Funded by the NC3Rs in 2009, Professor Sue Barnett, from the University of Glasgow, has developed a cell culture model of spinal cord injury, which has the potential to significantly reduce animal use in some studies, as well as avoiding the welfare issues associated with rodent models of spinal cord injury.
Principal Investigator: Sue Barnett, Professor of Cellular Neuroscience
Organisation: University of Glasgow
Award: £294,404, in 2009, over 36 months
Title: An in vitro model of spinal chord injury to replace the use of rodents
Read more about Professor Barnett's research
Spinal cord injuries cause permanent disabilities such as paralysis
Damage to the spinal cord is a major cause of permanent disability, causing a loss of sensation and paralysis below the point of injury which arises due to breakdown in communication between the brain and the spinal cord. The central nervous system (CNS) has very little capacity for repair and there are currently no proven treatments for spinal cord injury. Strategies used to promote CNS repair include cell transplantation and drug and antibody therapies. However, it is now accepted within the scientific and clinical communities that repair is ultimately likely to require a combination of these treatment strategies.
Animal models of spinal cord injury involve severing nerve fibres
The most commonly used model of spinal cord injury involves axotomy – severing of the nerve fibres – in the spinal cord, of rats and mice. As in humans, where this occurs in the spinal cord determines the degree of paralysis and disability. The procedure is typically classified as causing moderate or substantial suffering under the Animals (Scientific Procedures) Act 1986. Animals may require long term post-operative care; for example, having their bladders emptied manually. The surgery required for axotomy is technically demanding and studies can be difficult to reproduce because of variation in the level of injury. Ten rats or mice are used per treatment or time point in a typical study, plus control animals.
A new in vitro model of spinal cord injury
With NC3Rs funding, Professor Sue Barnett, University of Glasgow, has developed an in vitro model of the CNS which is able to mimic certain key aspects of intact spinal cord injury. This provides a new model to study CNS cell/cell interactions and to test potential therapeutics, replacing the use of animals for some experiments.
Cells are obtained from rat or mouse embryonic spinal cords and used to establish mixed neural cell cultures. Over a period of weeks, a carpet of spinal cord axons develops. The axons are ensheathed by myelin, interspersed with nodes of Ranvier, produced by the surrounding oligodendrocytes. Many of the key axonal, glial and nodal proteins found in vivo are expressed. Depending on the substrate the axons become arranged in long tracts which can be cut using a scalpel.
A cell-free area develops and the lesioned nerve fibres respond, as in vivo, with myelin loss, changes in the expression of specific neuronal proteins and cell death. No neurite growth occurs across the cell-free area. Importantly, however, neurite outgrowth and myelination can be stimulated by reagents which have been shown to promote nerve growth in animal models.
Animal use and suffering is significantly reduced
Although the new model does not entirely replace the use of animals, one pregnant rat can provide enough embryos for an experiment in vitro which if carried out in vivo would use 30 animals. This represents a 97% reduction in animal use. In addition, the in vitro assay avoids the animal welfare issues associated with surgery and caring for rats with spinal cord injury.
The in vitro model is currently being optimised as a screen to test the combination therapies which are likely to be required for progress in the treatment of spinal cord injury. Such screening would be difficult in animals because of practical issues including cost.
This case study was published in a review of our research portfolio in September 2011.