Every year, several thousand individuals suffer spinal cord injury (SCI) in North America, while 1.5 million suffer traumatic brain injury in the U.S.A. alone. Primary mechanical trauma to the CNS is followed by a complex pathology, including vascular dysregulation, ischemia, edema and traumatic hemorrhage. Secondary damage is to a large extent caused by oxidative stress and inflammatory processes, resulting in necrosis and apoptosis of neural cells. If secondary tissue injury could be limited by interference with any of the pathomechanisms involved, preservation of structure and function would increase the potential for functional recovery. Experiments performed in other laboratories have shown that the polyphenolic flavonoid quercetin acts as an anti-oxidant and anti-inflammatory, reduces edema formation and apoptotic cell death. Quercetin is also an excellent iron chelator. This action profile suggested a high therapeutic potential for acute CNS trauma. Therefore, I used models of both spinal cord injury and head trauma in adult male rats to test the hypothesis that administration of quercetin is beneficial for the therapy of acute traumatic CNS injury. While the primary focus of my work was on therapy of acute traumatic spinal cord injury, quercetin was also evaluated in the settings of chronic SCI and acute head trauma. I found that, in a rat model of mid-thoracic spinal cord compression injury, 1) administration of quercetin, starting 1 hr after injury and continued every 12 hr, improved recovery of motor function in the hind limbs in more than half of the injured animals to a degree that allowed previously paraplegic animals to step or walk. The minimum quercetin dose that was efficacious was 5 µmol/kg. The minimum treatment duration for optimal outcome was determined to be 3 days. In control animals, some spontaneous recovery of motor function did occur, but never to an extent that allowed animals to step or walk. Quercetin administration was associated with more efficient iron clearance from the site of injury, decreased inflammatory response as reflected in decrease of myeloperoxidase activity and decreased apoptosis of neural cells at the site of injury. 2) Quercetin administered in the same injury model as late as 2 weeks after injury, given in a higher dose than that used for treatment in the acute phase, still resulted in significant recovery of motor function in 40% of the injured animals, although at a lower level of performance, when compared to early onset of treatment. 3) Quercetin administered after moderate fluid percussion brain injury resulted in decreased oxidative stress, as reflected in higher tissue glutathione levels at the site of injury. In animals receiving quercetin, the amplitude of compound action potentials was significantly better maintained at 24 hr and 72 hr after injury than in saline-treated control animals. My experiments have shown that the flavonoid quercetin is neuroprotective in a rat model of brain trauma and in a rat model of spinal cord injury. My data show that administration of quercetin after CNS trauma promotes iron clearance, decreases oxidative stress and inflammation. Quercetin also decreases apoptotic cell death following neurotrauma. These results suggest that quercetin may be a valuable adjunct in the therapy of acute CNS trauma. There is a possibility that administration of quercetin may be beneficial even in certain settings of chronic CNS trauma. These conclusions are based solely on the results from animal experiments. However, the fact that few adverse reactions have been noted to date in either animal experiments or human trials targeting other diseases is encouraging for the progression to human clinical trials for patients with spinal cord injury.

Trauma-induced spinal cord injury (SCI) is the most prevalent form of spinal cord injury affecting over 80% of the 36,000 Canadians living with this condition. The pathophysiological profile of traumatic SCI consists of an initial stage of direct damage followed by a series of secondary events, including reduced blood flow and increased generation of free radicals that leads to excitotoxicity, oxidative stress, hemorrhagic necrosis, inflammation, and apoptosis. We examined the hypotheses that delayed administration of the flavonoid quercetin inhibits the propagation of secondary events and promotes functional recovery after traumatic SCI by inhibiting inflammatory processes and signaling pathways that promote apoptosis and thereby promoting axon survival. To determine whether delayed quercetin treatment promoted functional recovery following SCI, male Wistar rats were subjected to a spinal cord compression injury by application of a 50 g modified aneurysm clip at the mid thoracic cord level. A treatment regimen of 75 µmol quercetin per kg rat or saline only (controls) was administered for a period of 3 days, 1 week or 2 weeks beginning at 2 weeks post surgery. Delayed quercetin treatment improved locomotion in injured animals although with severe deficit. To determine whether improved functional outcome correlated with improved tissue preservation and reduced scarring, we performed histological examinations at the injury site. In saline treated animals, at 8 weeks post injury we found over 80% of tissue loss with the majority of the remaining cells undergoing apoptosis. However, with 2 weeks delayed quercetin treatment, at least 50% of the tissue was still present at 8 weeks post surgery with a significant reduction of apoptosis. Quercetin treated animals also showed a reduction of reactive gliosis. To determine which intracellular signaling pathways may mediate the protective effects of quercetin, we carried out Western blots and immunocytochemical analyses of a number of potential pro-apoptotic pathways. We found that quercetin reduced the levels of the phosphorylated (activated) forms of the MAPK p38, ERK 1/2 (p42/44) and SAPK/JNK seen after SCI. We conclude that delayed quercetin treatment likely rescues neurons that would otherwise have died between the third and sixth weeks following injury by inhibiting apoptosis of glia cells. Quercetin may be acting via selective inhibition of kinase pathways that have been shown to be involved in apoptosis and cell growth. These findings not only reveal the protective effects of quercetin in reducing secondary damage after chronic SCI but also shed some light on some of the mechanisms underlying its actions.

