CHO/dhFr-AC-free cell line

Hamster Chinese Ovary, serum-free

This is a derviative of the CHO/dhFr- cell line, Sigma Catalogue number. 94060607 which has been adapted to grow in the animal component free medium CHO DHFR (Sigma C8862). The CHO/dhFr- cell line lacks the enzyme dihydrofolate reductase (DHFR) which is necessary for purine synthesis. In the absence of exogenous purines, this enzyme is required for growth. Hence the CHO/dhFr- cell line has growth requirements for hypoxanthine (or adenine), glycine and thymidine. However, the cells will continue to grow without the addition of hypoxanthine and thymidine because the cells can obtain sufficient from the medium. α MEM minus does not contain the ribonucleosides or the deoxyribonucleosides, and will not support the growth of CHO/dhFr- or its serum free adaptation as neither contains the gene to produce DHFR.

CHO DHR medium (Sigma C8862) + 2mM Glutamine + 100uM Hypoxanthine + 16uM Thymidine (e.g. use HT supplement Sigma H0137). Addition of Aminopterin (Sigma A5159) 0.4uM is also advised. When freezing cells use freeze medium composed of 50:50 fresh:conditioned medium + 10% DMSO.

Maintain cultures between approximately 3-9x10⁵ cells/ml; 5% CO₂; 37°C. Cells grow as aggregates in suspension. Viability may be poor on resuscitation and may initially decrease further. Full recovery may take up to 2 weeks.

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