Editing Organ transplantation (section)

== Types of transplant ==

=== Autograft ===
{{Main|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 <span class="acronym" title="coronary artery bypass graft">[[CABG]]</span>, etc.). Sometimes an autograft is done to remove the tissue and then treat it or the person before returning it<ref>{{cite journal |vauthors=Giedraitis A, Arnoczky SP, Bedi A |date=March 2014 |title=Allografts in Soft Tissue Reconstructive Procedures |journal=Sports Health: A Multidisciplinary Approach |publisher=Sports Health |volume=6 |issue=3 |pages=256–264 |doi=10.1177/1941738113503442 |pmc=4000469 |pmid=24790696}}</ref> (examples include [[Hematopoietic stem cell transplantation#Graft types|stem cell autograft]] and storing blood in advance of surgery). In a [[rotationplasty]], a [[Interphalangeal articulations of foot|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]].{{citation needed|date=November 2021}}

=== Allograft and allotransplantation ===
{{Main|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|panel-reactive antibody]] level.{{citation needed|date=November 2021}}

==== 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 allografts, they do not trigger an [[immunology|immune response]].{{cn|date=March 2025}}

=== Xenograft and xenotransplantation ===
{{Main|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 [[fish|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.<ref>{{Cite news |last1=Bassett |first1=Laura |date=2016-11-03 |title=How House Republicans Derailed a Scientist Whose Research Could Save Lives |url=https://www.huffingtonpost.com/entry/eugene-gu-research-congress_us_581a3d79e4b01a82df6460de |newspaper=Huffington Post}}</ref>

=== 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.<ref>{{Cite journal |last1=Yacoub |first1=M. H. |last2=Banner |first2=N. R. |last3=Khaghani |first3=A. |last4=Fitzgerald |first4=M. |last5=Madden |first5=B. |last6=Tsang |first6=V. |last7=Radley-Smith |first7=R. |last8=Hodson |first8=M. |year=1990 |title=Heart-lung transplantation for cystic fibrosis and subsequent domino heart transplantation |journal=The Journal of Heart Transplantation |volume=9 |issue=5 |pages=459–66; discussion 466–67 |pmid=2231084}}</ref>

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.<ref>[https://med.stanford.edu/news/all-news/2016/03/after-rare-procedure-woman-can-hear-her-heart-beat-in-another.html After rare procedure, woman can hear her heart beat in another], Stanford Medicine News Center, Sara Wykes, 29 March 2016.</ref>

Another example of this situation occurs with a special form of liver transplant in which the recipient has [[familial amyloid 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.<ref>{{cite web |date=28 January 2003 |title=Mayo Clinic Performs First 'Domino' Transplant in Arizona; Rare Procedure Saves Two Lives at Once, Optimizing Organ Supply |url=http://www.mayoclinic.org/news2003-sct/1622.html |archive-url=https://web.archive.org/web/20030220000729/http://www.mayoclinic.org/news2003-sct/1622.html |archive-date=20 February 2003 |publisher=Mayo Clinic}}</ref>

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 Hospital]] in [[Baltimore]] and [[Northwestern University]]'s [[Northwestern Memorial Hospital]] have received significant attention for pioneering transplants of this kind.<ref>{{cite news |last=Blum |first=Karen |date=1 August 2003 |title=Seattle Times Article on domino transplants at Johns Hopkins |url=http://seattletimes.nwsource.com/html/nationworld/2004336130_kidney09.html |archive-url=https://web.archive.org/web/20060614134207/http://www.hopkinshospital.org/health_info/Bladder/Reading/triple_transplant.html |archive-date=14 June 2006 |access-date=17 April 2013 |publisher=Seattletimes.nwsource.com}}</ref><ref>{{cite web |date=8 April 2008 |title=Good Morning America Video on four-way domino 47674874 transplant at Northwestern Memorial Hospital |url=https://abcnews.go.com/GMA/OnCall/story?id=4611316&page=1 |access-date=17 April 2013 |publisher=Abcnews.go.com}}</ref> In February 2012, the last link in a record 60-person domino chain of 30 kidney transplants was completed.<ref>{{cite news |author=Turnbull, Barbara |date=24 February 2012 |title=Kidney transplant chains shorten the wait for wellness |url=http://www.healthzone.ca/health/newsfeatures/article/1136032--kidney-transplant-chains-shorten-the-wait-for-wellness |archive-url=https://web.archive.org/web/20120226092412/http://www.healthzone.ca/health/newsfeatures/article/1136032--kidney-transplant-chains-shorten-the-wait-for-wellness |archive-date=26 February 2012 |access-date=27 February 2012 |publisher=Healthzone.ca}}</ref><ref>{{cite news |author=Laurence, Jeremy |date=27 February 2012 |title=60 lives linked in kidney donor chain |url=http://www.northernstar.com.au/story/2012/02/27/60-lives-linked-kidney-donor-chain/ |access-date=27 February 2012 |newspaper=Northern Star}}</ref>

