By Mark Viney
About 4 million animals were used in experiments in the UK last year, and more than 3 million of these were mice and rats. Over the last 10 years, following the establishment of the National Centre for the 3Rs, a major research effort has been working to minimize animal experiments while not holding back scientific progress. The idea of the 3Rs, which dates back to the late 1950s, is to find ways to replace, reduce and refine the use of animals in scientific experiments. The NC3Rs has spent about £35 million over the last decade promoting the 3Rs in scientific research in the UK.
For example, Professor Suzanne Eccles of the Institute of Cancer Research, funded by the NC3Rs, has developed a new method of testing anti-cancer drugs that uses fewer animals. Previously, potential anti-cancer drugs were tested by growing cancer cells in the lab and testing to see whether the drug stopped the cancer growing. The problem was that if a drug stopped the lab cells growing, it still very often didn’t work at the next stage– testing the drug in mice. As Professor Eccles said, “we’re very good at curing cancer in mice, but we’re not very good at curing humans”.
Eccles thought that the reason for the failure was that the cells grown in the lab were growing in a flat sheet, one cell deep, whereas cancer in animals – and humans – usually grow in 3D as the cancer metastasises and invades surrounding tissue.
Eccles’ breakthrough was to grow 3D microcancers in the laboratory and to use these to test potential drugs. Drugs that stop the lab-based 3D cancers growing also often kill cancer in the mice too. This new approach means that fewer mice are used, but for the same scientific gain. This is a win for all.
Professor Sue Barnett of the University of Glasgow has made a similar breakthrough in a different area, spinal cord injuries. These injuries can be devastating because a damaged spinal cord scars, which stops the injury healing. At the moment there are no treatments to mend broken spinal cords. However, to develop test models for spinal cord injuries, the animal’s spinal cord has to be damaged to mimic an accidental spinal injury.
Professor Barnett’s research has offered a new alternative to injuring animals to enable the development of drugs to treat injured spinal cords. Her research team have grown mini versions of spinal cord in the laboratory that can be injured and will act in a similar way to real spinal cord. This work isn’t completely without the use of animals – spinal cord tissue is taken from rat embryos and grown in the laboratory, but many lab experiments can be done from one rat embryo, without the distress of breaking the creature’s spinal cord. Barnett is now using this artificial system to find drugs that can begin to help treat damaged spinal cords.
These case studies are just two examples of ways in which the NC3Rs are working to reduce the use of animals in research. There are many challenges for this field in the future, but these examples do highlight that while animal models may always be required at some stage of drug development for the foreseeable future, it is possible to develop new methods that can minimise the numbers of animals used.