Porcine Spinal Cord Research Articles

Quantification of porcine lower thoracic spinal cord morphology with intact dura mater using high-resolution μCT.

Spinal cord stimulation (SCS) is approved by the Food and Drug Administration for treating chronic intractable pain in the back, trunk, or limbs through stimulation of the dorsal column. Numerous studies have used swine as an analog of the human spinal cord to better understand SCS and further improve its efficacy. We performed high-resolution imaging of the porcine spinal cord with intact dura mater using micro-computed tomography (μCT) to construct detailed 3-dimensional (3D) visualizations of the spinal cord and characterize the morphology of the dorsal and ventral rootlets. We obtained spinal cords from Yorkshire/Landrace crossbred swine (N=7), stained samples with osmium tetroxide, and performed μCT imaging of the T12-T15 levels at isotropic voxel resolutions ranging from 3.3 to 50μm. We measured the anatomical morphology using the 3D volumes and compared our results to measurements previously collected from swine and human spinal cords via microdissection techniques in prior literature. While the porcine thoracic-lumbar spinal cord is a popular model for SCS, we highlight multiple notable differences compared to previously published T8-T12 human measurements including rootlet counts (porcine dorsal/ventral: 12.2±2.6, 26.6±3.4; human dorsal/ventral: 5.3±1.3, 4.4±2.4), rootlet angles (porcine ventral-rostral: 161±1°, ventral-caudal: 155±6°, dorsal-rostral: 148±9°, dorsal-caudal: 142±6°; human ventral-rostral: 170±3°, ventral-caudal: 22±10°, dorsal-rostral: 171±3°, dorsal-caudal: 15±7°), and the presence and count of dorsal rootlet bundles. Detailed measurements and highlighted differences between human and porcine spinal cords can inform variations in modeling and electrophysiological experiments between the two species. In contrast to other approaches for measuring the spinal cord and rootlet morphology, our method keeps the dura intact, reducing potential artifacts from dissection.

Evaluation of Neuroprotective Effects of Local Hypothermia in a Porcine Spinal Cord Injury Model

Abstract The goal of this study was to assess the therapeutic potential of a 5-hour local spinal cord (SC) hypothermia by 4 °C saline on preservation of SC tissue at the injury epicentre and 3 cranial and caudal 10 mm long SC segments in a porcine experimental model of spinal cord injury (SCI). The SCI was inflicted through L3 laminectomy by a metallic rod moved by a velocity of 30 mm.sec−1, and operated by a computer-controlled apparatus. A group of 15 female minipigs 5‒8-month-old weighing 28‒35 kg was randomly divided into 5 subgroups (each composed of 3 animals): 1) sham controls; 2) SCI by force 8N; 3) SCI by force 8N, 5-hour hypothermia; 4) SCI by force 15N; 5) SCI by force 15N, 5-hour hypothermia. After a 9-week survival period, the minipigs were in deep general anaesthesia transcardially perfused by 5000 ml of saline and fixed by 5000 ml 4 % neutral paraformaldehyde. White and grey SC matter damage was evaluated in specimens cut from the epicentre of injury as well as 3 cranial and 3 caudal 10 mm long SC blocks dyed according to Luxol fast blue (LFB) with cresyl violet (CV) protocol for light microscopic observations. The percentage of preserved SC white and grey matter was assessed in microphotographs and compared with data from sham controls (considered 100 %). The data were statistically evaluated by ANOVA test, the difference P ˂ 0.05 was considered significant. Results of the study suggest that 5-hour local cooling of the epicentre of SCI is well tolerated and facilitates the preservation of SC tissue integrity. Additional experimental and preclinical studies are necessary before introducing the method in practice.

Improving Sensitivity and Longevity of In Vivo Glutamate Sensors with Electrodeposited NanoPt.

