The expansion and then differentiation of anchorage dependent stem cells in vitro for further study or implantation back into the body is still poorly understood. This PhD programme will seek to characterise the growth of stem cells on microcarriers (scaffolds) in spinner flasks and then in conventional stirred tank bioreactors. The effects on cell differentiation, confluence and physiological state (including viability) of the main process conditions (dissolved O2/CO2 concentration, agitation intensity, ratio of microcarriers to cells etc) will be investigated using the novel analytical methods developed at all three partner Universities as well as more conventional imaging techniques based round differential fluorescent staining. This information will be used for improved bioreactor and bioprocess design.
Failure to grow thick bone tissue is mainly due to lack of tissue vascularisation resulting from fall in nutrient supply to cells as distance increases. Hollow fibre membrane bioreactor (HFMB) promises to solve this issue by efficient supply of nutrients to cells. In this project, we propose to study the multiscale behaviour of HFMB for growing thick (3D) bone tissue of clinically relevant size (mms to cms) by designing of bioreactors of various size. Human or mouse bone marrow mesenchymal stem will be seeded in a biodegradable & biocompatible (BB) jelly like scaffold around a BB HF network & hold them by a polycarbonate case to form a HFMB, where profuse media will be supplied. It will be necessary to measure various parameters, e.g., growth kinetics, viability & metabolism of cells and observe tissue morphology if formed with microscope at varied times.
This project will train the student in the methodology of converting pluripotent stem cells into differentiated cell types. The Nottingham teams focus on differentiation into cardiomyocytes and bone cells. The student will investigate specific aspects if differentiation based on current research breakthroughs.
This project will train the student in the manufacture of drug and cell delivery systems. A combination of materials science and stem cell biology will be used to investigate cell survival and differentiation into bone.
As a precursor to studies of automating and scaling up cell expansion this project will study the mechanisms of maintaining stem cell properties in the presence and absence of feeder cells.
There is an immediate need to understand and optimise current methods for the preservation of stem cell banks prior to expansion and subsequent differentiation. Empirical evidence has resulted in the use of cryogenic preservation techniques that rely on a preservant such as DMSO to prevent the formation of ice crystals, a process known to disrupt the delicate membrane structures within cells and hence compromise their viability. However, there is little informed or systematic work to back up its use so here we will undertake a systematic and informed examination of the methods used to preserve and, crucially, revive stock cultures to ensure subsequent reproducible biological performance. We will perform a large number of well-designed statistically robust trials in order to establish what are the most important factors for subsequent cryopreservation optimisation using multi-parameter flow cytometry, modern imaging techniques and actual subsequent bioprocess performance.
Microcarriers (scaffolds) may be made from a variety of polymer materials and can be particles of various sizes and surface properties. The most successful microcarriers are ones that provide a high surface area per unit volume that is accessible for the cells to attach and grow. The process of membrane emulsification will be used to produce the microcarriers, with consideration of the chemistry of the post-polymerisation process in order to control the surface properties of the carriers, as well as the bead size. Using membrane emulsification it is possible to precisely control the bead size over a range of possible bead diameters up to several 100's of micrometres. The project will investigate cell growth on microcarriers of various forms, both topological and grafted polymers, considering cell growth rate, viability and ability to differentiate. Analysis will be by conventional means and by employing particle characterisation techniques; to provide an instrumental technique for rapid analysis that may be applied in-situ.
This project will train the student in the synthesis of new hydrogel materials that convert into scaffolds in response to increases in temperature. These materials are under investigation for cornea repair. Rheological properties and drug release will be quanitified.
Many clinical trials are underway for a wide array of treatments. To date few groups have considered the need to develop bespoke delivery solutions for cells. This project will study the potential for delivery mechanisms to damage cells prior and during administration into the body.
