A transgenic cow in Brazil is the world’s first to produce human insulin in its milk – scientists who created it say it could usher in a new era for millions of insulin-dependent diabetics worldwide
A brown cow in southern Brazil recently made history as the first transgenic cow that can produce human insulin in its milk. The achievement, which belongs to researchers from the University of Illinois Urbana-Champaign and the University of São Paulo, is estimated to usher in a new era in insulin production that promises to produce the hormone for the millions of insulin-dependent diabetics worldwide with an easy and very cheaper way than today.
The mammary gland is a “factory” of proteins
“Mother Nature designed the mammary gland as a factory that produces proteins in a very efficient way. We can take advantage of this natural system to produce a protein that will help hundreds of millions of people around the world,” said Matt Wheeler, a professor in the Department of Animal Sciences at the University of Illinois who was lead author of a related study published in the journal Science. “Journal of Biotechnology”.
Introduction of human DNA into cow embryos
Professor Wheeler’s colleagues inserted a segment of human DNA that coded for proinsulin – the precursor molecule of active insulin – into the nuclei of the cells of 10 cow embryos. They then implanted these embryos into the wombs of cows in Brazil – eventually resulting in a transgenic calf.
Breast tissue is the exclusive target
Thanks to advances in genetic engineering, the human DNA introduced into cow cells was exclusively targeted to mammary tissue for expression (the process by which genetic sequences are “read” and “translated” into protein products ).
Targeted movements
“In the past, we just introduced DNA into the body and hoped that the DNA would be expressed where we wanted,” explained Dr. Wheeler, adding, “Now we can make much more strategic and targeted moves. By using DNA that is expressed exclusively in breast tissue we achieve that no human insulin circulates in the blood or other tissues. In addition, we take advantage of the ability of the mammary gland to produce large amounts of protein.”
Lactation after taking hormones
When the transgenic female chick matured the research team tried unsuccessfully to fertilize it using conventional artificial insemination methods. So he proceeded to… Plan B which involved inducing the first lactation using hormones. The goal was eventually achieved, however the cow produced less milk than she would have produced if she had become pregnant. However, both proinsulin and human insulin were detected in the milk. “Our goal was to produce proinsulin and convert it into insulin. However, the cow essentially did this processing herself. The mammary gland is magical,” said Professor Wheeler.
A few grams of insulin per liter of milk
The insulin and proinsulin that need to be extracted and processed to be used were expressed at the level of a few grams per liter of milk. However, because the cow’s milk production was induced through hormones and the amount of milk was less than expected, researchers do not currently know how much insulin a lactating cow will ultimately produce after the normal process of pregnancy and birth.
Estimation of too much insulin production in milk
By conservative calculations, Dr. Wheeler estimates that if a cow produces 1 gram of insulin per liter of milk – and given that a typical Holstein cow produces about 40-50 liters of milk per day – then we are talking about a very large production of insulin. In these calculations let’s take into account that one unit of insulin taken by diabetics corresponds to 0.0347 mg. “This means that each gram of insulin corresponds to 28,818 units of insulin. And that’s just one liter of milk. As Holstein cows produce up to 50 liters of milk per day, one can easily do the math.”
A plan to create an insulin-producing herd
The research team plans to clone the cow and hopes it will have more success with pregnancy and lactation cycles in the next generation. In the future, he aims to create transgenic bulls that will mate with the females and produce transgenic offspring, eventually creating an… insulin-producing herd.
A small flock more efficient than existing methods
According to Professor Wheeler, even a small herd would be able to outperform existing methods of insulin production (using transgenic yeasts and bacteria) even eliminating the need for sophisticated equipment and facilities.
100 cows will produce all the insulin the US needs
Of course, an efficient system for collecting and processing insulin products, as well as the approval of the relevant US Food and Drug Administration (FDA), will be required before transgenic cows can begin to provide insulin for diabetics around the world. Dr. Wheeler said, however, that he firmly believes that this day is not far away. “I see a future where a herd of 100 cows can produce all the insulin the US needs. A larger herd would probably be able to produce within a year all the insulin needed by patients around the world,” concluded the professor.
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