A revolution in organ transplantation

Imagine an engineering career where every working day involves a life-or-death situation and decisions. That has been the chosen path of Professor Constantin Coussios OBE FREng – one that he describes as being “fun and a huge privilege”.

Coussios was born in Greece and, aged six, moved to Belgium with his parents. His father was a civil engineer, and he would often accompany him on work projects. “I was seeing the practical side of construction,” he says. “What struck me, from a young age, was the idea of building things from the ground up where there was nothing before.”

A family friend introduced him to astronomy and another introduced him to his areas of expertise: astrophysics and chaos theory. “I was inspired and fascinated by the idea of, say, exploring Mars, but I couldn’t see where I could achieve an impact [in these fields] over my lifetime.” He felt they were too removed from day-to-day practical application and that idea of “building things from the ground up”.

So, at 16, Coussios decided to study aeronautical engineering. A geography teacher at his international school suggested he could apply to study engineering at the University of Cambridge. “I would never have considered applying to the university or moving to the UK.” He applied, “and was accepted, to my surprise, even to this day”.

He entered Cambridge young, at 17. “It was a lifechanging experience”. First, although he had felt he was a “pretty good student in school”, at the university he felt “distinctly below average in a cohort of extremely bright people”. He turned that into a positive; feeling “lifted” by their brilliance encouraged him to “find another gear to be able to exist in that environment”.

He is also very glad he chose to study general engineering: “At 17, I knew very little about what engineering really was, and a general course allowed me just long enough to figure out what my true passion is.” Work experience was instrumental in figuring that out. He spent a summer at Balfour Beatty Civil Engineering, working on concrete castings for the A13 – “I would advise avoiding this road, designed by a very inexperienced engineer, with excellent supervision!” – then at French Aerospace, and the Greek Air Force (as part of compulsory military service in his native country). 

Coussios concluded that civil engineering wasn’t for him, but he loved fluid mechanics and control engineering, “both of which I hadn’t even been aware of when starting my degree”. However, he still felt that something was missing, “something more soul than mind”. From a young age he had felt “empowerment and joy” whenever he was helping others. He ascribes it to being an only child, “and having your friends be your family”. His chosen field had to serve people in some way.

A fluid change

Searching for a final-year project, one title – ‘study of blood as a non-Newtonian fluid’ – jumped out. Non-Newtonian fluids are materials that don’t flow like regular fluids (flowing freely when gentle force is applied but becoming solid under shear stress), and he’d found these unpredictable materials one of the most exciting aspects of fluid mechanics. The project stemmed from a call by eminent transplant surgeon Professor Peter Friend FMedSci. He needed engineering help in the field of perfusion – the passage of fluid through the circulatory or lymphatic system to an organ or a tissue. Friend was looking for an efficient way to make blood flow through an organ to be able to use and make that organ function outside the body. “I really wanted that project,” says Coussios. He was so enthused that, when he found out the project’s supervisor, the late Dr Jeffrey Lewins, was on sabbatical in Fiji, he used a “significant amount” of his monthly income to call him. “I think he was sufficiently impressed by my tenacity that he took me on.”

A few weeks into his fourth year, he was sitting in an operating room with Friend, and two medical research fellows, attempting to keep a pig liver alive outside the body by flowing non-Newtonian blood through it. “I remember holding this liver connected to a machine, and it was making bile. I thought: ‘this is incredible! This is what I want to do for the rest of my life’.” He couldn’t then see the practical implications of the research, but it did have the strong connection to people he sought: “we needed to be four of us around this machine to make it work”. This “life-changing” moment sealed his path in biomedical engineering.

At the time of his first experiments with Friend, in 1997 and 1998, the technology was “the size of two upright pianos. It had about 1,600 control variables … it was completely unusable by anyone other than Peter, me and the other two research fellows involved in the project.” He was “educated very rapidly” by his medical colleagues and besides quick thinking, he needed stamina – and sheer staying power. He recalls often going into the lab on a Friday “and not sleeping until Monday, when my first lecture was, in order to get an experiment done”. This was his choice; he was driven by “fire in the belly … something exciting was happening – much more exciting than going home to watch The Simpsons.”

