What is Organ Transplantation? How is Organ Transplantation Performed?

What is Organ Transplantation?

Organ transplantation is a surgical procedure in which an organ or tissue, such as a kidney, liver, bone marrow, heart, or cornea, is removed from a living or deceased donor and transplanted to a person in need. It is used for therapeutic purposes when one or more vital organs lose their function.

Transplant organs or tissues can be taken from living bodies or cadavers. Transplantation medicine is one of the most challenging and complex fields of modern medicine.

A key issue in organ transplantation is the potential for transplant rejection, which can lead to an immune response against the transplanted organ, potentially leading to transplant failure and the need for immediate organ removal from the recipient.

When appropriate, serotyping should be performed to determine the most suitable donor-recipient match to minimize the likelihood of transplant rejection. Furthermore, the use of immunosuppressant medications can also reduce the likelihood of transplant rejection.

What are the Types of Organ Transplantation?

Organ transplantation is the transplantation of an incurable, non-functional organ or tissue from a living or cadaver donor to a diseased recipient. The goal of organ transplantation is to replace the non-functioning organ with a functioning one, thus improving the patient's treatment and survival. Transplantation for these purposes can occur in several types. When the same person is both a recipient and donor, that is, when an organ or tissue is transplanted within the same body, it is called an autograft. Transplants between two individuals of the same species are called allografts. Allografts can be from a living body or a cadaver.

Autograft

An autograft is a tissue transplant performed on the same person. In some cases, this procedure involves using excess tissue, regenerating tissue, or tissue more desperately needed elsewhere for life.

Examples include skin grafts or vein extraction for coronary artery bypass surgery. In other cases, the removal of tissue is performed to treat the tissue separately or to treat the individual without it, and then the tissue is added back to the individual.

Examples include stem cell autografts and pre-operative blood storage. Another example is rotationplasty, where a distal (far) joint is used to replace a more proximal (near) one. Typically, a foot or ankle joint is used to replace a knee joint. The person's foot is amputated and turned, the knee is removed, and the tibia is fused to the femur.

Allograft and Allotransplantation

Allograft is the name given to the procedure of transplanting an organ or tissue between two genetically non-identical members of the same species. Tissue and organ transplants performed in humans are generally allografts.

However, due to genetic differences between the organ and the recipient, the recipient's immune system may recognize the organ as a foreign body and attempt to destroy it, causing transplant rejection. The risk of transplant rejection can be estimated by measuring the level of panel-reactive antibodies.

Isograft

Isograft is a subset of allograft in which organs or tissues are transplanted between a genetically identical donor, such as an identical twin, and the recipient. While isografts are similar to allografts in terms of anatomical procedures, they generally do not trigger an immune response, unlike other types of transplants.

Xenograft and Xenotransplantation

Xenograft and xenotransplantation are the names given to tissue and organ transplants performed between two different species. A highly common and successful example is the pig heart valve transplant. However, xenotransplantation is generally an extremely dangerous type of transplant due to the increased risk of compatibility, rejection, and disease caused by interspecies transmission.

To minimize these risks and address the limited number of organs available for transplant, research is underway to transplant human organs grown in various animal models and then transplanted into humans.

Domino transplants

Domino transplants are multiple transplants performed in a chain for various reasons. For example, a liver that secretes a protein that causes long-term damage to the body can be transplanted from a younger individual to an older, diseased liver, whose lifespan will be less severe due to its slow progression, and a healthy liver from the older individual can be given to the younger individual.

For example, in cases where two lungs need to be replaced, it is technically easier to remove the heart along with the lungs and replace it with a complete new lung/heart system. However, since the removed heart will still be healthy in such cases, the original transplanted heart can be transplanted to another patient requiring a heart transplant.

ABO-Incompatible Transplants

Because very young children, usually under 12 months of age, have not yet fully developed immune systems, it is possible to receive organs from donors with whom they would normally be incompatible. This is known as an ABO-incompatible transplant, or simply ABOi.

Limited success has been achieved with ABO-incompatible heart transplants in adults. In these cases, it has been observed that adult recipients are required to have low levels of anti-A or anti-B antibodies. Kidney transplants are more successful in these cases, and long-term survival rates are similar to those of ABOc transplants.

Which Tissues and Organs Can Be Transplanted?

Tissues and organs that can be transplanted include the heart, kidneys, liver, lungs, pancreas, intestine, thymus, and uterus. A global review of medical data shows that the most commonly transplanted organs are the kidneys, followed by the liver and heart. Tissues include bones, tendons, cornea, skin, heart valves, nerves, and blood vessels. Bone and tendon transplants are called musculoskeletal grafts. Corneal and musculoskeletal grafts are the most commonly transplanted tissues, and these types of transplants are much more common than organ transplants.

Under normal circumstances, the types of donors from which successful transplants can be performed are listed below.

