Spinal Tissue Research Articles

Associations between Vertebral Localized Contrast Changes and Adjacent Annular Fissures in Patients with Low Back Pain: A Radiomics Approach.

Low back pain (LBP) is multifactorial and associated with various spinal tissue changes, including intervertebral disc fissures, vertebral pathology, and damaged endplates. However, current radiological markers lack specificity and individualized diagnostic capability, and the interactions between the various markers are not fully clear. Radiomics, a data-driven analysis of radiological images, offers a promising approach to improve evaluation and deepen the understanding of spinal changes related to LBP. This study investigated possible associations between vertebral changes and annular fissures using radiomics. A dataset of 61 LBP patients who underwent conventional magnetic resonance imaging followed by discography was analyzed. Radiomics features were extracted from segmented vertebrae and carefully reduced to identify the most relevant features associated with annular fissures. The results revealed three important texture features that display concentrated high-intensity gray levels, extensive regions with elevated gray levels, and localized areas with reduced gray levels within the vertebrae. These features highlight patterns within vertebrae that conventional classification systems cannot reflect on distinguishing between vertebrae adjacent to an intervertebral disc with or without an annular fissure. As such, the present study reveals associations that contribute to the understanding of pathophysiology and may provide improved diagnostics of LBP.

Cervical spinal hemisection effects on spinal tissue oxygenation and long-term facilitation of phrenic, renal and splanchnic sympathetic nerve activity

HypothesesModerate acute intermittent hypoxia (mAIH) elicits plasticity in both respiratory (phrenic long-term facilitation; pLTF) and sympathetic nerve activity (sympLTF) in rats. Although mAIH produces pLTF in normal rats, inconsistent results are reported after cervical spinal cord injury (cSCI), possibly due to greater spinal tissue hypoxia below the injury site. There are no reports concerning cSCI effects on sympLTF. Since mAIH is being explored as a therapeutic modality to restore respiratory and non-respiratory movements in humans with chronic SCI, both effects are important. To understand cSCI effects on mAIH-induced pLTF and sympLTF, partial or complete C2 spinal hemisections (C2Hx) were performed and, 2 weeks later, we assessed: 1) ipsilateral cervical spinal tissue oxygen tension; 2) ipsilateral & contralateral pLTF; and 3) ipsilateral sympLTF in splanchnic and renal sympathetic nerves. MethodsMale Sprague-Dawley rats were studied intact, or after partial (single slice) or complete C2Hx (slice with ∼1 mm aspiration). Two weeks post-C2Hx, rats were anesthetized and prepared for recordings of bilateral phrenic nerve activity and spinal tissue oxygen pressure (PtO2). Splanchnic and renal sympathetic nerve activity was recorded in intact and complete C2Hx rats. ResultsSpinal PtO2 near phrenic motor neurons was decreased after C2Hx, an effect most prominent with complete vs. partial injuries; baseline PtO2 was positively correlated with mean arterial pressure. Complete C2Hx impaired ipsilateral but not contralateral pLTF; with partial C2Hx, ipsilateral pLTF was unaffected. In intact rats, mAIH elicited splanchnic and renal sympLTF. Complete C2Hx had minimal impact on baseline ipsilateral splanchnic or renal sympathetic nerve activity and renal, but not splanchnic, sympLTF remained intact. ConclusionGreater tissue hypoxia likely impairs pLTF and splanchnic sympLTF post-C2Hx, although renal sympLTF remains intact. Increased sympathetic nerve activity post-mAIH may have therapeutic benefits in individuals living with chronic SCI since anticipated elevations in systemic blood pressure may mitigate hypotension characteristic of people living with SCI.

Development of a finite element full spine model with active muscles for quantitatively analyzing sarcopenia effects on lumbar load