Some of those nights he spent sleeping with the pigs being used in pre-clinical research to make sure they were OK. “We had to look after the donor and the recipient. On a skeleton crew, you do what you need to.” He believes all engineers need to follow their invention, to understand the reality. “As a technologist, as an inventor, you live and breathe your invention. Understand how it interacts with its natural environment.”

Building a life-changing innovation

His thesis would form a significant part of what would become OrganOx (‘Keeping transplant livers alive’, Ingenia 81), the world’s first normothermic machine perfusion (NMP) device for liver transplantation. During its development, Coussios faced many challenges. He recalls: “I remember sitting there thinking: ‘it’s wonderful what they’re doing by twiddling knobs, but I’m a half-decent engineer. I can model this away in about six months, build a predictive controller that is going to anticipate every little thing the liver is going to do. Building a control system is going to be child’s play.’ Twenty-eight years on, I’m still trying.”

Biomedical engineering taught him “a lesson in humility” as “everything in biology is interconnected in ways we cannot yet hope to begin to understand”.

Having a great sense of humour helped, though. During his PhD in acoustics under the supervision of Professor Shôn Ffowcs Williams, one of the designers of Concorde, he recalls conducting experiments using ultrasound to detect whether red blood cells had been damaged when flowing around the artificial circuit keeping the organ alive. These required latex: “and the most widely available commercial form of latex is condoms,” he grins. A legislation change meant the nonlubricated condoms needed were going to be withdrawn from sale. “I needed a thousand [condoms] to complete my experiments. So I went to my local Sainsbury’s and filled a trolley with their entire stock. I’ll never forget the person at the till, scanning these condoms robotically – click, click – and when they had finished, leaning over to me and saying: ‘Got a big weekend planned, sir?’.”

He then moved to the US for two years and trained in therapeutic ultrasound, returning to Oxford in 2004, when he restarted work with Friend and colleagues in NMP for liver preservation before transplantation. One of his greatest concerns was that his algorithms would one day fail (thankfully that hasn’t happened). But in his work, he can never forget that “someone’s life is ending and someone’s life is being prolonged”.

Raising capital and building belief in the project were other ongoing challenges. But by 2004, he was fully engaged in making OrganOx happen. “I gave it my time and passion, I really believed in it.” There were many landmarks on the way: in 2008, the key method patent that underpinned the metra® was granted, and OrganOx was spun out independently from the University of Oxford; in 2009 product development began on metra® for liver; in 2016 it received its CE mark; and in 2021 it gained FDA approval for liver transplants in the US.

What the team created was a world-first technology that mimics conditions as if the liver is already in the donor, keeping an organ alive and functioning outside the body for at least twice as long as conventional cold preservation techniques. It has dramatically increased the number of transplants for patients and reduced the need for nighttime and weekend operations. It allows medics to make better use of donor pools. A second device from the team is being developed to do the same for kidneys; a third, patient-connected device to provide ‘liver dialysis’ is under development and has entered clinical trials.

Saving livers and lives

The OrganOx metra® can enable safe transplantation of more than 70% of organs that are currently being discarded. In 2024 it was being used in four transplants a day, rising to more than 10 per day in 2025. Today there are “over seven and a half thousand lives saved and accelerating”. His teams have counters on display, notching up the lives saved: “That’s what drives us as a company.”

The device is in use in more than 15% of NHS transplants in the UK, and across 12 countries. Adoption was always a key driver, as was an egalitarian ethos: to this end the company leases the devices free, for a commitment it will be used a certain number of times in a year.

Today its success is such “you can’t walk into a transplant conference without it being dominated by these technologies,” says Coussios. He credits his “extraordinary” research team, and fundamental to that was Friend, OrganOx Co-Founder and Chief Medical Officer, with whom he felt “an incredible connection” from day one and “without whom none of this would have happened.” Whatever else was happening, be it marriage, children, or examining work, their loyalty and friendship was never in question.

