Untitled

Abstract

Consistent perfusion culture production requires reliable cell retention and control of feed rates. An on-line cell probe based on capacitance was used to assay viable biomass concentrations. A constant cell specific perfusion rate controlled medium feed rates with a bioreactor cell concentration of approximately 5 x 10(6) cells mL(-1). Perfusion feeding was automatically adjusted based on the cell concentration signal from the on-line biomass sensor. Cell specific perfusion rates were varied over a range of 0.05 to 0.4 nL cell(-1) day(-1). Pseudo-steady-state bioreactor indices (concentrations, cellular rates and yields) were correlated to cell specific perfusion rates investigated to maximize recombinant protein production from a Chinese hamster ovary cell line. The tissue-type plasminogen activator concentration was maximized ( approximately 40 mg L(-1)) at 0.2 nL cell(-1) day(-1). The volumetric protein productivity ( approximately 60 mg L(-1) day(-1) was maximized above 0.3 nL cell(-1) day(-1). The use of cell specific perfusion rates provided a straightforward basis for controlling, modeling and optimizing perfusion cultures.

Perfusion Processes

“…An example is given in Fig. 13.10 from a study of Dowd et al (2003) where the CSPR was varied. The metabolic rates increased as a function of the CSPR due to a higher glucose and nutrient availability.…”

“…In (a), the t-PA concentrations, in (b), the cell specific productivity and in (c), volumetric productivity. Steady-state glucose, lactate and ammonium concentrations and cell specific rates as a function of cell specific perfusion rates (Below) (Reproduced from Dowd's report (Dowd et al 2003), permission of reproduction Springer) established and the consumption rates known, these main substrates can then advantageously be delivered together in the fresh medium formulation.…”

A protocol to transfer a fed‐batch platform process into semi‐perfusion mode: The benefit of automated small‐scale bioreactors compared to shake flasks as scale‐down model

“…The detected importance of the CSPR for the semi-perfusion culture is in good agreement to results from literature that report controlling, modeling, and optimizations of semi-perfusion processes based on the CSPR. 16 Even more, the highlighted condition was constantly bled to the smallest investigated bleed level of 20 million cells/mL. According to previous observations, the decrease of the CSPR below 50 pL/(c*day) in each shake flask run, was aligned with a lower viability in the following culture days.…”

“…To keep the cell culture in a pseudo-steady-state, feed rates and uptake rates need to be well-known and controlled during the complete cultivation time. 16 The cell-specific perfusion rate (CSPR) is one indicator giving the relation of the chosen perfusion rate and existing cell concentration in a process (see Eq. 1).…”

Development of PCL-PEG nanofibrous mats as alternative carriers for recombinant Chinese hamster ovary cells

“…At present, fed-batch and perfusion cultures are the two dominant technologies for the industrial operation of mammalian cell culture processes, especially for the production of recombinant pharmaceuticals such as antibodies and growth factors required in large amounts [5,6] . Efforts in the area of production technology are continuously being made to increase volumetric productivity, batch consistency, and homogeneity of product quality at competitive costs.…”