Mapping the acoustic properties of tissues at low temperatures for ultrasound rewarming

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1) Brief description of the context of the research including potential impactOver 6000 people in the UK are waiting for organ transplants. Simultaneously, theutilization rate of organ transplantation is not high (approximately 60% of donor hearts are not used), limited by the short time they can be preserved. Storage organs at low temperature (cryopreservation) has the potential to facilitate the increased availability. However, the volume of cryopreservation in clinical use is less than 3 mL, since there are difficulties in rewarming the large-volume tissues, when using standard water bath immersion, and even with advanced magnetic nanoparticle and microwave methods. The key solution for organ cryopreservation lies in finding a suitable method to rewarm the tissue uniformly and quickly.Ultrasound heating is a potential tool for rewarming large-volume tissues. Energy is deposited as heat as ultrasound passes through the tissues. By controlling ultrasound propagation, energy can be deposited for rapid and uniform warming. To deliver the ultrasound energy optimally, knowledge of the physical properties of tissues at low temperatures is needed. This Ph.D. research aims to develop methods for mapping the acoustic properties of tissues at low temperatures, which will accelerate the development of ultrasound rewarming.2) Aims and ObjectivesThe aim is to characterise the acoustic properties of biological materials at low temperatures to inform the development of ultrasonic rewarming of biological tissues after cryopreservation. This will help identify the optimal ultrasonic parameters for warming and contribute to development of models of ultrasound propagation in frozen tissues.The specific objectives are: 1. To develop and validate experimental methods for mapping the acoustic properties of biological materials at low temperatures,2. To characterise the acoustic and thermal properties of a range of biological materials at low temperatures.3) Novelty of Research MethodologyThe characterisation of acoustic material properties of solid materials is challenging and more so at low temperatures, where the thermal environment of both the sample and the measurement equipment must be tightly controlled. There is limited information in the literature on the acoustic properties of biological materials at temperatures below zero so the research will generate new methods and knowledge which will be significant for this research and for the academic community. These techniques will be extended to spatially resolved mapping or imaging of the acoustic properties. 4) Alignment to EPSRC's strategies and research areasThis project forms part of a programme of work that is strongly multidisciplinary and focused on future clinical translation. This research has the potential for broad impact in transplant surgery, regenerative medicine, and tissue engineering. The development of ultrasonic rewarming will support the development and clinical translation of tissue-engineered (which aligns with the Biomaterials and tissue engineering research area) and cell therapy products and support the long-term preservation of donor tissues for transplant, as well as enable basic scientific studies of the cryobiology of cells and tissues. The research is aligned with the UKRI 'Technology touching life' priority area, and with advances in regenerative medicine within the current EPSRC strategy. Specifically, the EPSRC Healthcare technologies grand challenges include 'Developing Future Therapies' and 'Frontiers of Physical Intervention', with possible impacts achieved through innovative technologies for regenerative medicine.5) Any companies or collaborators involvedCollaborators on the programme of work with which this project is aligned include academics from UCL/Royal Free London, scientists from the UCL/Royal Free London, scientist from the National Physical Laboratory, and Precision Acoustics Ltd