organ transplantation organ transplantation organ transplantation is a medical procedure in which an organ is removed from one body and placed in the body of a recipient, to replace a damaged or missing organ. the donor and recipient may be at the same location, or organs may be transported from a donor site to another location. organs and/or tissues that are transplanted within the same person's body are called autografts. transplants that are recently performed between two subjects of the same species are called allografts. allografts can either be from a living or cadaveric source. organ transplantreenactment of the first heart transplant, performed in south africameshd016377 transplant surgeonoccupationnames physician surgeon occupation typespecialtyactivity sectorsmedicine, surgerydescriptioneducation required doctor of medicine (m.d.) doctor of osteopathic medicine (d.o.) bachelor of medicine, bachelor of surgery (m.b.b.s.) bachelor of medicine, bachelor of surgery (mbchb) fields ofemploymenthospitals, clinics organs that have been successfully transplanted include the heart, kidneys, liver, lungs, pancreas, intestine, thymus and uterus. tissues include bones, tendons (both referred to as musculoskeletal grafts), corneae, skin, heart valves, nerves and veins. worldwide, the kidneys are the most commonly transplanted organs, followed by the liver and then the heart. corneae and musculoskeletal grafts are the most commonly transplanted tissues; these outnumber organ transplants by more than tenfold. organ donors may be living, brain dead, or dead via circulatory death. tissue may be recovered from donors who die of circulatory death, as well as of brain death – up to 24 hours past the cessation of heartbeat. unlike organs, most tissues (with the exception of corneas) can be preserved and stored for up to five years, meaning they can be "banked". transplantation raises a number of bioethical issues, including the definition of death, when and how consent should be given for an organ to be transplanted, and payment for organs for transplantation. other ethical issues include transplantation tourism (medical tourism) and more broadly the socio-economic context in which organ procurement or transplantation may occur. a particular problem is organ trafficking. there is also the ethical issue of not holding out false hope to patients. transplantation medicine is one of the most challenging and complex areas of modern medicine. some of the key areas for medical management are the problems of transplant rejection, during which the body has an immune response to the transplanted organ, possibly leading to transplant failure and the need to immediately remove the organ from the recipient. when possible, transplant rejection can be reduced through serotyping to determine the most appropriate donor-recipient match and through the use of immunosuppressant drugs. types of transplant autograft main article: autotransplantation autografts are the transplant of tissue to the same person. sometimes this is done with surplus tissue, tissue that can regenerate, or tissues more desperately needed elsewhere (examples include skin grafts, vein extraction for cabg, etc.). sometimes an autograft is done to remove the tissue and then treat it or the person before returning it (examples include stem cell autograft and storing blood in advance of surgery). in a rotationplasty, a distal joint is used to replace a more proximal one; typically a foot or ankle joint is used to replace a knee joint. the person's foot is severed and reversed, the knee removed, and the tibia joined with the femur. allograft and allotransplantation main article: allotransplantation an allograft is a transplant of an organ or tissue between two genetically non-identical members of the same species. most human tissue and organ transplants are allografts. due to the genetic difference between the organ and the recipient, the recipient's immune system will identify the organ as foreign and attempt to destroy it, causing transplant rejection. the risk of transplant rejection can be estimated by measuring the panel-reactive antibody level. isograft an isograft is a subset of allograft in which organs or tissues are transplanted from a donor to a genetically identical recipient (such as an identical twin). isografts are differentiated from other types of transplants because while they are anatomically identical to autografts, they do not trigger an immune response. xenograft and xenotransplantation main article: xenotransplantation a xenograft is a transplant of organs or tissue from one species to another. an example is porcine heart valve transplant, which is quite common and successful. another example is attempted piscine–primate (fish to non-human primate) transplant of pancreatic islets. the latter research study was intended to pave the way for potential human use if successful. however, xenotransplantation is often an extremely dangerous type of transplant because of the increased risk of non-functional compatibility, rejection, and disease carried in the tissue. in the opposite direction, attempts are being made to devise a way to transplant human fetal hearts and kidneys into animals for future transplantation into human patients to address the shortage of donor organs. domino transplants in people with cystic fibrosis (cf), where both lungs need to be replaced, it is a technically easier operation with a higher rate of success to replace both the heart and lungs of the recipient with those of the donor. as the recipient's original heart is usually healthy, it can then be transplanted into a second recipient in need of a heart transplant, thus making the person with cf a living heart donor. in a 2016 case at stanford medical center, a woman who was needing a heart-lung transplant had cystic fibrosis which had led to one lung expanding and the other shrinking, thereby displacing her heart. the second patient who in turn received her heart was a woman with right ventricular dysplasia which had led to a dangerously abnormal rhythm. the dual operations required three surgical teams, including one to remove the heart and lungs from a recently deceased initial donor. the two living recipients did well and had an opportunity to meet six weeks after their simultaneous operations. another example of this situation occurs with a special form of liver transplant in which the recipient has familial amyloidotic polyneuropathy, a disease where the liver slowly produces a protein that damages other organs. the recipient's liver can then be transplanted into an older person for whom the effects of the disease will not necessarily contribute significantly to mortality. this term also refers to a series of living donor transplants