Background and objectiveThe musculoskeletal imbalance caused by disease is one of the most critical factors leading to spinal injuries, like sarcopenia. However, the effects of musculoskeletal imbalances on the spine are difficult to quantitatively investigate. Thus, a complete finite element spinal model was established to analyze the effects of musculoskeletal imbalance, especially concerning sarcopenia. MethodsA finite element spinal model with active muscles surrounding the vertebrae was established and validated from anatomic verification to the whole spine model in dynamic loading at multiple levels. It was then coupled with the previously developed neuromuscular model to quantitatively analyze the effects of erector spinae (ES) and multifidus (MF) sarcopenia on spinal tissues. The severity of the sarcopenia was classified into three levels by changing the physiological cross-sectional area (PCSA) of ES and MF, which were mild (60% PCSA of ES and MF), moderate (48% PCSA of ES and MF), and severe (36% PCSA of ES and MF). ResultsThe stress and strain levels of most lumbar tissues in the sarcopenia models were more significant than those of the normal model during spinal extension movement. The sarcopenia caused load concentration in several specific regions. The stress level of the L4-L5 intervertebral disc and L1 vertebra significantly increased with the severity of sarcopenia and showed relatively larger values than other segments. From the normal model to a severe sarcopenia model, the stress value of the L4-L5 intervertebral disc and L1 vertebra increased by 128% and 113%, respectively. The strain level of L5-S1 also inclined significantly with the severity of sarcopenia, and the relatively larger capsule strain values occurred at lower back segments from L3 to S1. ConclusionsIn summary, the validated spinal coupling model can be used for spinal injury risk analysis caused by musculoskeletal imbalance. The results suggested that sarcopenia can primarily lead to high injury risk of the L4-L5 intervertebral disc, L1 vertebrae, and L3-S1 joint capsule regarding significant stress or strain variance.

Reconfigurable Magnetic Liquid Building Blocks for Constructing Artificial Spinal Column Tissues.

All-liquid molding can be used to transform a liquid into free-form solid constructs, while maintaining internal fluidity. Traditional biological scaffolds, such as cured pre-gels, are normally processed in solid state, sacrificing flowability and permeability. However, it is essential to maintain the fluidity of the scaffold to truly mimic the complexity and heterogeneity of natural human tissues. Here, this work molds an aqueous biomaterial ink into liquid building blocks with rigid shapes while preserving internal fluidity. The molded ink blocks for bone-like vertebrae and cartilaginous-intervertebral-disc shapes, are magnetically manipulated to assemble into hierarchical structures as a scaffold for subsequent spinal column tissue growth. It is also possible to join separate ink blocks by interfacial coalescence, different from bridging solid blocks by interfacial fixation. Generally, aqueous biomaterial inks are molded into shapes with high fidelity by the interfacial jamming of alginate surfactants. The molded liquid blocks can be reconfigured using induced magnetic dipoles, that dictated the magnetic assembly behavior of liquid blocks. The implanted spinal column tissue exhibits a biocompatibility based on in vitro seeding and in vivo cultivating results, showing potential physiological function such as bending of the spinal column.

Lipomeningocele with Tethered Cord Syndrome in an Adult: A Case Report

Lipomeningocele is a closed neural tube defect characterized by the presence of spinal tissue within the spinal cord, with a junction between the spinal cord and a lipoma. It has a prevalence of 0.6 per 10,000 live births. A 29-year-old female presented to the outpatient clinic with complaints of weakness in both legs (more on the right) and tingling sensation and pain over her right thigh and legs for 1 year. She also mentioned swelling in her lower back since birth, which has been growing progressively since childhood. Magnetic resonance imaging of the spine revealed a low-lying spinal cord with the conus lying at the lower end of the L2 vertebral body. Spinal decompression with detethering of the cord and excision of the lipomeningocele was undertaken via a posterior midline incision. Prompt surgical intervention are crucial for symptom relief and prevention of neurological deterioration.

Role of Inflammatory Mediators, Growth Factors, and Osteodystrophy in Recurrent Lumbar Disk Herniation

Introduction. Reintervention in patients with spinal disk herniation is shown to significantly decrease likelihood of favorable outcomes in the postoperative period. Thus, it is important to individually assess risk factors for and likelihood of spinal disk herniation recurrence for each patient, and choose a suitable surgical option.
 Objective: to evaluate changes in the levels of immunoregulatory mediators in the blood serum and extracted spinal disc tissue of allegedly healthy individuals and patients with lumbar disk herniation relapses.
 Materials and methods. We examined 60 patients. The control group included 19 patients with traumatic spinal cord injuries at the lumbar level. The main group included 41 patients with spinal disk herniation. Twenty-two individuals had primary herniation while 11 patients presented with single clinical and neurological relapses at the pre-operated lumbar level and 8 patients presented with recurrent relapses. Solid-phase enzyme immunoassay detected proinflammatory cytokines (interleukin-6, tumor necrosis factor-), chemokines (interleukin-8, monocyte chemoattractant protein-1), growth factors (vascular endothelial growth factor, transforming growth factor-1), and osteodestruction markers (osteoprogesterin, matrix metalloproteinase-8) in the blood serum and the extracted spinal disc tissue.
 Results. We found that spinal disk destruction and chronic inflammation developed with both locally and generally elevating levels of proinflammatory cytokines/chemokines, growth factors, and matrix metalloproteinase 8.
 Conclusion. The results emphasize the significance of local changes in the studied parameters to choose and plan personalized surgical treatment in patients with spinal disk herniation.

