Lysis-free separation of hybridoma cells by continuous disc stack centrifugation

Enhanced harvest performance predictability through advanced multivariate data analysis of mammalian cell culture particle size distribution

The industry's pursuit for higher antibody production has led to increased cell density cultures that impact the performance of subsequent product recovery steps. This increase in cell concentration has highlighted the critical role of solids concentration in centrifugation yield, while recent product degradation cases have shed light on the impact of cell lysis on product quality. Current methods for measuring solids concentration and cell lysis are not suited for early-stage high-throughput experimentation, which means that these cell culture outputs are not well characterized in early process development. This article describes a novel approach that leveraged the data from a widely-used automated cell counter (Vi-CELL™ XR) to accurately predict solids concentration and a common cell lysis indicator represented as lactate dehydrogenase (LDH) release. For this purpose, partial least squares (PLS) models were derived with k-fold cross-validation from the particle size distribution data generated by the cell counter. The PLS models showed good predictive potential for both LDH release and solids concentration. This novel approach reduced the time required for evaluating the solids concentration and LDH for a typical high-throughput cell culture system (with 48 bioreactors in parallel) from around 7 h down to a few minutes.

Evaluation of predictive tools for cell culture clarification performance

Recent advances in the productivity of industrial mammalian cell culture processes have resulted in part in increased cell density. This increase and the associated increase in cellular debris are known to challenge harvest operations, however this understanding is limited and largely qualitative. Part of the issue arises from the heterogeneous size and composition of cellular debris, which makes harvest feed stream extremely difficult to characterize. Improved characterization methods would facilitate the development of clarification approaches that are consistent and scalable. This work describes how both particle size and cholesterol analysis can be used to characterize the feed stream. Particle size analysis by focused beam reflectance and dynamic light scattering are shown to be predictive of centrate filterability under certain harvest conditions. Because of the particle size range limitations of each detector, their applicability is limited to a particular stage or method of clarification. The measurement of cholesterol present in the cell culture supernatant or centrate was successfully used in providing relative amount of lysed cellular debris and enabled us to predict clarification performance of acid precipitated harvest regardless of particle size distribution profile.

Bioseparations

Here we review key applications of separation technology in applied biology. We first sketch out the field as a whole, but then narrow our scope to the processing of fermentation products, particularly to high-value biologicals such as proteins and nucleotides. We go on to provide a qualitative overview describing the importance and general nature of this large field, major trends, and the strategies that have proven most fruitful in evolving effective separation and purification processes. We then give a detailed description of individual separations equipment and the principles governing their operation. We concentrate throughout on making the available literature accessible to the reader; we provide what is hoped to be a representative set of basic references. However, these references, in turn, include some that suggest promising new developments as well as a number of more specialized reviews. We hope that our overall result provides the reader with access to the most relevant literature.

Cell retention devices for suspended-cell perfusion cultures

Perfusion cultures of animal cells have several advantages over batch or fed-batch cultures. They give, for instance, higher productivities and a consistent product quality, and allow steady state operation and better cell physiology control. However, one of the main aspects limiting performance and scale-up of perfusion processes is the need for an adequate cell retention device. The devices currently in use for stirred perfusion bioreactors are continuous centrifuges, tangential flow membrane filters, dynamic filters, spin-filters, ultrasonic and dielectrophoretic separators, gravity settlers and, more recently, hydrocyclones. The advantages and disadvantages of each of these methods will be discussed.