The lack of successful regeneration after injury in the mature central nervous system is due to intrinsic and environmental obstacles. Though progress in the field has been made, overcoming these barriers to result in robust functional axon regeneration and recovery is still a significant challenge. We build upon preliminary data and hypothesize that recurrent DREADD-mediated neuronal activation after injury is a means to enhance functional axon regeneration. Additionally, we will test the hypothesis that neuronal activation increases axon regeneration via both mTOR activation and increasing dynamic microtubules. We will these our hypotheses both in vitro using adult dorsal root ganglion neuron cultures and in vivo using dorsal root crush, dorsal columns spinal cord injury (SCI)/peripheral nerve graft (PNG), and incomplete cervical SCI/PNG models.
In Aim 1, we will elucidate how repeated, chemogenetic neuronal activation enhances axon regeneration.
In Aim 2, we will assess if neuronal activation ? alone or in combination with manipulations that increase dynamic microtubules and mTOR activation ? promotes functional axon regeneration. Collectively, we will: 1) elucidate mechanisms behind how neuronal activation enhances growth, potentially identifying new therapeutic targets; 2) determine the extent to which neuronal activation enhances regeneration in different injury models (dorsal root crush, SCI); 3) determine if neuronal activation has disparate or similar effects in different populations of neurons (DRG vs. CNS); 4) test whether meaningful axonal regeneration is facilitated using a unique, multi-faceted approach that: a) uses chemogenetic neuronal activation ? possibly along with further increasing dynamic microtubules and/or mTOR activation ? to enhance the axonal growth response; b) provides a more growth-permissive environment after an injury (i.e. mitigation of the inhibitory matrix of the glial scar with chondroitinase; transplantation of a PNG into an SCI cavity; chondroitinase digestion of plasticity-limiting perineuronal nets). After the completion of these experiments, we will have identified novel therapeutic avenues to foster functional repair after SCI.

Public Health Relevance

? RELEVANCE TO PUBLIC HEALTH Spinal cord injury (SCI) affects 1.3 million Americans. The proposed experiments in this application are relevant to public health because they will elucidate mechanisms for how neuronal activation promotes axon growth, thus identifying potential therapeutic targets. Additionally, they will test whether neuronal activation ? alone or in combination with other manipulations ? promotes functional axon regeneration after SCI.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS085426-07
Application #
10075988
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Bambrick, Linda Louise
Project Start
2014-05-01
Project End
2024-12-31
Budget Start
2021-01-01
Budget End
2021-12-31
Support Year
7
Fiscal Year
2021
Total Cost
Indirect Cost
Name
Drexel University
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
002604817
City
Philadelphia
State
PA
Country
United States
Zip Code
19102
Hou, Shaoping; Saltos, Tatiana M; Iredia, Idiata W et al. (2018) Surgical techniques influence local environment of injured spinal cord and cause various grafted cell survival and integration. J Neurosci Methods 293:144-150
Ahn, Jemin; Saltos, Tatiana M; Tom, Veronica J et al. (2018) Transsynaptic tracing to dissect supraspinal serotonergic input regulating the bladder reflex in rats. Neurourol Urodyn 37:2487-2494
Mironets, Eugene; Osei-Owusu, Patrick; Bracchi-Ricard, Valerie et al. (2018) Soluble TNF? Signaling within the Spinal Cord Contributes to the Development of Autonomic Dysreflexia and Ensuing Vascular and Immune Dysfunction after Spinal Cord Injury. J Neurosci 38:4146-4162
Wu, Di; Klaw, Michelle C; Connors, Theresa et al. (2017) Combining Constitutively Active Rheb Expression and Chondroitinase Promotes Functional Axonal Regeneration after Cervical Spinal Cord Injury. Mol Ther 25:2715-2726
Mironets, Eugene; Wu, Di; Tom, Veronica J (2016) Manipulating extrinsic and intrinsic obstacles to axonal regeneration after spinal cord injury. Neural Regen Res 11:224-5
Wu, Di; Klaw, Michelle C; Kholodilov, Nikolai et al. (2016) Expressing Constitutively Active Rheb in Adult Dorsal Root Ganglion Neurons Enhances the Integration of Sensory Axons that Regenerate Across a Chondroitinase-Treated Dorsal Root Entry Zone Following Dorsal Root Crush. Front Mol Neurosci 9:49
Hou, Shaoping; Carson, David M; Wu, Di et al. (2016) Dopamine is produced in the rat spinal cord and regulates micturition reflex after spinal cord injury. Exp Neurol 285:136-146
Partida, Elizabeth; Mironets, Eugene; Hou, Shaoping et al. (2016) Cardiovascular dysfunction following spinal cord injury. Neural Regen Res 11:189-94
Wu, Di; Klaw, Michelle C; Connors, Theresa et al. (2015) Expressing Constitutively Active Rheb in Adult Neurons after a Complete Spinal Cord Injury Enhances Axonal Regeneration beyond a Chondroitinase-Treated Glial Scar. J Neurosci 35:11068-80
Xu, Chen; Klaw, Michelle C; Lemay, Michel A et al. (2015) Pharmacologically inhibiting kinesin-5 activity with monastrol promotes axonal regeneration following spinal cord injury. Exp Neurol 263:172-6