Injectable Ventral Spinal Stimulator Evokes Programmable and Biomimetic Hindlimb Motion.

Spinal cord neuromodulation can restore partial to complete loss of motor functions associated with neuromotor disease and trauma. Current technologies have made substantial progress but have limitations as dorsal epidural or intraspinal devices that are either remote to ventral motor neurons or subject to surgical intervention in the spinal tissue. Here, we describe a flexible and stretchable spinal stimulator design with nanoscale thickness that can be implanted by minimally invasive injection through a polymeric catheter to target the ventral spinal space of mice. Ventrolaterally implanted devices exhibited substantially lower stimulation threshold currents and more precise recruitment of motor pools than did comparable dorsal epidural implants. Functionally relevant and novel hindlimb movements were achieved via specific stimulation patterns of the electrodes. This approach holds translational potential for improving controllable limb function following spinal cord injury or neuromotor disease.

DNA Variation in Spinal Pathologies: Genetics Running Down the Spine

Commentary Nearly 400 types of skeletal malformations, including those that involve the spine, have been characterized by molecular and cellular analyses1. Identification of genetic components that control the integrity of intervertebral discs—and that predispose to spinal degeneration in aging patients when mutated—represents a challenging goal. Spinal conditions that occur later in life may emerge from faulty musculoskeletal tissue repair after accidental injury and the influences of comorbidities. The collective stochastic and often undocumented events in the life of a patient can easily complicate attempts at defining genetic predispositions. To manage the statistical noise that comes from random mutations within the human population (“nature”) and the randomness of life’s events (“nurture”), it is necessary to examine massive genetic data sets with many thousands of patients. Technological advances that allow cost-effective DNA sequencing have made it feasible to compare large patient populations matched on the basis of specific codes for medical conditions. Consequently, several studies have made impressive attempts at defining genetic variations linked to a range of surgically relevant musculoskeletal complications, including degenerative rotator cuff disease2, arthroplasty3, adhesive capsulitis of the shoulder4, and end-stage knee osteoarthritis5. The current paper by Bovonratwet et al. at the Hospital for Special Surgery in New York provides the latest installment in a growing set of orthopaedic studies in this journal that investigate the relationship between genetic variations and the risk of surgery for spinal conditions. Similar to prior published efforts by Yanik et al.2, Brüggemann et al.3, and Kulm et al.4,5, the study by Bovonratwet et al. leverages the power of the UK Biobank, which has genetic data for about 400,000 patients, of whom a total of about 20,000 (∼5%) had 1 of 4 spinal conditions (i.e., lumbar spondylolisthesis, spinal stenosis, degenerative disc disease, and pseudarthrosis after spinal fusion). Results from this large data set (“training population”) were then tested using the FinnGen database (“test population”) for validation. The analysis yielded multiple different genetic variants across 7 chromosomes. On average, the authors discovered 2 distinct loci per spinal condition. These findings are consistent with the genetic complexities of spinal conditions and suggest that the diseases are polygenic, as expected. Several nucleotide variants associated with 4 common spinal conditions were located in loci encoding anonymous genes that have not been experimentally explored. Degenerative disc disease was associated with a locus containing 2 genes that affect chondrogenesis: CHST3 (for carbohydrate sulfotransferase 3) promotes sulfation of chondroitin, and SMAD3 is the inducible target of chondrogenic transforming growth factor (TGF)-β signaling. Remarkably, 1 chromosomal region significantly associated with both lumbar spondylolisthesis and spinal stenosis contained overlapping sets of genes (i.e., GFPT1 and NFU1) that encode proteins involved in cell metabolism. These genes represent attractive targets for studies on genetic causality for these 2 spinal conditions. While it is tempting to speculate about potential mechanistic implications, the genetic biomarkers for spinal conditions mapped to large regions containing several genes. Whether these genes are even expressed in cell types and tissues relevant to homeostasis and repair of spinal tissues remains to be determined. Lack of similarity among studies indicates that endogenous tissue-specific repair processes may be predominant in the genetic landscape. One major strength of this study is the control for demographics and comorbidities. Yet, even with access to nearly 400,000 people who form a fairly homogeneous study cohort (i.e., White elderly people in Britain), this population size is not nearly large enough to identify the many genes that undoubtedly contribute to spinal conditions. The observation that only a few genetic variants were replicated in the Finnish cohort may further reflect the polygenicity of disease factors and genetic differences of Finnish patients. In closing, just as our emotions can run up or down our spine depending on whether we are in a positive or negative mood, genetic variation appears to affect spinal diseases. Some DNA mutations may literally be running down our spine, by destroying either disc integrity or our capacity for repair after injury. The positive news is that recognition of genetic predispositions may enhance consideration of behavioral modifications or guide surgical decisions. The paper by Bovonratwet et al. will inspire future studies, while bringing us 1 step closer to that goal.

