A big challenge that we face in the Raw Material Characterization initiative is the development of good, sensitive bioassays. We not only want to show enhanced analytical profiles, we want to understand how, say impurities, affect biological performance or more subtly at what level does a particular impurity become a performance problem for the system.
So how are we going to do that? One idea is to identify multiple cell lines expressing model proteins that we can use in growth and productivity assays. We also will look at product quality. Likely, these will be CHO lines mimicking popular industry platforms but likely will not exclusively be CHO lines. Our goal is to then develop assays with sufficient throughput, sensitivity and reproducibility to be reliably used in screening and characterization of large numbers of raw materials. We’re testing our screening equipment with a scaled down model test system now. Our cell line selection is underway with a variety of parental CHO (DG 44, K1, etc) and non-CHO lines.
Medium selection is critical, as we don’t want it to mask component effects in our screening process. But the medium still needs to support cells over multiple passages and to support productivity. Screening our in-house medium library is a way to accelerate the process. In developing the assays, we need to determine suitable positive and negative controls. We can use a library of “bad” components to test the system.
To date, we have been able to qualify several cell lines that will work. We have several good positive and negative effectors. We have shown that known "bad" components can be detected in our assay system. We continue to extend and fine-tune the system. And, we're able to embark on biological characterization of our Top 100 raw materials.
Posted by Bruce Lehr Jan 21, 2010