Development of a prototype micro fluidic device for the study of cell function within a tissue environment

The Micro Reactor Research Group at Hull has now carried out over 200 man-years of research, to establish the fundamental design and operational parameters e.g. channel shape, size, flow methodology and surface functionalisation, that give micro fluidic devices significant advantages in the field of analytical chemistry. Recently this work has been extended into the field of cell biology and now features a number of ongoing collaborative projects with the Cellular Processes Group at Hull. In general the main practical advantages of micro fluidic methodology, apart from requiring small sample sizes, can be summarised as devices which offer (i) a very high degree of spatial (nano meter) and temporal (micro second) control of processes originating from diffusive mixing processes occurring within a laminar flow regime; (ii) the possibility of generating extremely high surface to volume ratios to intensify liquid/surface or surface/surface interactions and (iii) the opportunity to integrate complex processes with non-invasive analytical measurements in order to achieve significantly better temporal and spatial resolution of dynamic processes than is currently possible. At present the main thrust of the work at Hull is to develop integrated process/measurement devices for forensic/environmental and drug discovery based processes which involves approximately 28 research staff drawn from a range of scientific and engineering disciplines. Given the support at Hull to develop integrated cellular processing and measurement technology it would seem timely and advantageous to align this current proposal with ongoing work whilst developing a unique focus in tissue based research. Thus by combining new science with a significant critical mass of research and know-how considerable added value will be achieved with the proposed funding. We propose therefore to use the expertise that resides within the pool of researchers at Hull to establish (micro fluidic) and exploit (biomedical) micro fluidic methodology in the area of tissue processing and by doing so establish a unique link between research scientists and clinicians. Biological tissue obtained, for example, from a small biopsy, represents a complex aggregation of cell types arranged within an intricate non-cellular structure which supports intercellular connections. However, maintaining a stable tissue sample for study in the laboratory has proved to be very difficult as nutrient delivery, removal of waste products and gaseous exchange all need to be achieved. In nature these processes are carried out via a complex network of blood and lymphatic vessels which give dynamic perfusion of the tissue. Micro fluidic systems mimic nature with their high surface to volume ratio, inherent fast perfusion and localised (single cell) interrogation capability, and so offer an ideal microenvironment for the development of novel technology encompassing integrated measurement capability. The proposed micro fluidic devices will enable the study of cell function and the role of the extracellular (EC) matrix in normal and diseased tissues to be carried out in a novel way. This in turn will lead to significant scientific advances in the understanding of cell and tissue biology. In this project the EC environment between cells will be conditioned using a selection of reagents that will modify the chemical and biological interactions in a defined and controlled way. By then testing the conditioned tissue with a drug-like compound, the effect of conditioning (i.e. modified EC environment) can be used to identify the importance of individual cell interactions. For example, tissue could be conditioned with a calcium inhibitor e.g. EDTA which will disrupt integrin function (a family of cell surface molecules involved in cell binding) allowing the tissue, which is otherwise unchanged, to be tested for responses to cytotoxic drugs in order to identify the role of integrins in mediating drug activity.

Whilst much of the cell based research carried out to date has focused primarily on cell processes, in reality cells in general do not exist in isolation but form complex networks or tissues in which the communication between cells is often as important as the individual cell function. Here we propose developing analytical tools that will enable the study of cellular interactions in tissues. Such methodology will be instrumental, for example, in identifying how drug delivery strategies (i.e. getting active agents to the right place) and disease states associated with tissue degradation (muscle wastage and dementia) will be treated in the future. The proposed methodology will be based on micro fluidic or capillary networks which can be used to control the temporal and spatial manipulation of cells and reagents. Such systems, which mimic to a great extent the natural supporting tissue infrastructure such as blood capillary and lymphatic systems, can be integrated with analytical and detection techniques to offer a unique environment in which to study tissue and cell processes. The applicants have already secured a number of grants in the research area including £721k recently awarded from EPSRC to develop a portable integrated DNA analyser. One of the exciting aspects of this current proposal is the opportunity to link it closely with the forensic project and develop in parallel a micro fluidic system that will allow the introduction and manipulation of tissue samples to be carried out in combination with DNA analysis. In addition the two analytical modules (mass spectrometry and FACS) that will be developed in this project, will create with the PCR work a truly unique and flexible research platform.