Organ and tissue transplantation is one of the greatest achievements of modern medicine. Not only has it made it possible to save the lives of hundreds of thousands of people in recent decades, but it has also drastically improved their quality of life. Patients who previously relied on long and exhausting treatments such as dialysis can now regain their independence and enjoy a full and active life.
Spain has established itself as a global benchmark in this field, leading organ donation for 33 consecutive years and also recording outstanding results in terms of the number of transplants performed. In 2023, 5,863 transplants were carried out in the country and 172,000 worldwide, although the World Health Organisation (WHO) estimates that two million would be needed to meet global demand. In 2024, Spain broke its own records with 6,464 transplants, thanks to the generosity of 2,562 deceased donors and 404 living donors who gave a kidney (397) or part of their liver (seven). According to data from the Spanish National Transplant Organisation (ONT), since records began 146,000 transplants have been performed in Spain. This success is underpinned by public solidarity, our national health system – which is public and universal – and the efficient organisation of the system, which revolves around transplant coordination units within hospitals, supported by the governments of autonomous communities and the ONT.
Transplants have a long history. The first successful operation in the world was a kidney transplant in 1954 between identical twins, which made it possible to avoid the issue of immunological rejection. In Spain, the first transplant, also of a kidney, was carried out in 1965. This was followed by a liver transplant in 1983, a heart transplant in 1984 and a lung transplant in 1990. Today, the most common transplants are those of the kidney, liver, heart, pancreas and lung; intestinal transplants are less frequent; and vascularised composite tissue transplants – such as face, limb or uterus transplants – remain experimental.
One of the greatest challenges in transplantation continues to be preventing rejection of the organ by the recipient’s immune system. To avoid this, patients must take immunosuppressants for life, which entails side effects such as an increased risk of infections, cancer and cardiovascular problems. For this reason, research is focusing on developing new immunosuppressive drugs that are more effective and have fewer adverse effects, as well as on optimising dose modulation to achieve more precise and less aggressive treatment for patients.
The shortage of organs is the main challenge in transplantation. Throughout 2023, around 100,000 people were on the transplant waiting list in Europe, and nearly 130,000 in the United States. However, fewer than 40 % of these patients received the organ they needed, leading to significant mortality on the waiting list. Population ageing and the rise in non-communicable diseases (it is estimated, for instance, that by 2040 chronic kidney disease could become the fifth leading cause of death worldwide) will exacerbate the problem, as demand for organs increases while potential donors will be older and more likely to have associated comorbidities.
In response to this situation, science is exploring innovative alternatives to make up for the lack of organs, although it still faces significant technical and ethical challenges. These alternatives include xenotransplantation, which involves using genetically modified animal organs to reduce rejection; the creation of bioartificial organs employing 3D printing or by using scaffolds from non-viable donor organs that are decellularised and repopulated with pluripotent cells from the patient themselves; and the generation of human organs in host animals.
While these technologies continue to advance, various short-term strategies are being implemented to increase organ availability and optimise their use. Spain has been a pioneer in many of these areas. The country has led initiatives aimed at enabling the transplantation of organs from older donors with good clinical outcomes and has built the necessary evidence to redefine the safety limits for the use of organs in transplantation. Spain also leads internationally in controlled donation after circulatory death (DCD), a type of donation that in 2024 already accounted for 51% of those recorded donations. Only 26 countries have implemented this model, which is particularly complex due to the harmful effects of cardiac arrest on organ viability. Moreover, Spain is the only country in the world to have successfully transplanted all types of organs from these donors, thanks to the implementation of a pioneering preservation technique known as normothermic regional perfusion. This approach has revolutionised the logistics of such procedures and improved post-transplant outcomes.
Artificial intelligence (AI) has also emerged as a valuable tool in this field of medicine. Algorithms are being developed that are capable of improving organ validation prior to transplantation and optimising donor-recipient matching in order to minimise the risk of rejection.
In all of this context, research is essential. With insights from four experts working in the field – Beatriz Domínguez-Gil González, Oriol Bestard Matamoros, Xabier Aranguren López and Concepción Gómez Gavara – this debate will explore the key issues shaping the present and future of transplantation, and will highlight the latest advances in the field.
Beatriz Domínguez-Gil heads the ONT, an agency under the Ministry of Health that coordinates and organises the donation and transplantation of organs, tissues and cells. The ONT devised what is known as the Spanish model, a management model that is responsible for the programme’s success in terms of donation rates and access to transplants. In recent years, the ONT has led several initiatives that have enabled Spain to reach levels of excellence that would be difficult to imagine for most neighbouring countries. This excellence has also relied on ongoing clinical and epidemiological research activity coordinated by the ONT in collaboration with the transplant and coordination teams.
Oriol Bestard and his team are developing a new second-generation immunosuppressive drug. This structurally modified medication works by suppressing the activity of T and B lymphocytes – the cells responsible for rejection – but without the adverse effects associated with current treatments. Its aim is to prevent the production of antibodies against the transplanted organ in order to improve immunological tolerance. The project is currently in the preclinical phase, assessing its efficacy in animal models and establishing protocols for future large-scale production.
The Livercolor project, co-led by Concepción Gómez and her team, uses artificial intelligence to improve the selection of transplantable livers. Excess fat in donors’ livers is a major issue, as these organs are often discarded due to the risk of postoperative complications. At present, the assessment of livers is done visually by the surgeon, a subjective method with a high margin of error. Livercolor enables a more accurate evaluation of the fat content in the liver, thereby improving decision-making.
Xabier Aranguren and his team are researching one of the most futuristic lines of work: the generation of human organs in pigs through blastocyst complementation. This technique involves genetically modifying animal embryos so that they do not develop a specific organ – for example, the heart – and injecting them with human stem cells to generate organs compatible with transplant patients. Although still at an early stage, the project aims to overcome the main hurdle: the low integration of human cells into animal embryos. If successful, it could pave the way for personalised organ cultivation.
Speakers:
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Beatriz Domínguez-Gil González, director general of the Spanish National Transplant Organisation (ONT).
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Oriol Bestard Matamoros, head of the Nephrology and Renal Transplant Department at Vall d’Hebron University Hospital (HUVH), leader of the Nephrology and Renal Transplant Research Group at the Vall d’Hebron Research Institute (VHIR), and associate professor of medicine at the Universitat Autònoma de Barcelona.
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Xabier Aranguren López, principal investigator of the In vivo Organ Generation by Stem Cells group at CIMA, University of Navarra.
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Concepción Gómez Gavara, surgeon in the Hepatobiliary, Pancreatic and Transplant Surgery Department at Vall d’Hebron University Hospital (HUVH) and researcher in the Hepatobiliary, Pancreatic and Liver Transplant Surgery Group at the Vall d’Hebron Research Institute (VHIR).
Moderator:
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Núria Jar, journalist specialising in international news, science and health.
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