Sonic Hedgehog signalling promotes perilesion cell proliferation and functional improvement following cortical contusion injury

Pringle, Ashley K., Solomon, Elshadaie, Coles, Benjamin J., Desousa, Brandon R., Shtaya, Anan, Gajavelli, Shyam, Dabab, Nedal, Zaben, Malik J. ORCID: https://orcid.org/0000-0002-7446-4532, Bulters, Diederik O., Bullock, M. Ross and Ahmed, Aminul I. 2021. Sonic Hedgehog signalling promotes perilesion cell proliferation and functional improvement following cortical contusion injury. Neurotrauma Reports 2 (1) , pp. 27-38. 10.1089/neur.2020.0016

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Abstract

Traumatic brain injury (TBI) is a leading cause of death and disability globally. No drug treatments are available, so interest has turned to endogenous neural stem cells (NSCs) as alternative strategies for treatment. We hypothesized that regulation of cell proliferation through modulation of the sonic hedgehog pathway, a key NSC regulatory pathway, could lead to functional improvement. We assessed sonic hedgehog (Shh) protein levels in the cerebrospinal fluid (CSF) of patients with TBI. Using the cortical contusion injury (CCI) model in rodents, we used pharmacological modulators of Shh signaling to assess cell proliferation within the injured cortex using the marker 5-Ethynyl-2’-deoxyuridine (EdU); 50mg/mL. The phenotype of proliferating cells was determined and quantified. Motor function was assessed using the rotarod test. In patients with TBI there is a reduction of Shh protein in CSF compared with control patients. In rodents, following a severe CCI, quiescent cells become activated. Pharmacologically modulating the Shh signaling pathway leads to changes in the number of newly proliferating injury-induced cells. Upregulation of Shh signaling with Smoothened agonist (SAG) results in an increase of newly proliferating cells expressing glial fibrillary acidic protein (GFAP), whereas the Shh signaling inhibitor cyclopamine leads to a reduction. Some cells expressed doublecortin (DCX) but did not mature into neurons. The SAG-induced increase in proliferation is associated with improved recovery of motor function. Localized restoration of Shh in the injured rodent brain, via increased Shh signaling, has the potential to sustain endogenous cell proliferation and the mitigation of TBI-induced motor deficits albeit without the neuronal differentiation.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Medicine Neuroscience and Mental Health Research Institute (NMHRI)
ISSN:	2689-288X
Date of First Compliant Deposit:	7 January 2021
Date of Acceptance:	14 December 2020
Last Modified:	05 May 2023 18:55
URI:	https://orca.cardiff.ac.uk/id/eprint/137312

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