Preparation of Drug Sustained-Release Scaffold with De-Epithelized Human Amniotic Epithelial Cells and Thiolated Chitosan Nanocarriers and Its Repair Effect on Spinal Cord Injury

The disability rate of spinal cord injury (SCI) is extremely high, and stem cell inhibition is one of the most effective schemes in treating the spinal cord, but the survival rate is extremely low after stem cell transplantation, so it cannot be widely used in clinic. Studies have revealed that loading stem cells with biological scaffolds can effectively improve the survival rate and effect after stem cell transplantation. Therefore, this research was devised to analyze the repair effect of thiolated chitosan nanocarriers scaffold carrying de-epithelized human amniotic epithelial cells (HAECs) on SCI. And we used thiolated chitosan as nanocarriers, aiming to provide a reliable theoretical basis for future clinical practice. Through experiments, we concluded that the Tarlov and BBB scores of rats with SCI were raised under the intervention of thiolated chitosan carrying HAECs, while the inflammatory factors in serum, oxidative stress reaction in spinal cord tissue, apoptosis rate of nerve cells, and autophagy protein expression were all suppressed. Thus, the thiolated chitosan carrying HAECs may be applied to treat SCI by suppressing autophagy protein expression, oxidative stress response, and release of inflammatory factors in spinal cord tissue, which may be a new clinical therapy for SCI in the future. Even though we cannot understand exactly the therapeutic mechanism of thiolated chitosan carrying HAECs for SCI, the real clinical application of thiolated chitosan carrying HAECs needs to be confirmed by human experiments.

The Repression of the HMGB1-TLR4-NF-κB Signaling Pathway by Safflower Yellow May Improve Spinal Cord Injury

Spinal cord injury (SCI) often results in abnormal sensory and motor functions. Current interventions for SCI in the clinical setting are not effective partly due to the complexity concerning its pathophysiological mechanism. In the wake of SCI, considerable inflammatory cells assemble around the injured area that induces a series of inflammatory reactions and aggravates tissue lesions, thereby affecting the recovery of the damaged nerve tissue. Therefore, the inhibition of inflammatory responses can improve the repair of the injured spinal cord tissue. Safflower Yellow (SY) is the main active ingredient of Carthamus tinctorius. SY has anti-inflammatory effect, as it can inhibit IκBα phosphorylation to impede the NF-κB signaling pathway and p53 nuclear translocation. Besides, SY can limit the release of pro-inflammatory factors, which in turn may alleviate secondary SCI and prevent further complications. In this report, we analyze the pathophysiological mechanism of SCI, the role of inflammatory responses, and how SY interferes with the HMGB1-TLR-4-NF-κB signaling pathway to attenuate inflammatory responses in SCI.

Glial-Neuronal Interactions in Pathogenesis and Treatment of Spinal Cord Injury

Traumatic spinal cord injury (SCI) elicits an acute inflammatory response which comprises numerous cell populations. It is driven by the immediate response of macrophages and microglia, which triggers activation of genes responsible for the dysregulated microenvironment within the lesion site and in the spinal cord parenchyma immediately adjacent to the lesion. Recently published data indicate that microglia induces astrocyte activation and determines the fate of astrocytes. Conversely, astrocytes have the potency to trigger microglial activation and control their cellular functions. Here we review current information about the release of diverse signaling molecules (pro-inflammatory vs. anti-inflammatory) in individual cell phenotypes (microglia, astrocytes, blood inflammatory cells) in acute and subacute SCI stages, and how they contribute to delayed neuronal death in the surrounding spinal cord tissue which is spared and functional but reactive. In addition, temporal correlation in progressive degeneration of neurons and astrocytes and their functional interactions after SCI are discussed. Finally, the review highlights the time-dependent transformation of reactive microglia and astrocytes into their neuroprotective phenotypes (M2a, M2c and A2) which are crucial for spontaneous post-SCI locomotor recovery. We also provide suggestions on how to modulate the inflammation and discuss key therapeutic approaches leading to better functional outcome after SCI.

