Medicines don't just come from the pill bottle or pharmaceutical plant -- many are
assembled by biological factories that we call plants, animals or bacteria. After all, organisms are the original experts at making the hormones, proteins and enzymes that underpin life.
Over the past few years, scientists have "taught" animals to make drugs in their milk through genetic manipulation. Already three drugs -- chemicals purified from milk -- are in clinical trials. Indeed, Dolly, the cloned sheep, was created as a step toward producing identical sheep that secrete drugs in their milk.
Knowing that it's difficult to isolate compounds from the complex chemical soup called milk, Bob Wall of the U.S. Department of Agriculture's Agricultural Research Service was intrigued by the idea of purifying another bodily liquid. This one is yellow, not white, and it's rarely saved, let alone pasteurized and bottled for sale in supermarkets.
If you're thinking urine, you're way ahead of this game. Wall notes that this fluid, designed to rid the body of the byproducts of metabolism, has several advantages over milk. First, there's the simple fact that all animals make urine, while only females make milk. Second, urine could be cheaper -- since, as Wall points out, much of the cost of making bio-drugs comes from the purification stage.
On Golden Pond
Working with experimental mice, Wall and Tung-Tien Sun of New York University inserted a piece of DNA that contained the instructions for human growth hormone into a mouse gene that is active only in the bladder. He chose growth hormone, a chemical that regulates growth and development, because only a tiny amount circulating in the blood can make a female lab mouse sterile. That makes it easy to detect "leaks" from the bladder or hormone being produced in the wrong part of the animal.
He found that the system indeed made hormone, although not as much as would be made in milk using the same technique. Some growth hormone, for an unknown reason, was present in the circulation.
For now, the advance awaits industrial interest, Wall says. He notes that USDA did not patent the discovery, so it's available to anybody, yet ironically enough, the absence of a patent may have quelled industrial interest. A company that spent money bringing the advance on the market could not be sure of profiting from its investment.
Is urine a questionable source of medicine? It may be unappealing, but it does seem to work. Wall observes that urine from 75,000 Canadian horses is currently supplying replacement estrogen that's used as a drug by menopausal women.
WARNING! Worms invade science labs.
