Stable Cell Line Construction Service
To create stable cell lines is a key method in reducing the production costs of biopharmaceuticals. We use a modified FRT/Flp-In recombinase system to produce human proteins in CHO cells and 293 cells for stable expression. We have pre-selected CHO cell lines [and 293 cell lines] that contain a single stably integrated FRT site at a transcriptionally active genomic locus and we have proven that they can produce high level expressers of recombinant proteins.
We have also developed a unique series of high-yield vector system, in which two GC-rich regions flanking the gene expression cassette makes the promoter and enhancer continuously exposed to transcriptional machinery by preventing chromatin condensing. This revolutionary ground-breaking technology allows the available highest yields in all common mammalian cell protein production host cell lines, such as 293, CHO and NSO. Antibody yields of up to 2.0- 5.5 grams/liter [80-120pg/cell/day] have been achieved using this system in chemically defined, animal component-free medium. The selection strategy has been designed to identify cell lines that are highly productive and have the ability to grow well in suspension culture in a state-of-the-art, fed-batch fermentation process, in which cell density can reach 1.5×107/mL.
In addition, Creative Biolabs is also specialized in Engineered Bacterial construstruction and large scale fermentation. As an example, our specific bacterial expression vector pCD-Bac is a temperature-inducible prokaryotic expression vector, which contains a PRPL promoter, cIts857 gene [temperature-sensitive CI repressor], multiple cloning sites and two strong transcription terminators. With genetic codons optimized into that bacterial preference, this vector enables high-yield protein expression of most proteins in the host bacterial strain Escherichia coli DH5α when our propriety fermentation protocol is employed using NLF-22 fermentor (Bioengineering). Our fermentation process is a batch process, not a continuous process.