Genetically modified mice produce human milk protein

Scientists in Russia have genetically modified mice to successfully produce a human milk protein. The achievement raises hopes that the proteins could be commercially produced to use in healthier baby formula. Currently, synthetic baby formula contains proteins mainly from soybeans or cow's milk. Some experts dispute that it provides babies with as many health benefits as natural human breast milk.

In this study, carried out at the Institute of Gene Biology at the Russian Academy of Sciences in Moscow, human genes were spliced into the mouse genome, which resulted in mice producing lactoferrin. Lactoferrin is a protein present in human breast milk that is vital to protecting growing babies against viruses and bacteria while their immune systems are still developing. It is produced by breastfeeding mothers at a natural concentration of about four to five grams per litre of breast milk. Elena Sadchikova, a researcher on the team, says that the mice produced about 160 grams of lactoferrin per litre.

'Mouse milk is very protein-rich, and this can also translate into very high concentrations of transgenic protein', says Patrick van Berkel, a senior director at the Danish biotech company Genmab.

To harvest the milk in order to isolate the protein, the scientists had to anaesthetise the mice and use tiny pumps adapted to fit their teats. 'Larger animals such as rabbits, goats or cows are required for commercial application', says van Berkel.

Some companies are already using larger animals to produce human proteins for other uses. For example, Pharming, a Netherlands-based biotech company, uses rabbits to produce milk containing a human protein that is used for treating hereditary angioedema, a severe blood disorder that causes body tissues to swell.

Larger volumes of lactoferrin, however, will be required to make formula, meaning that larger animals would have to be used. Sadchikova says that the Russian team favours transgenic goats, explaining that this was because 'the most attractive advantage of a goat is that its pregnancy period is twice [as short as] that of a cow. A goat also reaches breeding age three times faster than a cow, has good resistance to illnesses and does not share any diseases with a human being'.