Chest:

• Heart (cadaveric donor only)
• Lung (cadaveric and living donor)

Abdominal Cavity:

• Kidney (cadaveric and living donor)
• Liver (either a cadaver donor or multiple living donors if a whole liver is needed; cadaver and living donors if a partial liver transplant is sufficient)
• Pancreas (cadaver donor only; a very severe form of diabetes occurs when the pancreas of a living person is removed)
• Intestine (cadaver and living donor; normally occurs in the small intestine)
• Stomach (cadaver donor only)
• Testicle (cadaver and living donor)
• Penis (cadaver donor)

Tissues, cells, and body fluids

• Hand (cadaver donor only)
• Cornea (cadaver donor only)
• Skin transplantation, including autograft face grafts and, very rarely, face transplants
• Islets of Langerhans, i.e., pancreatic islet cells (cadaver and living donor)
• Bone marrow/Adult stem cells (living donor and autograft)
• Blood transfusion/Blood Products Transfusion (living donor and autograft)
• Blood Vessels (Cadaveric donor and autograft)
• Heart Valves (Living donor and xenograft [pig/cattle])
• Bone (Cadaveric donor and living donor).

Organ donors can be living, dead, or brain-dead individuals whose lives are maintained by machines. Organs removed from the body within 24 hours of the heart stopping or brain death can be used for transplantation. Unlike organs, most tissue types, except corneas, can be preserved for up to five years and stored in special tissue "banks."

Organ transplantation raises a number of ethical issues, including the medical definition of death, when and how consent should be given for an organ to be transplanted, donor consent, and whether organs received for transplantation are financially viable.

Other ethical issues related to this situation include transplant tourism and, more broadly, the socioeconomic conditions that organ procurement or transplantation may create or be considered a solution for.

Who is Eligible for Organ Transplantation?

Kidney transplantation is recommended for kidney patients with chronic kidney failure, and liver transplantation is recommended for patients with irreversible liver function impairment and liver failure. In general, organ transplantation is also performed for the following conditions:

• Heart disease patients with congestive heart failure who are unresponsive to medical treatments
• Lung disease patients who cannot improve with medications and other treatment methods to replace one or both lungs
• Diseases requiring organ transplantation, such as corneal transplants to replace a damaged or diseased cornea

Who Can Be a Tissue or Organ Donor?

Almost anyone can donate tissue or organs, saving one or many lives. Organ donors can be living individuals or individuals who have experienced brain death.

Brain death typically refers to the cessation of brain function due to traumatic or pathological injury to the brain or interruption of blood flow to the brain due to conditions such as drowning.

In such cases, breathing or a pulse can be maintained artificially by artificial means. Brain death criteria vary from country to country. However, brain deaths generally represent a very small percentage of normal deaths, meaning the overwhelming majority of deaths are unsuitable for organ donation.

If an individual who is expected or has already died has donated an organ, the organs can be kept in a suitable operating room for transplantation to give life to others.

Tissues can also be transplanted from individuals who have died from brain or circulatory death. Tissues can generally be recovered within 24 hours of the heartbeat ceasing.

Unlike organs, most tissues, except corneas, can be preserved and stored for up to five years. However, a single tissue donor can donate multiple grafts, enough to provide life to more than 60 recipients. Due to these factors, tissue transplants are much more common than organ transplants.

Living Donor

Living donors can donate organs if they are expected to survive partial or total organ removal and can maintain healthy bodily functions. Examples of such organ donations include single kidney donation, partial liver donation, lung lobe donation, and small intestine donation.

Deceased (Cadaveric) Donor

Cadaveric donors are individuals whose bodies are declared brain dead and whose bodies continue to function organically using ventilators or other mechanical mechanisms until their organs are removed for transplantation.

What is the Recovery Process Like After Organ Transplantation?

After an organ transplant, patients are admitted to the intensive care unit for a period of time and monitored there. If all goes well, the patient is removed from the ventilator. After the intensive care phase, the patient is monitored in the hospital ward room, depending on their condition. This period can range from 2 to 3 weeks.

During this period, the patient is evaluated for jaundice, fever, new medications, and potential organ rejection. If necessary, liver biopsies may be taken during this period. If all findings are positive, the discharge process begins. Afterward, the patient returns to the transplant center once a week for follow-up, and examinations and liver tests are performed. Medication doses are adjusted if necessary. Special attention should be paid to infection prevention. As the risk of infection and organ rejection decreases, the frequency of follow-up visits also decreases. It is important to keep the surgical site clean after surgery. Any swelling, redness, or fluid buildup should be reported to the doctor.

Frequently Asked Questions About Organ Transplantation

What is an organ transplant?

Organ transplantation is a surgical procedure in which a functioning organ, either from a living donor or a cadaver, is transplanted to someone whose organ has ceased to function or is about to fail. In other words, organ transplantation involves removing a healthy organ and replacing it with a non-functional organ from another body.Organ transplantation can also be done from one part of the body to another within the same individual.

When is organ transplantation performed?

Organ transplantation is most commonly performed on patients with chronic organ failure. When a suitable and healthy organ is found, organ transplantation is planned for these individuals.