Online Encyclopedia
Organ transplant
An organ transplant is the transplantation of an organ (or part of one) from one body to another, for the purpose of replacing the recipient's damaged or failing organ with a working one from the donor. Donors can be living, or cadaveric (dead).
| Contents |
Origin of the transplantate
Blood transfusion and bone marrow transplants are special cases of a transplant where the transplanted part of the body is renewable; in other cases, the living organ donor either has another of the same organ (such as kidneys) or can donate part of an organ (such as split-liver, segmental pancreas and small intestine transplants).
Apart from brain-stem dead donors, who have formed the majority of cadaveric donors for the last twenty years, there is increasing use of non-heart beating donors to increase the potential pool of donors as demand for transplants continues to grow.
Types of transplants
Solitary transplants
Organs and tissues that can currently be transplanted include:
- Liver - liver transplant (one of the most difficult)
- Kidney - kidney transplant
- Pancreas - pancreas transplant (often together with the kidney in a pancreas-kidney transplant )
- Small intestine - intestinal transplant
- Lung - lung transplant
- Heart - heart transplant
- Corneas (the front clear part of the eye) - cornea transplant
- Skin - a skin graft
- Blood vessels
- Bone
Combined transplants
The heart and lungs are sometimes transplanted together, in a heart-lung transplant. This operation is usually performed for cystic fibrosis as both lungs need to be replaced and it is a technically easier operation to replace the heart and lungs en bloc. As the recipient's native heart is usually healthy, this can then itself be transplanted into someone needing a heart transplant; this is called a domino transplant. That term is also used for a special form of liver transplant, in which the recipient suffers from familial amyloidotic polyneuropathy causing the liver to produce a (very slow) poison; their liver can be transplanted into an older patient who is likely to die from other causes before a problem arises. [1] http://www.mayoclinic.org/news2003-sct/1622.html
Most pancreas transplants are performed for diabetes mellitus with chronic renal failure due to diabetic nephropathy and are transplanted together with a kidney. Diabetes alone does not typically justify a transplant.
Newer types
Hand transplant operations have been performed since 1998. The yield is not good enough to recommend this on a routine basis to those with mutilating injuries or congenital malformations.
Transplants that are nearly feasible today include:
- Face transplant
- Pancreatic islet cells (experimentally)
Organ transplants that can not be performed today include:
- Cardia or lower esophageal sphincter (LES) for achalasia
- Head transplant or whole-body transplant (apart from the science fiction overtones, there would be ethical issues with these modalities)
History
Successful inter-human allotransplants have a relatively long history, the operative skills were present long before the necessities for post-operative survival were discovered. Rejection was, is, and may always be the key problem.
The third century saints Damian and Cosmas are recorded as performing the first medical transplant - replacing the gangrenous leg of a white man with the leg of a dead Moor. Less miraculous was the work of French surgeon Alexis Carrel, in the 1900s, with the transplantation of arteries or veins. His skillful anastomosis operations, the new suturing techniques, laid the ground for later transplant surgery. From 1902 Carrel performed transplant experiments on dogs. Surgically successful in moving kidneys, hearts and spleens, he was one of the first to identify the problem of rejection.
Autotransplants, transfer of material on the same patient, was successfully demonstrated by Jean Casimir Guyon with skin in 1869. Slightly later, Jacques Reverdin used a similar technique to aid wound healing. Major steps in skin transplant s occurred during WW I, notably in the work of Harold Gillies at Aldershot. Among his advances was the tubed pedicle graft, maintaining a flesh connection from the donor site until the graft established its own blood flow. Gillies' assistant, Archibald McIndoe, carried on the work into WW II as reconstructive surgery . In 1962 the first successful replantation surgery was performed - re-attaching a severed limb and restoring (limited) functioning and feeling.
The first successful cornea transplant, a keratoplastic operation, was performed by Eduard Zirm in Austria in 1906; for all other transplants rejection seemed an insurmountable problem. In the late 1940s Peter Medawar, working for the National Institute for Medical Research , improved the understanding of rejection. Identifying the immune reactions in 1951 Medawar suggested that immunosuppressive drugs could be used. Cortisone had been recently discovered and the more effective azathioprine was identified in 1959, but it was not until the discovery of cyclosporine in 1970 that transplant surgery found a sufficiently powerful immunosuppressive.
The first successful human organ transplant was the kidney on 23 December 1954 in Boston by Joseph Murray and J. Hartwell Harrison. The kidney was the easiest organ to transplant, tissue-typing was simple, the organ was relatively easy to remove and implant, live donors could be used without difficulty, and in the event of failure kidney dialysis was available from the 1940s. Tissue-typing was essential to the success, early attempts in the 1950s on sufferers from Bright's disease had been very unsuccessful. The 1954 transplant was between identical twins.
The success with the kidney led to attempts with other organs. There was a successful cadaveric lung transplant into a lung cancer sufferer in June 1963 by James Hardy in Jackson, Mississippi. The patient survived for eighteen days before dying of kidney failure. Thomas Starzl of Denver attempted a liver transplant in the same year, but was not successful until 1967.
The heart was a major prize for transplant surgeons. But, as well as rejection issues the heart deteriorates within minutes of death so any operation would have to be performed at great speed. The development of the heart-lung machine was also needed. Lung pioneer James Hardy attempted a human heart transplant in 1964, but a premature failure of the recipient's heart caught Hardy with no human donor, he used a chimpanzee heart which failed very quickly. The first success was achieved December 3rd 1967 by Christiaan Barnard in Cape Town, South Africa. Louis Washkansky, the recipient, survived for eighteen days amid what many saw as a distasteful publicity circus. The media interest prompted a spate of heart transplants. Over a hundred were performed in 1968-69, but almost all the patients died within sixty days. Barnard's second patient, Philip Blaiberg , lived for 19 months.
As mentioned, it was the advent of cyclosporine that altered transplants from research surgery to life-saving treatment. In 1968 surgical pioneer Denton Cooley performed seventeen transplants including the first heart-lung transplant. Fourteen of his patients were dead within six months. By 1984 two-thirds of all heart transplant patients survived for five years or more. With organ transplants becoming commonplace, limited only by donors, surgeons moved onto more risky fields, multiple organ transplants on humans and whole-body transplant research on animals. On March 9th 1981 the first successful heart-lung transplant took place at Stanford University Hospital. The head surgeon, Bruce Reitz, credited the patient's recovery to cyclosporine-A.
The latest record transplant operation of eight organs, the liver, stomach, pancreas, small and large intestine, spleen, and two kidneys, was performed in the USA in March 2004.
Other researchers moved onto the use of artificial, xenotransplants or trans-genic organs.
See also
Reference
- Morris PJ. Transplantation — A Medical Miracle of the 20th Century. N Engl J Med 2004;351:2678-80. Fulltext. http://content.nejm.org/cgi/content/extract/351/26/2678?view=extract Medline abstract http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstra
ct&list_uids=15616201 (PMID 15616201).
External link
- Immune find may help transplants http://news.bbc.co.uk/2/hi/health/3950021.stm
- TransWeb http://www.med.umich.edu/trans/transweb/index.htm
- Flash presentation of face transplant http://www.guardian.co.uk/flash/0,5860,1092780,00.html
- Research work on inducing transplant tolerance in humans http://www.immunetolerance.org/research/core/index.html
- United Network for Organ Sharing http://www.unos.org/