ABSTRACT
Monoclonal antibodies (mAbs) require a high level of purity for regulatory approval and safe administration. High-molecular weight (HMW) species are a common impurity associated with mAb therapies. Hydrophobic interaction chromatography (HIC) resins are often used to remove these HMW impurities. Determination of a suitable HIC resin can be a time and resource-intensive process. In this study, we modeled the chromatographic behavior of seven mAbs across 13 HIC resins using measurements of surface hydrophobicity, surface charge, and thermal stability for mAbs, and hydrophobicity and zeta-potential for HIC resins with high fit quality (adjusted R2 > 0.80). We identified zeta-potential as a novel key modeling parameter. When using these models to select a HIC resin for HMW clearance of a test mAb, we were able to achieve 60% HMW clearance and 89% recovery. These models can be used to expedite the downstream process development for mAbs in an industry setting.
ABSTRACT
The significant increase in product titers, coupled with the growing focus on continuous bioprocessing, has renewed interest in using precipitation as a low-cost alternative to Protein A chromatography for the primary capture of monoclonal antibody (mAb) products. In this work, a commercially relevant mAb was purified from clarified cell culture fluid using a tubular flow precipitation reactor with dewatering and washing provided by tangential flow microfiltration. The particle morphology was evaluated using an inline high-resolution optical probe, providing quantitative data on the particle size distribution throughout the precipitation process. Data were obtained in both a lab-built 2-stage countercurrent washing system and a commercial countercurrent contacting skid that provided 4 stages of continuous washing. The processes were operated continuously for 2 h with overall mAb yield of 92 ± 3% and DNA removal of nearly 3 logs in the 4-stage system. The high DNA clearance was achieved by selective redissolution of the mAb using a low pH acetate buffer. Host cell protein clearance was 0.59 ± 0.08 logs, comparable to that based on model predictions. The process mass intensity was slightly better than typical Protein A processes and could be significantly improved by preconcentration of the antibody feed material.
ABSTRACT
We report the successful culture of oil palm (Elaeis guineensis Jacq.) suspension cells in a bioreactor. In vitro propagation of this perennial monocotyledonous tree is an important part of the oil palm industry's approach to clonal propagation of high-yielding accessions. During culture of oil palm cells in a batch bioreactor, nutrients and extracellular metabolites were monitored, and kinetic parameters and nutrient-to-biomass conversion yields were calculated. The biomass increased approximately 3.5-fold per month, consistent with values reported for shake flask cultures. Although the carbon source was completely depleted by the end of the run, nitrogen sources remained in large excess and the sugar-to-biomass conversion yield remained low. Linear growth indicated that the cells were limited. The results obtained from the bioreactor runs indicated that we should be able to improve biomass production by carrying out optimization studies. Therefore, we initiated multi-factorial analyses using response surface experimental designs to investigate the effects of different nitrogen sources, as well as inoculum size and conditioned medium, on biomass production in flask cultures. Whereas glutamine does not have a significant effect on biomass production, ammonia has a positive effect up to an optimum concentration. Both inoculum density and conditioned medium have positive, synergistic effects on biomass production.