ID: 207630 MR Thermal Imaging for Low Intensity Focused Ultrasound Modulation of Spinal Nervous Tissue

In multiple models of pain across rodents and swine, we have shown that external low intensity focused ultrasound (liFUS) can be delivered to modulate pain responses.1 In previous work, a single thermocouple was used to ensure that liFUS therapy stimulates the target (L5 dorsal root ganglia (DRG)) with no adverse heating. To increase confidence that no adverse heating occurs in/ around the entire L5 DRG region, we examine whether magnetic resonance thermometry imaging (MRTI) can accurately assess thermal changes in 2D/ 3D in the region.

A novel rodent model of chronic spinal implant-associated infection

BACKGROUND CONTEXTBacterial infection of spinal instrumentation is a significant challenge in spinal fusion surgery. Although the intraoperative local application of powdered vancomycin is common practice for mitigating infection, the antimicrobial effects of this route of administration are short-lived. Therefore, novel antibiotic-loaded bone grafts as well as a reliable animal model to permit the testing of such therapies are needed to improve the efficacy of infection reduction practices in spinal fusion surgery. PURPOSEThis study aims to establish a clinically relevant rat model of spinal implant-associated infection to permit the evaluation of antimicrobial bone graft materials used in spinal fusion. STUDY DESIGNRodent study of chronic spinal implant-associated infection. METHODSInstrumentation anchored in and spanning the vertebral bodies of L4 and L5 was inoculated with bioluminescent methicillin-resistant Staphylococcus aureus bacteria (MRSA). Infection was monitored using an in vivo imaging system (IVIS) for 8 weeks. Spines were harvested and evaluated histologically, and colony-forming units (CFUs) were quantified in harvested implants and spinal tissue. RESULTSPostsurgical analysis of bacterial infection in vivo demonstrated stratification between MRSA and phosphate-buffered saline (PBS) control groups during the first 4 weeks of the 8-week infection period, indicating the successful establishment of acute infection. Over the 8-week chronic infection period, groups inoculated with 1 × 105 MRSA CFU and 1 × 106 MRSA CFU demonstrated significantly higher bioluminescence than groups inoculated with PBS control (p = 0.009 and p = 0.041 respectively). Histological examination at 8 weeks postimplantation revealed the presence of abscesses localized to implant placement in all MRSA inoculation groups, with the most pervasive abscess formation in samples inoculated with 1 × 105 MRSA CFU and 1 × 106 MRSA CFU. Quantification of CFU plated from harvested spinal tissue at 8 weeks post-implantation revealed the 1 × 105 MRSA CFU inoculation group as the only group with a significantly greater average CFU count compared to PBS control (p = 0.017). Further, CFU quantification from harvested spinal tissue was greater than CFU quantification from harvested implants across all inoculation groups. CONCLUSIONOur model demonstrated that the inoculation dosage of 1 × 105 MRSA CFU exhibited the most robust chronic infection within instrumented vertebral bodies. This dosage had the greatest difference in bioluminescence signal from control (p < 0.01), the lowest mortality (0% compared to 50% for samples inoculated with 1 × 106 MRSA CFU), and a significantly higher amount of CFUs from harvested spine samples than CFUs from control harvested spine samples. Further, histological analysis confirmed the reliability of this novel rodent model of implanted-associated infection to establish infection and biofilm formation of MRSA for all inoculation groups. CLINICAL SIGNIFICANCEThis model is intended to simulate the infection of instrumentation used in spinal fusion surgeries concerning implant locality and material. This model may evaluate potential antimicrobial and osteogenic biomaterials and investigate the relationship between implant-associated infection and failed fusion.

