BY dR. DAVE HEPBURN | OCTOBER 3, 2012
As a species, humans apparently aren’t terribly bothered about farming other species for food, clothing or luggage, yet controversy swirls around the use of animals bred to save the lives of thousands of people waiting for organ transplants. Xenotransplantation refers to the transplanting of live organs from one species to another.
It appears that the baboon kidney and heart happens to be the best size match for a human organ. In addition, baboon tissue is less severely rejected by the human host’s immune system. Unfortunately finding a baboon, outside of Ottawa, is relatively rare.
Ranch hand, willing to relocate to exciting new baboon ranch in the Kootenays. Must be able to recover quickly from convulsive fits of laughter after hours of gazing upon hundreds of brilliant psychedelic butts. Imagine the thrill on a beautiful Fernie morning as the foreman stirs your soul with “Round up them ‘boons boys, its harvest time!” Call now and wrangle yerself a baboon.
The more similar an animal is to a human, the less likely the human’s immune system is to reject that animal’s organ. A yak liver or a muskrat ovary, for example, would be savagely rejected in nanoseconds by a human host. And while any organ belonging to a rat would likely happily survive for years in most men of the male variety, it is the pig that is most like man and has become the chosen animal for xenotransplantation research. (Did I just sense a collective nod from women the world over?) Porcine tissue has already been used for years as insulin and for replacement of defective heart valves.
As if genetically modified foods haven’t stirred enough controversy, genetically modified organs are sure to raise concerns. With a deft touch of genetic manipulation, pigs can now be bred possessing major organs that are more human than pig. These organs are therefore less likely to be rejected by the human host. As sacrificing a pig is slightly more acceptable than sacrificing Snooki, pigs are the animals of choice.
Advantages of xenotransplantation are obvious in a world where too many recipients await too few human organ donors. Plump pieces of pig pancreas could function in diabetics. Fetal pig brain may be used to mitigate the symptoms of Parkinson’s disease.
(SORRY: I pause here, once again distracted by my trusty hound, Leo, who is now handing me a pair of slippers to go along with the newspaper, clean socks and hot chocolate brought to me earlier. Normally this dog has an irritating habit of reading over my shoulder, trying to fix my spelling misteaks. This past weak, however, the ignowrant beast has been extra nice but has refused to help me on the column at all.)
The major risk of animal organ transplants is the potential for transmission of animal viruses into the human population. The pig, for example, coexists peacefully with a virus known as Porcine Endogenous RetroVirus (PERV) that cannot be eliminated. Studies have shown that PERV transmission to lab rats has caused no disease, though apparently the PERV rats did zip about trying to peek at other rats in the shower. We don’t know what a PERV might do in man, but considering the effects of other cross species viruses such as Ebola and possibly the AIDS virus, caution cannot be overemphasized. And before running down to the barnyard market in search of those farm-fresh spare organs to replace a clogged kidney or a pickled liver, realize that only 31 people have attempted xenotransplantation and none have survived. The human body eventually rejects the xenograft. The wee Californian, Baby Fae, lasted a whopping 20 days with a baboon heart. The use of these xeno-organs as a temporary measure (actually kept outside the body), while awaiting a human donor, is also being studied. But as the race for more powerful anti-rejection (immunosuppressant) drugs escalates and herds of transgenic swine carry ready-to-harvest human organs, hospital orders may include; “Hello, Swine's Surrogate Sow Ranch? This is the hospital and we’d like to order two hearts, 17 kidneys, one liver and a couple of pounds of bacon.”
(Excuse me- it’s the dog again.) “No Leo, I do not want more slippers or the Johnson’s cat!” I mean how smart can an animal be, especially one who drinks from toilets, chases his tail and day trades. Now, this next section on canine xenotransgraggjtpasa$*s^!\##~` kv% kuvqwey##wqpj.