The 10 types of donors (of organs and tissues)

The human body is an almost perfect machine. A feat of biological evolution where the 30 million million cells that make up our body are specialized and distributed in such a way that we can fulfill biological functions that are incredibly complex and unique within the animal kingdom. But like any machine, it can fail.

And the list of both congenital and acquired diseases that we can develop is, unfortunately, incredibly long. And although many of them can be treated with clinical therapies that "repair" the pathology in the patient, there are many other occasions in which the last alternative to save the patient's life is to perform a transplant.

Transplants are clinical procedures that consist of replacing the damaged organ or tissue of a sick patient with one that functions correctly from another person who, living or dead, plays the role of donor. And it is that the 135,000 transplants performed worldwide in 2018 were possible thanks to the 34,000 donors who gave part of their body to someone who needed it.

For this reason, in today's article, with the aim of paying tribute to all these donors who saved thousands of lives, we are going to investigate, hand in hand, as always, with the most prestigious scientific publications, in what kinds of donors there are depending of different parameters. Because not all donors are the same. Let us begin.

What do we understand by donor and what classes exist?

A donor is a person who, being alive or dead, gives some of his or her organs or tissues to another individual who, due to the disease he or she suffers from, needs to receive a transplant.. Thus, a donation can be understood as the medical procedure, generally surgical, that consists of extracting an organ or tissue (or several, in which case we speak of multi-organ or multi-tissue donation) from a donor to implant it in the patient who needs the transplant.

In this context, we can understand the role of donor as that of the person who, living or dead, voluntarily and altruistically donates their organs or tissues so that they can be used immediately or deferred in a clinical center for therapeutic purposes based on this transplant. A transplant that, as we have said, is the surgical procedure that consists of replacing a damaged organ or tissue of the patient with the donated one that does work properly.

Now, although this general definition may be very simple, the truth is that many nuances are hidden here. And it is that there are many different types of donors depending on both the biological material donated and its condition, as well as the relationship with the recipient of the donation or other parameters. Let's see, then, how donors are classified.

1. Living donor

By living donor we understand one who give up their organs or tissues in life. Obviously, this donation cannot endanger the person's life, so it can only deliver portions of tissue that can regenerate (such as blood), parts of organs that, despite losing part of their structure, continue to function (like the liver) or an organ that comes in pairs and we can do without one of them (like the kidneys). In addition to the obvious donor-recipient compatibility tests, the donor must go through very exhaustive health examinations to determine their physical and mental health.

2. Deceased donor

By deceased donor we understand one who gives up its organs or tissues once it has died. It should be clear, however, that a deceased person is only suitable as a donor if the death was caused by brain death (the brain has died, usually due to cerebral hemorrhage, but the organs can function for a while) or by asystole. (a form of cardiac arrest).

In addition, the donor must necessarily die in a hospital where optimal resources are available to artificially maintain blood circulation and pulmonary ventilation until the time of extraction, since it is absolutely essential to ensure the correct oxygenation of the organs or tissues that are to be removed. to transplant.

3. Organ donor

By organ donor we understand someone who delivers not a tissue, but an organ, that is, a set of tissues that are organized and structured to form a physiological piece that performs a complex function in the body. There are a total of 80 organs in the human body. and, in case they fail irreversibly and seriously, a transplant through a donation can be considered.

The most common organ transplants in the world are the following: kidney (89,823 transplants), liver (30,352 transplants), heart (7,626 transplants), lung (5,497 transplants) and pancreas (2,342 transplants). There are others such as the intestine (less than 200 operations are performed annually in the world), the cornea (the external transparent lens of the eyes) or the skin, which is reserved for serious cases of burns, skin cancer, infections or serious injuries.

Although it depends on the transplanted organ, such a surgical operation is risky for both the recipient and the donor (if you are a living donor), but clinical advances are making it less and less dangerous from an operative point of view, despite the fact that it is a very invasive and complex surgery.

4. Tissue donor

By tissue donor we understand someone who delivers not an organ, but a tissue, that is, a set of cells that are similar at a morphological and physiological level. The 80 organs of the human body are born from the combination of the 14 different types of tissues present in our body. In general, it is a less dangerous and surgically less complex procedure than that of an organ, among other things because they can be preserved for longer.

The most common tissue donation is bloodbut there are also others such as the donation of bone marrow, bone tissue, ovules, semen, tendons, heart valves, vascular segments (portions of arteries or veins) or cell cultures.

5. Donor for research

By donor for research we understand one who has stipulated that, once deceased, their organs and/or tissues can be donated to science for research with them. Donating your body to research is an act of great value, as it allows you to train new generations of doctors and progress in your understanding of the human body. That is to say, this donation of organs and tissues has both educational and professional purposes.

6. Ordinary donor

By ordinary donor we understand one who, while alive, voluntarily expressed a desire to donate all or part of their organs or tissues to be used, either for performing transplants or for research purposes, after death. Therefore, it was the person himself who determined that his body could be donated to science, both to deliver his organs or tissues to a patient who needs them and to advance research and teaching.

7. Extraordinary donor

By extraordinary donor we understand one who, while alive, did not legally express the donation of their organs or tissues; but his closest relatives, in principle knowing the will of the deceased, authorize the donation of all or part of his body. Thus, it is the closest family that allows the organs or tissues of the loved one who has just died to be used for a transplant or for research in the event that the person has not authorized but has not rejected said donation.

8. Related donor

By related donor we understand a donor who, in life, donate an organ or tissue to a family member. To speak of "related", there must be at most a second degree of affinity (grandparents of my spouse, spouses of my siblings, step-siblings or spouses of my grandchildren) or a fourth degree of consanguinity (first cousins, that is, children of my parents' brothers). Anything that is equal to or more closely related by affinity or consanguinity is included within the related gift.

9. Cross Donor

By cross donor we understand that donation process that develops reciprocally between unrelated couples. To understand it, let's take an example. Let's imagine that donor 1 and recipient 1, which would be the first pair, are not compatible. And we have another situation where a donor 2 and a recipient 2, which would be the second pair, are also not. But donor 1 and recipient 2 are; while donor 2 and recipient 1 are also. In this situation, cross-pair donation may be considered.

10. Altruistic donor

All donations are altruistic, but this one especially. And it is that by altruistic donor we understand one who, while alive, donates an organ or tissue to a recipient who was on the waiting list for a transplant and whose identity, unlike the previous cases, is totally unaware.