In vivo glutamate sensing has provided valuable insight into the physiology and pathology of the brain. Electrochemical glutamate biosensors, constructed by cross-linking glutamate oxidase onto an electrode and oxidizing H2O2 as a proxy for glutamate, are the gold standard for in vivo glutamate measurements for many applications. While glutamate sensors have been employed ubiquitously for acute measurements, there are almost no reports of long-term, chronic glutamate sensing in vivo, despite demonstrations of glutamate sensors lasting for weeks in vitro. To address this, we utilized a platinum electrode with nanometer-scale roughness (nanoPt) to improve the glutamate sensors' sensitivity and longevity. NanoPt improved the GLU sensitivity by 67.4% and the sensors were stable in vitro for 3 weeks. In vivo, nanoPt glutamate sensors had a measurable signal above a control electrode on the same array for 7 days. We demonstrate the utility of the nanoPt sensors by studying the effect of traumatic brain injury on glutamate in the rat striatum with a flexible electrode array and report measurements of glutamate taken during the injury itself. We also show the flexibility of the nanoPt platform to be applied to other oxidase enzyme-based biosensors by measuring γ-aminobutyric acid in the porcine spinal cord. NanoPt is a simple, effective way to build high sensitivity, robust biosensors harnessing enzymes to detect neurotransmitters in vivo.

A novel minimally invasive and versatile kyphoplasty balloon-based model of porcine spinal cord injury.

Spinal cord injury (SCI) animal models often utilize an open surgical laminectomy, which results in animal morbidity and also leads to changes in spinal canal diameter, spinal cord perfusion, cerebrospinal fluid flow dynamics, and spinal stability which may confound SCI research. Moreover, the use of open surgical laminectomy for injury creation lacks realism when considering human SCI scenarios. We developed a novel, image-guided, minimally invasive, large animal model of SCI which utilizes a kyphoplasty balloon inserted into the epidural space via an interlaminar approach without the need for open surgery. The model was validated in 5 Yucatán pigs with imaging, neurofunctional, histologic, and electrophysiologic findings consistent with a mild compression injury. Few large animal models exist that have the potential to reproduce the mechanisms of spinal cord injury (SCI) commonly seen in humans, which in turn limits the relevance and applicability of SCI translational research. SCI research relies heavily on animal models, which typically involve an open surgical, dorsal laminectomy which is inherently invasive and may have untoward consequences on animal morbidity and spinal physiology that limit translational impact. We developed a minimally invasive, large animal model of spinal cord injury which utilizes a kyphoplasty balloon inserted percutaneously into the spinal epidural space. Balloon inflation results in a targeted, compressive spinal cord injury with histological and electrophysiological features directly relevant to human spinal cord injury cases without the need for invasive surgery. Balloon inflation pressure, length of time that balloon remains inflated, and speed of inflation may be modified to achieve variations in injury severity and subtype.

Anisotropic longitudinal water proton relaxation in white matter investigated ex vivo in porcine spinal cord with sample rotation

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Topical Application of Hypothermia in a Porcine Spinal Cord Injury Model