This thesis describes the research, design, and development of a mid-drive wheelchair for use by the elders living independently, in assisted living facilities, and in nursing homes created by a design team at Georgia Tech's Center for Assistive Technology and Environmental Access (CATEA). This wheelchair stands to significantly improve the mobility of elders through better drive wheel placement and design features that could stand to improve their quality of life.

Spinal cord injury, acute pain, and morphine tolerance are important issues in the clinical practice. A primary injury to the spinal cord causes both morphological and biochemical changes with initiation of the devastating secondary pathophysiological pathways that ultimately destroy CNS cells and cause degeneration of nerve fibers. Tissue injury is associated with sensitization of nociceptors and subsequent changes in the excitability of central neurons, known as central sensitization. Nociceptor sensitization and central sensitization are believed to underlie the development of primary and secondary hyperalgesia, respectively. The most efficacious drugs used to relieve pain are the opioid analgesics. Chronic administration leads to the development of tolerance. Tolerance is manifested as a decreased potency of the drug, so that progressively larger doses must be administered to achieve a given level of analgesia. The processes underlying opioid tolerance still need to be elucidated. Recently, it is found calpain-Cdk5 (cyclin-dependent kinase-5)-p35 pathway modulation implicated in neuroprotection, acute nociceptive response, and morphine analgesia. In this thesis, we evaluate calpain inhibitor-MDL28170 and Cdk5 inhibitor-roscovitine against rat spinal cord hemisection, formalin-induced acute nociceptive responses, and chronic morphine tolerance. We found calpain-Cdk5-p35 pathway inhibition could protect spinal cord hemisection and subsequent neurodegeneration, inhibit formalin-induced flinch response involving DARPP-32 (dopamine and c-AMP regulated phosphoprotein, MW=32 kDa) phosphorylation, and reverse right shifted morphine dose-response curve with upregulated ED50 (50% of effective dose) reduction. Taken together, calpain-Cdk5-p35 pathway inhibition is useful in the management of spinal cord injury, acute inflammatory pain, and attenuate morphine tolerance development with further clinical application.

Current treatments for spinal cord injury (SCI) are extremely limited due to the fact that the central nervous system lacks the intrinsic ability to regenerate, and constitutes a poor environment for regenerative axon growth. Nerve tissue engineering is an emerging field with the aim of repairing or creating new nerve tissues to promote functional recovery by using artificial tissue repair scaffolds. The design of a stable and consistent animal model of SCI is essential to study the effectiveness of scaffolds in promoting nervous system repair. In this study, a partial transection animal model was created with a three dimensional lesion at T8-T9 that disrupts axonal pathways unilaterally in the dorsal columns of the rat spinal cord. Alginate hydrogel scaffolds incorporating living Schwann cells were fabricated to evaluate the abilities of those scaffolds to foster axonal regeneration. The surgical technique was improved to provide better outcomes related to bleeding during surgery, weight control, neurological function and surgery duration. The survival rate of animals during the surgical procedure and post-surgery period was ultimately increased to 100%. Histology and immunohistochemistry results indicated that implanted alginate scaffolds may induce larger cavities and extenuate harmful inflammation responses, but that effect was ameliorated by inclusion of Schwann cells in the scaffold. However, neither plain alginate scaffolds nor scaffolds containing living Schwann cells were able to improve regeneration of identified axon tracts in the spinal dorsal columns. This research also employed a synchrotron based x-ray phase contrast imaging technique coupled with computed-tomography to visualize the low optical density structural features of scaffolds and spinal cord tissues in formaldehyde fixed specimens. The imaging results suggest that this is a promising method for analyzing the structure of tissue repair scaffolds within the spinal cord. This degree of structural characterization, potentially applicable to living tissue, is not afforded by other conventional image analysis techniques.