Selected Thiadiazine-Thione Derivatives Attenuate Neuroinflammation in Chronic Constriction Injury Induced Neuropathy

Neuropathic pain refers to a lesion or disease of peripheral and/or central somatosensory neurons and is an important body response to actual or potential nerve damage. We investigated the therapeutic potential of two thiadiazine-thione [TDT] derivatives, 2-(5-propyl-6-thioxo-1, 3, 5-thiadiazinan-3-yl) acetic acid [TDT1] and 2-(5-propyl-2-thioxo-1, 3, 5-thiadiazinan-3-yl) acetic acid [TDT2] against CCI (chronic constriction injury)-induced neuroinflammation and neuropathic pain. Mice were used for assessment of acute toxicity of TDT derivatives and no major toxic/bizarre responses were observed. Anti-inflammatory activity was assessed using the carrageenan test, and both TDT1 and TDT2 significantly reduced carrageenan-induced inflammation. We also used rats for the induction of CCI and performed allodynia and hyperalgesia-related behavioral tests followed by biochemical and morphological analysis using RT-qPCR, immunoblotting, immunohistochemistry and immunofluorescence. Our findings revealed that CCI induced clear-cut allodynia and hyperalgesia which was reversed by TDT1 and TDT2. To determine the function of TDT1 and TDT2 in glia-mediated neuroinflammation, Iba1 mRNA and protein levels were measured in spinal cord tissue sections from various experimental groups. Interestingly, TDT1 and TDT2 substantially reduced the mRNA expression and protein level of Iba1, implying that TDT1 and TDT2 may mitigate CCI-induced astrogliosis. In silico molecular docking studies predicted that both compounds had an effective binding affinity for TNF-α and COX-2. The compounds interactions with the proteins were dominated by both hydrogen bonding and van der Waals interactions. Overall, these results suggest that TDT1 and TDT2 exert their neuroprotective and analgesic potentials by ameliorating CCI-induced allodynia, hyperalgesia, neuroinflammation and neuronal degeneration in a dose-dependent manner.

Pregabalin alleviates postherpetic neuralgia by downregulating spinal TRPV1 channel protein

Purpose: To determine the mechanism involved in pregabalin-induced alleviation of postherpetic neuralgia in a rat model.Methods: Ninety-sixty healthy Sprague-Dawley (SD) rats were assigned to sham, model andpregabalin groups (32 rats per group). A model of postherpetic neuralgia (PN) was established. The expressions of IL-1β and TNF-α in spinal cord tissue were determined 7 days after administration of treatments. The proportions of fluorescence areas in astrocytes in the dorsal horn, prefrontal lobe and hippocampus, and level of spinal cord TRPV1 channel protein in each group were evaluated.Results: Relative to model rats, IL-1β and TNF-α in spinal cord of pregabalin rats were significantly reduced (p < 0.05). The areas of fluorescence in astrocytes in dorsal horn of spinal cord, prefrontal lobe and hippocampus of model group were significantly increased, relative to sham, but were decreased in rats in pregabalin group (p < 0.05).Conclusion: Pregabalin significantly alleviates postherpetic neuralgia via mechanisms which may be related to the inflammatory response of spinal dorsal horn and downregulation of TRPV1 channel protein expression. This finding may be useful in developing new drugs for alleviating postherpetic neuralgia.

Identification of a stereotypic molecular arrangement of endogenous glycine receptors at spinal cord synapses

Precise quantitative information about the molecular architecture of synapses is essential to understanding the functional specificity and downstream signaling processes at specific populations of synapses. Glycine receptors (GlyRs) are the primary fast inhibitory neurotransmitter receptors in the spinal cord and brainstem. These inhibitory glycinergic networks crucially regulate motor and sensory processes. Thus far the nanoscale organization of GlyRs underlying the different network specificities has not been defined. Here, we have quantitatively characterized the molecular arrangement and ultra-structure of glycinergic synapses in spinal cord tissue using quantitative super-resolution correlative light and electron microscopy (SR-CLEM). We show that endogenous GlyRs exhibit equal receptor-scaffold occupancy and constant packing densities of about 2000 GlyRs µm-2 at synapses across the spinal cord and throughout adulthood, even though ventral horn synapses have twice the total copy numbers, larger postsynaptic domains and more convoluted morphologies than dorsal horn synapses. We demonstrate that this stereotypic molecular arrangement is maintained at glycinergic synapses in the oscillator mouse model of the neuromotor disease hyperekplexia despite a decrease in synapse size, indicating that the molecular organization of GlyRs is preserved in this hypomorph. We thus conclude that the morphology and size of inhibitory postsynaptic specializations rather than differences in GlyR packing determine the postsynaptic strength of glycinergic neurotransmission in motor and sensory spinal cord networks.

