Development of Disposable Bioreactors for the Production of hCTLA4Ig in Transgenic Rice Cell Cultures

초록

During the last several years, disposable bioreactors have been increasingly incorporated into preclinical, clinical, and production-scale biotechnological facilities where process simplicity, safety and flexibility are top priority. Driven by the demands of the market and the manufacturing industry, numerous studies reporting their advantage in use for mammalian expression system have contributed to new developments. As a result, many types of disposable bioreactors are now available. However, there are few studies regarding their suitability for the production of pharmaceutical proteins in plant cell cultures. Plant cell-based production system has been studied as a potentially cheap, safe, and scalable alternative to mammalian and bacterial production of biopharmaceuticals. In this study, two kinds of disposable bioreactors were successfully applied to transgenic rice cell cultures for the production of recombinant human cytotoxic T-lymphocyte antigen 4-immunoglobulin (hCTLA4Ig) and compared to 5-L stirred tank bioreactor system. The first one is wave-mixed bag, the most common disposable bioreactor, modified with a fritted sparger to increase oxygen transfer. The second is an airlift disposable bioreactor, similar to the one developed by Protalix for the production of plant-derived protein pharmaceuticals under GMP condition. In both systems, a fed-batch culture method was used for the efficient production of hCTLA4Ig by feeding concentrated amino acids. Dissolved oxygen level was regulated at 30% by supplementing pure oxygen with solenoid valve during the run. Although 1.15-fold higher maximum cell density (11.9 g/L) was obtained in disposable airlift bioreactor, the doubling time in both bioreactors was almost the same (4.8 days). Maximum hCTLA4Ig concentration was higher in airlift system (44.5 mg/L) than that in wave-mixed bag (39.3 mg/L). However, the time needed to obtain maximum hCTLA4Ig level was much shorter in wave-mixed bag (34 vs. 22 days). In additi