Concentrations of Co-Administered Meropenem and Vancomycin in Spinal Tissues Relevant for the Treatment of Pyogenic Spondylodiscitis-An Experimental Microdialysis Study.

Co-administration of meropenem and vancomycin has been suggested as a systemic empirical antibiotic treatment of pyogenic spondylodiscitis. The aim of this study was, in an experimental porcine model, to evaluate the percentage of an 8-h dosing interval of co-administered meropenem and vancomycin concentrations above the relevant minimal inhibitory concentrations (MICs) (%T>MIC) in spinal tissues using microdialysis. Eight female pigs (Danish Landrace breed, weight 78-82 kg) received a single-dose bolus infusion of 1000 mg of meropenem and 1000 mg vancomycin simultaneously before microdialysis sampling. Microdialysis catheters were applied in the third cervical (C3) vertebral cancellous bone, the C3-C4 intervertebral disc, paravertebral muscle, and adjacent subcutaneous tissue. Plasma samples were obtained for reference. The main finding was that for both drugs, the %T>MICs were highly reliant on the applied MIC target, but were heterogeneous across all targeted tissues, ranging from 25-90% for meropenem, and 10-100% for vancomycin. For both MIC targets, the highest %T>MIC was demonstrated in plasma, and the lowest %T>MIC was demonstrated in the vertebral cancellous bone for meropenem, and in the intervertebral disc for vancomycin. When indicated, our findings may suggest a more aggressive dosing approach of both meropenem and vancomycin to increase the spinal tissue concentrations to treat the full spectrum of potentially encountered bacteria in a spondylodiscitis treatment setting.

Astaxanthin ameliorates spinal cord edema and astrocyte activation via suppression of HMGB1/TLR4/NF-κB signaling pathway in a rat model of spinal cord injury.

Spinal cord edema is a quick-onset phenomenon with long-term effects. This complication is associated with inflammatory responses, as well as poor motor function. No effective treatment has been developed against spinal edema, which urges the need to provide novel therapies. Astaxanthin (AST) is a fat-soluble carotenoid with anti-inflammatory effects and a promising candidate for treating neurological disorders. This study aimed to investigate the underlying mechanism of AST on the inhibition of spinal cord edema, astrocyte activation, and reduction of inflammatory responsesin a rat compression spinal cord injury (SCI) model. Male rats underwent laminectomy at thoracic 8-9, and the SCI model was induced using an aneurysm clip. After SCI, rats received dimethyl sulfoxide or AST via intrathecal injection. The effects of AST were examined on the motor function, spinal cord edema, integrity of blood-spinal cord barrier (BSCB), and expression of high mobility group box 1 (HMGB1), toll-like receptor 4 (TLR4), nuclear factor-kappa B (NF-κB), glial fibrillary acidic protein (GFAP), and aquaporin-4 (AQP4), and matrix metallopeptidase- 9 (MMP-9) post-SCI. We showed that AST potentially improved the recovery of motor function and inhibited the spinal cord edema via maintaining the integrity of BSCB, reducing the expression of HMGB1, TLR4, and NF-κB, MMP-9 as well as downregulation of astrocyte activation (GFAP) and AQP4 expression. AST improves motor function and reduces edema and inflammatory responses in the spinal tissue. These effects are mediated by suppression of the HMGB1/TLR4/NF-κB signaling pathway, suppressing post-SCI astrocyte activation, and decreasing AQP4 and MMP-9 expression.

Clinical Value of Metagenomic Next-Generation Sequencing Using Spinal Tissue in the Rapid Diagnosis of Spinal Tuberculosis.

