Design of cell expansion processes for adherent‐growing cells with mDoE‐workflow

Adherent cells, mammalian or human, are ubiquitous for production of viral vaccines, in gene therapy and in immuno‐oncology. The development of a cell‐expansion process with adherent cells is challenging as scale‐up requires the expansion of the cell culture surface. Microcarrier (MC)‐based cultures are still predominate. However, the development of MC processes from scratch possesses particular challenges due to their complexity. A novel approach for the reduction of development times and costs of cell propagation processes is the combination of mathematical process models with statistical optimization methods, called model‐assisted Design of Experiments (mDoE). In this study, an mDoE workflow was evaluated successfully for the design of a MC‐based expansion process of adherent L929 cells at a very early stage of development with limited prior knowledge. At the start, the analytical methods and the screening of appropriate MCs were evaluated. Then, cause‐effect relationships (e.g., cell growth related to medium conditions) were worked out, and a mathematical process model was set‐up and adapted to experimental data for modeling purposes. The model was subsequently used in mDoE to identify optimized process conditions, which were proven experimentally. An eight‐fold increase in cell yield was achieved basically by reducing the initial MC concentration.