Spinal cord injury (SCI) is among the most disabling conditions affecting wounded members of the U.S. military. Unfortunately, no effective treatment has been available for patients with SCI. Developing novel repair strategies to mitigate the devastating nature of SCI and translating them to the clinic are urgent medical needs for our veterans with SCI. For functional recovery to occur after a SCI, regenerated axons need to follow the topography of grafted cells/growth factors and make accurate connections with specific subsets of neurons or subregions of dendritic architecture. The lumbar motoneurons (MNs) are the final common pathways for motor output to the hindlimbs and they undergo dendritic atrophy and synaptic stripping after an above-level SCI. The goal of our research is to reestablish neural circuitry across the lesion gap and to promote functional recovery after SCI. We hypothesize that a growth promoting pathway composed of grafted Schwann cells (SCs) overexpressing a growth factor called glial cell line-derived neurotrophic factor (GDNF) will promote the growth of descending propriospinal tract (dPST) axons across the lesion gap with extension caudally to the lumbar MNs in the host spinal cord, and that these axons will form target-specific synaptic contacts with lumbar MNs overexpressing a neurotrophin called neurotrophin-3 (NT-3). We also hypothesize that such a combinatorial approach will lead to greater recovery of function than either single treatment. Using a clinically-relevant contusive SCI model at the 9th thoracic (T9) level, transplantation of SCs-GDNF to form a continuous axonal growth-promoting pathway across and beyond a SCI, and adeno-associated virus serotype 2 expressing NT-3 (AAV2-NT-3) gene transfer approach to enhance NT-3 expression in lumbar MNs, we will determine (1) whether a continuous axonal growth-promoting pathway formed by grafted SCs-GDNF will promote dPST axonal growth through and beyond a contusive SCI, innervate the lumbar MNs pools, and enhance electrophysiological and locomotor recoveries; (2) whether combining the axonal growth-promoting pathway formed by SCs-GDNF with expression of NT-3 in lumbar MNs will synergistically enhance the innervation of dPST axons on lumbar MNs and, therefore, promote better recovery of function as compared to either treatment alone; (3) whether dPST-MN neurotransmission is necessary for hindlimb locomotor recovery in the combinatorial treatment; and (4) the molecular signature of lumbar MNs after the reestablishment of dPST-MN circuitry and synaptogenesis. Completion of this proposal will allow us to reveal mechanisms fundamental to rebuilding neural circuitry of the dPST-MN pathway and to identify new therapeutic strategies for locomotor recovery after clinically-relevant contusive SCIs.

Public Health Relevance

The goal of our research is to reestablish neural circuitry across the lesion gap and to promote functional recovery in a rat model of spinal cord injury (SCI). We hypothesize that a growth-promoting pathway composed of grafted Schwann cells (SCs) overexpressing a trophic factor called glial cell line-derived neurotrophic factor (GDNF) will promote the growth of descending propriospinal tract (dPST) nerve fibers across the lesion gap with extension caudally to the lumbar motoneurons (MNs) in the host spinal cord, and that these nerve fibers will form target-specific connections with lumbar MNs overexpressing a neurotrophic factor called neurotrophin-3 (NT-3). We also hypothesize that such a combinatorial approach will lead to greater recovery of function than either single treatment. Completion of this proposal will allow us to reveal mechanisms fundamental to rebuilding neural circuitry of the dPST-MN pathway and to identify new therapeutic strategies for locomotor recovery after clinically relevant SCIs.

Agency
National Institute of Health (NIH)
Institute
Veterans Affairs (VA)
Type
Non-HHS Research Projects (I01)
Project #
2I01BX002356-04
Application #
9563764
Study Section
Neurobiology C (NURC)
Project Start
2015-01-01
Project End
2022-12-31
Budget Start
2019-01-01
Budget End
2019-12-31
Support Year
4
Fiscal Year
2019
Total Cost
Indirect Cost
Name
Rlr VA Medical Center
Department
Type
DUNS #
608434697
City
Indianapolis
State
IN
Country
United States
Zip Code
46202
Wang, Ying; Wu, Wei; Wu, Xiangbing et al. (2018) Remodeling of lumbar motor circuitry remote to a thoracic spinal cord injury promotes locomotor recovery. Elife 7:
Ordaz, Josue D; Wu, Wei; Xu, Xiao-Ming (2017) Optogenetics and its application in neural degeneration and regeneration. Neural Regen Res 12:1197-1209
Al-Ali, Hassan; Ding, Ying; Slepak, Tatiana et al. (2017) The mTOR Substrate S6 Kinase 1 (S6K1) Is a Negative Regulator of Axon Regeneration and a Potential Drug Target for Central Nervous System Injury. J Neurosci 37:7079-7095
Chen, Chen; Zhang, Yi Ping; Sun, Yan et al. (2017) An In Vivo Duo-color Method for Imaging Vascular Dynamics Following Contusive Spinal Cord Injury. J Vis Exp :
Wu, Xiangbing; Zhang, Yi Ping; Qu, Wenrui et al. (2017) A Tissue Displacement-based Contusive Spinal Cord Injury Model in Mice. J Vis Exp :
Wu, Xiangbing; Walker, Chandler L; Lu, Qingbo et al. (2017) RhoA/Rho Kinase Mediates Neuronal Death Through Regulating cPLA2 Activation. Mol Neurobiol 54:6885-6895
Walker, Chandler L; Zhang, Yi Ping; Liu, Yucheng et al. (2016) Anatomical and functional effects of lateral cervical hemicontusion in adult rats. Restor Neurol Neurosci 34:389-400
Wu, Xiangbing; Xu, Xiao-Ming (2016) RhoA/Rho kinase in spinal cord injury. Neural Regen Res 11:23-7
Gianaris, Alexander; Liu, Nai-Kui; Wang, Xiao-Fei et al. (2016) Unilateral microinjection of acrolein into thoracic spinal cord produces acute and chronic injury and functional deficits. Neuroscience 326:84-94
Qu, Wenrui; Liu, Nai-Kui; Xie, Xin-Min Simon et al. (2016) Automated monitoring of early neurobehavioral changes in mice following traumatic brain injury. Neural Regen Res 11:248-56

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