In May 2023, [[New York Presbyterian Morgan Stanley Children's Hospital]] performed the first domino heart transplantation in a baby, eventually saving two baby girls.<ref>{{cite web |date=8 August 2023 |title=Groundbreaking 'domino' heart surgery at NYC hospital saves lives of 2 baby girls |url=https://www.nbcnewyork.com/news/good-news/groundbreaking-domino-heart-surgery-at-nyc-hospital-saves-lives-of-2-baby-girls/4575196/}}</ref>

=== ABO-incompatible transplants ===
{{Main|ABO-incompatible transplantation}}

Because very young children (generally under 12 months, but often as old as 24 months<ref name="west2009">{{cite web |date=30 July 2009 |title=ABO Incompatible Heart Transplantation in Young Infants |url=http://www.myast.org/podcasts/abo-incompatible-heart-transplantation-young-infants |url-status=dead |archive-url=https://web.archive.org/web/20131220072758/http://www.myast.org/podcasts/abo-incompatible-heart-transplantation-young-infants |archive-date=20 December 2013 |access-date=25 December 2013 |publisher=American Society of Transplantation}}</ref>) do not have a well-developed immune system,<ref name="west2001">{{cite journal |author1=West, L.J.|author2=Pollock-Barziv, S.M.|author3=Dipchand, A.I.|author4=Lee, K.J.J.|author5=Cardella, C.J.|author6=Benson, L.N. |display-authors=etal |year=2001 |title=ABO-incompatible (ABOi) heart transplantation in infants |journal=New England Journal of Medicine |volume=344 |issue=11 |pages=793–800 |doi=10.1056/NEJM200103153441102 |pmid=11248154 |doi-access=free}}</ref> 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.<ref name="saczkowski2010">{{cite journal |author1=Saczkowski, R.|author2=Dacey, C.|author3=Bernier, P.L. |year=2010 |title=Does ABO-incompatible and ABO-compatible neonatal heart transplant have equivalent survival? |journal=Interactive Cardiovascular and Thoracic Surgery |volume=10 |issue=6 |pages=1026–33 |doi=10.1510/icvts.2009.229757 |pmid=20308266 |doi-access=free}}</ref> While focus has been on infant heart transplants, the principles generally apply to other forms of solid organ transplantation.<ref name="west2009" />

The most important factors are that the recipient not have produced [[isohemagglutinin]]s, and that they have low levels of T&nbsp;cell-independent [[antigen]]s.<ref name="west2001" /><ref name="burch2004">{{cite journal |author1=Burch, M |author2=Aurora, P |year=2004 |title=Current status of paediatric heart, lung, and heart-lung transplantation |journal=Archives of Disease in Childhood |volume=89 |issue=4 |pages=386–89 |doi=10.1136/adc.2002.017186 |pmc=1719883 |pmid=15033856}}</ref> [[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,<ref name="unos_policy_3.7">{{cite web |date=31 January 2013 |title=OPTN Policy 3.7 – Allocation of Thoracic Organs |url=http://optn.transplant.hrsa.gov/policiesAndBylaws/policies.asp |url-status=dead |archive-url=https://web.archive.org/web/20131207035214/http://optn.transplant.hrsa.gov/policiesAndBylaws/policies.asp |archive-date=7 December 2013 |access-date=25 December 2013 |publisher=United Network for Organ Sharing}}</ref><ref name="urschel2013">{{cite journal |vauthors=Urschel S, Larsen IM, Kirk R, Flett J, Burch M, Shaw N, Birnbaum J, Netz H, Pahl E, Matthews KL, Chinnock R, Johnston JK, Derkatz K, West LJ |year=2013 |title=ABO-incompatible heart transplantation in early childhood: An international multicenter study of clinical experiences and limits |journal=The Journal of Heart and Lung Transplantation |volume=32 |issue=3 |pages=285–92 |doi=10.1016/j.healun.2012.11.022 |pmid=23305695 |doi-access=free}}</ref> and if there is no matching ABOc recipient.<ref name="unos_policy_3.7" /><ref name="urschel2013" /><ref name="almond2010">{{cite journal |vauthors=Almond CS, Gauvreau K, Thiagarajan RR, Piercey GE, Blume ED, Smoot LB, Fynn-Thompson F, Singh TP |date=May 2010 |title=Impact of ABO-Incompatible Listing on Wait-List Outcomes Among Infants Listed for Heart Transplantation in the United States: A Propensity Analysis |journal=Circulation |volume=121 |issue=17 |pages=1926–33 |doi=10.1161/circulationaha.109.885756 |pmc=4273502 |pmid=20404257}}</ref> 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.<ref name="fan2004">{{cite journal |vauthors=Fan X, Ang A, Pollock-Barziv SM, Dipchand AI, Ruiz P, Wilson G, Platt JL, West LJ |year=2004 |title=Donor-specific B-cell tolerance after ABO-incompatible infant heart transplantation |journal=Nature Medicine |volume=10 |issue=11 |pages=1227–33 |doi=10.1038/nm1126 |pmid=15502841 |s2cid=26566529}}</ref> 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.<ref name="west2009" /><ref name="urschel2013" />

