Transient expression systems are quite useful strategy for studying elements that regulate gene expression or when experimental results need to be obtained in short time. This system provides a convenient way to compare different vectors, as well as to confirm that the selected expression plasmid is functional plasmid before using it to establish a stable expression system. More recently, this approach has proven capable of large-scale production of recombinant proteins and virus-based products, including adeno-associated virus and lentivirus.

Some gene delivery reagents work only in serum-free media, while others are insensitive to the presence of serum, which, in addition, can significantly increase the expression of recombinant products. The presence of cell metabolism by-products in the conditioned medium has been associated with low transfection yields, therefore, a complete medium change prior to transfection is often required. However, this step does not meet the need for a robust large-scale transient transfection process. Furthermore, during the production of secreted proteins, serum can greatly interfere with subsequent purification steps. Many issues are also related to the presence of serum in cultures, with possible contamination by infectious microorganisms or serum proteins, as well as high costs and batch-to-batch variability. The development of serum-free media for transient transfection systems is one strategy to address this challenge and has the advantage of reducing the burden of recombinant product purification.

HEK293 is widely used in the production of recombinant proteins due to its many advantages, including high transfection efficiency by most gene delivery vectors, simple adaptability to suspension culture and serum-free media. In addition, low-cost reagents such as polyethyleneimine or calcium phosphate can be used to efficiently transfect cells in suspension culture systems. HEK293 cells have been used for virus production, cell cycle studies, gene expression, metabolism, and other studies.

Transpro CD01

Transpro CD01 is universal cell culture media for transient transfection, it can be used for seed-train, high cell density and transient transfection culture of both HEK293 and CHO cells, and media exchange by centrifugation during transient transfection is not required.

Transpro CD01 can be used for HEK293 cells, including HEK293, Expi293, 293F, and CHO cells, including expiCHO, CHOS, in transient transfection expression of antibody, recombinant protein and virus during development.

Benefit:

? Animal-free

? Protein-free

? Chemical-defined

Transpro feed 1

Transpro feed 1 is universal feed media for transient transfection, combined use with Transpro CD01 media. It can be used for transient transfection culture of both HEK293 and CHO cells.

Transpro feed1 can be used for HEK293 cells, including HEK293, Expi293, 293F, and 293E CHO cells, in transient transfection expression of antibody, recombinant protein and virus during development.

Benefits:

?   Animal-free

?   Protein-free

?   Chemical-defined

Case study

Serial passage

Inoculated with density of 0.5×10⁶ cells/mL, 1X passage by every 2 days, after 10X serial passages, the viable cell density of Expi293 can be stable at ~2.5×10⁶cells/mL, while 293F stable at ~2.0×10⁶ cells/mL, both viability >98%， cell morphology is regular circle, with normal doubling time.

Inoculated with density of 0.3×10⁶ cells/mL, 1X passage by every 2 days, after 10X serial passages, the viable cell density of ExpiCHO can be stable at ~2.8×10⁶ cells/mL, viability >98%，with regular circle cell morphology and normal doubling time.

Batch culture

Inoculated with density of 0.5×10⁶ cells/mL, culture for 7 days and feed glucose, achieved peak viable cell density of ~16×10⁶ cells/mL for Expi293, ~9×10⁶ cells/mL for 293F and ~20×10⁶ cells/mL for ExpiCHO, respectively.

GFP Transient transfection