Application of anoxia with glucose addition for the enhanced production of hCTLA4Ig in transgenic rice suspension cell cultures.

To enhance the production of hCTLA4Ig in transgenic rice suspension cell cultures, anoxic conditions were applied during the production phase. Under the anoxic conditions in sugar-depleted media, cell viability was reduced rapidly and protease activity increased compared to aerobic conditions. However, the maximum production level of hCTLA4Ig with sugar-depleted anoxic conditions was the same as that in aerobic conditions. In addition, the production of hCTLA4Ig under anoxic conditions reached a peak 2 days earlier than that in aerobic conditions. Addition of 30 mM glucose at the production phase under anoxic conditions markedly improved cell viability. A viability level over 65% could be maintained for more than 30 days. Repression of the RAmy3D promoter by residual sugar in the production of hCTLA4Ig was not observed under anoxic conditions with 30 mM glucose. In addition, the production periods of hCTLA4Ig was extended up to 30 days and the maximum production level of hCTLA4Ig under anoxic conditions was 2.1-fold higher. Therefore, anoxic conditions could be used for the enhanced production of hCTLA4Ig in transgenic rice cell cultures.