Metabolic imaging of cells in 3D tissue engineered scaffolds

Research within the multidisciplinary Biomaterials and Bioengineering group has several broad aims including the development of novel tissue engineering scaffolds and novel methods to synthesise the scaffolds, the translation of these developments to the clinic and new ways to characterise and image the behaviour of these scaffolds. When working with tissue engineering scaffolds and 3D cell culture it is very useful to be able to monitor cell responses to the scaffold and other environmental factors during culture over time.

Cell metabolism can vary with the type of cells used and as these cells proliferate, differentiate and respond to oxygen and nutrient gradients within the scaffolds.

Cell metabolism is generally measured by assays such as the accumulation of metabolites in the culture medium over time or other more destructive methods such as changes in gene expression. In all cases these assays measure global changes across the culture and are not able to detect variations in response within the culture, a point which is particularly relevant when considering a heterogeneous 3D culture.

Non-invasive imaging techniques allow researchers to monitor what is occurring without destroying the sample under study and are therefore very useful for monitoring the cells growing on the 3D scaffolds. A number of important biomolecules can be studied through non-invasive imaging techniques using their inherent fluorescence without the addition of exogenous fluorescent labels. Studies have shown that it is possible to determine the ratio of two of these molecules, NADH and FAD, to give information on the metabolic state of cells; a technique often referred to as optical redox imaging.

This non-invasive imaging technique has been developed to allow the metabolic activity of cells to be monitored non-destructively over time, however studies have focussed upon cells growing in standard 2D cultures, or thin sections of tissue.

This project aims to develop the non-invasive, metabolic imaging process for cells growing in 3D and evaluate the response of cells in 3D to different scaffold structures and materials. To this end we will use a combination of cell culture techniques, scaffold synthesis and characterisation, non-invasive metabolic imaging and comparison with other techniques currently used to measure metabolic activity. This project will enable us to develop our understanding of cell response to 3D culture in a cell specific manner.