Novel Strategies for Improving Cell Viability and Production Yield
Transporters play a crucial role in regulating cell metabolism, so we hypothesized that some transporters might be suitable targets for cell engineering to enhance MAb yield. The taurine transporter (TAUT) is stably expressed in CHO-DXB11 cells and may not only transport organic osmolytes but also alter the net cellular content of osmolytes, thereby affecting cell function. We found that MAb1/DXB11/TAUT cells that expressed pHyg-TAUT had higher MAb1 yield (p < 0.01) and lower lactate production (p < 0.05). One high-yield MAb1/DXB11/TAUT cell line (T10) maintained >80% viability for more than 1 month. T10 cells also showed suppression of ammonia accumulation and activation of glutathione metabolism. Their higher glutamine consumption may contribute to their increased viability and yield. These results demonstrate that overexpression of TAUT enhances cell culture performance by prolonging the culture period and increasing MAb yield. A further challenge was to find a way to modify the metabolic machinery for even high yields in a shorter culture period. We therefore engineered T10 cells to co-overexpress alanine aminotransferase (ALT1), which participates in the glucose-alanine cycle. We found that co-overexpression of ALT1 and TAUT gave even higher yield in 1-L bioreactors in a shorter time (5.3 g/L on Day 21).
KeywordsCulture Period Parent Cell Bioreactor Culture Taurine Transporter Improve Cell Viability
This study was supported by a grant from the Bioprocess Development Project of the New Energy and Industrial Technology Development Organization (NEDO), Japan.