Human insulin in cow milk
A cow has been created that produces enzymes for human insulin in its milk In a new study, the production of "human" insulin was achieved for the first time in the milk of genetically modified cows. Scientists from the University of Illinois, Urban-Champaign, USA, placed a specific segment of human DNA that encodes proinsulin (a protein that turns into insulin) into the cell nuclei of 10 cow embryos. The embryos were then placed in the stomachs of normal cows. A transgenic calf (female) was successfully delivered in one case After the genetically modified cow grew up, many attempts were made to artificially inseminate it, in vitro fertilization, and even old-fashioned impregnation. None of them were successful. Eventually, milk was produced using cow hormone therapy. Although she gave little milk, mass spectrometry showed that it contained C-peptide, an enzyme in such cow's milk that can convert "human" proinsulin into insulin. x