AbstractSpinal cord injuries (SCIs) are catastrophic events in humans and animals. They often result in permanent loss of motor, sensory, and autonomic functions caudally from the site of the spinal cord (SC) lesion. The natural history of spontaneous recovery from SC trauma is disappointing and currently available therapeutic interventions fail to operate. Hence further research using bigger experimental animals or primates is necessary. The results of this study performed by the authors in 21 Göttingen-Minnesota-Liběchov female minipigs (3 sham controls, and 18 members of an experimental subgroup) showed that these animals are suitable for SCI research. All mini-pigs survived rather complex experiments carried out in general anaesthesia induced by 5 % thiopental solution administered i.v., maintained by endotracheal inhalation of 1.5 % sevoflurane with O2as well as a subsequent 9-week monitoring period. The experimental procedures comprised of L3 laminectomy, SCI inflicted by computer-controlled metallic piston crushing the SC with 8N, 15N, or 18N force. After the SCIs there were 9 minipigs left over during the next 5.5 hours in general anaesthesia, without application of hypothermia, then the surgical wounds were sutured, and the animals were allowed to awaken under supervision. Just 30 min following SCIs was in 6 mini-pigs started with the 5-hour application of 4 °C saline via perfusion chambers placed at the epicenter of the SCI, the chambers were removed, surgical wounds sutured, and animals were allowed to awaken. Just 30 minutes following the SCIs, there was in 3 minipigs started with a 5-hour administration of ≈24 °C saline at the epicentre of the SCIs, and then the perfusion chamber was removed, surgical wounds sutured, and the animals were allowed to awaken. The 5.5-hour local hypothermia and protracted general anaesthesia required monitoring of rectal temperature, and external warming of the minipig, if the temperature dropped below 36 °C. The currently available information on the therapeutic capacity of the method, and all technical aspects of its routine employment, needs validation in further experiments and preclinical trials.

Porcine Models of Spinal Cord Injury.

Large animal models of spinal cord injury may be useful tools in facilitating the development of translational therapies for spinal cord injury (SCI). Porcine models of SCI are of particular interest due to significant anatomic and physiologic similarities to humans. The similar size and functional organization of the porcine spinal cord, for instance, may facilitate more accurate evaluation of axonal regeneration across long distances that more closely resemble the realities of clinical SCI. Furthermore, the porcine cardiovascular system closely resembles that of humans, including at the level of the spinal cord vascular supply. These anatomic and physiologic similarities to humans not only enable more representative SCI models with the ability to accurately evaluate the translational potential of novel therapies, especially biologics, they also facilitate the collection of physiologic data to assess response to therapy in a setting similar to those used in the clinical management of SCI. This review summarizes the current landscape of porcine spinal cord injury research, including the available models, outcome measures, and the strengths, limitations, and alternatives to porcine models. As the number of investigational SCI therapies grow, porcine SCI models provide an attractive platform for the evaluation of promising treatments prior to clinical translation.

Contribution of impactor misalignment to the neurofunctional variability in porcine spinal cord contusion models.

Traumatic spinal cord lesions studies are often carried out with animal models or numerical simulations. Unfortunately, animal models usually present a high variability in severity and type of neurofunctional impairments following impact surgery. We postulate that the variability of outcomes is strongly dependent on the positioning and alignment of the impactor during the contusion. A finite elements model of the spinal cord, predicting the action potential (AP) conduction alteration, was proposed and used to perform nine numerical simulations of a 50 g weight dropped from 200 mm on the exposed spinal cord in its spinal canal. Simulations followed a 32 factorial design with impactor eccentricity and spinal cord tilt angle as factors on two outcomes: injured spinal cord area (AP < 10 % of its baseline, 1h post-injury), and asymmetry of injury (ratio of right/left injured area of both half spinal cord). Eccentricity contributed highly and significantly on both outcomes, but not tilt angle. Damaged axons were found in conscious motor, sensory, and unconscious proprioception tracts. Variability in impactor alignment beyond ±6.2 % of the spinal canal width affects neurofunctional outcomes, and careful assessment of the impactor course is therefore key when producing spinal cord injury by contusion.Clinical Relevance- A precision value is proposed to mitigate the contribution of impactor misalignment to neurofunctional variability in animal models, allowing the reduction of animal used in research. The proposed method of action potential conduction assessment could easily be implanted in human numerical models for the cross-study of patient's cases.

Integration of multiple prognostic predictors in a porcine spinal cord injury model: A further step closer to reality.

