The OptiCHO™ Express Kit is designed for efficient growth and transfection of dihydrofolate reductase- deficient (DHFR^-) Chinese hamster ovary (CHO) DG44 cells in suspension culture. The kit provides a complete workflow protocol as well as the necessary components for efficient transfection of DHFR^- DG44 cells in a serum-free environment and subsequent stable cell line development, including:
• pOptiVEC™-TOPO™ vector - a bicistronic cloning vector containing a DHFR gene for stable cell line development in CHO-DG44 cells (Figure 1); the vector is TOPO™ adapted and enables cloning of a PCR product containing your gene of interest with >85% efficiency
• FreeStyle™ MAX Transfection Reagent - an animal origin-free transfection reagent offering high transfection efficiencies and consistent results
• CD OptiCHO™ Medium - a chemically defined, protein-free medium (without hypoxanthine or thymidine) specifically designed for high-density suspension cell culture of recombinant CHO-DG44 cells and secreted protein yield
• CD DG44 Medium - a chemically defined, protein-free medium supplemented with hypoxanthine and thymidine to support optimal growth of DG44 cells in suspension culture
• DG44 cells - preadapted to CD DG44 medium and selected for superior cell growth and transfection efficiencies

In addition, the OptiCHO™ Express Kit provides GIBCO™ OptiPRO™ SFM for improved DNA-lipid complex formation, L-glutamine (provided separately for increased media stability), and Pluronic™ F-68 to control shear forces in suspension cultures.

Storage:
Store Pluronic™ F-68 at 15°C to 30°C. Store CD DG44 Medium, OptiPRO™ SFM, CD OptiCHO™ Medium, and FreeStyle™ MAX Transfection Reagent at 2°C to 8°C in the dark. Store L-glutamine, pOptiVEC™-TOPO™ vector, CMV Forward Sequencing Primer, and EMCV IRES Reverse Sequencing Primer at -5°C to -20°C. Store One Shot™ TOP10 Chemically Competent E. coli cells at -80°C. Store DG44 cells in liquid nitrogen.