Characterising the pro-regenerative extracellular matrix in a spinal cord lesion

After a spinal cord injury, the lesion site is filled with fibroblasts and extracellular matrix (ECM) material that inhibits regeneration of the spinal cord in mammals. The Becker group (Edinburgh) have recently shown that in zebrafish, which are perfectly capable of functional spinal cord regeneration, the lesion site ECM contains Col XII. Coll XII deposition is controlled by Wnt signalling and is necessary and sufficient to promote axon regeneration across a lesion site (Wehner et al., 2017). This indicates that in the zebrafish model, pro-regenerative ECM components can be identified. This collaborative PhD project between the Becker group (Edinburgh) and the Barnett group (Glasgow) will be based on elucidating pro-regenerative ECM components, their interplay, and their regulation, with particular focus on localising proteogylcans such as heparan and chondroitin sulphate proteogylcans (HSPGs, CSPGs) in the lesion site. The Barnett group finds that these proteogylcans are key players in binding and organising additional components of the ECM (O'Neill et al., 2017). Heparin mimetics (present in Barnett group) can be used to manipulate their function, in addition to knocking out sulfatases that are necessary to control HSPG and CSPG sulfation levels (using CRISPR/Cas9 techniques). As read-outs, axonal regeneration and functional recovery will be assessed. For an unbiased approach, expression profiles of spinal injury sites in zebrafish will be compared between different regenerating and non-regenerating conditions, e.g. wnt-inhibition or inhibition of immune function. The resulting profiles will be analysed for changes in the expression of ECM-related genes and these will be functionally analysed as above. Hence this project will identify pro-regenerative components and mechanisms of the ECM in a spinal lesion site in zebrafish and thus provide targets for future manipulations of these molecules in a mammalian system to improve regenerative outcome.