Organ transplantation

Organ transplantation is the surgical replacement of a failing, damaged, or absent organ with a healthy organ recovered from a donor. It is an established treatment for end-stage organ failure across several organ systems and, for most recipients, requires lifelong immunosuppressive medication to prevent the recipient's immune system from rejecting the graft.[1][2] In the United States, the transplantable solid organs are the kidney, liver, heart, lung, pancreas, and intestine; vascularized composite allografts (VCA) such as the hand and face were added to the federal definition of "organ" in 2014.[3] Organs are recovered from deceased donors (after death determined by neurologic or by circulatory criteria) or, for the kidney and for segments of the liver and other organs, from living donors.[1][4]

In 2024, a record 48,149 organ transplants were performed in the United States, made possible by 16,988 deceased donors and 7,030 living donors; the figure represented a 3.3 percent increase over 2023 and a 23.3 percent increase over the preceding five years.[5] Despite the growth in volume, the number of candidates waiting for a transplant continues to exceed the number of organs available (see Organ donation and the donation-gap article).

This article is an overview hub. Dedicated articles cover the individual organs (for example, Kidney transplantation, Liver transplantation, Heart transplantation, and Lung transplantation), the donor pathway, the immunology, and the governing law.

Types of transplant

Transplants are classified by the genetic relationship between donor and recipient:[2][6]

• Autograft, tissue moved from one site to another within the same person (for example, a skin graft or a saphenous-vein graft). Not subject to rejection.
• Isograft (syngeneic graft), between genetically identical individuals (identical twins); the first successful human kidney transplant, by Joseph Murray in 1954, was an isograft.[7]
• Allograft, between genetically non-identical members of the same species; this is the dominant form of clinical organ transplantation and the principal subject of transplant immunology.[6]
• Xenograft, across species (for example, experimental pig-to-human transplantation); investigational as of 2026.[2]

Solid-organ grafts are also described by anatomic placement: orthotopic (the graft is placed in the recipient's normal anatomic position after removal of the native organ, as in liver, heart, and lung transplantation) versus heterotopic (the graft is placed in a different site and the native organ may be left in place, as in the iliac-fossa placement of a kidney).[1][8]

Transplantable organs and indications

| Organ | Principal indication(s) | Typical donor source | |---|---|---| | Kidney | End-stage renal disease | Deceased or living | | Liver | End-stage liver disease, acute liver failure, selected liver cancers | Deceased; living/split | | Heart | End-stage heart failure | Deceased | | Lung | End-stage lung disease | Deceased (rare living-lobar) | | Pancreas | Type 1 diabetes (often with kidney) | Deceased | | Intestine | Irreversible intestinal failure when parenteral nutrition fails | Deceased | | VCA (hand, face, others) | Disfiguring or disabling tissue loss | Deceased |

Kidney transplantation is the most commonly performed solid-organ transplant and is the preferred treatment for many patients with end-stage renal disease.[8] Sources for organ-specific indications appear in each organ's article.[8][9][10][11]

Donor types

Organs come from two broad donor categories:[4]

• Deceased donors, the source of most transplanted organs, where death is determined either by neurologic criteria (donation after brain death, DBD) or by circulatory criteria (donation after circulatory death, DCD). See Deceased donation.
• Living donors, who may donate a kidney or a portion of an organ (most commonly a segment of liver) during life. See Living donation.

The transplant process

Deceased-donor transplantation follows a defined sequence: hospital referral of an imminent or declared death to an organ procurement organization, donor evaluation, authorization, donor management, surgical recovery, organ preservation and transport, allocation through the national match, transplantation, and lifelong recipient follow-up.[12] The full sequence is described in The donation pathway. Candidates are listed at transplant centers and matched to donor organs through the national allocation system; allocation considers only medical and logistical factors and varies by organ (for example, the MELD score for liver and KDPI for kidney).[13]

Immunology and immunosuppression

Because an allograft carries foreign human leukocyte antigens (HLA), the recipient's immune system can mount a rejection response unless it is suppressed.[6] Pre-transplant immunologic assessment includes ABO blood-type compatibility, HLA tissue typing, screening for preformed antibodies (panel-reactive antibody / cPRA), and a crossmatch.[6] After transplantation, recipients typically receive induction immunosuppression at the time of surgery followed by lifelong maintenance therapy, commonly combining a calcineurin inhibitor, an antiproliferative agent, and a corticosteroid.[2] Rejection is categorized as hyperacute, acute (T-cell-mediated or antibody-mediated), or chronic. These topics are detailed in Transplant immunology.