Spinal Cord Tissue Bridges Validation Study: Predictive Relationships With Sensory Scores Following Cervical Spinal Cord Injury

Background: Using magnetic resonance imaging (MRI), widths of ventral tissue bridges demonstrated significant predictive relationships with future pinprick sensory scores, and widths of dorsal tissue bridges demonstrated significant predictive relationships with future light touch sensory scores, following spinal cord injury (SCI). These studies involved smaller participant numbers, and external validation of their findings is warranted. Objectives: The purpose of this study was to validate these previous findings using a larger independent data set. Methods: Widths of ventral and dorsal tissue bridges were quantified using MRI in persons post cervical level SCI (average 3.7 weeks post injury), and pinprick and light touch sensory scores were acquired at discharge from inpatient rehabilitation (average 14.3 weeks post injury). Pearson product-moments were calculated and linear regression models were created from these data. Results: Wider ventral tissue bridges were significantly correlated with pinprick scores (r = 0.31, p &lt; 0.001, N = 136) and wider dorsal tissue bridges were significantly correlated with light touch scores (r = 0.31, p &lt; 0.001, N = 136) at discharge from inpatient rehabilitation. Conclusion: This retrospective study’s results provide external validation of previous findings, using a larger sample size. Following SCI, ventral tissue bridges hold significant predictive relationships with future pinprick sensory scores and dorsal tissue bridges hold significant predictive relationships with future light touch sensory scores.

Activation of Three Major Signaling Pathways After Endurance Training and Spinal Cord Injury

We aimed to investigate the effects of endurance training on expression of growth factors (GFs) and stimulation of neurotrophin-dependent signaling pathways (PI3k/Akt, PLCγ/PKC, PLCγ/CAMKII, Ras-Erk1/2 and Rac1-Cdc42) responsible for neuroplasticity, neuroregeneration, survival and growth after spinal cord injury (SCI). Wistar rats were divided into four groups: (i) intact controls; (ii) 6 weeks of endurance training; (iii) SCI; (iv) pre-training + SCI. The animals survived for 6 weeks after SCI. Firstly, endurance training markedly upregulated mRNA expression and protein levels (up to four times) of growth factors (BDNF, GDNF) and their receptors (TrkB, Gfrα) in low thoracic segments (Th8–Th10) compared to levels in untrained animals. Secondly, we found that spontaneous neuroplasticity seen in the SCI alone group was GF-specific and was activated through both PLCγ-PKC and PLC-CAMKII signaling pathways. In addition, training prior to SCI markedly increased the activity of PLCγ-PKC signaling at both transcript and protein levels at and around the lesion site. Similar effects were seen in expression of PI3k/Akt and Ras/Erk1/2 signaling responsible for cell survival and regeneration. Thirdly, rats which underwent physical activity prior to SCI were more active and had significantly better neurological scores at the 14th and 42nd days of survival. These results suggest that regular physical activity could play an important role after SCI, as it maintains increased expression of GFs in spinal cord tissue 6 weeks post-SCI. The BDNF- and/or BDNF + GDNF-dependent signaling pathways were significantly affected in pre-trained SCI animals. In contrast, GDNF-dependent Rac1-Cdc42 signaling was not involved in training-affected SCI response.

Therapeutic Effects of Azithromycin on Spinal Cord Injury in Male Wistar Rats: A Role for Inflammatory Pathways

Background Inflammatory responses, including macrophages/microglia imbalance, are associated with spinal cord injury (SCI) complications. Accumulating evidence also suggests an anti-inflammatory property of azithromycin (AZM). Material and Methods Male Wistar rats were subjected to T9 vertebra laminectomy. SCI was induced by spinal cord compression at this level with an aneurysmal clip for 60 seconds. They were divided into three groups: the sham-operated group and two SCI treatment (normal saline as a vehicle control vs. AZM at 180 mg/kg/d intraperitoneally for 3 days postsurgery; first dose: 30 minutes after surgery) groups. Locomotor scaling and behavioral tests for neuropathic pain were evaluated and compared through a 28-day period. At the end of the study, tissue samples were taken to assess neuroinflammatory changes and neural demyelination using ELISA and histopathologic examinations, respectively. In addition, the proportion of M1/M2 macrophage polarization was assessed by using flow cytometry. Results Post-SCI AZM treatment (180 mg/kg/d for 3 days) significantly improved locomotion (p < 0.01) and decreased sensitivity to mechanical (p < 0.01) and thermal allodynia (p < 0.001). Moreover, there was a significant tumor necrosis factor-α (TNF-α) decline (p < 0.01) and interleukin-10 (IL-10) elevation (p < 0.01) in the spinal cord tissue of the AZM-treated group compared with the control groups 28 days post-SCI. AZM significantly improved neuroinflammation as evidenced by reduction of the M1 expression, elevation of M2 macrophages, and reduction of the M1/M2 ratio in both the dorsal root ganglion and the spinal cord tissue after SCI compared with controls (p < 0.01). Conclusion AZM treatment can be considered a therapeutic agent for SCI, as it could reduce neuroinflammation and SCI sensory/locomotor complications.