- Rena So, Chemical Engineering, University of Delaware
- Mark Blenner, Chemical and Biomolecular Engineering, University of Delaware
Conventional means of optimizing biopharmaceutical production is a time and labor-intensive process due to the heterogeneity observed within bulk populations. By addressing how to perform vector and cell line optimization, populations can be produced with less heterogeneity. The goal of this project is to develop cell lines with integrated, stable landing pads, ensuring consistent and reliable expression of desired genes. The landing pad design includes markers for positive and negative selection of integration and loss following recombinase-mediated cassette exchange (RMCE). This includes puromycin as a positive selection marker for enrichment of integration, internal eGFP and external mCherry for dual fluorescence selection of properly integrated landing pad, and a thymidine kinase gene for negative selection of the landing pad by conferring ganciclovir sensitivity. Additionally, the recombinase phiC31 enzyme enables the process of RMCE. To further scale up the process, mini-pool cloning is utilized, allowing for the simultaneous screening of multiple cell clones. Tracking mini-pool titers over time, such as stability, protein quality, and cell heterogeneity, can improve gene and vector performance. As an application of this workflow, we utilized Tocilizumab in addition to other monospecific and bispecific antibodies. However, the platform’s capabilities are not limited to these applications and can be a generalized platform for doing any vector optimization method.