Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.568011
Title: Improving three-dimensional (3D) embryonic stem cell bioprocess design
Author: Yeo, David Chen Loong
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2012
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Abstract:
Embryonic stem cells (ESCs) are promising as therapeutic material since they are pluripotent (potentially differentiate into any mature cell) and have “limitless” self-renewal capacity. To achieve widespread clinical utility, ESC cultures have to be designed to meet specific process requirements (e.g. quantity, quality etc.). Currently, most pluripotent stem cell (PSC) cultures are fragmented protocols relying on operator–intensive processing, as 2D monolayers on tissue culture plastic, at ambient O2 conditions. Incidentally, such culture conditions are sub-optimal, often leading to unscheduled stem cell behaviour. This thesis examines how ESC bioprocesses can be improved. Culture environment effects on ESCs are investigated, as well as computational tools for in silico design. I demonstrate how critical culture parameters and mathematical modelling can be exploited to improve the undifferentiated expansion of ESCs. Beginning with 3D murine ESCs (mESCs) cultures, 1) dynamic rotary cultures were demonstrated to improve self-renewal signalling activity, yielding improved proliferation of mESCs with higher “stemness” levels. 2) Culture metabolism was another critical factor. During batch feeding, metabolites accumulate within the culture environment especially at later stages in culture, causing stresses that impair ESC proliferation and “stemness”, independent of growth factor levels. In contrast, perfusion feeding maintained well-regulated culture environments that promoted the expansion of highly “naïve” mESCs. 3) Computational approaches can complement bioprocess design. Mathematical models identified novel multi-scale interactions within the bioprocess and effectively simulated bioreactor fluid dynamics. 4) As a means to further optimize the bioprocess, alternative signalling factors were combined with dynamic perfusion cultures in reduced (5%) O2 conditions, which generated increased cell yields having high “stemness” levels at half the costs. In conclusion, numerous ‘standard’ culture conditions were found to be sub-optimal for mESC culture, emphasizing the need for improved bioprocesses using rational design based on stem cell bioscience. It is anticipated that these integrated stem cell bioprocesses, can improve product yield and quality at reduced costs. Such bioprocess strategies will facilitate the usage of PSCs as therapeutics.
Supervisor: Panoskaltsis, Nicki ; Xu, Yun ; Mantalaris, Sakis Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.568011  DOI: Not available
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