Monday, January 23, 2012

Bacon, Ham, Heart Valves?

I am pleased to post this guest article by Elaine Hirsch

Pigs have been on the human menu for millennia, but medical research now has another use for the floppy-eared trotters. Thanks to their genetic similarities, pigs are believed to be excellent candidates for organ transplants. Exciting studies are going on right now, so how soon can we expect to see pigs as lifesavers instead of a rich and tasty source of cholesterol?

Researchers are very optimistic about the future of xenotransplantation. According to an article in Medical News Today, breakthroughs in genetic engineering mean that clinical trials in humans are only a few years away, Medical transcriptions of organ transplant surgeries often cite mismatched organs and blood types as reasons for the host rejecting the transplant. Luckily, advances are being made to counter this problem.

Xenotransplantation, or transplantation of an organ or cells from a different species into a human, has seen some very big developments recently. Currently, organ transplants come from human donors (deceased, except in the case of kidneys and parts of other organs including the lung, liver and pancreas that are now being transplanted from living donors.) It is very difficult to find a donor genetically similar enough to risk the operation, and even then, rejection rates are high. In addition, artificial devices are costly and inefficient. A plentiful source of viable, genetically compatible organs could save the lives of thousands of people every year.

Pigs are genetically very similar to humans and their organs are close in size to our own, so they are the main focus of transplant research. Scientists are working on genetically modifying pigs to produce organs that will not trigger an autoimmune response in recipients, meaning they will not be rejected by the host's body. Once a "donor strain" is established, these pigs can be bred naturally and produce further generations of donors at very little cost.

In New Zealand, scientists are experimenting with transplanting the pancreatic islets of pigs into other primates. The study has encountered problems, and researchers anticipate further issues with human candidates before the process can be perfected, but they expect significant advances in the coming years. One diabetic monkey survived for more than a year with no other therapy than these islets.

Another study hopes to use the neuronal cells of pigs to reverse the progress of degenerative conditions such as Parkinson's disease. Nonhuman primate recipients have shown improvement in locomotive function, but they have also succumbed to other conditions due to artificially weakened immune systems. The authors are cautiously optimistic and hope to solve this problem.

Less exotic uses of animal organs undergoing study include the transplant of liver and red blood cells and corneas. Ophthalmologists such as Dr. David Hwang are culturing bovine corneal epithelial cells for transplant into humans. The cloned cells would develop in the recipient's eye just like human cells, but cow cells are much easier to grow in a lab than those of a human.

There are and probably always will be ethical objections to using animals as cheap sources of organs. Animal activists decry the use of animals for experimentation and harvest, and many patients would refuse the transplants for religious reasons. A variant of Creutzfeldt-Jakob Syndrome may have been transmitted through human-to-human transplants, and fears of a retrovirus from foreign tissue attacking humans continue to surface despite scientists' reassurance that this is unlikely.

Will the ethical objections and experimental setbacks crush this field of study before it can grow? As with so many questions, the answer is in the flow of money. Researchers seem to have no problem acquiring funding to continue their studies. Given the scarcity of compatible human donors and the steadily increasing number of patients with diabetes, neural degenerative diseases, and heart problems, it's a safe bet that xenotransplantation will be the future of medicine. Ten years from now, the term pig-headed may have a whole new meaning.

About the author:
Elaine Hirsch is kind of a jack-of-all-interests, from education and history to medicine and videogames. This makes it difficult to choose just one life path, so she is currently working as a writer for various education-related sites, including and writing about all these things instead.

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