ISIS Report 26/04/11
Scientists attempting to create human-like transgenic cow’s milk for large-scale human consumption despite grave concerns over health hazards and unacceptable animal suffering Prof Joe Cummins
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Human milk is enjoyed by infants and essential for the survival of tiny premature infants. It is desirable for all neonates and it has been found to be effective in clinical settings such as post-operative nutritional management following intestinal resection, severe food allergies, metabolic diseases, immune deficiencies, chronic renal insufficiency, and heart diseases with failure to thrive due to feeding intolerance. It was reported that human milk therapy improved the quality of life measures in the psychological and spiritual domains for a group of patients with cancer. Growing clinical evidence has placed human milk feeding and the supply of donor milk as a basic right for preterm infants [1]. For several years, biotechnology has promoted the idea that human milk could be produced in quantity in dairy cattle that had been genetically modified for the purpose. In the brave new world, human milk – produced from genetically modified (GM) cows – will be placed on supermarket shelves side by side with ordinary cow’s milk. Babies need not be weaned at all but go through their lives with substitute mother’s milk in their cereal and coffee. Will unweaned people behave differently?
Human lysozyme
At present, the production of fully human milk in GM cattle has not yet been achieved. Nevertheless, Professor Ning Li, the director of the State Key Laboratories for AgroBiotechnology at the China Agricultural University has produced a number of cloned transgenic cattle producing important human protein components in their milk. Lysozyme is an enzyme that attacks bacterial pathogens. The human lysozyme (HLZ)-containing plasmid used to transform cells of cattle, called the pBC2-HLY-NEOR transgene vector, contains the HLZ coding region, a bovine b-casein signal peptide DNA sequence, and one selection marker, the neomycin resistance gene . After somatic cell nuclear transfer cloning (see [2] Cloned Meat and Milk Coming, SiS 50), 312 blastocyst embryos were transferred into surrogate mother cattle. Thirty-seven calves were born at full term (2 from nuclei donated by cells of foetal genital ridge, FG; 11 from nuclei donated by fetal oviduct epithelial cells, FOV; 23 from nuclei donated by fetal oviduct epithelial cells, FOV-19; and 1 from nuclei donated by bovine foetal fibroblasts, BWFF-b1). Seven calves died within a few hours after birth, and six calves died within 6 months after birth. Twenty-four calves survived and were healthy after weaning; these calves were from two cell types, genital ridge cells (2 calves) and oviduct epithelial cells (22 calves). Of these, 17 healthy cloned transgenic cattle resulted that expressed recombinant human lysozyme (rHLZ), but only 4 were lactating normally. Thus, the ‘success’ rate was only a little over 1 percent of the selected implanted embryos, hardly justifying the authors’ claim that [3]: “This approach could provide an inexpensive and industrial-scale method for the purification of rHLZ. In addition, we have shown that the enzymatic properties and physicochemical characteristics of rHLZ were identical to those of HLZ. Transgenic cow milk will likely be beneficial to the health of livestock as well.” Apart from the unacceptable death rates (and suffering) among calves, nothing was said of the suffering in surrogate mothers.
Human lactoferin
Ning Li’s laboratory earlier produced cattle producing human lactoferrin. The recombinant human lactoferrin gene (rhLF) was contained in a large bacterial artificial chromosome (BAC). Cattle foetal fibroblasts were co-microinjected with a 150-kb BAC containing the entire hLF gene (including 90-kb and 30-kb 59 and 39 flanking regions) and a plasmid encoding a marker gene. The nuclei of transformed fibroblasts were injected into the eggs of cows from which the cow nucleus had been removed. The eggs were then stimulated to produce blastocyst embryos which were implanted into surrogate cattle mothers to complete development. The success rate was not much better.
The researchers stated [4]: “With subsequent transgenic cloning, we obtained transgenic cattle that expressed a high-level of functional rhLF. Of 623 reconstructed embryos, 280 developed to blastocysts. Among these, 98 randomly chosen blastocysts were transferred to 50 recipient cows. Ten cows became pregnant after embryo transfer, and five calves were born at full term (the others were spontaneously aborted). Finally, two calves, named 211 and Xiang, survived after weaning and both were apparently healthy. Three out of five calves died of gastrointestinal disease after birth. It is well established that some unknown mechanisms affect the development, growth and/or survival of cloned animals. Though neonatal losses are common in cloning and decrease the overall success rate, the surviving calves are almost always transgenic.” The unknown factors make consuming the GM cloned milk very risky indeed.
