Protein Expression In Mammalian Cells In Suspension

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The service offers dedicated pipelines for small- and large-scale cell cultivation and protein expressions:

  • Small scale: utilizing commercial Expi293F cells, transient transfection is conducted with a plasmid containing the gene\s of interest (potentially with a fluorescent marker), provided by the applicant. Cell cultivation and transfection take place in Erlenmeyer flasks within dedicated shaker incubators; typically, 500 ml of cell culture per 2-liter flask is utilized up to a total cultivation volume of approximatively 10 litres. Transfection of an Expi293F cell culture is performed at approximately 2 to 3 x10^6 cells\ml, following a modified protocol with polyethylenimine (PEI). While no expression test will be performed, the efficiency of transfection can be readily assessed if the plasmid includes a fluorescent marker. Transfected cells are subsequently harvested by centrifugation, and either the frozen pellet or the refrigerated supernatant will be provided.
  • Large scale: bioreactor cultivation and protein expression are performed either with commercial cell lines (e.g., Expi293F cells) transiently transfected with applicant-provided plasmids, or with any mammalian cell line adapted to suspension cultivation supplied by the applicant. Preliminary tests are normally performed using a 0.5 litres scale bioreactor to define and optimize bioreactor cultivation conditions. Subsequently, a 10 litres scale bioreactor enables large-scale cell cultivation and protein expression, employing both transient transfection protocols and stable cell line expressions. Moreover, the implementation of perfusion, utilizing an acoustic retention device, may be explored to increase the biomass production and, consequently, protein expression. Similar to small-scale operations, no expression test will be performed. Instead, monitoring of transfection efficiency for transient expression can be undertaken if the plasmid carries a fluorescent marker or fluorescently tagged protein of interest.