To evaluate the accuracy of metagenomic next-generation sequencing (mNGS) for rapid diagnosis of spinal tuberculosis using spinal tissue specimens. Medical data regarding suspected spinal tuberculosis were retrospectively analyzed. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under the curve (AUC) of mNGS were calculated to determine its diagnostic efficacy, and these values were compared with culture and composite reference standard (CRS). Two hundred and three cases of spinal tuberculosis were included for analysis. The sensitivity, specificity, PPV, NPV, and AUC of mNGS compared with culture were all very good. When CRS was used for the comparison, the sensitivity of mNGS and culture were 71.2% and 73.0%; the specificity and PPV were 100% in all cases; the NPV were 74.2% and 75.4%; the AUCs were all 0.86. The sensitivity and NPV of culture were slightly higher than that of mNGS; however, the diagnostic efficacy of mNGS and culture was consistent (P > 0.05). Spinal tissue specimens for mNGS testing had very good accuracy for diagnosing spinal tuberculosis.

LSW-Net: Lightweight Deep Neural Network Based on Small-World properties for Spine MR Image Segmentation.

Segmenting spinal tissues from MR images is important for automatic image analysis. Deep neural network-based segmentation methods are efficient, yet have high computational costs. To design a lightweight model based on small-world properties (LSW-Net) to segment spinal MR images, suitable for low-computing-power embedded devices. Retrospective. A total of 386 subjects (2948 images) from two independent sources. Dataset I: 214 subjects/779 images, all for disk degeneration screening, 147 had disk degeneration, 52 had herniated disc. Dataset II: 172 subjects/2169 images, 142 patients with vertebral degeneration, 163 patients with disc degeneration. 70% images in each dataset for training, 20% for validation, and 10% for testing. T1- and T2-weighted turbo spin echo sequences at 3 T. Segmentation performance of LSW-Net was compared with four mainstream (including U-net and U-net++) and five lightweight models using five radiologists' manual segmentations (vertebrae, disks, spinal fluid) as reference standard. LSW-Net was also deployed on NVIDIA Jetson nano to compare the pixels number in segmented vertebrae and disks. All models were evaluated with accuracy, precision, Dice similarity coefficient (DSC), and area under the receiver operating characteristic (AUC). Pixel numbers segmented by LSW-Net on the embedded device were compared with manual segmentation using paired t-tests, with P < 0.05 indicating significance. LSW-Net had 98.5% fewer parameters than U-net but achieved similar accuracy in both datasets (dataset I: DSC 0.84 vs. 0.87, AUC 0.92 vs. 0.94; dataset II: DSC 0.82 vs. 0.82, AUC 0.88 vs. 0.88). LSW-Net showed no significant differences in pixel numbers for vertebrae (dataset I: 5893.49 vs. 5752.61, P = 0.21; dataset II: 5073.42 vs. 5137.12, P = 0.56) and disks (dataset I: 1513.07 vs. 1535.69, P = 0.42; dataset II: 1049.74 vs. 1087.88, P = 0.24) segmentation on an embedded device compared to manual segmentation. Proposed LSW-Net achieves high accuracy with fewer parameters than U-net and can be deployed on embedded device, facilitating wider application. 2. 1.

Stiffness and axial pain are associated with the progression of calcification in a mouse model of diffuse idiopathic skeletal hyperostosis

BackgroundDiffuse idiopathic skeletal hyperostosis (DISH) is characterized by progressive calcification of spinal tissues; however, the impact of calcification on pain and function is poorly understood. This study examined the association between progressive ectopic spine calcification in mice lacking equilibrative nucleoside transporter 1 (ENT1−/−), a preclinical model of DISH, and behavioral indicators of pain.MethodsA longitudinal study design was used to assess radiating pain, axial discomfort, and physical function in wild-type and ENT1−/− mice at 2, 4, and 6 months. At endpoint, spinal cords were isolated for immunohistochemical analysis of astrocytes (GFAP), microglia (IBA1), and nociceptive innervation (CGRP).ResultsIncreased spine calcification in ENT1−/− mice was associated with reductions in flexmaze exploration, vertical activity in an open field, and self-supporting behavior in tail suspension, suggesting flexion-induced discomfort or stiffness. Grip force during the axial stretch was also reduced in ENT1−/− mice at 6 months of age. Increased CGRP immunoreactivity was detected in the spinal cords of female and male ENT1−/− mice compared to wild-type. GFAP- and IBA1-immunoreactivity were increased in female ENT1−/− mice compared to wild-type, suggesting an increase in nociceptive innervation.ConclusionThese data suggest that ENT1−/− mice experience axial discomfort and/or stiffness and importantly that these features are detected during the early stages of spine calcification.

