Protein-free transfection of CHO host cells with an IgG-fusion protein: Selection and characterization of stable high producers and comparison to conventionally transfected clones
✍ Scribed by Christine Lattenmayer; Martina Loeschel; Kornelia Schriebl; Willibald Steinfellner; Thomas Sterovsky; Evelyn Trummer; Karola Vorauer-Uhl; Dethardt Müller; Hermann Katinger; Renate Kunert
- Book ID
- 101722838
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 313 KB
- Volume
- 96
- Category
- Article
- ISSN
- 0006-3592
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✦ Synopsis
Abstract
In order to improve the current techniques of cell cultivation in the absence of serum, we have developed a protein‐free transfection protocol for CHO cells, based on the Nucleofector™ technology. After starting with a heterogeneous pool of primary transfectants which express the fusion protein EpoFc, we isolated single clones and compared them with parallel clones generated by lipofection in serum‐dependent cultivation. Our intensive characterization program was based on determination of specific productivity (q~p~) and analysis of genetic parameters. In two nucleofection experiments, transfection with 5 µg of DNA resulted in best productivities of the primary cell pools. After subcloning, the q~p~ could be raised up to 27 pg · cells^−1^ · day^−1^. While the serum‐dependent transfectants exhibited specific productivities up to 57 pg · cells^−1^ · day^−1^ in serum‐dependent cultivation, a significant decrease that resulted in the range of q~p~ of the protein‐free transfectants was observed after switching to protein‐free conditions. Investigation of genetic parameters revealed higher mRNA levels and gene copy numbers (GCN) for the protein‐free adapted serum‐dependent transfectants. Therefore, we assume that problems during protein‐free adaptation (PFA) lead to a less efficient translation machinery after serum deprivation. We describe the generation of stable‐producing recombinant CHO clones by protein‐free transfection of a protein‐free adapted host cell line, which reduces the risk of adverse clonal changes after PFA. The main advantage of this approach is the earlier predictability of clone behavior, which makes the generation of production clones by protein‐free transfection, a viable and highly efficient strategy for recombinant cell line development. Biotechnol. Bioeng. 2007;96:1118–1126. © 2006 Wiley Periodicals, Inc.