68,942 research outputs found

    A Research Agenda for Uncooperative Federalists

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    Increasing demand on more effective cell culture reactors has driven optimization works to increase output of products. This has led to development of soft sensors that uses mathematical formulas to increase the available information for the parameters during runs. In the project two parameters was evaluated for use in such a soft sensor, viability by measuring on-line capacitance with Aber probe and L-lactate production using BioSenz apparatus. To determine how well these could be used both were used on batch reactors measuring on a mouse-mouse B cell hybridoma culture which produced IgG1. On-line measurements were performed by probes which measured directly on the cell suspension or withdrew sterile sample from the reactor. Measuring viability gave results with low error, which can be concluded to the variation in reference cell count, but it could not be determined if measuring L-lactate production with BioSenz works in reactors of this size. More work needs to be done on other types of reactors, like fed-batch or perfusion, or lower working volumes.

    Innovations in bioreactor operational modes ‚Äď Hybrid semi-continuous processes to push beyond the limits of conventional fed-batch cultures

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    Due to the limits of feed volume addition and the problem of amino acid counter ion, miscellaneous osmolyte, and cell growth inhibitor accumulation, the fed-batch mode of bioreactor operation for CHO cell production of protein therapeutics is inherently limited with respect to the cell densities and productivities that are achievable. Continuous or perfusion culture with cell retention can overcome some of these limitations, but suffers from the disadvantages of large volume media consumption, long times to reach peak cell densities, and complications with cell retention devices. We will describe hybrid versions of continuous culture that overcome many of these limitations and utilize a unique and simple technology which allows cells to control their own rate of perfusion with continuous feedback. Volumetric productivities of greater than 1 gram/L/day (more than double the optimized fed-batch culture) for several moderate specific productivity cell lines have been achieved with very modest medium volumes, comparatively simple bioreactor operations, and a batch length that fits in a standard fed-batch window. Methods of operation and experimental results obtained at the pilot scale when coordinating these hybrid continuous cultures with a continuous downstream process will also be discussed

    Ultra scale-down mimics for perfusion culture: Experimental study for rapid biopharmaceutical process development

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    With the industry driving towards the implementation of whole continuous bioprocess sequences, there becomes a requirement for the development of scale-down tools with the same consistency, reliability and throughput as those already available for traditional batch processes. This work aims to develop a perfusion scale-down system capable of reproducing the specific characteristics of the perfusion culture process, namely cell retention capabilities, the ability to support high cell densities and to operate for extended periods compared to fed-batch cultures. Cell culture in microwell plates in fed-batch mode is well defined and is in widespread use; however to the best of our knowledge this represents the first attempt at the development of quasi-perfusion cell culture at this scale. Cultivation approaches in the microscale have been developed using a GS-CHO cell line in 24 well microwell plates, with a working volume of 1.2mL. Quasi-perfusion was achieved via sedimentation or centrifugation of the plate and the subsequent removal of supernatant to mimic cell retention, generating separation efficiencies higher than 98%. Media exchanges commenced on day 3 at a rate of 1 vessel volume per day (VVD). The use of the quasi-perfusion approach generated improvements in cell densities of up to 2.5 fold in comparison to fed-batch studies. Additionally, volumetric productivities increased up to 1000 fold than those generated in fed-batch. Metabolic profiles in microwell plates are consistent with those typically obtained at large scale. The results demonstrate that many of the characteristics of perfusion culture can be simply mimicked in microwell plate systems. This suggests the ability of microwell plates to be implemented into early phase development of perfusion culture, for cell line and media screening, resulting in substantial time and cost savings. Integration into a liquid handling system and automated platform is under way in an effort to generate robust high-throughput cell line or media screening data in early-phase developmen

    Synthetic Polymers Provide a Robust Substrate for Functional Neuron Culture

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    Substrates for neuron culture and implantation are required to be both biocompatible and display surface compositions that support cell attachment, growth, differentiation, and neural activity. Laminin, a naturally occurring extracellular matrix protein is the most widely used substrate for neuron culture and fulfills some of these requirements, however, it is expensive, unstable (compared to synthetic materials), and prone to batch-to-batch variation. This study uses a high-throughput polymer screening approach to identify synthetic polymers that supports the in vitro culture of primary mouse cerebellar neurons. This allows the identification of materials that enable primary cell attachment with high viability even under ‚Äúserum-free‚ÄĚ conditions, with materials that support both primary cells and neural progenitor cell attachment with high levels of neuronal biomarker expression, while promoting progenitor cell maturation to neurons.Biomaterials & Tissue Biomechanic
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