Animal urine has the potential to become a new source of valuable hormones and other human drugs, according to Agricultural Research Service and cooperating scientists.

ARS and New York University researchers have developed transgenic mice that produce, in the lining of their bladders, human growth hormones that accumulate in the urine. This model system, the scientists say, shows that the approach could be used in larger animals that produce more urine. The scientists reported their findings in the January issue of Nature Biotechnology.

The researchers say producing medicine in animal urine has the potential to be more economical than mammary gland "pharming"--the current practice of producing pharmaceuticals in the milk of transgenic animals.

ARS scientists at the Gene Evaluation and Mapping Lab in Beltsville, Md., say it will be possible to collect urine from livestock about a day or two after the animals are born. This early collection is a major advantage over mammary gland pharming, since it takes two to three years before the female of most farm animal species reaches sexual maturity, gestates and lactates for the first time. Another advantage: urine can be taken from both males and females.

Pharmaceuticals, such as human growth hormones, alpha antitrypsin (used for treating emphysema) and lactoferrin (used to treat gut infections in babies), and other human medications, are typically produced in the milk of transgenic livestock.

The researchers stress that the findings are preliminary and that there are drawbacks. For one, scientists note that the bladder produces a much lower concentration of drugs than does the mammary gland, but because purification from urine should be less costly the low concentration should not pose a major problem. The scientists say this demonstrates that the approach is feasible, but more research is needed to perfect the system.

Scientific contact: Robert J. Wall, ARS Gene Evaluation and Mapping Lab, Beltsville, Md., phone (301) 504-8362, fax (301) 504-8414, bwall@ggpl.arsusda.gov.