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Part IV. Animal-to-human transplant: Xenotransplantation
The shortage of organs for transplant is a tragedy. According to the United Network of Organ Sharing, as of July 29 of this year, in the United States alone, there were more than 70,000 patients waiting for organs: almost 50,000 for kidneys, 16,000 for livers, more than 2,300 for kidney-pancreas, about 4,000 for hearts and more than 3,000 for lungs. And every 14 minutes a new name is added to the national organ transplant waiting list. In Europe 50,000 patients are on a waiting list for one organ or another. Thus, you can have an idea of what the numbers would be worldwide. On the other hand, in 1999 in the US almost 22,000 transplants were carried out, which tells you that the race between the number of transplants and the number of people in the waiting lists is a lost one. There is an always-increasing need for new organs. In my last article I told you about stem cells. Here, I will tell you about another hot avenue of research eagerly followed by several biotech companies with the hope of saving thousands of lives a year and making a lot of money in the process: xenotransplantation. How much money? It has been calculated that by the year 2010 the market for such organs could be on the order of $6 billion. The animal of choice for xenotransplantation is the pig. The reasons are that pig organs are anatomically very similar to human ones; thus, they fit well into human cavities. And the fact that pigs will be used as factories for human organs will supposedly raise fewer bioethical concerns, since pigs are already farmed for food. As usual, we will start with the problems. There are two major ones: immune rejection and porcine retroviruses. To try to humanize pigs, that is, to avoid the immune rejection, Nextran, Inc., in the US and Imutran in England have been working hard in this area. On one hand, they are trying to genetically manipulate the pigs' ova to eliminate from the piglets' organs a sugar that is an important factor in the rejection scenario. On the other, since everybody is immunologically different, transgenic pigs will have to be genetically tailored for each organ recipient. Both of these biotech companies have been studying those processes for more than ten years.
The copyright of the article MOLECULAR AND CELLULAR MEDICINE ADVANCES = ETERNAL YOUTH? in Molecular Biology/Medicine is owned by Juan C. Mendible. Permission to republish MOLECULAR AND CELLULAR MEDICINE ADVANCES = ETERNAL YOUTH? in print or online must be granted by the author in writing.
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