Diabetes breakthrough: Cow produces human insulin in world first

Could cow milk be the new cure for diabetes?

Researchers have genetically modified a brown cow in Brazil to produce human insulin in its milk, which marks a breakthrough in diabetes treatment research.

The innovative achievement could lead to more accessible and affordable diabetes treatment and potentially help relieve issues of insulin scarcity as well as financial burdens associated with treatment.

“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,” study lead author Matt Wheeler, a professor in the Department of Animal Sciences at the University of Illinois, said in a statement.

The study, published in Biotechnology Journal, used genetic engineering techniques to integrate a human DNA segment that produces proinsulin into cows’ embryos.

Researchers from the University of Illinois Urbana-Champaign and the Universidade de São Paulo ensured that the human precursor to insulin would be active only in the cows’ mammary tissues, preventing any insulin from entering the bloodstream and producing solely in its milk.

“In the old days, we used to just slam DNA in and hope it got expressed where you wanted it to,” Wheeler explained. “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.”

After the genetically modified cow reached maturity, the milk it produced contained both proinsulin and insulin itself — a “magical” breakthrough as the researchers only expected the cow to produce proinsulin and then to externally purify the proinsulin into insulin.

However, the mammary glands process the proinsulin into active insulin on its own.

“Our goal was to make proinsulin, purify it out to insulin, and go from there. But the cow basically processed it herself. She makes about three to one biologically active insulin to proinsulin,” Wheeler said. “The mammary gland is a magical thing.”

While researchers can’t say exactly how much insulin would be made in a typical lactation, Wheeler explained that if a cow could produce one gram of insulin per liter of milk, and a cow produces 40 to 50 liters per day, that’s a remarkable amount of insulin — especially if the typical unit of insulin is just 0.0347 milligrams.

“That means each gram is equivalent to 28,818 units of insulin,” he said. “And that’s just one liter; Holsteins can produce 50 liters per day. You can do the math.”

Researchers hope to continue refining their technique through re-cloning and optimizing the lactation process, aiming to create a herd of these transgenic cows that could outpace current insulin production without the need of high-tech facilities.

“With regard to mass-producing insulin in milk, you’d need specialized, high-health-status facilities for the cattle, but it’s nothing too out of the ordinary for our well-established dairy industry,” Wheeler said. “We know what we’re doing with cows.”

“I could see a future where a 100-head herd, equivalent to a small Illinois or Wisconsin dairy, could produce all the insulin needed for the country,” he added. “And a larger herd? You could make the whole world’s supply in a year.”