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By R Mann, G Lees, P Wills

There have been 3 attempts to date in New Zealand to produce human proteins in animals' milk by genetic engineering, including the work by AgResearch® at Ruakura. In theory the proteins envisaged for production could have medical use, but such limited trials as have been reported indicate little prospect of medical benefit. Some other human proteins produced by splicing human genes into microbes do have proven medical value, e.g. human-type insulin, growth hormone, and blood product factor VIII used for the treatment of the commonest form of haemophilia.

The first 'dairy GE' attempt was carried out at Lincoln University in 1993, funded by Genzyme Corp of the USA. It was hoped to produce a human protein which might be of use for treatment of cystic fibrosis (CF). This is a misleading impression. Even if it turned out that insertion into goats of the human gene for the lung protein CFTR (cystic fibrosis transmembrane-conductance regulator) was successful and human CFTR could be found in the goats' milk, there would still remain the difficulty that no therapy is in prospect using any such protein. Medical experts on cystic fibrosis have found themselves in the unpleasant role of breaking the news to parents of CF sufferers that no therapy is in prospect.

A second similar proposal to produce a human protein, called AAT, in goats' milk had little prospect of utility or market value but was also touted with the phrase "pharmaceutical protein". These experiments were a complete flop, the goats were destroyed, and Professor Bullock, the instigator, departed overseas.

The ERMA approved in 1999 a similar proposal from the Scottish creators of 'Dolly' for a flock of 10,000 not-just-sheep near Whakamaru to produce human-type AAT in their milk - nothing to go offsite except the milk for processing at a proposed factory in Hamilton. Again a deceptive image was touted that a treatment for CF was in prospect. Genuine human AAT is already available as a byproduct from blood-banks, and has been tested as a treatment for some lung disorders - achieving little or no benefit. This form of gene-manipulation holds very little promise of helping sufferers from human disease.

The latest image of "pharmaceutical human protein in animal milk" has been put up by the Crown research institute AgResearch, whose Ruakura group led by Wells & l'Huillier have been creating more-than-just-cows by transferring artificially altered cell nuclei, with human genes inserted, into bovine ova. AgResearch wish to produce in cows' milk a human-type protein, MBP, which they claim may be a treatment for multiple sclerosis (MS). In MS, nerve cells gradually lose their sheaths of the insulating substance called myelin, composed partly of myelin basic protein (MBP). This process is termed 'demyelination'. The degeneration of nerves in MS involves a destructive reaction of a person's own immune system against their own MBP. The theory behind the suggestion of feeding human MBP to such patients is that aggressive (type 1) immune responses can be converted to the tolerance (type 2) response. Even in small animals this is not fully successful - and needs to be done very early in life. Oral tolerance does occur in humans, but inducing it appears to be a very difficult exercise inlater life. There is a real risk that attempts to do so may actually worsen the aggressive response, since mice injected with MBP may actually develop the disease rather than be cured of it. Details can be found at http://www.genesanddairying.com/.

In any case, tests could be done with small amounts of genuine human MBP - there is no need to attempt production in cows' milk to test the idea. Moreover, any 'engineered' version of MBP would have to be examined extremely carefully to check whether it was actually an exact copy of human MBP.

Treatment for MS can not result soon, if ever, from this project. The claim that oral MBP will help MS sufferers has very little scientific basis. In our opinion it was unethical to put this notion about in public, because it tends to raise false hopes.

Genetic engineering's brief quarter-century of history has often been characterised by exaggerated claims of benefit, confusing fantasy with fact - and sometimes improving the share price of the companies involved. The reported decision by Ruakura scientists to proceed with haste on their field trials involving genetically modified cows is not only in conflict with the recommendations of the Royal Commission on Genetic Modification, but is either cynical or ignorant given the lack of evidence that what they want to produce will have any benefit to MS patients.

Drs Lees and Mann are retired Senior Lecturers in Biochemistry, and Dr Wills is an Associate-professor in Physics, University of Auckland, Aotearoa New Zealand.

ENDS

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