The current proposal is designed to develop of a new research area that is aimed at transplanting mitochondria into the injured rodent spinal cord as a therapeutic strategy following traumatic spinal cord injury (SCI). We and others have found that maintaining normal mitochondrial bioenergetics after contusion SCI fosters both neuroprotection and functional recovery. However, no studies have examined the effects of transplanting exogenous mitochondria into spinal cord tissue after injury in an attempt to normalize overall cellular bioenergetics and spare adjacent host tissues. Accordingly, this new line of investigations will test, ultimately, whether transplanting exogenous healthy mitochondria into the injured spinal cord promotes functional neuroprotection. Using a rat model of contusion SCI, we have preliminary data showing that allogeneic transgenically-labeled (turboGFP) mitochondria derived from PC12 cells microinjected around the injury site maintain overall cellular bioenergetics assessed 24 hrs later. Moreover, using confocal microscopy to evaluate specific antibodies to both inner and outer mitochondrial membranes, we have preliminary evidence that grafted turboGFP mitochondria integrate within nave and injured spinal cord tissues. Based on these seminal findings, we propose to conduct a series of transplantation strategies to deliver mitochondria around the injury sites. The ultimate goal is to identify a potential autologous cell source of mitochondria (i.e., leg muscle) to prevent secondary tissue injury that is mediated, in large part, by mitochondrial loss and dysfunction. In summary, Aim 1a will comparatively employ a dose-response approach to assess whether transplanted MitoTracker Red-labeled mitochondria isolated from muscles are equally effective as allogeneic turboGFP mitochondria on cellular bioenergetics and the extent of inflammation following acute contusion SCI.
Aim 1 b will then assess comparatively the frequency and distribution of labeled mitochondria incorporated into host cells over the first week post-injury. Finally, Aim 2 will establish whether transplantation of muscle-derived mitochondria increases long-term tissue sparing and recovery of hindlimb locomotion following SCI. This project has translational potential wherein mitochondria, notably autologous, can be transplanted around the injury site to spare penumbral tissues. Based on the collective expertise of the PI in cellular transplantation into injured spinal cord tissue and both Co-Is in bioenergetic assessments and mitochondrial-targeted therapeutics for neurotrauma, along with our preliminary feasibility data, there are no foreseen technical obstacles to successfully carry out this project. Notably, future experiments stemming from the results of the current proposal will be designed to test delayed grafting paradigms to extend a more clinically relevant therapeutic time window for transplantation of mitochondria to promote functional recovery in more chronic SCI models.

Public Health Relevance

The current proposal is an innovative research plan to determine, for the first time, whether intraspinal transplantation of healthy mitochondria acutely after contusion spinal cord injury (SCI) results in improved sparing of host tissue and functional recovery. The knowledge gained from the proposed experiments will provide direct insight into the potential of this novel therapeutic intervention to maintain cellular bioenergetics while reducing both oxidative stress and inflammation following acute SCI. The planned research is relevant to aspects of the NIH's mission to discover new therapies for SCI by utilizing seminal mitochondrial transplantation techniques to provide neuroprotection manifested in improved long-term behavioral recovery.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Exploratory/Developmental Grants (R21)
Project #
5R21NS096670-02
Application #
9210134
Study Section
Neural Oxidative Metabolism and Death Study Section (NOMD)
Program Officer
Jakeman, Lyn B
Project Start
2016-04-01
Project End
2018-03-31
Budget Start
2017-04-01
Budget End
2018-03-31
Support Year
2
Fiscal Year
2017
Total Cost
$169,312
Indirect Cost
$56,812
Name
University of Kentucky
Department
Neurology
Type
Schools of Medicine
DUNS #
939017877
City
Lexington
State
KY
Country
United States
Zip Code
40506