The 5 most common types of transplants (and their characteristics)

A summary of the most common types of transplants practiced in medicine today.

The Clínica Universidad Navarra (CUN) defines transplantation as the implantation of an organ or tissue from one living being to another or, failing that, from one part of the same organism to another part.. There are many clinical events that may require a transplant to be addressed, but the most common of them all is irreparable organ failure. When the kidneys or liver cease to function, it is time to get on a transplant list.

In 2007, some 275,000 Europeans were living with a transplanted organ or tissue. With a higher average general life expectancy, more chronic pathologies are appearing in the population, and this is reflected numerically: in countries such as France, the need for transplants increased by 45% from 2000 to 2007, for example.

However, organ transplantation also has its macabre side, beyond the life expectancy they report. Today, 107,000 Americans are on the waiting list to receive an organ, a new patient is added every 10 minutes and about 20 people die every 24 hours because they do not receive adequate treatment.

A transplant gives a patient a new chance at life, but the lack of viable organs results in thousands of unintended deaths. In the U.S., nearly 5,000 people died waiting for a kidney transplant in 2015. With these data in hand, we tell you everything you need to know about the most commonly used types of transplants.

What are the types of transplants?

This subject can be approached in many ways, since it is possible to group the types of transplantation according to the site of implantation, the relationship of the patient with the donor or the methodology used, among other criteria.

1. Autologous transplants

To begin with, we will say that an autologous transplant is one that is performed within the same organism, i.e. the recipient and the donor are the same individual..

An example of an autologous transplant is the collection of stem cells from a neoplastic patient before chemotherapy. So that they are not damaged during the procedure, they are extracted from the individual's bone marrow and, after chemotherapy, are reintroduced into his or her body. The great advantage of autologous transplants is that there is no possibility of the patient rejecting them, since they are interacting with his or her own tissue.

2. Isotransplants

On the other hand, isotransplants are those that occur between different individuals but are practically the same at the genetic level, such as monozygotic twins.as in the case of monozygotic twins. There is almost no risk of rejection.

3. Xenotransplantation

Another variant is xenotransplantation, where the donor and recipient are of different species.. For example, aortic valve repair and replacement in humans can be done with transplants made from porcine or bovine tissue.

4. Allotransplants

In fourth and last place, we have the allotransplants or typical transplants, known all over the world.known all over the world. In this case, donor and recipient are of the same species, but with different genomes.

The most frequent allotransplants

The following are the most common types of allogeneic transplants in today's society.

1. Kidney transplantation

Kidney transplants are the most common and necessary in today's society.. In the United States, some 3,000 patients are added to waiting lists each month, and in countries such as Spain, more than 2,500 such procedures are performed each year, far more than in other organs.

The kidneys are essential for the functioning of the organism, as they allow us to filter toxins from the Blood and promote the maintenance of homeostatic balance by regulating circulating electrolytes. When kidney failure is severe, dialysis can be used, but transplantation is the definitive option.

Kidney transplantation has a 90% success rate, even more so if the donor is genetically related to the recipient.. Unfortunately, the biggest problem is the shortage of these organs in public health organizations. This is not surprising, as the prevalence of chronic kidney disease has grown by 30% in the last 10 years.

2. Liver transplantation

In Spain, the second place is occupied by liver transplantation, with about 1,034 annual procedures. The liver is the largest internal organ and performs several critical functions for our wellbeing, including processing nutrients and nutrients from the liver.These include processing nutrients, drugs and hormones, producing bile (which secretes bilirubin and helps digest food), manufacturing proteins, removing bacteria and toxins from the blood, and much more. It is literally impossible to live without a liver.

Liver transplantation **is used for critically ill patients with hepatitis B and C, alcoholic cirrhosis, non-alcoholic fatty liver disease and many other pathologies **more. Survival rates 5 years after the procedure are estimated at 80% in adults and 90% in children, respectively.

