Supervisors: Prof Inke Näthke and Prof Sandy Cochran
The importance of mechanics in the development of tissues and cancers is becoming increasingly clear. This project aims to quantitate the biomechanical properties of cells and tissue, specifically in the context of colorectal cancer.
Colorectal cancer currently causes more than 700,000 deaths in the world every year, and is forecast to increase in incidence in the future, as more people adapt to a Western lifestyle and live longer. In the past few years, novel models have been developed to study the characteristics and development of colorectal cancer, such as gut organoids. These “mini-guts” show similar cell organisation and behaviour as tissue in the gut, and provide a useful tool for research. A simpler model system is provided by Madine-Darby Canine Kidney (MDCK) spheroids. MDCK spheroids can be grown in the same 3D culture environment and have similar size as organoids. Moreover, MDCK cell lines exist that allow expression of truncated forms of the adenomatous polyposis coli (APC) protein. Such truncations in the Apc gene are found in over 90% of colorectal tumours.
The objective of this project is to combine novel techniques to quantitatively study the mechanical properties of cells and 3D tissue models to investigate the effect of Apc mutations on the mechanical properties of cells and tissues. To this end, atomic force microscopy (AFM), microultrasound (µUS) and optical coherence elastography (OCE) are being used. After developing means to optimise sample preparation and experimental protocol, preliminary data has been collected revealing the potential for each technique.
AFM experiments were carried out during a secondment at nuomedis (Liestal, Switzerland) and Biozentrum (Universität Basel, Basel, Switzerland). AFM allows the measuring mechanical properties of different cellular domains. So far, results show that MDCK cells expressing a truncated form of APC leads to changes in local mechanical properties over time. Furthermore, applying AFM to 3D cysts composed of MDCK cells has the potential to reveal the local mechanical properties of the basal side of cells within 3D structures. Establishing robust protocols for AFM measurements in 3D will permit detecting differences between cells in wild type and Apc-mutated organoids.
To complement the main project, polydimethylsiloxane (PDMS) structures will be used to investigate biomechanics. One idea currently being explored is to grow spheroids in rings of PDMS pillars. The forces exerted by a spheroid while growing can be measured by observing the deflection on the PDMS pillars. Another approach is based on confining spheroids within arrays of PDMS microwells, which act as a scaffold for exerting mechanical pressure on cysts or organoids. So far, MDCK spheroids have been successfully confined within PDMS microwells. We are currently trying to identify mechanotransduction markers that can serve as a readout for mechanical stress.
Ultimately, this project aims to reliably and quantitatively measure mechanical properties to determine how they are linked to tissue organisation and function. One specific aim is to identify the effect of Apc mutations, which model a precancerous condition, on mechanical properties of tissue. This will lead to better understanding of colon cancer and provide novel tools for mechanical studies in cell and tissue biology.
Journal and Conference Papers and Posters
[July 2017] Biomechanical studies with ultrasound in cell biology. Poster presented at the joint conference of the 19th IUPAB Congress and 11th ESBA Conference, 16th-20th July 2017.
[April 2017] The biomechanics of cells and the 3D structures they form: novel tools for mechanobiology. Poster and flash talk presented at the BSCB Meeting, Warwick, 2nd-5th April 2017.
[March 2017] Quantitative microultrasound imaging to study 3D tissue structures. Poster presented at the SUG Meeting, Edinburgh, Scotland, 8th March 2017.
[November 2016] Examining mechanical properties of three-dimensional hollow tissue structures: microultrasound, atomic force microscopy and computational modelling. Oral presentation at the Biophotonics North conference, St Andrews, Scotland, 3rd November 2016.
[October 2016] Examining mechanical properties of three-dimensional hollow tissue structures: microultrasound, atomic force microscopy and computational modelling. Poster presented at the 7th Annual PiCLS Symposium, Dundee, Scotland, 17th October 2016.
[August 2016] A tumour associated APC fragment changes the response of MDCK cells to compression. Poster presented at the Biophotonic approaches: From molecules to living systems conference, Dundee, Scotland, 23rd August 2016.
[June 2016] A multimodal approach to measure mechanical properties of three-dimensional tissue structures over different length scales. Poster presented at at PHOTONEX SCOTLAND, Edinburgh, Scotland.
[March 2016] A multimodal approach to measure mechanical properties of three-dimensional tissue structures over different length scales. Poster presented at University of Dundee School of Life Sciences Research Symposium, Crieff, Scotland.
[November 2015] Measuring the mechanical properties of three-dimensional tissue structures. Poster presented at the 43rd Scottish Microscopy Group Symposium, Dundee, Scotland.
[September 2015] Measuring the mechanical properties of three-dimensional tissue structures. Poster presented at the PiCLS Symposium, Dundee, Scotland.