By Daniel Cressey of Nature magazine
Scientists are increasingly turning to non-invasive imaging to further the '3Rs' of work in animals--replacement, refinement and reduction. Although the use of animals in modern medicine and biology is essential, researchers are actively working to reduce the numbers used and improve on how they are used.
Medical technologies, such as computed tomography (CT) scans and magnetic resonance imaging (MRI), together with imaging techniques specific to biology, can assist in this.
"The big trend is combining all the available techniques together in the same animal, increasing the amount of information we get out of the subject," says François Lassailly, a biologist specializing in imaging at the Cancer Research UK London Research Institute (LRI). "This is beneficial to the animals and beneficial to the science."
For example, he told a conference in London last week, if you want to investigate disease progression in an animal model, you would normally have to sacrifice a few of your study group every week or so. But by using imaging, you can look at disease progression through the lifetimes of individual animals and thus drastically reduce the number used. Imaging also offers the possibility of looking at several biomarkers at once, thereby answering more questions in a single experiment.
With Lassailly's help, teams at the LRI are using micro-CT to detect lung tumors in animals. They are also using optical imaging, for example with cancer cells that have been engineered to emit light to image tumors inside animal subjects.
A key concept, says Lassailly, is that researchers should be treating an 'ani-patient'--so that the study of the animal mimics the treatment of a patient in the clinic. This includes applying all the scanning and imaging techniques to which a hospital doctor would have access and thus bridging the gap between the laboratory and the clinic.
TB in vivo
Sally Sharpe, a senior immunologist at the Health Protection Agency's Porton Down research site, also presented her latest work. This involves using MRI and CT scans to improve the relevance of animal models of infectious diseases, particularly with regard to drugs and vaccines for tuberculosis.
So far, her team has shown that images can be collected from live animals, and that CT and MRI images of tissue collected from infected individuals are useful not just for visualizing the disease, but also for quantifying the degree to which progression or protection has occurred.
For example, we have compared the diagnostic sensitivity of X-ray images with CT and MRI images of some individuals. Where the individual is giving a normal X-ray, the disease can be picked up by MRI and CT," she says.
Now the team is investigating whether it can collect useful images from infected animals kept under isolation conditions. For this, the researchers use a device Sharpe likens to a sealed baby incubator, ventilated by means of high-efficiency filters. This work could allow the efficacy of treatments for the disease and vaccines to be established more quickly.
"If you can get better data, there is less chance that you need to repeat experiments, and you can get more information from fewer animals," she adds. "It would be an amazing refinement if we were able to track this disease [in living animals]."
The meeting was organized by the London-based National Centre for the Replacement, Refinement and Reduction of Animals in Research, which funds '3Rs' work, and the Society of Biology, headquartered in London.
This article is reproduced with permission from the magazine Nature. The article was first published on June 28, 2011.