beyond the novelty of “humanized” milk
There’s been quite a stir this week over genetically modified cows. These cows are capable of producing more “human” milk, which is expected to hit the Chinese market in just two years. My initial response to this news was on par with my reaction to the unveiling of “Baby Gaga” breast milk ice cream in London last month. Why do something like that? The very idea of breast milk ice cream makes me cringe, and the thought of pouring human-like milk over my cereal each morning seems a little bizarre and pretty unappetizing.
But as I thought more about the genetically modified cows, something didn’t quite add up. While it makes sense for an ice cream shop to make novelty ice cream, why would scientists go to all the trouble of making transgenic cows just to make novelty milk? Could there be benefits to producing or consuming this milk? And could there be other motivations for making these transgenic cows that the media have been overlooking?
After spending some quality time on PubMed and Google Scholar, I tracked down a series of papers published by the cows’ creators. It appears that these scientists have two primary goals: (1) to increase the nutritional value of milk by adjusting its protein composition, and (2) to engineer cows to mass produce proteins with pharmaceutical applications.
Modified protein levels in “humanized” milk may enhance its nutritional value
While it’s true that the researchers are trying to “humanize” cow milk, none of the recent news articles offer much explanation for what this actually involves. In the introduction to one study, the scientists provide their rationale and approach for creating more human-like milk:
Cow milk provides important nutrients for the improvement of human health. However, due to the distinct composition of cow milk, it is essential to adjust the components of cow milk to resemble that of human milk to better satisfy the nutritional requirements of infants and adults… The humanizing process of cow milk should include selectively elevating the levels of [particular proteins like α-lactalbumin], lactoferrin, and lysozyme, all of which are highly expressed in human milk… or removing [β-lactoglobulin], the primary allergen in cow milk.
This isn’t the first time scientists have altered the composition of milk to improve its nutritional value. Last year, a different group of researchers unveiled a genetically modified cow that produced milk with extra omega-3 fatty acids.
Cows could be protein-producing powerhouses
In addition to humanizing milk, it is clear that the scientists behind the new transgenic cows are also very interested in finding efficient, economical ways of mass-producing human proteins like lactoferrin that have pharmaceutical applications. To summarize the abstract from one of their papers:
Large-scale production of biopharmaceuticals by current bioreactor techniques is limited by low transgenic efficiency and low expression of foreign proteins… We describe here the use of cattle mammary bioreactor to produce functional recombinant human lactoferrin (rhLF) by a novel procedure of transgenic cloning… The cattle mammary bioreactors generated with this novel procedure produce functional rhLF on an industrial scale.
At the time this study was published, several human proteins had already been produced in the milk of sheep, goats, and rabbits, or pigs. And the idea of a “mammary bioreactor” (you can’t make this stuff up…) first appeared over two decades ago. The FDA has even approved the pharmaceutical use of human antithrombin purified from the milk of genetically modified goats.
I admit that I’m still not ready to down a glass of humanized milk, but after all that reading I can at least understand and even appreciate what the researchers are trying to accomplish from a scientific standpoint. And that still doesn’t mean I necessarily agree with everything the researchers are doing. I honestly don’t know how I feel about using animals as living pharmaceutical factories, and I expect there will be a lively debate over the next many years about the ethics of this practice. Whether or not we agree with this kind of research, striving to understand the scientific rationale behind it (and not just reacting to what may seem strange or unnatural) will ultimately make future conversations about the ethics of transgenic organisms much more meaningful.
