CAN THE OXYGEN TENSION IN A MICROFLUIDIC STEM CELL CULTURE DEVICE BE PRECISELY CONTROLLED DURING BOTH CONTINUOUS AND INTERMITTENT MEDIA EXCHANGE?

Therapies using human cells have great promise for addressing serious medical conditions for which we lack effective treatments. These include particularly those chronic degenerative diseases of old age such as stroke, heart failure, age-related blindness and later stages of both insulin dependent diabetes and Parkinson's disease. In particular, stem cells that can be converted to a variety of specialised cells are especially important. The chemical, biological and physical cues needed for such conversions are complex and it is necessary to examine a large number of permutations to achieve a good outcome. Because many of the biochemical cues required are of very high cost, even basic discovery research and early translational studies in culture flasks are often restricted such that optimal conditions can be missed. In principle it is possible to address this problem by smaller and smaller flasks but in practice the necessary manipulations including removal of spent nutrient and the addition of fresh nutrient becomes difficult to manage. The proposed research addresses this by using micro-fabrication methods to create chambers with gas permeable membranes to provide the oxygen cells need. We will use such microfluidic systems and further develop them to enable best possible control over oxygen which is an important cue for the conversion from stem cells to specialised cells. The project will provide the foundation for a technology with which it will ultimately be possible to achieve more rapid and comprehensive examination of the best conditions for human cell culture to produce the quantities needed for both basic and applied research. Because mouse stem cells are particularly well defined they will be used in this study as a surrogate for human cells to establish the proof of principle.

The application of microfluidics to stem cell research is an emerging and multi-disciplinary area. Additionally, cell-based therapies and cell-based drug discovery are two fields with very broad impact. Advances in these fields will ultimately benefit the economy, the health and the quality of life in the UK and world-wide. The work proposed here provides the foundation for a technology underpinning these fields and contributing to their advances. The immediate beneficiaries of the proposed work are researchers in the broader stem cell biology and bioprocessing community and researchers in microfluidics. The proposed research will lay the foundation for a cost-effective novel methodology to investigate the impact of gaseous tensions on the stem cell fate. Such a method will be valuable to both basic researchers and those seeking translation to cell-based therapies. By demonstrating a novel way of integrating a gas permeable membrane to a microfluidic cell culture chamber, the proposed research will also benefit those working in microfluidics who seek to improve and control gas transfer in other microfluidic systems and geometries. To ensure impact, the concepts and results from this research will be made publicly available through peer-reviewed journals such as Biotechnology and Bioengineering and Lab on a Chip (Royal Society of Chemistry), and we have requested funds for the PI to attend international conferences (see Justification of Resources). The methodology developed will also be introduced into the Stem Cells MBI training course on Bioprocessing at UCL, which is attended by international industrialists. Additionally, a mini-workshop will be held on microfluidics for stem cell biology and bioprocessing. It is envisaged that we will invite overseas and UK-based experts in stem cell biology and bioprocessing (including selected company representatives). We will discuss two selected topics in detail following short introductory talks by the invited experts. Of particular interest would be whether microfluidic systems could be applied to accelerate the scale up of stem cell processes. Several groups and companies are interested and have developed microfluidics systems for the scale-up of microbial fermentation and biopharmaceutical processes. The workshop could address whether there is a similar opportunity for microfluidic systems with stem cells, what the design criteria for the microfluidic systems would be, what analytical methods they would need to provide, etc. The findings of this workshop will be made public in a short report, which can for example be uploaded on the departmental website, or presented as a short communication in a relevant journal.