A number of platforms exist for developing high specific productivity stable mammalian cell lines.  The most commonly employed platform takes advantage of a single gene capable of rescuing a specific metabolic defect or auxotrophy in the parental cell line.  Examples are the dihydrofolate reductase (dhfr)-deficient Chinese Hamster Ovary (CHO) cell line variants, and the glutamine synthetase (GS) NS0 (non-secreting null) murine myeloma line.  The CHOLCelect system exploits another known auxotrophy of NS0 cells, one related to cholesterol biosynthesis.  This auxotrophy has been mapped to a deficiency in expression from the 17beta-hydroxysteroid dehydrogenase type 7 gene (HSD17B7) locus in the NS0 genome.  A vector expressing HSD17B7 rescues the cholesterol biosynthetic deficiency in transfected NS0, allowing cells to grow in cholesterol-free medium.  Thus, a system was engineered that allows generation of stable NS0 lines using this novel selection method. This system has several advantages over the NS0-GS system: 1. Stable cell lines can be generated from the onset in chemically defined serum-free medium (CD-SFM); 2. Medium is supplemented with highly soluble glutamine, but not with cholesterol, which is commonly supplied in carbohydrate-coupled form to retain solubility; 3. Cell lines can be generated in approximately half the time of conventional methods, thus permitting a significant reduction in development timelines for leading candidate biologicals. We commonly generate clonal stable NS0 lines in our laboratory in ~60 days.

Product co-development partnerships
Zalgen Labs employs the CHOLCelect system to generate its leading candidate molecules requiring expression in mammalian systems. The system available for co-development of biologicals between Zalgen Labs and commercial, academic, and institutional entities.

The CHOLCelect NS0-based platform is also commercially available from Zalgen Labs.
To request additional information regarding contract cell line development and CHOLCelect licensing options contact us via email at or by phone at our mobile transfer line (504)252-0889.