[Domestication of suspension CHO cells and its application in the expression of anti-PSMA antibody].

OBJECTIVE:To domesticate adherent Chinese hamster ovary (CHO) cells into suspension CHO cells (CHO-S) cultured in serum-free medium,and evaluate the application of the CHO-S cells in antibody expression. METHODS:Adherent CHO cells were domesticated into CHO-S cells through suspension culture and gradually decreasing the serum concentration, and eventually the cells were cultured in serum-free medium. Based on the anti-prostate-specific membrane antigen ( PSMA) single chain antibody fragment ( Sc Fv) gene sequence obtained from a phage display library, the genes of heavy and light chains were designed, synthesized and cloned into the pc DNA3. 1 vector,and the products were named pc DNA3. 1-HC and pc DNA3. 1-LC respectively. The plasmids were transiently transfected at the ratio of light and heavy chain 3 ∶ 1 into CHO-S cells using Free Style MAX transfection reagent, and the supernatants were harvested at day 7 after transfection. SDS-PAGE and Western blotting were used to detect the antibody expression,and flow cytometry was applied to evaluate its binding activity to PSMA positive cells. RESULTS:The adherent CHO cells were successfully domesticated into CHO-S cells. Expression plasmids for anti-PSMA antibody heavy chain and light chain were successfully constructed,and anti-PSMA antibody could be secretively expressed in CHO-S cells. Flow cytometry showed that the expressed antibody could specifically bind to PSMA positive cells. CONCLUSION:CHO-S cel s were successful y domesticated from adherent CHO cells, and could be used for antibody expression. This study provided a useful tool for further antibody expression, purification and function study.