Can I leave my Expi293F culture expressing for more than 7 days?
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.
Find additional tips, troubleshooting help, and resources within our Protein Expression Support Center.
If I let my Expi293F cells grow to a higher density than recommended, will they be okay?
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.
Find additional tips, troubleshooting help, and resources within our Protein Expression Support Center.
What is the difference between the Expi293F Inducible Cell Line and the T-REx -293 Cell Line?
The Expi293F Inducible Cell Line was created using the same technology as the T-REx -293 Cell Line. Both cell lines have been created by stable transfection with the pcDNA 6/TR vector; thus, they ubiquitously express the tetracycline repressor (TetR) protein. The parental cell line of Expi293F Inducible cells is Expi293F Cells (Cat. No. A14527). The key differences between these 2 cell lines are:
- Expi293F Inducible cells are grown in suspension and are adapted to high-density culture (> 15x10E6 cells/mL).
- Expi293F Inducible cells grow in Expi293 Expression System and perform equivalently to parental Expi293F cells, thus making them ideal for high-yield, inducible protein expression.
Find additional tips, troubleshooting help, and resources within our Protein Expression Support Center.
What method do you recommend for quantifying rabbit IgG expression from pRABBIT IgG IRES-EmGFP Positive Control Vector, Cat. No. A39243?
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.
Find additional tips, troubleshooting help, and resources within our Protein Expression Support Center.
Do you offer a GFP-expressing mammalian expression vector that I can use as a control to monitor my transfection and expression with the Expi systems?
We offer pRABBIT IgG IRES-EmGFP Positive Control Vector, Cat. No. A39243, which you can use to monitor your transfection and expression.
Find additional tips, troubleshooting help, and resources within our Protein Expression Support Center.
