High-throughput downstream process development for cell-based products using aqueous two-phase systems (ATPS) - A case study

The availability of preparative-scale downstream processing strategies for cell-based products presents a critical juncture between fundamental research and clinical development. Aqueous two-phase systems (ATPS) present a gentle, scalable, label-free, and cost-effective method for cell purification, and are thus a promising tool for downstream processing of cell-based therapeutics. Here, the application of a previously developed robotic screening platform that enables high-throughput cell partitioning analysis in ATPS is reported. In the present case study a purification strategy for two model cell lines based on high-throughput screening (HTS)-data and countercurrent distribution (CCD)-modeling, and validated the CCD-model experimentally is designed. The obtained data are shown an excellent congruence between CCD-model and experimental data, indicating that CCD-models in combination with HTS-data are a powerful tool in downstream process development. Finally, the authors are shown that while cell cycle phase significantly influences cell partitioning, cell type specific differences in surface properties are the main driving force in charge-dependent separation of HL-60 and L929 cells. In order to design a highly robust purification process it is, however, advisable to maintain constant growth conditions.