µg^-mL). However, the biological activities of FIX variants were 15-31 times greater than FIX-WT in the chromogenic assay. Moreover, the new variants FIX-YKALW, FIX-LLW and FIX-ALL also presented higher specific activity than FIX-WT (17, 20 and 29-fold higher, respectively). FIX variants demonstrated a better clotting time than FIX-WT. In hemophilia B mice, we observed that FIX-YKALW promoted hemostatic protection.

CONCLUSION

We have developed three improved FIX proteins with potential for use in protein replacement therapy for hemophilia B.

The role of magnetic field in the biopharmaceutical production: Current perspectives

Current scientific evidence on the influence of magnetic field on mammalian cell lines used for industrial production of biopharmaceuticals, on human cell lines and on potential cell lines for the biopharmaceutical production is presented in this review. A novel magnetic coupling induced agitation could be the best solution to eliminate sources of contamination in stirred tank bioreactors which is especially important for mammalian cell cultures. Nevertheless, the side effect of magnetically-coupled stirring mechanism is that cells are exposed to the generated magnetic field. The influence of magnetic field on biological systems has been investigated for several decades. The research continues nowadays as well, investigating the influence of various types of magnetic field in a variety of experimental setups. In the context of bioreactors, only the lower frequencies and intensities of the magnetic field are relevant.

Production of Recombinant Factor VIII in Human Cell Lines

Human cell lines can produce recombinant proteins much more similar to their natural counterpart, compared to other mammalian cell lines, reducing potential immunogenic reactions. Recombinant proteins produced in nonhuman cells can have in its structure glycan epitopes, such as Galα1,3-Gal (alpha-Gal) and N-glycolylneuraminic acid (Neu5Gc) residues, that are antigenic to humans and can potentially affect the efficacy of the recombinant product. Therefore, the production of recombinant factor VIII (rFVIII) in human cell lines is a new approach to avoid nonhuman glycosylation. Here, we describe a protocol to produce rFVIII in the human cell line SK-HEP, using a lentiviral vector to produce high quantities of the recombinant protein.

Purification Methods for Recombinant Factor VIII Expressed in Human Liver SK-Hep Cells

Coagulation factor VIII is one of the largest proteins attempted to be expressed in recombinant form. A very complex and labile protein which has a very short half-live and need a fast and efficient purification chain. Here, we describe a simple purification sequence using multimodal Capto MMC, affinity FVIII select and ion exchange SP-Fastflow chromatography steps without subjecting the target molecule to mechanical and temperature stress, separating impurities from rFVIII using net charge, hydrophobicity, and affinity of the molecules.

Quantification of Coagulation Factor VIII by Selective Reaction Monitoring

Coagulation factor VIII (FVIII) is an important glycoprotein involved in the extrinsic coagulation cascade. Mutations in FVIII gene results in hemophilia A, a recessive coagulation disorder that is clinically managed by administration of purified FVIII from blood donors or recombinant FVIII. Because of its fundamental therapeutic application, biotechnological production of FVIII requires rigid quality control and monitoring in patients and clinical trials. Here, we describe a protocol for a mass spectrometry based approach termed selective reaction monitoring (SRM) as an important alternative tool for accurate and sensitive quantitation of purified or recombinant FVIII.

Production of recombinant coagulation factors: Are humans the best host cells?

The main treatment option for Hemophilia A/B patients involves the administration of recombinant coagulation factors on-demand or in a prophylactic approach. Despite the safety and efficacy of this replacement therapy, the development of antibodies against the coagulation factor infused, which neutralize the procoagulant activity, is a severe complication. The production of recombinant coagulation factors in human cell lines is an efficient approach to avoid such complication. Human cell lines can produce recombinant proteins with post translation modifications more similar to their natural counterpart, reducing potential immunogenic reactions. This review provides a brief overview of the most important characteristics of recombinant FVIII and FIX products available on the market and the improvements that have recently been achieved by the production using human cell lines.

Lentiviral Vectors Mediate Long-Term and High Efficiency Transgene Expression in HEK 293T cells

OBJECTIVES

Lentiviral vectors have been used successfully to rapidly produce decigram quantities of active recombinant proteins in mammalian cell lines. To optimize the protein production platform, the roles of Ubiquitous Chromatin Opening Element (UCOE), an insulator, and selected promoters were evaluated based on efficiency and stability of foreign gene expression mediated by lentiviral vectors.

METHODS

Five lentiviral vectors, pFIN-EF1α-GFP-2A-mCherH-WPRE containing EF1α promoter and HS4 insulator, p'HR.cppt.3'1.2kb-UCOE-SFFV-eGFP containing SFFV promoter and UCOE, pTYF-CMV(β-globin intron)-eGFP containing CMV promoter and β-globin intron, pTYF-CMV-eGFP containing CMV promoter, and pTYF-EF1α-eGFP with EF1α promoter were packaged, titered, and then transduced into 293T cells (1000 viral genomes per cell). The transduced cells were passaged once every three days at a ratio of 1:10. Expression level and stability of the foreign gene, green fluorescence protein (GFP), was evaluated using fluorescent microscopy and flow cytometry. Furthermore, we constructed a hepatitis C virus (HCV) E1 recombinant lentiviral vector, pLV-CMV-E1, driven by the CMV promoter. This vector was packaged and transduced into 293T cells, and the recombinant cell lines with stable expression of E1 protein were established by limiting dilution.

RESULTS

GFP expression in 293T cells transduced with the five lentiviral vectors peaked between passages 3 and 5 and persisted for more than 5 weeks. The expression was prolonged in the cells transduced with TYF-CMV (β-globin intron)-eGFP or TYF-CMV-eGFP, demonstrating less than a 50% decrease even at 9 weeks post transduction (p>0.05). The TYF-CMV-eGFP-transduced cells began with a higher level of GFP expression than other vectors did. The percentage of GFP positive cells for any of the five lentiviral vectors sustained over time. Moreover, the survival rates of all transfected cells exceeded 80% at both 5 and 9 weeks post transduction. Surprisingly, neither the HS4 insulator nor the UCOE sequence improved the GFP expression level or stability. Clonal cell lines with HCV E1 gene were generated from LV-CMV-E1 vector-infected 293T cells. A representative recombinant cell line maintained stable E1expression for at least 9 weeks without significant difference in morphology compared with untreated 293T cells.

CONCLUSION

The results suggest that all five vectors can stably transduce 293T cells, producing long term transgene expression with different efficiencies. However, neither the insulator nor the UCOE improved the GFP expression. The vectors containing the promoter CMV or CMV (β-globin intron) generated the highest gene expressions, manifesting as more favorable candidates for recombinant protein production in HEK293T cells.