Transgenic animals help us ‘understand disease’
By Frances-Catherine Quevenco, on 10 June 2011
Fluorescent fish, goats’ milk producing silk and mice with bat-like limbs are just some of the peculiar outcomes of genetically engineered animals. “Who in the audience finds tinkering with the animal genome a little disconcerting?” asked Mark Lythgoe. A few hands shot up…and why shouldn’t they? What do transgenic animals offer apart from quirky phenotypes?
Dr Robin Lovell-Badge outlined a variety of practical uses of transgenic animals. Transgenic animals such as the ‘brainbow mouse’ could be used to map the mind. In addition research using transgenic animals, such as Richard Behringer’s work, could be an effective method of investigating evolution. Genetically sterilised animals, such as mosquitoes, could be used for population control. Another study in which the stathmin gene has been removed to create ‘fearless’ mice can be used to study behaviour. Transgenic animals can also be used for environmental improvement – such as the ‘enviropig’, which can breakdown phosphorus more effectively in its saliva, reducing the phosphorus concentration in its waste. Transgenic farm animals can also act as bioreactors to produce valuable proteins, for example transgenic cows, which produce human milk proteins in their milk.
But the most crucial role of transgenic animals according to Lovell-Badge is their contribution to helping us understand disease. Dr Tom Weaver particularly emphasised the importance transgenic mice have in developing potential cancer treatments. A study done by Gerard Evans activated a gene that induced terminal brain cancer, resulting in an expressed phenotype of 100% mortality in mice. By turning ‘off’ the cancer gene, Evans observed an expressed phenotype of an effective ‘cure’ to brain cancer. These findings, says Weaver, can be extrapolated to other forms of cancer as well. Transgenic cancer mice act as models of human diseases and help us understand pathological processes and explore possible treatments.
Not only are transgenic mice important to modelling cancer pathology, they are also highly involved in research on Frontotemporal Dementia and Alzheimer’s. Dementia affects about a quarter of people 85 years and older, and more shockingly it affects about half of those over 90 years of age. Dr Adrian Isaacs, of the MRC Prion Unit at UCL Institute of Neurology, believes that the “gene is the way in’’ to explore treatments for those diseases.
When looking at the effects of neurodegenerative disease on the brain, we can only observe human brains at the end-stage. To explore treatments we need to look at the progression of the disease, and this is done most effectively through animal models. In fact, with Alzheimer’s, researchers observed “big lumps of protein“, which they thought were connected to the pathology of Alzheimer’s. They then developed a vaccine to get rid of these plaques and were successful, but this treatment is still going through clinical trials although these findings were published in 1999.
All in all it seems transgenic animals are more than fluorescent fish or funny-looking mice – they offer a broader understanding of the pathology of diseases and further research into the area holds promise in finding new and better treatments.