An unassuming brown bovine from the south of Brazil has made history as the first transgenic cow capable of producing human insulin in her milk. The advancement, led by researchers from the University of Illinois Urbana-Champaign and the Universidade de São Paulo, could herald a new era in insulin production, one day eliminating drug scarcity and high costs for people living with diabetes.
“Mother Nature designed the mammary gland as a factory to make protein really, really efficiently. We can take advantage of that system to produce a protein that can help hundreds of millions of people worldwide,” said Matt Wheeler, professor in the Department of Animal Sciences, part of the College of Agricultural, Consumer and Environmental Sciences (ACES) at U. of I. He is also affiliated with the Carle Illinois College of Medicine, The Grainger College of Engineering, the College of Veterinary Medicine, the Beckman Institute, and the Carl R. Woese Institute for Genomic Biology.
Wheeler is lead author on a new Biotechnology Journal study describing the development of the insulin-producing cow, a proof-of-concept achievement that could be scaled up after additional testing and FDA approval.
Wheeler’s colleagues in Brazil inserted a segment of human DNA coding for proinsulin — the protein precursor of the active form of insulin — into cell nuclei of 10 cow embryos. These were implanted in the uteruses of normal cows in Brazil, and one transgenic calf was born. Thanks to updated genetic engineering technology, the human DNA was targeted for expression — the process whereby gene sequences are read and translated into protein products — in mammary tissue only.
“In the old days, we used to just slam DNA in and hope it got expressed where you wanted it to,” Wheeler said. “We can be much more strategic and targeted these days. Using a DNA construct specific to mammary tissue means there’s no human insulin circulating in the cow’s blood or other tissues. It also takes advantage of the mammary gland’s capabilities for producing large quantities of protein.”
When the cow reached maturity, the team unsuccessfully attempted to impregnate her using standard artificial insemination techniques. Instead, they stimulated her first lactation using hormones. The lactation yielded milk, but a smaller quantity than would occur after a successful pregnancy. Still, human proinsulin and, surprisingly, insulin were detectable in the milk.
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Categories: Wisconsin, Livestock, Dairy Cattle