OrganOx’s groundbreaking achievements were crowned when it won the Royal Academy of Engineering’s MacRobert Award in 2025 – “a pinnacle of my career” he beams. At the Academy’s Innovation incoming: adventures in organ preservation event, its President Sir John Lazar CBE FREng praised it as “a breakthrough that exemplifies the power of engineering to change lives”. Judge Dr Loubna Bouarfa saluted its “serious science, AI, fluid dynamics, gas analysis, all designed to keep the organ healthy for longer. It’s medical brilliance powered by engineering magic.” During the accompanying interview, when asked about the use of AI in organ preservation, Coussios described the challenge of finding one set of control algorithms that would work for every organ, coupled with surgeons working in different ways. “Using AI to make tech adaptive is a challenge,” he said, adding that AI “can’t describe what isn’t described in the original data set”.

Routes to expansion

The dust hadn’t settled on the MacRobert Award before another big announcement, in August 2025: OrganOx was to be bought by Terumo, a Japanese multinational biomedical company. “It felt right,” says Coussios. “We had already managed to get the technology out to 12 countries on four continents. [This] was a unique opportunity to go to the next level up, a company that has the capability to bring it to almost every single country on the globe.” OrganOx being acquired, not sold, allowed it great opportunities he notes, including keeping most of its R&D in the UK for the foreseeable future, and attracting greater investment.

Other projects are OxSonics, launched in 2014, a clinicalstage therapeutics company that has discovered a new way to enhance the delivery of anti-cancer drugs into tumours, using ultrasound and tiny gas bubbles: and OrthoSon, launched in 2016, which has “developed an extraordinary material to repair the intervertebral disc in the spine”, with lower back pain the biggest most and expensive cause of missed work days and disability worldwide, he points out.

OrganOx has grown from “three people for the first three years to almost 300 today”. With it, he has fulfilled his vocation: to make a real difference to people. “When you find something that feels like your calling – and you inspire others to find theirs – you get the best out of yourself, individuals and teams.” There’s still so much to be done, he believes; OrganOx can be “the foundation for transforming the entire field of organ technology”. Did it at times almost feel as if he was going through medical training? “I tease my medical mentors – not just Peter, but those in radiology, oncology and orthopaedics – and say I get to experience the exciting bits of medicine without the boring bits.” Running or co-running “really exciting clinical trials” and seeing major advances has been a huge privilege. “It’s also very ironic, because there was a small part of 16-year-old me who wanted to be a doctor. I decided not to do it because I thought I couldn’t stand the sight of blood or rapid decision- making under pressure. And 20 years on, I have spent more of my life elbows deep in blood than most surgeons I know.”

When Coussios recently handed over as director at the Institute of Biomedical Engineering in Oxford, after a decade, a colleague noted he had achieved a lot, but what he was really about was people and helping them feel equally important, whatever their role. “That was very touching, and if it’s true, I’m sure it has a lot to do with my parents.” To his father, he owes his dynamism and ability to make things happen; his mother has “an incredible maturity and inner peace” and he feels “had the biggest influence on me emotionally”. “And my wife,” Niki Trigoni FREng, with whom he shares a common passion for bringing transformative technologies to life, which led them to become one of several married couples to both be Fellows of the Academy.

Although work has “never stopped being 24/7 for me” he does strive for balance. His passion for sport is part of that and fed into the January 2024 official launch of Podium Institute for Sports Medicine and Technology at the University of Oxford. It aims to improve sport safety with particular focus on youth, community and women’s sport. His wife, who he met at Cambridge, was “very understanding” when his birthday weekend plans for her were railroaded as he had to rush off to save a “major bit of data acquisition” concerning a rugby match. Their three sons share his interest in “creating something out of nothing”, he feels; one is studying architecture; one is considering medicine; one may become an engineer but is also an extraordinary cook. He doesn’t mind what they want to do, but he’d like them to have “the privilege I have of going to work for fun and working with your best friends”.

He reflects on his career: “When I came to the UK alone at 17, my main language was French. But I was never made to feel like a foreigner. I was embraced … Being on that journey has been so important and so empowering. And to have had the recognition and support from organisations such as the Royal Academy of Engineering and the Academy of Medical Sciences … I feel very fortunate to have had it in spades.”