Spinal cord injury (SCI) is a devastating neurological disorder with an enormous impact on individual's life and society. A reliable and reproducible animal model of SCI is crucial to have a deeper understanding of SCI. We have developed a large-animal model of spinal cord compression injury (SCI) with integration of multiple prognostic factors that would have applications in humans. Fourteen human-like sized pigs underwent compression at T8 by implantation of an inflatable balloon catheter. In addition to basic neurophysiological recording of somatosensory and motor evoked potentials, we introduced spine-to-spine evoked spinal cord potentials (SP-EPs) by direct stimulation and measured them just above and below the affected segment. A novel intraspinal pressure monitoring technique was utilized to measure the actual pressure on the cord. The gait and spinal MRI findings were assessed in each animal postoperatively to quantify the severity of injury. We found a strong negative correlation between the intensity of pressure applied to the spinal cord and the functional outcome (P < 0.0001). SP-EPs showed high sensitivity for real time monitoring of intraoperative cord damage. On MRI, the ratio of the high-intensity area to the cross-sectional of the cord was a good predictor of recovery (P < 0.0001). Our balloon compression SCI model is reliable, predictable, and easy to implement. By integrating SP-EPs, cord pressure, and findings on MRI, we can build a real-time warning and prediction system for early detection of impending or iatrogenic SCI and improve outcomes.

Porcine Model of the Growing Spinal Cord—Changes in Diffusion Tensor Imaging Parameters

Diffusion tensor imaging (DTI) is an advanced magnetic resonance imaging (MRI) technique that has promising applications for the objective assessment of the microstructure of the spinal cord. This study aimed to verify the parameters obtained using DTI change during the growth process. We also wanted to identify if the DTI values change on the course of the spinal cord. The model organism was a healthy growing porcine spinal cord (19 pigs, Polish White, weight 24-120 kg, mean 48 kg, median 48 kg, age 2.5-11 months, mean 5 months, median 5.5 months). DTI parameters were measured in three weight groups: up to 29 kg (five pigs), 30-59 kg (six pigs), and from 60 kg up (eight pigs). DTI was performed with a 1.5 Tesla magnetic resonance scanner (Philips, Ingenia). Image post-processing was done using the Fiber Track package (Philips Ingenia workstation) by manually drawing the regions of interest (nine ROIs). The measurements were recorded for three sections: the cervical, thoracolumbar and lumbar segments of the spinal cord at the C4/C5, Th13/L1, and L4/L5 vertebrae levels. In each case, one segment was measured cranially and one caudally from the above-mentioned places. The values of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were obtained for each ROIs and compared. It is shown that there is a correlation between age, weight gain, and change in FA and ADC parameters. Moreover, it is noted that, with increasing weight and age, the FA parameter increases and ADC decreases, whereas the FA and ADC measurement values did not significantly change between the three sections of the spinal cord. These findings could be useful in determining the reference values for the undamaged spinal cords of animals and growing humans.

Dural Changes Induced by an Ultrasonic Bone Curette in an Excised Porcine Spinal Cord.

In spinal surgery, ultrasonic bone curettes are considered unlikely to cause mechanical injury to the dura; however, there is little evidence to support this claim. We investigated the effect of direct contact with an ultrasonic bone curette on the dura and the protective effect of covering the dura with a cotton pattie using an excised porcine spinal cord. The ultrasonic bone curette was pressed against the porcine spinal cord with constant force and activated for 1 s, with or without covering the dura with a cotton pattie. The dural surface and cross-section were observed using electron and light microscopy. When the ultrasonic bone curette was applied directly against the dura, most specimens showed non-perforating dural injuries. However, none of the specimens showed dural perforation. Histological changes were also observed. The use of a cotton pattie reduced the occurrence of these changes, although it did not prevent them when ultrasonic vibration was applied with a large force. We considered ultrasonic bone curettes to have a low risk of dural perforation and, thus, to be a safe surgical device as long as they did not accidentally make strong contact with the dura.

Spinal cord decellularized matrix scaffold loaded with engineered basic fibroblast growth factor-overexpressed human umbilical cord mesenchymal stromal cells promoted the recovery of spinal cord injury.

