Replacing rodents in CNS studies

Spinal cord injuries can lead to permanent disabilities such as paralysis. Research in rats and mice for new treatments involve severing nerve fibres, which can cause moderate or severe suffering. Professor Sue Barnett, University of Glasgow, who is a 3Rs Prize 2012 runner up, writes about an in vitro technique, funded by NC3Rs, to replace the use of rodents in her laboratory.

Sue Barnett receives her highly-commended 3Rs Prize at the 2013 Annual Science Review meeting.

Sue Barnett receives her highly-commended 3Rs Prize at the 2013 Annual Science Review meeting.

Research is my passion. I love the excitement of that unexpected result, or the connection between a hypothetical idea appearing in thought-provoking results. It’s very important to me that my work has a clinical focus and I hope that, eventually, something I work on could be translated into the clinic for treatment in patients.

My lab works on devising ways to repair the damaged central nervous system (CNS), tissue that includes the brain and spinal cord. During my career I have always worked on how cells grow and differentiate into a cell with a purpose, such as a nerve cell. A nerve cell needs to be wrapped in myelin – an insulating material made by an oligodendrocyte cell – for it to send signals properly around the body. These cells can be damaged after injury and as a result of many diseases, including multiple sclerosis (MS) and spinal cord injury.

My recent publication in the journal, Glia, funded by NC3Rs was to:

  1. Develop a way to study a mixture of cells from the CNS in their differentiated function.
  2. Create an injury in the isolated cells, making sure it represents CNS injury seen in mammals.
  3. Assess if we can promote repair using a combined-treatment approach.

Developing a technique that reduces animal use

Spinal cord injury is very complex. It is thought that successful treatments will include a combination of drugs, growth factors and even cell transplantation to replace the damaged cells. To test these combinations would require a large number of animals using a procedure which requires a Home Office animal license. So we aimed to reduce and replace the number of animals used in our research by studying mixtures of CNS cells in their differentiated function in petri dishes – an in vitro approach to this research. To generate cells for research does not require a Home Office license, nor does it involve severing nerve fibres in animals.

Professor Barnett and Dr Stephanie Boomkap in their lab at the University of Glasgow.

Professor Barnett and Dr Stephanie Boomkap in their lab at the University of Glasgow.

In our prize-winning paper we show that cells from the spinal cord made into a single-cell suspension and put on top of a monolayer of astrocytes can form a carpet of differentiated nerves wrapped in myelin. These cultures look very similar to a piece of CNS tissue. We then cut across the nerves using a scalpel blade to make an area that looks like a lesion, which is seen after induced spinal cord injury in more traditional experiments using animals.

We saw many features in these cells that were seen in spinal cord injury in an animal – including lack of nerve outgrowth and the loss of their insulating myelin wrapping. Interestingly, we also saw features of scarring, which also occur in CNS tissue after injury. We validated the effectiveness of this model of spinal cord injury by adding drugs known to promote repair in animals and saw similar repair features in our isolated cells.

The benefits of an in vitro approach

The benefit of our system is that we can use markers to look at the various cells, add other cells to the mix and also carry out molecular and biochemical studies that will provide data on how these cells interact with each other. One real advantage is that we can study many combinations of drugs and cells in the dish, something that we wouldn’t be able to do in an animal, to see which is the most beneficial to make these damaged nerves repair and grow again.

Our in vitro model challenges the traditionally held dogma that animal studies of spinal cord injury can never be replaced, and I hope that this can be used by other CNS researchers to bring down the number of animals used in this area as well as helping patients overcome the burdens of spinal cord injury.

Read more about Professor Barnett’s work in the NC3Rs Research Review 2011 and Glia.

Boomkamp, S., Riehle, M., Wood, J., Olson, M., & Barnett, S. (2012). The development of a rat in vitro model of spinal cord injury demonstrating the additive effects of rho and ROCK inhibitors on neurite outgrowth and myelination Glia, 60 (3), 441-456 DOI: 10.1002/glia.22278

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