Reaching and Grasping Training Improves Functional Recovery After Chronic Cervical Spinal Cord Injury

Abstract

Previous studies suggest locomotion training could be an effective non-invasive therapy after spinal cord injury (SCI) using primarily acute thoracic injuries. However, the majority of SCI patients have chronic cervical injuries. Regaining hand function could significantly increase their quality of life. In this study, we used a clinically relevant chronic cervical contusion to study the therapeutic efficacy of rehabilitation in forelimb functional recovery. Nude rats received a moderate C5 unilateral contusive injury and were then divided into two groups with or without Modified Montoya Staircase (MMS) rehabilitation. For the rehabilitation group, rats were trained 5 days a week starting at 8 weeks postinjury (PI) for 6 weeks. All rats were assessed for skilled forelimb functions with MMS test weekly and for untrained gross forelimb locomotion with grooming and horizontal ladder (HL) tests biweekly. Our results showed that MMS rehabilitation significantly increased the number of pellets taken at 13 and 14 weeks PI and the accuracy rates at 12 to 14 weeks PI. However, there were no significant differences in the grooming scores or the percentage of HL missteps at any time point. Histological analyses revealed that MMS rehabilitation significantly increased the number of serotonergic fibers and the amount of presynaptic terminals around motor neurons in the cervical ventral horns caudal to the injury and reduced glial fibrillary acidic protein (GFAP)-immunoreactive astrogliosis in spinal cords caudal to the lesion. This study shows that MMS rehabilitation can modify the injury environment, promote axonal sprouting and synaptic plasticity, and importantly, improve reaching and grasping functions in the forelimb, supporting the therapeutic potential of task-specific rehabilitation for functional recovery after chronic SCI.

Systematic analysis of purified astrocytes after SCI unveils Zeb2os function during astrogliosis

“…The result revealed a reduction of the lesion volume at 17 days post-SCI in Zeb2os KD-treated mice compared to the control group ( Figure 6E ). Furthermore, we assessed neuroinflammation by staining CD68, a common marker of microglia/macrophages ( Cheng et al, 2018 ; Gallegos et al, 2020 ). Result showed the percentage of CD68-IR area in cross sections at various distance from epicenter showed no significant difference between Zeb2os KD and control groups, indicating the neuroinflammation was not exacerbated by Zeb2os KD ( Figures S7A and S7B ).…”

“…We also used 5-HT (serotonin) immunostaining to evaluate whether knocking down Zeb2os affected serotonin axon sprouting after SCI. 5-HT-positive axons originated from the brainstem serotonergic neurons mainly innervate neurons at spinal ventral horns ( Gallegos et al, 2020 ; Lee et al, 2010 ). We observed an increasing trend at 400, 800, and 1,600 µm rostral and 400, 1,600, and 2,000 µm caudal to the injury epicenter at 7D after Zeb2os KD although they were not statistically significant ( Figures S7C and S7D ).…”

“…Images of the injury site were captured starting from the epicenter and every 400 µm traversing rostrally and caudally at 20x magnification on a Zeiss Observer Z1 inverted microscope. GFAP-IR and pSTAT3-IR area were quantified based on previously studies with modifications ( Cao et al, 2001 ; Gallegos et al, 2020 ; Mattugini et al, 2019 ) using ImageJ/Fiji (v1.52n). Briefly, a set threshold was used to automatically calculate the areas of GFP-IR and the GFAP-IR within GFP-IR were analyzed using ImageJ/Fiji.…”

“…Images were captured on the sections every 400 µm over a total distance of 2,000 mm rostral and caudal to the epicenter at 20x magnification. To assess neuroinflammation, total area of cross section was manually traced and cross-sectional CD68-IR area was measured using ImageJ following the same method as previously described ( Cheng et al, 2018 ; Gallegos et al, 2020 ). The percentage of CD68-IR to the total area was calculated at all measured sections (n = 5–6).…”

“…The percentage of CD68-IR to the total area was calculated at all measured sections (n = 5–6). To assess the sprouting of serotonin axons, an area of approximately 229 µm diameter circle in the ventral horns was applied as the region of interest (ROI) and 5-HT-IR area within the ROI was measured by setting a threshold ( Gallegos et al, 2020 ; Lee et al, 2010 ). The percentage of 5-HT-IR area was calculated by dividing 5-HT-IR area by ROI area (n = 5).…”