Spinal cord injury (SCI) will lead to irreversible damage of sensory and motor function of central nervous system, which seriously affects patient's quality of life. A variety of nerve engineering materials carrying various stem cells and cell growth factors had used to promote the repair of SCI, but they could not mimic the actual matric niche at spinal cord to promote cell proliferation and differentiation. Thus, developing novel biomaterial providing better niche of spinal cord is a new strategy to treat the severe SCI. In this study, we constructed porcine spinal cord decellularized matrix scaffold (SC-DM) with biocompatibility to load engineered basic fibroblast growth factor-overexpressing human umbilical cord mesenchymal stromal cells (bFGF-HUCMSCs) for treating SCI. The continuously released bioactive bFGF factors from grafted bFGF-HUCMSCs and three-dimensional niche by SC-DM promoted the differentiation of endogenous stem cells into neurons with nerve conduction function, leading a markedly motor function recovery of SCI. These results indicated that the functional bFGF-HUCMSCs/SC-DM scaffold provided more suitable matric niche for nerve cells, that would be a promising strategy for the clinical application of SCI.

Peptide Tool-Driven Functional Elucidation of Biomolecules Related to Endocrine System and Metabolism.

The enhancement of basic research based on biomolecule-derived peptides has the potential to elucidate their biological function and lead to the development of new drugs. In this review, two biomolecules, namely "neuromedin U (NMU)" and "myostatin," are discussed. NMU, a neuropeptide first isolated from the porcine spinal cord, non-selectively activates two types of receptors (NMUR1 and NMUR2) and displays a variety of physiological actions, including appetite suppression. The development of receptor-selective regulators helps elucidate each receptor's detailed biological roles. A structure-activity relationship (SAR) study was conducted to achieve this purpose using the amidated C-terminal core structure of NMU for receptor activation. Through obtaining receptor-selective hexapeptide agonists, molecular functions of the core structure were clarified. Myostatin is a negative regulator of skeletal muscle growth and has attracted attention as a target for treating atrophic muscle disorders. Although the protein inhibitors, such as antibodies and receptor-decoys have been developed, the inhibition by smaller molecules, including peptides, is less advanced. Focusing on the inactivation mechanism by prodomain proteins derived from myostatin-precursor, a first mid-sized α-helical myostatin-inhibitory peptide (23-mer) was identified from the mouse sequence. The detailed SAR study based on this peptide afforded the structural requirements for effective inhibition. The subsequent computer simulation proposed the docking mode at the activin type I receptor binding site of myostatin. The resulting development of potent inhibitors suggested the existence of a more appropriate binding mode linked to their β-sheet forming properties, suggesting that further investigations might be needed.

483 Improvement in Behavioral, Cellular and Molecular Outcomes with Connexin Inhibitors Administration in a Porcine Spinal Cord Injury Model

INTRODUCTION: Connexin inhibition has demonstrated promising results in rodents spinal cord injury models (SCI) as a neuroprotective strategy that improves SCI outcomes. However, it has not been tested in a larger animal yet, a necessary step before conducting a human clinical trial. METHODS: SCI was induced using a compression/contusion weight drop model in three groups of pigs with 2 animals per group. Group A: control, Group B: treated with nonselective gap junctions blocker: Carbenoxolone, Group C: treated with connexin-43 memetic peptide: Gap26. All medications were delivered intrathecally at the time of injury. We assessed the locomotor development of the animals over 11 weeks. After which the animals were euthanized and their spinal cords were harvested for histological and immunofluorescence assessment. RESULTS: Treatment with intrathecal connexins inhibitors improved SCI outcomes. In terms of locomotion recovery, Groups B and C regained the stepping ability in their hind limbs, whereas the control group did not. Similarly, groups B and C exhibited a decreased level of astrocytes activation at the injury site, and their PGE2 serum levels remained low in the two treated groups. The histological damage was particularly limited in Gap 26-treated group (C). CONCLUSION: We translated the positive neuroprotective effect of a connexin-43 mimetic peptide and a gap junction blocker in a porcine SCI model. This study supports the potential role of these agents in improving SCI outcome.