Human α-lactalbumin
A-lactalbumin forms the regulatory subunit of the lactose synthase (LS) and b-1,4-galactosyltransferase forms the catalytic component. Together, these proteins enable LS to produce lactose by transferring galactose to glucose. As a monomer, a-lactalbumin strongly binds calcium and zinc ions and may possess bactericidal or antitumor activity. A folding variant of a-lactalbumin, called HAMLET, may induce apoptosis (programmed cell death) in tumour and immature cells. The expression vector used to transform cattle contained the human a -LA gene along with the neomycin resistance gene. The expression vector phLa4-EGFP-NEO was transfected into foetal oviduct epithelial cells from Chinese Holstein cows. Transgenic human α-LA epithelial cells were transferred into the enucleated oocytes from ovaries of adult yellow cattle obtained from a slaughterhouse. Artificial activation of the reconstructed embryos occurred 0.5 h after fusion. The embryos were cultured for 7 days to blastocyst stage, and transferred to synchronized Chinese Luxi yellow cattle surrogate mothers. Six transgenic calves were born at full term. Three transgenic cows, Xingwa, Longwa, and Huiwa (about 30 mo of age at the time of this study), apparently healthy, were milked for characterization of the recombinant protein and analysis of milk composition. The three surviving cattle (from 121 full term animals) appeared to be normal at 30 months. The researchers concluded [5]: “In summary, recombinant human α-LA expressed in milk from transgenic cows had the same physicochemical characteristics as the natural counterpart and did not show any side effect on transgenic milk. Because the recombinant human α-LA is equivalent to natural human α-LA, utilization of this recombinant protein as an additive to infant formula and health-promoting foods is likely to be safe.” But their claim is false.
Glycosylation pattern of GM human protein is cow-like
Glycosylation is the addition of short carbohydrate chains to protein in fixed patterns to proteins, which are related to signal activity and immune response. The human protein produced in cattle has taken on the cow’s glycosylation pattern. Ning Li’s team believe that the human-like pattern could be introduced into the GM cattle by a single human gene that controls human glycosylation. However, that modification has not yet been done on the cattle producing human proteins [6]. Without that modification the human proteins with cow glycosylation are likely to be allergenic or otherwise toxic to some people. This was demonstrated in the previous case of a harmless bean protein that when transferred to transgenic pea, caused serious immune reactions in mice, and provoked generalized sensitivity to food (see [7] Transgenic Pea that Made Mice Ill, SiS 29). That brought an abrupt end to a ten year project.
The holy grail to obtain mother’s milk from cloned transgenic cattle will no doubt continue. We have published numerous reports critical of cloned transgenic farm animals. One salient feature is that the clones are not identical [2]. First, cells accumulate mutations in the course of development so each cell in an organism has the potential to have a genome that’s different substantially from the original germline genome the organism inherited from its parents, as well as to be different from other cells in the organism. Second, an important part of the individual animal’s genetic inheritance is in the mitochondria, which is not normally transferred with the nucleus, but contributed by the recipient eggs which were collected from animals being butchered for food. In the cloned animals, mitochondria are transferred to the eggs along with the nucleus from somatic cells, leading to a mixture of mitochondrial genes from egg and the somatic cell from which the nucleus was obtained. This mixture of mitochondria (called heteroplasmy) introduces incompatibility between mitochondrial and nuclear genetic material that contribute to the high rates of abnormalities and deaths among clones and leads to cell and tissue disruption as the cloned animal develops. The impact of mitochondrial dysfunction is great because the mitochondria provide energy for the cells (see also [8] ‘Cloned’ food animals not true clones SiS 48,[9] Cloned BSE-Free cows, not safe nor proper science SiS 33, [10] Is FDA promoting or regulating cloned meat and milk? SiS 33,[11] Death sentence on cloning SiS 19, and [12] Unacceptable Death Rates End Cloning Trials in New Zealand, SiS 50).
In conclusion human-like milk produced in cloned transgenic cattle is definitely not ready for human consumption.
References
1. Italian Association of Human Milk Banks Associazione Italiana Banche del Latte Umano Donato (AIBLUD: www.aiblud.org)., et al. Guidelines for the establishment and operation of a donor human milk bank. J Matern Fetal Neonatal Med. 2010, 2, 1-20.
2. Ho MW. Cloned meat and milk coming, be very afraid. Science in Society 50 (to appear).
3. Yang B., et al. Characterization of bioactive recombinant human lysozyme expressed in milk of cloned transgenic cattle. PLoS One. 2011, 6, e17593.
4. Yang P., et al. Cattle mammary bioreactor generated by a novel procedure of transgenic cloning for large-scale production of functional human lactoferrin. PLoS One. 2008, 3, e3453
5. Wang J., Expression and characterization of bioactive recombinant human alpha-lactalbumin in the milk of transgenic cloned cows. J Dairy Sci. 2008, 91, 4466-76.
6. Yu T., Comprehensive characterization of the site-specific N-glycosylation of wild-type and recombinant human lactoferrin expressed in the milk of transgenic cloned cattle. Glycobiology. 2011, 21, 206-24.
7. Ho MW. Transgenic pea that made mice ill. Science in Society 29, 28-29, 2006.
8. Cummins J and Ho MW. ‘Cloned’ food animals not true clones. Science in Society 48, 48-50, 2010
9. Ho MW and Cummins J. Cloned BSE-Free cows, not safe nor proper science. Science in Society 33, 28-31, 2007.
10. Ho MW and Cummins J. Is FDA promoting or regulating cloned meat and milk? Science in Society 33,24-27,2007.
11. Ho MW and Cummins J. Death sentence on cloning. Science in Society 19, 46-47, 2003.
12. Ho MW. Unacceptable death rates end cloning trials in New Zealand. Science in Society 50 (to appear).