Spinal cord injury is a devastating source of suffering in the spectrum of human pathophysiology; advancement for clinical therapy in this area has been stagnant in comparison to modern medical development. Current treatments are palliative, and functional recovery is minimal. During the first two weeks after injury, dense glial scar forms that is impenetrable by regenerating axons. Intervention is imperative to minimize scar formation and provide a supportive environment for axonal regeneration. Oligodendrocytes are critical to maintain the health of growing axons during development and after injury. Obtaining these cells through differentiation of neural progenitor cells (NPCs) is a viable option, but current clinical trials involving stem cells are plagued by poor cell survival and undirected differentiation. Research indicates that local extracellular matrix (ECM) is vital to progenitor differentiation and tissue regeneration. During development, spinal cord ECM is comprised of high concentrations of laminin and hyaluronic acid (HA), which provide essential cues to direct NPC migration and differentiation. The purpose of this research is to create a biomaterial optimized to direct NPC differentiation to oligodendrocytes. Natural biomaterials were optimized from distinct combinations of collagen I, HA, and laminin I to model the native ECM signals found during oligodendrocyte maturation. Four material combinations (collagen, collagen-HA-laminin, collagen-HA, and collagen-laminin) were fabricated into injectable hydrogels to mimic the range of compressive and shear mechanical properties present in neonatal central nervous system (CNS) tissue. Differentiation was assessed by culturing rodent fetal NPCs in these materials without specific soluble factors to direct cellular behavior. The three-component hydrogel performed optimally and achieved a 66% oligodendrocyte differentiation rate compared to approximately 15% in the collagen alone hydrogel. An in vivo study was then conducted using a rat contusion model of spinal cord injury with intervention using the injectable, three-component hydrogel seeded with rat NPCs. Functional recovery was assessed using six behavioral tests. Significant recovery was observed using two behavioral tests six weeks post-treatment. Lesion size was measured and correlated well with behavioral outcomes. The data obtained in this research indicate that a multi-component hydrogel mimicking native, developmental CNS tissue may address problems associated with current clinical practice. / text

Abstract Purpose: To characterize physical activity of people using manual wheelchairs with spinal cord injury in Manitoba. Methods: An observational study of manual wheelchairs users with spinal cord injury. Participants completed surveys related to self-efficacy for exercise, physical activity participation, and shoulder pain. Accelerometers were worn for 7 days on the wrist and trunk (GT3X, 100 Hz, 5 s epochs) and completed an activity log concurrently. Individual specific thresholds were determined for moderate intensity during a pace graded wheeling trial. Physical activity and sedentary time were characterized using various derived variables. Results: Twenty five participants (12 tetra:13 para, 21M:4F) demonstrated excellent accelerometer adherence achieving an average of 6.2 days worn for over 13 hours per day. A total of 74.6 min (all activity) and 115 min (contiguous bouts of activity) were achieved over time worn (6.2 days), corresponding to 11.8 and 18.5 min/day respectively. The participants substantially exceeded the published SCI guidelines (40 min/week, P<0.01) but were under the able bodied threshold of 150 min/week (P<0.01). No relationships were observed between surveys and objectively measured PA. Characterization of PA bouts revealed few participants (n=7) exhibiting single bout durations greater than 10 minutes, with an average contiguous bout duration of 30 s. A new functional classification scheme revealed positive correlations to PA variables and wheeling performance. Sedentary times ranged from 6.25 to 8.4 hours per day depending upon accelerometer placement. Conclusion: Arm based accelerometry can be used to determine PA and sedentary characteristics of manual wheelchair users with individual specific moderate intensity thresholds. Participants exceeded the SCI specific activity guidelines in terms of time per week, and failed to reach bout durations of 20 min. This study supports the use of able-bodied PA guidelines as a target. A new functional classification scheme was derived based upon wheeling dependent muscle innervation that had enhanced prediction of PA relative to standard anatomical classification / October 2015

