Allotransplant (allo- from the Greek meaning "other") is the transplantation of cells, tissues, or organs, to a recipient from a genetically non-identical donor of the same species. The transplant is called an allograft, allogeneic transplant, or homograft. Most human tissue and organ transplants are allografts. A xenograft is a graft from a different species, such as when animal tissue is grafted into human tissue, or when human cancer cells are implanted in mice for experimental tumor studies. Allografts can be referred to as "homostatic" if they are biologically inert when transplanted, such as bone and cartilage.
Informed consent is required before tissue is harvested from a donor, alive or dead. Proper screening for pathology and risk factors for communicable diseases such as HIV and Hepatitis B and C is then conducted.
In the US, donor tissue must be harvested and processed adhering to the Current Good Tissue Practices rule. In most cases it is sent to tissue banks for processing and distribution. Each year, Food and Drug Administration regulated and American Association of Tissue Banks-accredited tissue banks distribute 1.5 million bone and tissue allografts.
Transplantable organs and tissues
A variety of organs and tissues can be used for allografts, including:
- Anterior cruciate ligament (ACL) repair
- Joint reconstruction in the knee and ankle
- Meniscal replacement
- Reconstruction due to cancer or trauma
- Ridge augmentation in dental procedures
- Shoulder repair
- Spinal fusion
- Urological procedures
- skin transplants
- corneal transplants
- heart transplants
- heart valves
- lung transplantation
- Intestinal transplantation (Isolated Small Bowel, Intestine & Liver, Multivisceral)
- liver transplants
- kidney transplants
- pancreas transplantation
- islet cell transplantation
- bone marrow transplants
- bone allograft
- ligament or tendon allograft
Laws and regulations
In the US, the Federal government Food and Drug Administration (FDA) has regulated human tissue intended for transplants since 1993. In order to ensure the quality of donor tissue and reduce contamination and disease transmission risks, three regulations addressing manufacturing activities associated with human cells, tissues, and cellular and tissue-based products (HCT/Ps) were promulgated in May 2005: The first requires companies producing and distributing HCT/Ps to register with the FDA. The second, called the “Donor Eligibility” rule, proscribes criteria for donor eligibility. The third, the “Current Good Tissue Practices” rule, oversees overall processing and distribution practices of each company.
Other transplant options
- Autograft, tissue transplanted from one site to another on the same patient. An autograft reduces the risk of rejection but requires a second surgery site, adding pain, risk and possible longer aftercare.
- Xenograft, a transplant from another species
- Isograft, a transplant from a genetically identical donor, such as an identical twin.
- Synthetic and metal implants. Unlike allografts, such grafts do not corporate into the body.
As with many operations, allotransplantation also has some side effects. A limiting factor in tissue allotransplantation for reconstructive surgery deals with the side effects of immunosuppression (metabolic disorders, malignancies, opportunistic infections) which is a predominant issue. Also it can not be forgotten that the risk of transmitting infection is very high.
- Surgery For ACL Tears
- (W. P. Longmire, J. National Cancer Institute 14, 669: The term homostatic graft might be applied to inert tissues such as bone and cartilage when transferred from one individual to another of the same species; and the term homovital graft might be used in reference to grafts whose cells must continue to grow and reproduce for the graft to be effective after similar transplantation; H. Conway, The Bulletin of the Hong Kong Chinese Medical Association 13, 43: These grafts persist however as homostatic grafts and are completely replaced by host tissues in time.)
- "Composite Tissue Allotransplantation and Reconstructive Surgery". US National Library of Medincine.
- http://www.organdonor.gov/donor/registry.shtm (How to register to be a donor in the USA)
- Allogeneic stem cell transplantation entry in the public domain NCI Dictionary of Cancer Terms
- Allogeneic bone marrow transplantation entry in the public domain NCI Dictionary of Cancer Terms