Increased CHO Transfection Efficiency and Production in a Straight Forward System

Transient protein production enables quick and efficient production of milligram to gram quantities of recombinant protein, which saves time and cost compared to developing a genetically stable cell line for use in bioproduction. This is particularly important in drug development where preclinical material is needed quickly in order to make informed go/no go decisions. Having access to preclinical material faster can greatly impact the overall drug development timeline.  The challenge has been low transfection efficiency and productivity, particularly in CHO cells. CHO cells are typically more difficult to transfect, but are the preferred vehicle of antibody production due to their use in larger scale production of clinical material.

Increased efficiency and productivity for transient production in CHO Cells

To address issues of efficiency and productivity and create an easy to use system, Polyplus Transfection recently launched an advanced transient expression system, FectoCHO™. The system is comprised of a novel CHO chemically defined medium, a powerful CHO transfection reagent, and an expression booster that enhances gene expression. The system is optimized to facilitate adaption and cultivation of various strains of CHO cells such as CHO-K1, CHO-S and ExpiCHO™-S without the need for extensive sequential adaptation.

Key features of the FectoCHO™ Expression System include:

Increased CHO Transfection Efficiency

Transfection efficiency is critical to the success of transient production and traditionally CHO cells have been more difficult to transfect than HEK293 cells, for example. This typically results in lower transfection efficiency when using CHO cells. With CHO cells now more broadly used in transfection, this efficiency has been increasing, but still often not ideal. Polyplus Transfection has presented impressive transfection efficiency data for both ExpiCHO™-S and CHO-K1 cell lines (Figure 1).

Figure 1:Transfection efficiency of FectoCHO Expression system

Increased Transient Protein Production Yields in Suspension CHO Culture

Polyplus Transfection designed the FectoCHO™ Expression medium to maintain cells in an ideal physiological state before, during and after transfection. FectoPRO® has been optimized to provide high transfection efficiency and maximize protein and antibody yields. According to data provided by Polyplus Transfection, the FectoCHO™ Expression system increased protein yield up to 4 times versus other competitive systems (Figure 2).

Figure 2: CHO-K1 cells were transfected following recommended protocols. Similar results have been obtained in CHO-S cells (2-fold increase).

Ideally suited for high density cell lines

Another strategy to increase productivity and product titer is the use of high-density cell lines in transient protein production. The FectoCHO™ Expression system is particularly well suited for high density cells. FectoCHO™ CD medium has been optimized to sustain growth and viability for high density cultures for up to 10 days. When coupled with the FectoPRO® transfection reagent, high protein yields and increased CHO transfection efficiency has been demonstrated in high density cell lines like ExpiCHO™-S cells. (Figure 3)

Figure 3: ExpiCHO-S™ cells were either cultivated in FectoCHO™ CD Expression Medium and transfected with FectoPRO® reagent following the recommended protocol, or in ExpiCHO™ Expression Medium and transfected following the recommended protocol with ExpiFectamine™ CHO transfection reagent. IgG3-Fc production was assayed over 10 days post-transfection using protein G Biosensors (fortéBIO® BLItz).

Scalable System

The required amount of protein generated during transient production can vary from milligrams to several grams. Thus, it is important that CHO transfection systems be scalable from flasks for small volumes to bioreactors for larger protein demands. Polyplus Transfection has demonstrated that the FectoCHO™ Expression System also performs well in bioreactor processes (Figure 4).

Figure 4: CHO-S cells were seeded the day before transfection at 1×106 cells/mL in a Mobius® single-use 3 L bioreactor (Merck) with 1.5 L of FectoCHO™ CD Expression Medium. The culture parameters were set as follows : 130 rpm, pH 7.1, 37°C, 40% pO2. 24 hours after seeding, cells were transfected with FectoPRO® (0.8 µg DNA/mL) following the recommended protocol. (A) Cell viability and density were monitored regularly using Trypan Blue exclusion. (B) IgG3-Fc production was assayed regularly using protein G Biosensors (fortéBIO® BLItz).

To see a FectoCHO™ Expression System tutorial, please see video below

For more information, please see FectoCHO™ Expression System

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