Complications

Major categories of post-transplant complication include rejection; the adverse effects of chronic immunosuppression, such as opportunistic infection (for example, cytomegalovirus and BK virus), malignancy (including post-transplant lymphoproliferative disorder), nephrotoxicity, and new-onset diabetes after transplantation; surgical and vascular complications; and recurrence of the original disease in the graft.[2][6] Long-term graft survival is also limited by chronic, organ-specific processes such as chronic lung allograft dysfunction in lung recipients.[11]

Allocation and policy

In the United States, deceased-donor organs are allocated through the Organ Procurement and Transplantation Network (OPTN) under federal rules. Policy is bounded by the OPTN Final Rule (42 CFR Part 121) and implemented as a computerized "match run" that ranks candidates using only medical and logistical factors.[13][14] The national system was created by the National Organ Transplant Act of 1984.[15]

Ethics

Transplantation raises a distinctive set of ethical questions, presented in dedicated articles: the prohibition on buying and selling organs (financial neutrality); the determination of death and the "dead donor rule"; consent and authorization models (opt-in versus opt-out); equity in allocation; and the ethics of emerging recovery techniques such as normothermic regional perfusion, which remains contested.[16][17] The international ethical framework against organ trafficking and transplant tourism is set out in the Declaration of Istanbul and the World Health Organization Guiding Principles.[18]

History

Modern transplantation dates to the first successful human kidney transplant between identical twins, performed by Joseph Murray and colleagues in Boston in 1954.[7] Christiaan Barnard performed the first human-to-human heart transplant in 1967, and Thomas Starzl performed early successful liver transplants in the 1960s. The introduction of ciclosporin (cyclosporine), approved in the United States in 1983, sharply improved graft survival and enabled the modern era of multi-organ transplantation. The U.S. transplant system was placed on a statutory footing by the National Organ Transplant Act in 1984.[7][15] Murray shared the 1990 Nobel Prize in Physiology or Medicine for his transplantation work.[7]

Research

Active areas of investigation include ex-vivo machine perfusion to assess and recondition donor organs and extend preservation, strategies to induce immune tolerance (so recipients require little or no maintenance immunosuppression), and xenotransplantation as a potential means of addressing the persistent organ shortage.[2]

See also

• Organ donation
• The donation pathway
• Deceased donation · Living donation
• Transplant immunology
• National Organ Transplant Act (NOTA)

References

• Health Resources and Services Administration. Organ Procurement and Transplantation Network (OPTN). https://www.hrsa.gov/optn
• Wikipedia. Organ transplantation. https://en.wikipedia.org/wiki/Organ_transplantation (used as a structural/overview reference; biomedical claims cross-checked to MEDRS sources cited here).
• Organ Procurement and Transplantation Network. Vascularized composite allograft (VCA) policy; VCA added to the OPTN definition of "organ" effective July 3, 2014.
• HRSA/OPTN. Deceased donation. https://www.hrsa.gov/optn/patients/organ-donation/deceased-donation
• HRSA. Organ Transplants Exceeded 48,000 in 2024; a 3.3 Percent Increase From the Transplants Performed in 2023. https://www.hrsa.gov/optn/news-events/news/organ-transplants-exceeded-48000-2024-33-percent-increase-transplants-performed-2023 (as of 2024 preliminary OPTN data).
• Justiz Vargas AN, Cortés-Penfield NW, et al. Transplantation Immunology. StatPearls. NBK538218. https://www.ncbi.nlm.nih.gov/books/NBK538218/
• The Nobel Prize in Physiology or Medicine 1990 (Joseph E. Murray, E. Donnall Thomas). https://www.nobelprize.org/prizes/medicine/1990/summary/
• Kidney Transplantation. StatPearls. NBK567755. https://www.ncbi.nlm.nih.gov/books/NBK567755/
• Liver Transplantation. StatPearls. NBK559161. https://www.ncbi.nlm.nih.gov/books/NBK559161/
• Heart Transplantation. StatPearls. NBK557571. https://www.ncbi.nlm.nih.gov/books/NBK557571/
• Lung Transplantation. StatPearls. NBK565849. https://www.ncbi.nlm.nih.gov/books/NBK565849/
• OPTN. The basic path of donation. https://optn.transplant.hrsa.gov/learn/about-donation/the-basic-path-of-donation
• United Network for Organ Sharing. How we match organs. https://unos.org/transplant/how-we-match-organs/
• OPTN Final Rule, 42 CFR Part 121, §121.4. https://www.ecfr.gov/current/title-42/chapter-I/subchapter-K/part-121/section-121.4
• National Organ Transplant Act of 1984, Pub. L. 98-507; 42 U.S.C. §274e. https://www.congress.gov/bill/98th-congress/senate-bill/2048
• OPTN. White paper analyzes ethical issues in normothermic regional perfusion. https://optn.transplant.hrsa.gov/news/white-paper-analyzes-ethical-issues-in-normothermic-regional-perfusion/
• Omelianchuk A. Neither Ethical nor Prudent: Why Not to Choose Normothermic Regional Perfusion. Hastings Cent Rep. 2024. doi:10.1002/hast.1584
• World Health Organization. WHO Guiding Principles on Human Cell, Tissue and Organ Transplantation (WHA63.22, 2010). https://www.who.int/publications/i/item/WHO-HTP-EHT-CPR-2010.01