Word: pigged
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...often think of the first couple of years after a drug has been approved as its guinea-pig period. After all, even the most careful clinical trials of a new medication usually involve just a few thousand patients. So, in the beginning, only a drug's most common side effects are known. But once a pharmaceutical clears the Food and Drug Administration's review process, hundreds of thousands, if not millions, of people start taking it. That's when you get a better idea of the true rate of complications, as well as any untoward interactions with other drugs...
What causes porcine organs to be rejected so quickly is a sugar molecule on the surface of pig cells that identifies the tissue as unmistakably nonhuman. When the immune system spots this marker, it musters its defenses. PPL scientists recently succeeded in finding the gene responsible for the sugar and knocking it out of the nucleus of a pig cell. Their next step would be to extract that nucleus, insert it into a hollowed-out pig ovum and insert the ovum into the womb of a host sow. The sugar-free piglet that was eventually born could then be cloned...
...cloned piglets PPL introduced to the world last week were created in just this way, though for this first experiment in pig replication, the scientists left the sugar genes intact. "We wanted to work with pristine cells to make sure our cloning technique would indeed work," says Ayares. Now that they've proved it does, the scientists plan to raise the bar and try the same procedure with modified genes...
...sugar gene solves only the problem of short-term rejection. Long-term rejection, caused by blood coagulating around the new organ, requires that researchers re-engineer an entirely different set of genes that code for anticoagulants. But even this would not be a perfect solution, and recipients of pig organs would probably still have to take the same rainbow of antirejection drugs recipients of human organs must now endure...
Nonetheless, Ayares is optimistic, insisting that pig organs could be available in as little as five years. Hardy believes that whenever the tissue does come along, it will at first be rather small-bore stuff--pancreatic islet cells for diabetics, say--rather than hearts, kidneys or lungs. Whatever it is, even a little new transplant material is a big improvement over what's available now, and for gravely ill patients awaiting a donor, that's no small thing...