MR thermometry imaging for low intensity focused ultrasound modulation of spinal nervous tissue

ObjectivesPreviously in rodent and swine models, we have shown that external low intensity focused ultrasound (liFUS) can be used to modulate pain responses. To ensure no adverse heating events occur with liFUS modulation in a non-invasive manner, we perform initial work in swine to show that magnetic resonance thermometry imaging (MRTI) is capable of measuring <2.0 °C changes at the L5 DRG. Further, we show that our device can be constructed in an MR-compatible fashion to minimize artifact. MethodsThree MRTI techniques (referenceless, corrected proton resonance frequency shift (PRFS), and PRFS) were applied to assess accuracy of detecting thermal changes at the L5 DRG in unheated euthanized swine. A region of interest (ROI) that includes the L5 DRG was delineated, within which MRTI temperature changes were spatially averaged (ground truth 0 °C). In separate experiments with phantoms, B0 field-inhomogeneity, RF transmit (B1+) and fast gradient echo (fSPGR) magnitude images were acquired to downselect liFUS device materials that produce the least MRI artifacts. ResultsReferenceless, corrected PRFS, and PRFS MRTI resulted in temperature measurements of 0.8 ± 1.1 °C, 1.1 ± 1.3 °C and 5.2 ± 5 °C, respectively. Both materials caused B0 perturbation but minimal B1+ and MRTI artifacts. The presence of imaging artifacts did not preclude thermal imaging of the region. SignificanceWe provide preliminary data suggesting that referenceless MRTI can adequately detect small thermal changes at the DRG that may occur with neuromodulation, which is one of the first steps in creating a table of safe parameters for liFUS therapy in humans.

Tail nerve electrical stimulation promoted the efficiency of transplanted spinal cord-like tissue as a neuronal relay to repair the motor function of rats with transected spinal cord injury

Following transected spinal cord injury (SCI), there is a critical need to restore nerve conduction at the injury site and activate the silent neural circuits caudal to the injury to promote the recovery of voluntary movement. In this study, we generated a rat model of SCI, constructed neural stem cell (NSC)-derived spinal cord-like tissue (SCLT), and evaluated its ability to replace injured spinal cord and repair nerve conduction in the spinal cord as a neuronal relay. The lumbosacral spinal cord was further activated with tail nerve electrical stimulation (TNES) as a synergistic electrical stimulation to better receive the neural information transmitted by the SCLT. Next, we investigated the neuromodulatory mechanism underlying the action of TNES and its synergism with SCLT in SCI repair. TNES promoted the regeneration and remyelination of axons and increased the proportion of glutamatergic neurons in SCLT to transmit brain-derived neural information more efficiently to the caudal spinal cord. TNES also increased the innervation of motor neurons to hindlimb muscle and improved the microenvironment of muscle tissue, resulting in effective prevention of hindlimb muscle atrophy and enhanced muscle mitochondrial energy metabolism. Tracing of the neural circuits of the sciatic nerve and tail nerve identified the mechanisms responsible for the synergistic effects of SCLT transplantation and TNES in activating central pattern generator (CPG) neural circuits and promoting voluntary motor function recovery in rats. The combination of SCLT and TNES is expected to provide a new breakthrough for patients with SCI to restore voluntary movement and control their muscles.

Protocatechuic aldehyde promotes the functional recovery of spinal cord injury by activating the Wnt/β-catenin signaling pathway

