More than milk: Indian scientists find new use for the simple goat. Credit: Courtesy of the Centre for Liver Diseases, Hyderabad

The Indian government has agreed to fund research on the humble goat, Capra hircus, as a source of cells for liver transplants. If monkey trials planned for June confirm encouraging results in rats, goat hepatocytes may be transplanted into Indian patients suffering from acute liver failure before the end of the year.

“To our knowledge we are the first to show that goat is an alternative to pig for xenotransplantation,” says Chittoor Mohammed Habibullah, head of the Center for Liver Research and Diagnostics at the Deccan College of Medical Sciences. He and his colleagues have also filed a US patent.

The Indian Department of Biotechnology, which spent Rs 50 million (roughly $1 million) on the project over the last four years, has granted Rs 10.7 million for the monkey trials and for potential human experiments. The researchers' preliminary findings are extremely promising, says Manju Sharma, secretary to the department.

Based on in vitro comparative studies, goat hepatocytes are similar to human fetal liver cells in both morphology and biochemical function, says Habibullah. In terms of hepatic functions like albumin synthesis, bile formation and converting ammonia into urea, he adds, “goat hepatocytes are as good as liver cells from pig or human fetus.” Last year, his group designed a bioreactor module with encapsulated goat hepatocytes—a crude bio-artificial liver support system like a dialyzer for kidney failure patients—and demonstrated its ability to detoxify ammonia to urea and to metabolize glucose (Ind. J. Gastroenterol. 21, 55–58; 2002).

Although pig liver cells are readily available, various risks—such as immune rejection and transmission of endogenous retroviruses to recipients—limit their use. Because Indians have for centuries bred goats for their milk, the highly domesticated animals should have a lesser chance of harboring viruses harmful to humans, Habibullah says. Goat hepatocytes may carry their own share of risks, such as prions or ruminant virus infection, experts warn. But a screening of 20 goats by the Hyderabad-based Veterinary Biological Research Institute has turned up no known pathogens or zoonotic diseases.

Habibullah says the “α-gal epitope” responsible for graft rejection is more pronounced on pig cells than on goat cells, suggesting goat cells are less likely to be rejected. For religious reasons, goats would also be more acceptable than pigs to Jews and Muslims.