Expi293F™ GnTI- Cells - FAQs

The growth and expression characteristics of Expi293F cells are such that, by 7 days post-transfection, the culture medium should be close to being spent and maximal protein expression should have already been achieved. Continued incubation will result in a large decrease in cell culture viability.

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While the Expi293 Expression Medium can support much higher cell densities, we do not recommend growing your Expi293F cultures beyond 5-6 x 10e6 cells/mL, as subsequent transfection and protein expression efficiencies may be reduced. At higher densities, there is also the increased possibility of reaching the point of reduced culture viability. If your seed culture does exceed 5-6 x 10e6 cells/mL, passage them once or twice as detailed in the manual, monitoring them for viability and growth rate. Perform a test transfection using the Protein Expression Control IgG or an expression construct of known yield to determine if cell expression performance has been impacted.

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The formation of intact IgG molecules may be quantified using a sandwich ELISA designed to capture and detect rabbit IgG. Besides the rabbit IgG positive control vector, reagents, and consumables that are included in the kit, you will also need purified rabbit IgG to be used as a standard, F(ab')2-Goat anti-Rabbit IgG (H+L) Cross-Adsorbed Secondary Antibody, HRP (Cat. No. A10547), Protein A Coated Plates, Clear, 96-Well (Cat. No. 15130), TMB Substrate Kit (Cat. No. 34021), SuperBlock (TBS) Blocking Buffer (Cat. No. 37535), and PBS or TBS buffer for washes. There is an example procedure in our Protein A Coated Plates manual (https://tools.thermofisher.com/content/sfs/manuals/MAN0011310_Thermo Scientific_ProteinA_G_AG_Coat_96Well_UG.pdf). Please note that our R&D scientists determine titer values from crude cell culture supernatants using a Pall Life Sciences FortéBio Octet instrument equipped with a Protein A biosensor.

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We offer pRABBIT IgG IRES-EmGFP Positive Control Vector, Cat. No. A39243, which you can use to monitor your transfection and expression.

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Expi293F GnTI-, Expi293F Inducible, and Expi293F Inducible GnTI- cell lines were derived from the parental Expi293F Cells (Cat. No. A14527) and therefore, share similar morphology and growth characteristics. They are cultured in Expi293 Expression Medium and transfected using ExpiFectamine 293 Transfection Kit following our standard Expi293 protocol.

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Expi293F cells must be recovered from freezing and passaged at least 3 times using the procedure outlined in the manual to ensure optimal performance. Cells should maintain performance for at least 30 passages if maintained in accordance with the protocol in the manual.