Context/objective This study aimed to explore the anti-inflammatory and neuroprotective effects of protocatechuic aldehyde (PCA) in rats with spinal cord injury (SCI) and to clarify the molecular mechanisms underlying its pharmacological effects. Design Male Sprague Dawley rat model of moderate spinal cord contusion were established. Setting Third-class first-class hospital. Outcome measures The Basso, Beattie, and Bresnahan scores and performance on the inclined plane test were evaluated. Histological analyses were performed via hematoxylin and eosin staining. Apoptosis in the spinal cord and neurons was detected by 5 terminal deoxynucleotidyl-transferase-mediated dUTP nick end labeling staining. Apoptotic factors (Bax, Bcl-2, and cleaved caspase-3) were also evaluated. INOS, IL-1β, IL-10, TNF-α, Wnt-3α, β-catenin, iBA-1, and NeuN were assessed by real-time reverse transcription-polymerase chain reaction (RT–PCR), western blotting (WB), and enzyme-linked immunosorbent assay. Cell viability and the immunofluorescence of IL-1β were measured in PC-12 cells. Results Using WB and quantitative reverse transcription-PCR, we confirmed that PCA treatment activated the Wnt/β-catenin signaling axis in vivo and in vitro. Hematoxylin and eosin staining and hindlimb motor functional evaluation revealed that treatment with PCA improved tissue protection and functional recovery via the Wnt/β-catenin axis. The upregulation of TUNEL-positive cells, downregulation of neurons, elevated apoptosis-associated factors in rats, and increased apoptotic rates were observed in microglia and PC-12 after PCA application. Finally, PCA mitigated SCI-induced inflammation by targeting the Wnt/β-catenin axis. Conclusion This study provided preliminary evidence that PCA inhibits neuroinflammation and apoptosis through the Wnt/β-catenin pathway, thereby attenuating the secondary injury after SCI and promoting the regeneration of injured spinal tissues.

Estrogen Mediates the Sexual Dimorphism of GT1b-Induced Central Pain Sensitization.

We have previously reported that the intrathecal (i.t.) administration of GT1b, a ganglioside, induces spinal cord microglia activation and central pain sensitization as an endogenous agonist of Toll-like receptor 2 on microglia. In this study, we investigated the sexual dimorphism of GT1b-induced central pain sensitization and the underlying mechanisms. GT1b administration induced central pain sensitization only in male but not in female mice. Spinal tissue transcriptomic comparison between male and female mice after GT1b injection suggested the putative involvement of estrogen (E2)-mediated signaling in the sexual dimorphism of GT1b-induced pain sensitization. Upon ovariectomy-reducing systemic E2, female mice became susceptible to GT1b-induced central pain sensitization, which was completely reversed by systemic E2 supplementation. Meanwhile, orchiectomy of male mice did not affect pain sensitization. As an underlying mechanism, we present evidence that E2 inhibits GT1b-induced inflammasome activation and subsequent IL-1β production. Our findings demonstrate that E2 is responsible for sexual dimorphism in GT1b-induced central pain sensitization.

Construction of adhesive and bioactive silk fibroin hydrogel for treatment of spinal cord injury.

Spinal cord injury (SCI) often causes severe and permanent disabilities due to the complexity of injury progression. The promising methods are generally based on tissue engineering technology using biocompatible hydrogels to achieve SCI repair. However, hydrogels are commonly incapable of close contact with the damaged spinal cord stumps and fail to support neural regeneration in SCI. Therefore, it is still a challenge to achieve stable contact with the transected nerve stumps and accelerate neural regeneration in the lesion microenvironment. Here, an in situ forming glycidyl methacrylated silk fibroin/ laminin-acrylate (SF-GMA/LM-AC) hydrogel was fabricated for SCI repair. The polymer chains formed a network quickly after ultraviolet (UV)-light trigger, in topological entanglement with the spinal cord, stitching the hydrogel and wet tissues together like a suture at the molecular scale. The SF-GMA/LM-AC hydrogel also provided a favorable environment for the growth of cells due to the incorporation of LM-AC. Compared with physical entrapment of LM, LM-AC immobilized in the hydrogel by covalent technology provided better microenvironments for neural stem cells (NSCs) growth. The repair of complete transection SCI in rats demonstrated that this hydrogel guided and promoted neural regeneration over 8 weeks, leading to hind limb locomotion recovery. This adhesive and bioactive SF-GMA/LM-AC hydrogel may open many opportunities in various therapeutic indications, including SCI. STATEMENT OF SIGNIFICANCE: Many materials have been developed for building transplanted scaffolds, but it is still a challenge to fabricate bioactive scaffolds and adhesion to wet tissues. In this study, we successfully developed an in situ forming SF-GMA/LM-AC hydrogel for SCI repair. This in situ forming hydrogel formed significant adhesion to the native spinal cord, stitching hydrogel and tissue together like a suture at the molecular scale. In addition, covalent immobilized LM-AC was used as the contact guidance biochemical cues for axonal outgrowth and had much better bioactive effects than physically entangled LM. Moreover, this universal strategy would open an avenue to fabricate adhesive and bioactive hydrogel for various disease treatments including SCI.