Innovation Fellowship: Computational modelling of cryopreservation of biological tissue

The preservation of organs and biological tissue is currently in its infancy. The lack of preservation capacity results in 2/3 of donor hearts and 4/5 of lungs being rejected for transplant for logistical reasons. Current estimates of the incidence of diseases that could be treated by on-demand organ replacement amount to several millions in the United States and Europe combined. Hence, advances in biological tissue preservation would revolutionize medicine and biotechnology. Moreover, since synthetic tissue growth is time and labour intensive, such advances would also enable large-scale drug-screening and toxicology testing using organoids grown from human stem cells.

Cryopreservation, where very low temperatures are used, is a standard procedure for the preservation of embryos, oocytes and sperm. It allows tissue availability on demand (as opposed to waiting several months for fresh culture), allows economies of scale to reduce costs, facilitates quality control, and prevents wastage. However, state-of-the-art freezing and thawing techniques lead to tissue damage in anything larger than 1-3mm3. Above-freezing storage times of human organs range from approximately 3 to 24 hours - depending on organ - before becoming unviable.

Currently, cryopreservation is mainly an experimental process, and lacks a guiding computational component. The control of the spatial influence of cryoprotectant agents, their administered quantity, and the timing of induced temperature changes remain largely subject to a black-box approach. However, with the advent of modern computing technologies, the automated analysis of large datasets and detailed computer simulations have become possible.

In this fellowship, I aim at the computational analysis and modelling of cryogenic processing, to provide a systematic framework that generates novel protocols. Physical processes, such as the diffusion of chemicals, mechanical interactions, heat transfer and ice propagation will be incorporated in 3D computer models. This implementation will benefit from the BioDynaMo collaboration with CERN openlab, which aims at a cloud-based software platform for computer simulations of biological tissue dynamics. Cells will be modelled in an agent-based approach. Overall, this computational model will be able to predict tissue-specific cryogenic processing methodologies to ensure optimal tissue viability.

This fellowship will initially focus on the retina, which is part of the central nervous system, and is particularly well-suited because its function can be assessed relatively easily and cost-effectively. Mouse retinal tissue will be used as the model system, because of the consistency of retinal structure across vertebrates. Additionally, retinal organoids, which were synthetically grown in culture in the lab of Prof. Majlinda Lako, will be used. After successful retinal cryopreservation, other tissues (e.g. mouse kidney and cortex) will be cryogenically processed to demonstrate the power of the research approach. Asymptote Ltd (GE Healthcare) will provide expertise, equipment and support for the freezing and thawing processes, hence adding to a prestigious network of well-established collaborators for this fellowship.

Different cryopreservation protocols will be applied to generate samples for computational analysis. Serial block-face scanning electron microscopy, immunocytochemistry, quantitative polymerase chain reaction and multi-electrode array recordings will be used to quantify damage to the tissue after thawing. Based on these data, a 3D computational model will be informed to generate optimal cryogenic processing parameters. Ultimately, this fellowship will allow me to become an international leader in cryopreservation. I will also pursue commercial activities based on the research results. To this end, the computational approach will be used for consulting purposes, e.g. for pharmaceutical, cosmetics or cryopreservation companies.

This fellowship has a wide range of beneficiaries, including industrial and academic stakeholders.

Quality of life. This research will advance cryopreservation of organs and organoids. Ultimately, the wider public will benefit from such progress: firstly, more donated organs will become available. According to NHS Blood and Transplant, about 500 people died last year in the UK while waiting for a transplant. Moreover, pharmaceutical companies will be able to test drugs and potentially toxic substances on tissues grown from human stem cells, which will facilitate the development of novel drugs and cosmetic products. Importantly, this research will benefit the UK medical supply chain in accordance with the Industrial Strategy Green Paper.

Industrial stakeholders. Currently, the preservation of many biological tissues is very limited, and so tissue availability for drug-screening, disease modelling or substance safety evaluation is highly constrained. The possibility to scale up such in-vitro studies is of great interest to the industry (e.g. pharma and cosmetics companies). The project partner Newcells Biotech already has links with multiple companies interested in cryopreservation (Roche, Novartis, Bayer, etc.), and will provide support to bring the research results to the market. Software enabling automated tissue analysis and prediction of viable cryogenic protocols is a likely candidate product. Moreover, it is anticipated that consulting based on computational modelling can be commercialized. This commercialization will be supported by presentations at conferences, publications and a website. Routes to commercialisation will be identified in regular meetings with members of the university's enterprise services and the Director of Business & Engagement. Moreover, a workshop on cryopreservation will facilitate the dissemination of the research results to relevant companies.

The project partner Asymptote will support this fellowship with modern equipment, including a freezer (worth £20,000) and a thawer (worth £9,500). In return, advances in the cryogenic processing will benefit Asymptote because its equipment will gain further application areas, and its economic competitiveness will be fostered.

Computational biologists. This fellowship will lead to at least five publications in high-impact journals. Hence, future computational modelling efforts where biological tissue dynamics are modelled will be facilitated. Importantly, such models are relevant for a wide range of topics. For example, in an EPSRC project (EP/K026992/1) where I worked as an RA, normal and abnormal brain development was modelled. The computational approach taken in this fellowship will facilitate such biology research.

Animal welfare. Based on the computational model developed in this fellowship, promising experimental protocols will be identified, while protocols that would likely yield bad outcomes can be discarded. Hence, the number of mice required for cryopreservation research will be reduced. Also, this research will support tissue engineering research. Ultimately, human tissues grown from stem cells will strongly decrease the use of animals for pharmaceutical research.

Societal impact. It is crucial that more people become aware of the fact that millions of people die each year, because of a lack of transplantable organs. To raise awareness of this problem, I will regularly publish my results on a website for the fellowship and present my findings to a wide audience. Importantly, the computer simulations in this research often yield aesthetically pleasing animations. For example, a publication of mine was featured on the Cerebral Cortex journal cover, and a video has attracted almost 10,000 views on YouTube. Since such animations are often easily understandable by the general public, I will show my results via various channels (YouTube, website, public talks, etc.) to raise public awareness for the lack of donated organs.