Influence of carboxymethyl dextran and ferric citrate on the adhesion of CHO cells on microcarriers.

Due to the inherent risks of animal-derived raw materials, the biopharmaceutical industry has an increasing demand for serum-free and protein-free media for industrial cell culture bioprocesses. The absence of serum often changes the characteristics of mammalian cells, especially growth, productivity, and adherence properties. This study is mainly focused on the influence of media additives on cell adherence characteristics. An array of different carboxymethyl dextrans and different ferric citrate concentrations was tested with a number of CHO clones, using standard cell culture Roux-flasks and Cytoline 1 macroporous microcarriers. A prototype mixing system with controlled shear force input was developed as a screening system for adherence characteristics. The results of this evaluation revealed a negatively correlated dose-dependent influence on adhesion for ferric citrate. It was also found that certain carboxymethyl dextrans are capable of increasing the adherence on Roux-flasks and microcarriers.

Comparison of fluidized bed and ultrasonic cell-retention systems for high cell density mammalian cell culture.

Economically viable biopharmaceutical production is to a high degree dependent on high product yields and stable fermentation systems that are easy to handle. In the current study we have compared two different fermentation systems for the production of recombinant protein from CHO cells. Both systems are fully scaleable and can be used for industrial high cell density bioprocesses. As a model cell line we have used a recombinant CHO cell line producing the enzyme arylsulfatase B (ASB). CHO cells were cultivated as adherent cell culture attached on Cytoline macroporous microcarrier (Amersham Biosciences, Sweden) using a Cytopilot Mini fluidized bed bioreactor (FBR, Vogelbusch-Amersham Biosciences, Austria) and as suspension culture using a stirred tank bioreactor equipped with a BioSep ultrasonic resonator based cell separation device (Applikon, The Netherlands). Both systems are equally well-suited for stable, long-term high cell density perfusion cell culture and provide industrial scalability and high yields. For products such as the recombinant ASB, high perfusion rates and therefore short product bioreactor residence times may be of additional benefit.

Pre-clinical safety evaluation of pyrrolidine dithiocarbamate.

Pyrrolidine dithiocarbamate (PDTC) was examined for its potential in the intranasal treatment of human rhinovirus infections. Prior to clinical testing, a comprehensive non-clinical programme was performed to evaluate the general toxicity of PDTC. The animal experiments included investigations in rodents with study durations ranging from single dose to repeated dosing over a period of 28 days. The routes of administration were intranasal, inhalative, oral and intravenous for single-dose toxicity and pharmacokinetic studies, and intranasal for repeated dose studies. Blood and tissue samples were obtained from PDTC-treated rats to analyse pharmacokinetics and tissue distribution. Accumulation of selected metals due to PDTC treatment was examined in liver, brain, nerves and fat tissues.