A transplant, also called organ transplantation, is when an organ from the body is removed, and a new organ from a donor site (such as a deceased individual who was an organ donor) is implanted into the body. Organ transplants are done when their existing organ is failing, damaged, or absent. There are also new developments including regenerative medicine where scientists create organs from the patient’s stem cells, though it isn’t used in modern medicine just yet. Not only can organs be transplanted, but so can other body parts and tissues including bones, skin, and veins.
What Can be Transplanted?
The most recognizable type of transplantations are organ transplants, including heart, liver, lungs, kidney, pancreas, thymus, and intestines. However, tissues can be transplanted, as can bones, cornea, heart valves, skin, and veins. The most common transplanted organ is the kidney, followed by the liver and then the heart. The most commonly transplanted tissues are cornea and bones (musculoskeletal grafts); these two types of transplants are actually done more often than organ transplants.
The potential donor site for organs or tissues will depend on the type of transplant. Organ donors can be living or brain dead and be someone who became an optional organ donor, per their driver’s license or state ID card. For tissue donors, they can be from someone who is considered cardiac dead up to 24 hours after their heartbeat stopped beating. Tissues can be preserved for up to 5 years which is one of the reasons these transplants are more common than organ transplants, which have a very small window in which they are viable for transplantation.
Types of Transplants
There are 6 main types of transplant; autografts, allograft and allotransplantations, isografts, xenograft and xenotransplantations, split transplants, and domino transplants. An autograft is done when the tissues are from the same person, either surplus tissue or tissue that regenerates. Allograft and allotransplantations involve transplanting organs or tissues between 2 of the same species who are not genetically identical. Isografts on the other hand, involve an organ or tissue transplant for genetically identical people, such as identical twins. Xenograft and xenotransplantations are when an organ or tissue is donated from one species to another, such as a non-human organ being transplanted in a human. A common type of xenograft is a porcine heart valve transplant. A split transplant is done when one organ can be split and used for more than one recipient, such as a liver. Finally, there are dominio transplants where it is more successful when more organs are transplanted, such as the lungs and liver.