Influence of hydrodynamic stress and conditioned medium on hCTLA4Ig production in transgenic rice cell cultures

초록

Transgenic plant cell cultures have been utilized as an alternative platform for the production of recombinant proteins due to their safety, cost-effective bioprocessing and the capability of post-translational modification. However, low productivity of transgenic plant cells compared to the other systems is a main obstacle. Transgenic rice cells using RAmy3D promoter can provide higher productivity than the other species of plant cells and the production of recombinant protein is induced by sugar starvation. In previous study, production level of human cytotoxic T-lymphocyte antigen-immunoglobulin 4 (hCTLA4Ig) in 5-L bioreactors was found to be only 15% of the production level in 100-mL flasks. Erlenmeyer shaking flask is a common culture vessel and requires low establishment cost and simple process control in producing recombinant protein. Therefore, scale-up in the flask levels ranging from 100-mL to 5-L could be adequate vessels for transgenic rice cell cultures. To ensure the influences of shear rate and oxygen transfer rate (OTR), which are a function of orbital shaking speed, diameter of rotation and working volume, the mixing performances were investigated in 1-L flask under various mixing performance and the scale-up suitability of flask cultures. In addition, inoculation methods including suspended cells and filtered cells were investigated considering the ratio between the volume of cells and conditioned medium. Working volumes and shaking speeds were 300, 500 mL and 80, 120, 160 rpm, respectively. The ratio between suspended cells and conditioned medium was fixed as 1:1. In conclusion, flask cultivation with reduced shear stress and optimized inoculation methods could be an alternative production method in transgenic rice cell cultures.