A human protein that regulates blood clotting, usually presentin trace amounts, is being secreted in quantity in the milk oftransgenic pigs, a Virginia Polytechnic Institute scientistreported Monday.
The American Red Cross is collaborating on the transgenic pigwork and will help the Institute commercialize Protein C,chemical engineer William Velander told BioWorld.
Protein C, discovered in the 1970s, is a complicated protein thatdepends on the liver's adequate supply of vitamin K for properprocessing into its active form. Eli Lilly and Co. has plans tocommercialize the clotting regulator, but has only been able toproduce the protein in low levels by engineered cell culture,Velander said.
The work to engineer production of the protein in pigsgenetically altered to bear the human gene will be publishedsoon in the Proceedings of the National Academy of Sciences,Velander said. He presented his findings Monday at the annualmeeting of the American Chemical Society in San Francisco.
The pigs typically lactate twice a year for 60 days, yielding 10to 20 kilograms of milk per day with a 6 percent proteincontent. Velander's laboratory has developed a purificationstrategy to separate the Protein C with monoclonal antibodies.
The collaboration between Velander's lab and the Red Cross isalso developing transgenic versions of Factor IX and anotherclotting regulator called anti-thrombin 3.
Protein C prevents the clotting cascade from "getting out ofhand," Velander said. Protein C would prevent the excessclotting, particularly in trauma or in bloody surgeries such aship or knee replacements.
"There are two key throttle points of the clotting cascade,"Velander said, "and Protein C acts at both."
-- Roberta Friedman, Ph.D. Special to BioWorld
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