Neuromedin U induces an invasive phenotype in CRC cells expressing the NMUR2 receptor

BackgroundSuccessful colorectal cancer (CRC) therapy often depends on the accurate identification of primary tumours with invasive potential. There is still a lack of identified pathological factors associated with disease recurrence that could help in making treatment decisions. Neuromedin U (NMU) is a secretory neuropeptide that was first isolated from the porcine spinal cord, and it has emerged as a novel factor involved in the tumorigenesis and/or metastasis of many types of cancers. Previously associated with processes leading to CRC cell invasiveness, NMU has the potential to be a marker of poor outcome, but it has not been extensively studied in CRC.MethodsData from The Cancer Genome Atlas (TCGA) were used to analyse NMU and NMU receptor (NMUR1 and NMUR2) expression in CRC tissues vs. normal tissues, and real-time PCR was used for NMU and NMU receptor expression analysis. NMU protein detection was performed by immunoblotting. Secreted NMU was immunoprecipitated from cell culture-conditioned media and analysed by immunoblotting and protein sequencing. DNA demethylation by 5-aza-CdR was used to analyse the regulation of NMUR1 and NMUR2 expression. NMU receptor activity was monitored by detecting calcium mobilisation in cells loaded with fluo-4, and ERK1/2 kinase activation was detected after treatment with NMU or receptor agonist. Cell migration and invasion were investigated using membrane filters. Integrin expression was evaluated by flow cytometry.ResultsThe obtained data revealed elevated expression of NMU and NMUR2 in CRC tissue samples and variable expression in the analysed CRC cell lines. We have shown, for the first time, that NMUR2 activation induces signalling in CRC cells and that NMU increases the motility and invasiveness of NMUR2-positive CRC cells and increases prometastatic integrin receptor subunit expression.ConclusionsOur results show the ability of CRC cells to respond to NMU via activation of the NMUR2 receptor, which ultimately leads to a shift in the CRC phenotype towards a more invasive phenotype.

Neuromedin U modulates neuronal excitability in rat hippocampal slices

Neuromedin U (NMU) is a neuropeptide that was initially isolated from the porcine spinal cord and later from several species. Although NMU receptors exist in the CA1 region of the hippocampus, the role of NMU in hippocampal synaptic transmission remains unknown. In the present study, we demonstrated that the colocalization ratio of NMU type 1 (NMUR1) or type 2 (NMUR2) receptors was higher with neuronal nuclei (a neuronal marker) than with glial fibrillary acidic protein (an astrocyte marker) in the CA1 region of rats. Moreover, we revealed that the bath application of NMU (1 μM) enhanced extracellular field excitatory postsynaptic potentials at Schaffer collateral-CA1 synapses in rat hippocampal slices (+28.9 ± 1.3%; P < 0.05). After extracellular recordings, we examined the pattern of neuronal activation induced by NMU using c-Fos immunohistochemistry (Fos-IR). Histological analyses revealed that NMU increased Fos-IR in the CA1 region, but reduced the proportion of Fos-IR colocalized with glutamic acid decarboxylase (a GABA neuron marker). These results suggest that the activation of NMU receptors contributes to GABAergic neuronal activity in the CA1 region of the hippocampus.

