Currently, over 100,000 people lie in wait of needed organs (1). There are approximately 14,000 donations per year (2). Unfortunately, many on the wait list will not receive organs.
Medicine should take (and is taking) efforts to right this organ shortage. Xenotransplantation, transplantation of animal organs into human beings, is a proposed mechanism to alleviate the organ shortage. Given that the food industry kills animals for the sake of feeding the population, it would seem that xenotransplantation would be valid. Unfortunately not – though xenotransplantation may save many lives on organ waiting lists, fears of disease transfer from animals to humans is too great to allow trans-species transplantation.
“Genetically engineered pigs, bred under special conditions,” are imagined to be the primary source of transplants. Even though no specific porcine disease has been transferred to humans through xenotransplantation (3), there is an increasing fear of various retroviruses mutating to infect humans. For example, the porcine endogenous retrovirus has been shown to infect human cells in vitro (4).
Given viruses’ exceedingly fast mutation rate (5), it is troubling to consider both human and animal organs side by side – Darwinian evolution would select viruses that could infect all types of cells. This is not a danger for just the individual harboring the xenotransplant – if these viruses mutated, they could cause diseases widespread in populations.
Trans-species viruses are worrisome – some past instances (e.g. HIV, swine flu) seem to have “a protein structure that [makes] vaccines work badly or never” (6). Saving some lives through xenotransplantation seems almost negligible in comparison to the number of lives threatened by virus mutations.
Given the pandemic nature of some similar viruses, enhancing probabilities of trans-species viruses seems foolhardy. If scientists can replace organs entirely with mechanical devices as they did with the Jarvik-7 artificial heart (7), xenotransplantation should not be considered. The real question is of priorities – since xenotransplantation is still in its infancy, scientists should emphasize alternative research because of probable trans-species disease propagation.
Sources:
2. http://optn.transplant.hrsa.gov/latestData/rptData.asp
3. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC88959/
4. http://www.uq.edu.au/oppe/PDFS/Xenotransplantation.pdf
5. http://www.college.ucla.edu/webproject/micro12/m12webnotes/viralevolution.htm
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