Individuals with spinal cord injury (SCI) demonstrate reduced limb blood flow and muscle spasticity. It is plausible that the accumulation of metabolites, resulting from reduced perfusion, could exacerbate spasticity via activation of fusimotor neurons by Group III and IV afferents. PURPOSE: To determine the association between peripheral blood flow and muscle spasticity in persons with SCI. METHODS: A total of 16 individuals with SCI were classified into high (N=6), low (N=5), and no (N=5) spasticity groups according to their spasticity levels indicated by the modified Ashworth scale scores. Blood flow was measured in femoral and brachial arteries using duplex Doppler ultrasound and was normalized to limb lean mass obtained with dual energy X-ray absorptiometry. RESULTS: There were no significant group differences in age (30.5±4.15, 38.48±4.61, 32.6±4.89 years), time post SCI (8.5±4.2, 12.6±4.74, 6.8±1.66 years), American SCI Association motor scores (39.2±7.78, 59±12.34, 53.4±1.08), or sensory scores (96±22.1, 144.4±13.97, 130±13.8). Femoral artery blood flow, adjusted for limb lean mass, was significantly different (p=0.002) across the three leg spasticity groups (high 76.03±6.44, low 95.12±15.49, no 142.53±10.86 ml/min/kg).Total leg muscle spasticity scores were significantly and negatively correlated with femoral artery blood flow (r=-0.60, p=0.014). There was no significant difference in brachial artery blood flow between the three groups, indicating that the reduction in blood flow was confined to injured limbs and not due to systemic cardiovascular disorder. CONCLUSION: Among SCI patients, whole-leg blood flow is progressively lower in individuals with greater spasticity scores. These results suggest that a reduction in lower limb perfusion, among other factors, plays a significant role in the pathogenesis leading to muscle spasticity after SCI. / text

Bipeds and quadrupeds are inherently unstable and their bodies sway during quiet stance and require complex patterns of muscle activation to produce direction-specific forces to control the body’s center of mass. The relative strength of length and force feedback within and across muscles collectively regulates the mechanical properties of the limb as a whole during standing and locomotion (Bonasera and Nichols 1994; Ross and Nichols 2009). Loss of posture control following spinal cord injury (SCI) is a major clinical challenge. While much is known about intermuscular force feedback during crossed extension reflex (XER) and locomotion in decerebrate cats, these have not been well characterized in animals with spinal cord injury. In this study, we mapped the distribution of heterogenic force feedback in hindlimb ankle extensor muscles using muscle stretch (natural stimulation) in intercollicular, non-locomoting, decerebrate cats with chronic lateral spinal hemisection (LSH). We also, determined the time of onset of redistribution of heterogenic force feedback following LSH by collecting force feedback data from cats with acute sci. In addition we revisited heterogenic force feedback between ankle extensors in decerebrate non-locomoting cats during mid-stance to ascertain whether these cats with intact spinal cord depict a certain pattern of force feedback. The goal was to ascertain whether the patterns and strength of feedback was different between the two states (cats with intact spinal cord and cats with SCI). We found that heterogenic feedback pathways remained inhibitory in non-locomoting decerebrate cats in two states. The latencies of inhibition also corresponded to those observed for force feedback from Golgi tendon organs. We observed variable patterns of force feedback between ankle extensors in decerebrate/control cats. On the other hand we observed consistent results in cats with chronic LSH exhibiting very strong distal to proximal pattern of inhibition from 2 weeks to 20 weeks following chronic LSH. The same results were obtained in acute LSH cats suggest that the change in neuromuscular system appears immediately after SCI and persists even after the animal start walking following SCI. The observed altered pattern of force feedback after spinal cord injury suggests either presence of a pattern intrinsic to the spinal cord or a unique pattern exhibited by the damaged spinal cord. The results are important clinically because even with vigorous rehabilitation attempts patients do not regain posture control after SCI even though they regain ability to walk. Therefore, to effectively administer treatment and therapy for patients with compromised posture control, a complete understanding of the circuitry is required.

Patients suffering from central neuropathic pain have thermal sensory deficits within the painful area. Prior research proposed that the loss of thermal sensation in regions of central neuropathic pain may reflect similar central nervous system interaction between warm and cold sensory inputs that underlie the Thermal Grill Illusion (TGI) in which burning pain is felt while reduced warm/cold sensations are reported. This work presents a portable and reliable device that was used to systematically evaluate the characteristics of the TGI in healthy individuals. The results suggest that the spatial distribution of the warm and cool stimuli significantly affected the quality of perceived TGI. Additionally, simultaneous tactile and thermal stimulation was shown to be significantly less painful than thermal stimulation alone. A high correlation was also seen in the subject‘s TG intensity scores and their cold pain threshold. These results are useful for future TGI studies for central neuropathic pain.