
Scientists
Serve Up a Dish of Pig Liver CellsBy Jan Suszkiw October 19, 2001Using in vitro techniques,
Agricultural Research Service scientists
have cultured a pig liver cell line that performs some of the organ's functions
in a petri dish. In swine, humans and other animals, the liver's duties include detoxifying
blood, making blood-clotting substances and secreting bile. The pig liver
culture, PICM-19, contains hepatocyte and bile duct cells that synthesize serum
proteins, show P450 (enzyme) activity and display other liverlike behaviors. With PICM-19, animal researchers can design in vitro models of the
liver to study gene expression, nutrient metabolism, drug toxicity and bile
duct formation outside the animal's body, notes Neil Talbot of ARS'
Gene Evaluation and
Mapping Laboratory in Beltsville, Md. There, he and Tom Caperna of ARS'
Growth Biology Laboratorydeveloped PICM-19 to expedite research aimed at improving swine traits such as
lean muscle production. The liver is of interest since it aids digestion and
regulates important growth hormones. In other research, biomedical scientists have used pig liver cells in
bio-artificial liver devices (BALD), which are undergoing clinical trials to
provide temporary dialysis for human patients. But culturing and maintaining
such cells has proven difficult: Once removed from the body, they soon lose
their normal functioning. Starting in 1993, Talbot and Caperna overcame the problem by developing a
novel procedure for culturing hepatocyte and bile duct cells from pig embryo
stem (ES) cells, as well as from intact pig livers. In a first for swine that
may also have biomedical applications, the ARS researchers coaxed the ES cells
to become liverlike hepatocytes and bile duct cells, which comprise 98 percent
of the organ's tissues. After four years in continuous culture, PICM-19 has retained its desired
properties. Tests with mice show it's not tumor-causing, a feature critical to
nutrient metabolism research and BALD applications. PICM-19 also lends itself
to developing in vitro alternatives to testing experimental medicines or
other substances in live animals, according to Talbot. ARS, which holds two patents on PICM-19, is the
U.S. Department of Agriculture's chief
scientific research agency. U.S. Department of Agriculture |