Limited success has been achieved in ABO-incompatible heart transplants in adults,<ref name="tyden2012">{{cite journal |author1=Tydén, G.|author2=Hagerman, I.|author3=Grinnemo, K.H.|author4=Svenarud, P.|author5=van der Linden, J.|author6=Kumlien, G.|author7=Wernerson, A. |year=2012 |title=Intentional ABO-incompatible heart transplantation: a case report of 2 adult patients |journal=The Journal of Heart and Lung Transplantation |volume=31 |issue=12 |pages=1307–10 |doi=10.1016/j.healun.2012.09.011 |pmid=23107062}}</ref> though this requires that the adult recipients have low levels of anti-A or anti-B antibodies.<ref name="tyden2012" /> Renal transplantation is more successful, with similar long-term graft survival rates to ABOc transplants.<ref name="urschel2013" />

=== 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.<ref>{{cite web |title=Robotic transplant an option for obese kidney patients &#124; UIC Today |url=https://news.uic.edu/robotic-surgery-levels-field-for-obese-patients-needing-kidney-transplants |url-status=live |archive-url=https://web.archive.org/web/20160304003330/https://news.uic.edu/robotic-surgery-levels-field-for-obese-patients-needing-kidney-transplants |archive-date=4 March 2016 |access-date=2014-01-28}}</ref><ref>{{cite journal |vauthors=Oberholzer J, Giulianotti P, Danielson KK, Spaggiari M, Bejarano-Pineda L, Bianco F, Tzvetanov I, Ayloo S, Jeon H, Garcia-Roca R, Thielke J, Tang I, Akkina S, Becker B, Kinzer K, Patel A, Benedetti E |date=March 2013 |title=Minimally invasive robotic kidney transplantation for obese patients previously denied access to transplantation. |journal=Am J Transplant |volume=13 |issue=3 |pages=721–28 |doi=10.1111/ajt.12078 |pmc=3647345 |pmid=23437881}}</ref>

=== Impact of Human Herpesvirus 6 (HHV-6) Reactivation on Pediatric Liver Transplantation ===
[[Human herpesvirus 6]] (HHV-6) reactivation emerges as a notable concern in pediatric liver transplantation, potentially influencing both graft and recipient health. HHV-6, prevalent in a substantial portion of the population, can manifest in liver transplant recipients with inherited chromosomally integrated HHV-6 (iciHHV-6), predisposing them to heightened risks of complications such as graft-versus-host disease and allograft rejections. Recent case studies underscore the significance of HHV-6 reactivation, demonstrating its ability to infect liver grafts and impact recipient outcomes. Clinical management involves early detection, targeted antiviral therapy, and vigilant monitoring post-transplantation, with future research aimed at optimizing preventive measures and therapeutic interventions to mitigate the impact of HHV-6 reactivation on pediatric liver transplant outcomes.<ref>{{cite journal |last1=Hannolainen |first1=Leo |last2=Pyöriä |first2=Lari |last3=Pratas |first3=Diogo |last4=Lohi |first4=Jouko |last5=Skuja |first5=Sandra |last6=Rasa-Dzelzkaleja |first6=Santa |last7=Murovska |first7=Modra |last8=Hedman |first8=Klaus |last9=Jahnukainen |first9=Timo |last10=Perdomo |first10=Maria Fernanda |date=2024 |title=Reactivation of a transplant recipient's inherited human herpesvirus 6 and implications to the graft |journal=The Journal of Infectious Diseases |volume=231 |issue=2 |pages=e267–e276 |doi=10.1093/infdis/jiae268 |pmid=38768311 |doi-access=free|pmc=11841639 }}</ref>