Lung transplantation

To compare with other figures, about 336 lung transplants are performed annually in Spain. This number is much lower than in the rest of the procedures, as it is only carried out when absolutely all possible treatments have failed and the patient's life is in serious danger.

Unfortunately, survival rates are not as encouraging as in the other cases: 79% survive after one year after transplantation, 64% after 3 years and only 30% after 10 years after the operation.. Acute rejection is almost a universal problem in the first year, while bronchiolitis obliterans limits long-term survival. For all these reasons, lung transplantation is never an ideal situation.

4. Heart transplantation

In Spain, some 278 heart transplants are performed each year. This procedure may be used to address severe organ damage after a heart attack, to address failure when medications no longer work, to treat severe heart abnormalities that prevent proper blood pumping, and for abnormal palpitations.. As harsh as it may sound, these types of procedures are hardly conceivable for people over 70 years of age, since younger patients are given priority.

Survival rates 20 years after transplantation are 20-25%.. The heart is an extremely complex organ and, therefore, failures such as rejection by the recipient, problems with the arteries, conditions in the primary graft and susceptibility to certain infections are common. For all these reasons, the patient's prognosis is not very positive in the long term.

5. Pancreas transplantation

In Spain, fewer than 100 pancreas transplants are performed per year. Finland has the highest European rate, with 7 procedures per million inhabitants per year, but this is still a very low figure. It is used for some types of diabetes that are uncontrollable with conventional treatments, frequent reactions to insulin, severe kidney damage and other pathologies.. In many cases, pancreas and kidney transplants are performed simultaneously.

This situation is very curious, since it is estimated that 85% and 75% of patients survive pancreas transplantation after 1 and 5 years, respectively. These data reaffirm that all patients with life-threatening type 1 diabetes mellitus should be candidates for pancreas transplantation, but this is not the case.

This underuse of the technique is attributed to the lack of knowledge on the part of general practitioners and, in many cases, to the high rate of discarding organs when they arrive at the centers, due to their deteriorated macroscopic appearance (50%).

Summary

As you can see, the journey of a patient requiring a transplant is not an easy one. We have told you what happens to those who manage to be recipients of an organ (the "luckiest" ones) and even so, their survival rates drop drastically over the years. Many transplants are "expired", lasting 10 to 20 years and, after that, the only thing left to do is to hope that the patient does not die.

This is the most hopeful scenario, since the scenario of many thousands of other people is, directly, to die while waiting. We base ourselves on data to bring this painful statement, and it is that 35% of the people on the transplant lists in the world die for lack of resources. Maybe it's time to consider becoming a donor, don't you think?

Bibliographic references:

• Bezinover, D., & Saner, F. (2019). Organ transplantation in the modern era.
• Desschans, B., Evrard, P., & of the Belgian, C. T. S. (2014, November). Organ donation and transplantation statistics in Belgium for 2012 and 2013. In Transplantation proceedings (Vol. 46, No. 9, pp. 3124-3126). Elsevier.
• Number of organ transplants performed in Spain in 2020, by type, Statista. Retrieved April 8 from https://es.statista.com/estadisticas/596378/numero-de-trasplantes-de-organos-realizados-en-espana-por-tipo/.
• Organ Donation and Transplantation Statistics, National Kidney foundation. Retrieved April 8 from https://www.kidney.org/news/newsroom/factsheets/Organ-Donation-and-Transplantation-Stats
• What is stem cell transplantation (bone marrow transplantation), Cancer.net. Recogido a 8 de abril en https://www.cancer.net/es/desplazarse-por-atenci%C3%B3n-del-c%C3%A1ncer/c%C3%B3mo-se-trata-el-c%C3%A1ncer/qu%C3%A9-es-el-trasplante-de-c%C3%A9lulas-madre-trasplante-de-m%C3%A9dula-%C3%B3sea
• Randall, T. (1991). Too few human organs for transplantation, too many in need... and the gap widens. Jama, 265(10), 1223-1227.
• Types of organ transplant, NarayanHealth. Recogido a 8 de abril en https://www.narayanahealth.org/organ-transplant/