Researchers detected recombinant human insulin-related protein in milk from one genetically engineered cow. The 2024 Biotechnology Journal study was an early proof of concept: lactation was induced hormonally, milk output was low, and a usable insulin medicine was not established.
What the cow experiment showed
Paulo S. Monzani and colleagues combined gene transfer with cloning to produce the animal. The genetic construct linked human insulin sequences to a regulatory region associated with milk-protein production.
After unsuccessful attempts to obtain a pregnancy, the team induced lactation and tested the milk. Western blots showed bands consistent with proinsulin and insulin. Mass spectrometry detected a human C-peptide sequence, supporting production of the recombinant precursor.
The authors also noted an interpretive complication: trypsin used during sample preparation could contribute to protein cleavage. Low expression hampered purification and quantification. The results did not establish a reliable dose of biologically active insulin for patients.
Why enzymes matter
Insulin is a hormone, not an enzyme. Enzymes enter the story because its precursor, proinsulin, must be processed into the mature hormone, and unwanted protein breakdown can reduce recovery.
An earlier study in transgenic mice, published in 2014, illustrates the distinction between producing a precursor and testing a finished product. Researchers purified milk-derived proinsulin, treated it with processing enzymes and tested the resulting insulin’s activity in cells. Those mouse results cannot be transferred directly to a different construct in a cow.
How far is this from an insulin supply?
The university’s March 2024 announcement discussed future herds and potential production volumes. Those projections attracted attention, but they are not measurements of a validated manufacturing system.
For a production claim, the useful question is how much consistently active, purified insulin can be recovered—not simply how much milk an ordinary dairy cow produces. A cost comparison would also need to include animal care, purification, quality control and losses during processing.
The study offers a starting point for further research. Repeatable production, animal welfare, medicine quality and regulatory assessment would all matter before this approach could become a treatment source. Drinking the experimental milk is not a substitute for prescribed insulin.
For another example of enzymes in medical biotechnology, read our report on experimental blood-group conversion for kidney transplantation.
Sources
Monzani, P. S. et al. (2024). Human proinsulin production in the milk of transgenic cattle. Biotechnology Journal, 19(3), e2300307. Read the study.
Qian, X., Kraft, J., Ni, Y. and Zhao, F.-Q. (2014). Production of recombinant human proinsulin in the milk of transgenic mice. Scientific Reports, 4, 6465. Read the earlier study.
University of Illinois ACES (13 March 2024). Institutional announcement and proposed future applications.
Update note: This archived report retains its original publication date and URL. The revision places the one-animal result and analytical limits before possible future applications, and separates the cow findings from earlier mouse experiments.
