Can Babe save your bacon?
The worldwide shortage of human organ donors has led to research into xenotransplantation. Pigs organs are of a similiar size to human organs and they perform some similiar physiological functions, therefore they have become the focus of xenotransplantation research.There are three main concerns with xenotransplantation: 1. rejection of the transplanted organ by the recipient’s immune system; 2. zoonosis; and 3. ethical and animal welfare issues.
The body’s immune system can react aggressively against the pig organ tissue, which it recognises as ‘foreign’. Hyperacute rejection (one of four types of rejection) involves human antibodies attaching to sugar molecules on the surface of pig organ cells. Thus scientists have used genetic engineering techniques to produce cloned pigs where 5 alpha1,3-galactosyltransferase (the gene responsible for making the enzyme that attaches the sugar molecules to the pig cell surface) has been knocked out.
There are also concerns that pig viruses, in particular porcine endogenous retrovirus (PERV) could be transmitted to recipients via the transplant organ. Research has yet to ascertain conclusively whether this virus can be passed to humans via xenotransplantation, and the scientific community remains divided on the issue.
Ethical debate rages because many animals are killed during xenotransplantation research experiments. Welfare groups maintain these experiments cause unacceptable suffering to animals and should be halted.
From a scientific and medical perspective, xenotransplantation is undeniably fascinating. However, humankind will have to decide whether the associated risks and ethical questions have been addressed appropriately before embracing this biotechnology.
Primary Resources
The body’s immune system can react aggressively against the pig organ tissue, which it recognises as ‘foreign’. Hyperacute rejection (one of four types of rejection) involves human antibodies attaching to sugar molecules on the surface of pig organ cells. Thus scientists have used genetic engineering techniques to produce cloned pigs where 5 alpha1,3-galactosyltransferase (the gene responsible for making the enzyme that attaches the sugar molecules to the pig cell surface) has been knocked out.
There are also concerns that pig viruses, in particular porcine endogenous retrovirus (PERV) could be transmitted to recipients via the transplant organ. Research has yet to ascertain conclusively whether this virus can be passed to humans via xenotransplantation, and the scientific community remains divided on the issue.
Ethical debate rages because many animals are killed during xenotransplantation research experiments. Welfare groups maintain these experiments cause unacceptable suffering to animals and should be halted.
From a scientific and medical perspective, xenotransplantation is undeniably fascinating. However, humankind will have to decide whether the associated risks and ethical questions have been addressed appropriately before embracing this biotechnology.
Primary Resources
Dobson, Roger 2002, ‘Scientists produce genetically engineered, cloned pigs for xenotransplantation’ viewed 25 May 2007, http://www.bmj.com/cgi/content/full/324/7329/67. Access on-line here
Tai, HC, Zhu, X, Hara, H, Lin, YJ, Ezzelarab, M, Long, C, Ball, S, Avares, D 2007, ‘The pig-to-primate immune response: relevance for xenotransplantation.’, Xenotransplantation, 14(3):227-35. Access on-line here
Salleh, Anna 2004, ‘Pigs transplants may be safer than thought’, viewed 25 May 2007, http://www.abc.net.au/science/news/tech/InnovationRepublish_1189959.htm. Access on-line here.
Michler, Robert E 1996, ‘Xenotransplantation: Risks, Clinical Potential, and Future Prospects’ viewed 25 May 2007, http://www.cdc.gov/ncidod/EID/vol2no1/michler.htm. Access on-line here.
Secondary resources
Animal welfare website
Experimental biology website
Posted by Meghan Spencer
