Transplantation

What is Organ Transplant?

Organ transplantation is the operation in which an organ is removed from the donor, that is, the donor body, and then placed in a recipient body to replace a damaged or missing organ. The donor and the recipient may be in the same location, or organs from a donor located in a separate site may be transplanted to a recipient located elsewhere.

The organs or tissues to be transplanted can be taken from living bodies or cadavers. Transplantation medicine is one of the most challenging and complex fields of modern medicine. The organs that can be successfully transplanted today include the heart, kidneys, liver, lungs, pancreas, intestine, thymus and uterus. When medical data are analyzed globally, it is seen that the most common transplanted organs are the kidneys, followed by the liver and heart.

The key to organ transplantation are transplant rejection problems, such as the body's immune response to the transplanted organ, resulting in possible transplant failure and the need to remove the organ immediately from the recipient.

Serotyping should be performed to determine the most appropriate donor-recipient match to minimize the possibility of transplant rejection when appropriate. In addition, the use of immunosuppressant drugs can reduce the possibility of transplant rejection.

Tissues that can be transplanted include bones, tendons, cornea, skin, heart valves, nerves, and veins. Bone and tendon transplants are called musculoskeletal grafts. Cornea and musculoskeletal grafts are the most commonly transplanted tissues, and such transplants are performed much more commonly than organ transplants.

People who donate organs may be alive, dead, or individuals with brain death, whose lives are sustained by machines. It is possible to use organs removed from the body for transplantation within 24 hours after heartbeat has stopped or brain death has occurred. Most tissue types except corneas, unlike organs, 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, the consent of the donor, and whether or not the organs taken for the transplant have a financial equivalent.

Other ethical issues related to this situation include transplantation tourism and, more broadly, the socio-economic conditions that organ harvesting or transplantation can bring about or can be seen as a solution.

What are the Types of Organ Transplantation?

Organ and tissue transplantation can take place in several types, depending on who the recipient is. If the same person is both a recipient and a donor, that is, organ or tissue transplantation within the same body, is called an autograft. Transplants made between two individuals of the same species are called allografts. Allografts can originate from a living body or cadaver.

Autograft

Autograft is a tissue transplant applied to the same person. This procedure is done in some cases with tissues that are surplus, regenerative, or more desperately needed elsewhere to sustain life.

Examples of this are skin grafts or vessel extraction for coronary bypass treatment. In some cases, removal of the tissue is performed to treat the tissue separately or to treat the individual without that tissue, and then the tissue is added to the individual again.

Examples of this include stem cell autograft and blood storage before surgery. As another example, during rotationplasty, a distal joint is used instead of the more proximal, that is, closer one. Typically a foot or ankle joint is used to replace the knee joint. The person's foot is cut and turned over, the knee is removed and the tibia is joined with the femur.

Allograft and allotransplantation

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

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

Isograft

An isograft is a subset of allografts in which organs or tissues are transplanted between a genetically identical donor and recipient, such as an identical twin. Although isografts are the same as allografts in terms of anatomical procedures, they do not usually trigger an immune response unlike other types of transplantation.

Xenograft and Xenotransplantation

Xenograft and xenotransplantation It is the name given to tissue and organ transplantation between two different types of organisms. An example of this is swine heart valve transplantation, which is quite common and successful. However, xenotransplantation is often an extremely dangerous type of transplant due to increased compatibility, rejection, and disease risk due to cross-species transmission.

In order to minimize these risks and eliminate the problem of insufficient number of organs to be transplanted, studies on the transfer of organs belonging to the human body to humans after being cultivated on various animal subjects are being carried out.

Domino Transports

Domino transplants are multiple transplants that take place on a chain basis for various reasons. For example, the liver, which secretes a protein that causes long-term damage to the body, can be transplanted from a younger individual to an older individual who will not have much effect on life due to the slow progress of the diseased liver, and the healthy liver taken from the elderly person can be given to the young person.

As another example, in cases where two lungs need to be changed, it is technically easier to remove the heart along with the lungs and to insert a new lung / heart system as a whole. However, since the heart removed in such cases will still be healthy, another patient who needs a heart transplant can be inserted into the original removed heart.

ABO Incompatible Transfers

It is possible for very young children, who are usually under 12 months of age, to get organs from donors they would normally be incompatible with, as their immune system is not well developed yet. This condition is known as ABO incompatible transport, or ABOi for short.

Limited success has been achieved in ABO-incompatible heart transplants also in adults. In these cases, it has been found that adult recipients must have low levels of anti-A or anti-B antibodies. Kidney transplantation is more successful in these cases, and long-term survival rates are seen as values ​​similar to ABOc transplants.

Transferable Organs and Tissues

The following types of donors can be used for tissues and organs that have been successfully transplanted under normal conditions.

Chest:

  • Heart (cadaver donor only)
  • Lung (cadaver and living donor)
  • Abdominal cavity:
  • Kidney (cadaver and living donor)
  • Liver (either cadaver donor or more than one living donor if a whole liver is required, cadaver and living donor if partial liver transplantation is sufficient)
  • Pancreas (cadaver donor only; if a living person's pancreas is removed, a very severe form of diabetes occurs)
  • Intestine (cadaver and living donor; normally takes place in the small intestine)
  • Stomach (cadaver donor only)
  • Testis (cadaver and living donor)
  • Penis (cadaver donor)

Tissues, cells and body fluids.

  • Hand (cadaver donor only)
  • Cornea (cadaver donor only)
  • Including skin transplantation, autograft face graft and very rarely face transplant
  • 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 (Live donor and autograft)
  • Blood Vessels (Cadaver donor and autograft)
  • Heart Valve (Live donor and xenograft [pig / bovine])
  • Bone (cadaver and living donor).

Who Can Become a Tissue or Organ Donor?

Almost anyone can donate tissues or organs and thus save one or many lives. Organ donors can be individuals who are still alive or individuals who have undergone brain death.

Brain death typically means cessation of brain function due to injury to the brain due to traumatic or pathological causes, or when blood circulation to the brain is interrupted, such as choking.

In such cases, breathing or pulse can be preserved artificially by means. Brain death criteria vary from country to country. But overall, brain deaths represent a very low proportion of normal deaths, which means that the overwhelming majority of deaths are not eligible for organ donation.

If an individual whose brain death is expected or has already donated an organ, he / she may be kept in an appropriate operating room for the organs to be transplanted to give life to others.

Tissues can also be transplanted from individuals who died from brain or circulatory death. It is generally possible to recover tissues within 24 hours after the cessation of the heartbeat.

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

Live donor

Living donors can donate organs after the organ is partially or completely removed, when they survive and the body can maintain other functions in a healthy way. Examples of such organ donations are single kidney donation, partial liver donation, lung lobe donation and small intestine donation.

Deceased (Cadaver) Donor

Cadaver donors are people whose bodies maintain organic activity by ventilators or other mechanical mechanisms until their organs are removed for transplant, and they are declared brain dead.

Before the medical recognition of the concept of brain death in the 1980s, organ transplants were performed with organs taken from the bodies of donor individuals whose circulatory system had completely stopped. Organs taken from donors with a complete cessation of the circulatory system have less successful results than organs taken from a donor who have brain dead but maintain body activities due to machines.

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