Tensile mechanical properties of the cervical, thoracic and lumbar porcine spinal meninges

BackgroundThe spinal meninges play a mechanical protective role for the spinal cord. Better knowledge of the mechanical behavior of these tissues wrapping the cord is required to accurately model the stress and strain fields of the spinal cord during physiological or traumatic motions. Then, the mechanical properties of meninges along the spinal canal are not well documented. The aim of this study was to quantify the elastic meningeal mechanical properties along the porcine spinal cord in both the longitudinal direction and in the circumferential directions for the dura-arachnoid maters complex (DAC) and solely in the longitudinal direction for the pia mater. This analysis was completed in providing a range of isotropic hyperelastic coefficients to take into account the toe region. MethodsSix complete spines (C0 – L5) were harvested from pigs (2–3 months) weighing 43±13 kg. The mechanical tests were performed within 12 h post mortem. A preload of 0.5 N was applied to the pia mater and of 2 N to the DAC samples, followed by 30 preconditioning cycles. Specimens were then loaded to failure at the same strain rate 0.2 mm/s (approximately 0.02/s, traction velocity/length of the sample) up to 12 mm of displacement. ResultsThe following mean values were proposed for the elastic moduli of the spinal meninges. Longitudinal DAC elastic moduli: 22.4 MPa in cervical, 38.1 MPa in thoracic and 36.6 MPa in lumbar spinal levels; circumferential DAC elastic moduli: 20.6 MPa in cervical, 21.2 MPa in thoracic and 12.2 MPa in lumbar spinal levels; and longitudinal pia mater elastic moduli: 18.4 MPa in cervical, 17.2 MPa in thoracic and 19.6 MPa in lumbar spinal levels. DiscussionThe variety of mechanical properties of the spinal meninges suggests that it cannot be regarded as a homogenous structure along the whole length of the spinal cord.

The biomechanical characteristics of spinal dura mater in the context of its basic morphology

Purpose: Spinal dura mater plays a crucial role in the biomechanics and protection of the spine. Therefore, the present study investigated the dura mater's mechanical and basic morphological properties to learn more about the biomechanical behaviour of this fibrous membrane. Methods: Tissue strips, oriented in the longitudinal and circumferential directions, were cut from the cervical, thoracic, and lumbar vertebrae parts of the porcine spinal cord. Uniaxial tensile tests were performed using a device with a speed of 4 mm/min until rupture of the sample. Results: It was demonstrated that the dura mater is a heterogeneous, anisotropic material. The longitudinal excised specimens showed the highest values of mechanical properties (ultimate force (FU), the stiffness coefficient (k), ultimate tensile strength (σUTS), and Young’s modulus (E)) compared to those of the circumferentially. Confocal microscopy and sulforhodamine B (SRB) assay enabled us to visualise collagen and elastin elements more efficiently without a need for sample fixation. Conclusions: The spinal dura mater mechanical properties are not uniform along the entire length of the spinal cord, but, in the case of morphological features, no major differences were noticed. The utilisation of SRB occurred to be a non-destructive, fast, and efficient tool for visualising even the smallest elastic fibres on different depths of examined samples. The mechanical and morphological properties of the dura mater provided by this study can be further used in computational modelling to understand injury mechanisms better and help develop injury prevention strategies.

Viscoelastic mechanical behavior of the porcine spinal cord under micro-indentation

Viscoelastic mechanical behavior of the porcine spinal cord under micro-indentation

Identification of water compartments in spinal cords by 2 H double quantum filtered NMR.

In 2 H double quantum filtered (DQF) NMR, the various water compartments are characterized by their different residual quadrupolar interactions. The spectral separation between the different signals enables the measurement of the relaxation of each compartment and the magnetization transfer (MT) between them. In the current study, five water compartments were identified in the 2 H DQF spectra of porcine spinal cord. The most prominent signal was the pair of satellites with a quadrupolar splitting of about 550 Hz. 2 H DQF MRI optimized for the 550 Hz quadrupolar splitting indicated that this signal originated mainly from the white matter and it was assigned to the myelin water. This splitting does not change upon changing the orientation of the spinal cord relative to the magnetic field, indicating a liquid crystalline nature. Another site exhibiting splitting of about 1500 Hz was assigned to collagenous connective tissue. The narrow central peak was assigned to a combination of intra- and inter-axonal water. The assignment of the other two sites is not certain and requires further study. The rates of MT between the various sites were recorded.