Axonal outgrowth and Erk1/2 activation by training after spinal cord injury in rats

Mesenchymal stem cells (MSCs) have been proposed for spinal cord injury (SCI) applications due to their capacity to secrete growth factors and vesicles—secretome—that impacts important phenomena in SCI regeneration. To improve MSC survival into SCI sites, hydrogels have been used as transplantation vehicles. Herein, we hypothesized if different hydrogels could interact differently with adipose tissue-derived MSCs (ASCs). The efficacy of three natural hydrogels, gellan gum (functionalized with a fibronectin peptide), collagen, and a hydrogel rich in laminin epitopes (NVR-gel) in promoting neuritogenesis (alone and cocultured with ASCs), was evaluated in the present study. Their impact on ASC survival, metabolic activity, and gene expression was also evaluated. Our results indicated that all hydrogels supported ASC survival and viability, being this more evident for the functionalized GG hydrogels. Moreover, the presence of different ECM-derived biological cues within the hydrogels appears to differently affect the mRNA levels of growth factors involved in neuronal survival, differentiation, and axonal outgrowth. All the hydrogel-based systems supported axonal growth mediated by ASCs, but this effect was more robust in functionalized GG. The data herein presented highlights the importance of biological cues within hydrogel-based biomaterials as possible modulators of ASC secretome and its effects for SCI applications.

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Water Treadmill Training Ameliorates Neurite Outgrowth Inhibition Associated With NGR/RhoA/ROCK by Inhibiting Astrocyte Activation Following Spinal Cord Injury

10.21203/rs.3.rs-532819/v1 ◽

2021 ◽

Author(s):

Xinwang Ying ◽

Xiaolan Yu ◽

Jintao Zhu ◽

Xuqing Li ◽

Yujun Zheng ◽

...

Keyword(s):

Spinal Cord ◽

Spinal Cord Injury ◽

Neurite Outgrowth ◽

Treadmill Training ◽

Axonal Outgrowth ◽

Astrocyte Activation ◽

Nissl Staining ◽

Quantitative Expression ◽

Cord Injury ◽

Water Treadmill

Abstract Background: Axons become scattered and incomplete after spinal cord injury (SCI). Cross-talk between astrocytes and neurons plays a pivotal role in neurite outgrowth following SCI. Rehabilitative training is a recognized method for the treatment of SCI, but the specific mechanism of its effect on axonal outgrowth in the central nervous system (CNS) has not been determined.Methods: A total of 160 adult male SD rats weighing 200–250 g were randomly divided into three groups, and an SCI animal model was established. Rats were subjected to water treadmill training (TT) for 7 or 14 d. The Basso-Beattie-Bresnahan (BBB) motor function scale, hematoxylin-eosin (HE) staining, Nissl staining, Western blotting and immunofluorescence were used to measure the degree of neurological deficit, tissue morphology, quantitative expression and accurate localization of the corresponding proteins.Results: We found that TT decreased tissue structure damage and improved functional recovery. TT promoted the regeneration of neurons and reduced apoptosis induced by SCI around the lesion. TT significantly increased the expression of GAP43 and NF200 after SCI. In addition, the injury-induced increase in the expression of proinflammatory factors was significantly inhibited by TT. TT reduced the activation of astrocytes and microglia, accompanied by reduced expression of C3d and higher increased of S100A10. Finally, the level of chondroitin sulfate proteoglycan (CSPG) surrounding the lesion and activation of the NGR/RhoA/ROCK signalling pathway in neurons after SCI were effectively inhibited by TT.Conclusions: In this study, we found that TT played a novel role in recovery from SCI by promoting axonal outgrowth associated with the NGR/RhoA/ROCK by inhibiting astrocyte activation after SCI.

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