Xenograft: Difference between revisions
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Revision as of 14:05, 22 October 2012
Xenograft
- Definition
- Obstacles In Xenograft Usage
- References
Definition
A Xenograft is defined as the transplantation of a tissue or whole organ across species'. [1]
The process has been done many times within Research with Xenografts between rats and mice common, however there are many problems surrounding the continued acceptance of a xenograft from a recipient. If these issues could be overcome then the possibilities are enourmous to both medicine and Humanity as a whole; for one the crippling lack of donor organs would mean life to many on Transplant waiting lists.[2]
Obstacles In Xenograft Usage
There are a few key obstacles within Xenograft usage. Namely they are;
1) MHC Incompatibility
2) Other, Minor Alloantigens
Incompatibilities within the Donor and Recipient's Major and Minor Histocompatibility Complexes cause Non-self Specific T-Cells to be activated that in turn activate the production of Alloantibodies and the Complement and Clotting Cascades against the graft (Be it a Xenograft or Allograft, in this case the former.). Non-self Specific T-Cells are always produced by the Immune System and as a result hemorrhaging of the Graft occurs rapidly.[3] MHC Incompatobility is not as much of a problem as it was in the past however, Immuno-suppressent drugs and more recently anti-CD4 and anti-CD8 Monoclonal Antibodies can be given to the Recipient to overcome any MHC incompatibilities, thus prolonging the Recipient's tolerance to the graft.[4] Anti-CD4 and anti-CD8 Monoclonal Antibodies have the added benefit of not suppressing the entirety of the Recipient's Immune System, as well as avoiding the need for T-Cell Depletion, so that the Recipient is not vulnerable to oppurtunistic infections.
Other Minor Alloantigens, for example the mammalian ubiquitous Carbohydrate Antigen α-Gal, have natural antibodies against them within primates
References
- ↑ Game, DS. (2001 ). Rejection mechanisms in transplantation.. Wien Klin Wochenschr.. 113 (20-21), 832-8.
- ↑ Murphy, K (2012). Janeway's Immunobiology. 8th ed. New York: Garland Sciences. p.657-658
- ↑ Murphy, K (2012). Janeway's Immunobiology. 8th ed. New York: Garland Sciences. p.652-654, 657
- ↑ Zonghua Chen. (1992). Tolerance in the mouse to major histocompatibility complex-mismatched heart allografts, and to rat heart xenografts, using monoclonal antibodies to CD4 and CD8. European Journal of Immunology. 22 (3), p805-810. DOI: 10.1002/eji.1830220326