in which one donor donates to the highest recipient on the waiting list and the transplant center utilizes that donation to facilitate multiple transplants. these other transplants are otherwise impossible due to blood type or antibody barriers to transplantation. the "good samaritan" kidney is transplanted into one of the other recipients, whose donor in turn donates his or her kidney to an unrelated recipient. this method allows all organ recipients to get a transplant even if their living donor is not a match for them. this further benefits people below any of these recipients on waiting lists, as they move closer to the top of the list for a deceased-donor organ. johns hopkins medical center in baltimore and northwestern university's northwestern memorial hospital have received significant attention for pioneering transplants of this kind. in february 2012, the last link in a record 60-person domino chain of 30 kidney transplants was completed. abo-incompatible transplants main article: abo-incompatible transplantation because very young children (generally under 12 months, but often as old as 24 months) do not have a well-developed immune system, it is possible for them to receive organs from otherwise incompatible donors. this is known as abo-incompatible (aboi) transplantation. graft survival and people's mortality are approximately the same between aboi and abo-compatible (aboc) recipients. while focus has been on infant heart transplants, the principles generally apply to other forms of solid organ transplantation. the most important factors are that the recipient not have produced isohemagglutinins, and that they have low levels of t cell-independent antigens. united network for organ sharing (unos) regulations allow for aboi transplantation in children under two years of age if isohemagglutinin titers are 1:4 or below, and if there is no matching aboc recipient. studies have shown that the period under which a recipient may undergo aboi transplantation may be prolonged by exposure to nonself a and b antigens. furthermore, should the recipient (for example, type b-positive with a type ab-positive graft) require eventual retransplantation, the recipient may receive a new organ of either blood type. limited success has been achieved in abo-incompatible heart transplants in adults, though this requires that the adult recipients have low levels of anti-a or anti-b antibodies. renal transplantation is more successful, with similar long-term graft survival rates to aboc transplants. transplantation in obese individuals until recently, people with obesity were not considered appropriate candidate donors for renal transplantation. in 2009, the physicians at the university of illinois medical center performed the first robotic renal transplantation in an obese recipient and have continued to transplant people with a body mass index over 35 using robotic surgery. as of january 2014, over 100 people who would otherwise have been turned down because of their weight have successfully been transplanted. organs and tissues transplanted main article: transplantable organs and tissues chest heart (deceased-donor only; porcine xenograft attempted) lung (deceased-donor and living-related lung transplantation) thymus abdomen kidney (deceased-donor and living-donor; porcine xenograft attempted) liver (deceased-donor, which enables donation of a whole liver; and living-donor, where each donor can provide up to 70% of a liver) pancreas (deceased-donor only; a very severe type of diabetes ensues if a live person's entire pancreas is removed) intestine (deceased-donor and living-donor; normally refers to the small intestine) stomach (deceased-donor only) uterus (deceased-donor only) testis (deceased-donor and living-donor) penis (deceased-donor only) tissues, cells and fluids hand (deceased-donor only), see first recipient clint hallam cornea (deceased-donor only) see the ophthalmologist eduard zirm skin, including face replant (autograft) and face transplant (extremely rare) islets of langerhans (pancreas islet cells) (deceased-donor and living-donor) bone marrow or adult stem cell (living-donor and autograft) blood transfusion, whole blood or fractionated blood products (living-donor and autograft) blood vessels (autograft and deceased-donor) heart valve (deceased-donor, living-donor and xenograft ) bone (deceased-donor and living-donor) types of donor organ donors may be living or may have died of brain death or circulatory death. most deceased donors are those who have been pronounced brain dead. brain dead means the cessation of brain function, typically after receiving an injury (either traumatic or pathological) to the brain, or otherwise cutting off blood circulation to the brain (drowning, suffocation, etc.). breathing is maintained via artificial sources, which, in turn, maintains heartbeat. once brain death has been declared, the person can be considered for organ donation. criteria for brain death vary. because less than 3% of all deaths in the us are the result of brain death, the overwhelming majority of deaths are ineligible for organ donation, resulting in severe shortages. organ donation is possible after cardiac death in some situations, primarily when the person is severely brain-injured and not expected to survive without artificial breathing and mechanical support. independent of any decision to donate, a person's next-of-kin may decide to end artificial support. if the person is expected to expire within a short period of time after support is withdrawn, arrangements can be made to withdraw that support in an operating room to allow quick recovery of the organs after circulatory death has occurred. tissues may be recovered from donors who die of either brain or circulatory death. in general, tissues may be recovered from donors up to 24 hours past the cessation of heartbeat. in contrast to organs, most tissues (with the exception of corneas) can be preserved and stored for up to five years, meaning they can be "banked." also, more than 60 grafts may be obtained from a single tissue donor. because of these three factors – the ability to recover from a non-heart-beating donor, the ability to bank tissue, and the number of grafts available from each donor – tissue transplants are much more common than organ transplants. the american association of tissue banks estimates that more than one million tissue transplants take place in the united states each year. living donor in living donors, the donor remains alive and donates a renewable tissue, cell, or fluid (e.g., blood, skin), or donates an organ or part of an organ in which the remaining organ can regenerate or take on the workload of the rest of the organ (primarily single kidney donation, partial donation of