Animal models of spinal cord injury for evaluation of tissue engineering treatment strategies

Human Adipose-Derived Stem Cells Reduce Cellular Damage after Experimental Spinal Cord Injury in Rats

Traumatic spinal cord injury (SCI) is a devastating condition without an effective therapy. Cellular therapies are among the promising treatment strategies. Adult stem cells, such as mesenchymal stem cells, are often used clinical research for their immunomodulatory and regenerative potential. This study aimed to evaluate the effect of human adipose tissue-derived stem cells (ADSC) infusion through the cauda equina in rats with SCI. The human ADSC from bariatric surgery was isolated, expanded, and characterized. Wistar rats were subjected to blunt SCI and were divided into four groups. Two experimental groups (EG): EG1 received one ADSC infusion after SCI, and EG2 received two infusions, the first one after SCI and the second infusion seven days after the injury. Control groups (CG1 and CG2) received infusion with a culture medium. In vivo, cell tracking was performed 48 h and seven days after ADSC infusion. The animals were followed up for 40 days after SCI, and immunohistochemical quantification of myelin, neurons, and astrocytes was performed. Cellular tracking showed cell migration towards the injury site. ADSC infusion significantly reduced neuronal loss, although it did not prevent the myelin loss or enhance the area occupied by astrocytes compared to the control group. The results were similar when comparing one or two cell infusions. The injection of ADSC distal to the injured area was shown to be a safe and effective method for cellular administration in spinal cord injury.

Anatomical study of arterial arrangement of the spinal cord in Syrian hamsters (Mesocricetus auratus)

This study aimed to investigate the arterial arrangement of the spinal cord in Syrian hamsters, and to identify differences and similarities to humans and experimental animals that are mostly used as models in studies into ischemic spinal cord injuries. This observational anatomical study was conducted on 20 adult Syrian hamsters using dissection and corrosion casting technique. The general anatomy of the arterial blood supply of spinal cord was obtained and noted as follows: (1) high variability in the level of the origin of right and left vertebral arteries, (2) the independent origin of dorsal intercostal arteries, (3) origin of lumbar arteries as a common trunk with right and left divisions, (4) presence of dorsal and ventral radicular branches in both sides of the cervical spinal cord with almost the same frequency, (5) greater presence of ventral and dorsal radicular branches in the left side of the thoracolumbar spinal cord, (6) two dorsal spinal arteries originating from the posterior inferior cerebellar arteries and extending to the caudal end of the thoracic spinal cord, (7) continuous ventral spinal artery originating from both vertebral arteries and extending to the conus medularis, and (8) presence of the artery of Adamkiewicz in the thoracic region of the spinal cord. From comparative anatomy viewpoints, the arteries supplying the spinal cord of Syrian hamsters exhibit many similarities with humans, laboratory rodents, and rabbits in many aspects compared to dogs, cats, and pigs. Overall, Syrian hamsters can be used as a proposed model in experimental studies of the spinal cord ischemia.

Silk-Elastin-like Polymers for Acute Intraparenchymal Treatment of the Traumatically Injured Spinal Cord: A First Systematic Experimental Approach

Despite the promising potential of hydrogel-based therapeutic approaches for spinal cord injury (SCI), the need for new biomaterials to design effective strategies for SCI treatment and the outstanding properties of silk-elastin-like polymers (SELP), the potential use of SELPs in SCI is currently unknown. In this context, we assessed the effects elicited by the in vivo acute intraparenchymal injection of an SELP named (EIS)₂-RGD6 in a clinically relevant model of SCI. After optimization of the injection system, the distribution, structure, biodegradability, and cell infiltration capacity of (EIS)₂-RGD6 were assessed. Finally, the effects exerted by the (EIS)₂-RGD6 injection-in terms of motor function, myelin preservation, astroglial and microglia/macrophage reactivity, and fibrosis-were evaluated. We found that (EIS)₂-RGD6 can be acutely injected in the lesioned spinal cord without inducing further damage, showing a widespread distribution covering all lesioned areas with a single injection and facilitating the formation of a slow-degrading porous scaffold at the lesion site that allows for the infiltration and/or proliferation of endogenous cells with no signs of collapse and without inducing further microglial and astroglial reactivity, as well as even reducing SCI-associated fibrosis. Altogether, these observations suggest that (EIS)₂-RGD6-and, by extension, SELPs-could be promising polymers for the design of therapeutic strategies for SCI treatment.

The immune microenvironment and tissue engineering strategies for spinal cord regeneration

Regeneration of neural tissue is limited following spinal cord injury (SCI). Successful regeneration of injured nerves requires the intrinsic regenerative capability of the neurons and a suitable microenvironment. However, the local microenvironment is damaged, including insufficient intraneural vascularization, prolonged immune responses, overactive immune responses, dysregulated bioenergetic metabolism and terminated bioelectrical conduction. Among them, the immune microenvironment formed by immune cells and cytokines plays a dual role in inflammation and regeneration. Few studies have focused on the role of the immune microenvironment in spinal cord regeneration. Here, we summarize those findings involving various immune cells (neutrophils, monocytes, microglia and T lymphocytes) after SCI. The pathological changes that occur in the local microenvironment and the function of immune cells are described. We also summarize and discuss the current strategies for treating SCI with tissue-engineered biomaterials from the perspective of the immune microenvironment.

Distinct Glycosylation Responses to Spinal Cord Injury in Regenerative and Nonregenerative Models

Traumatic spinal cord injury (SCI) results in disruption of tissue integrity and loss of function. We hypothesize that glycosylation has a role in determining the occurrence of regeneration and that biomaterial treatment can influence this glycosylation response. We investigated the glycosylation response to spinal cord transection in Xenopus laevis and rat. Transected rats received an aligned collagen hydrogel. The response compared regenerative success, regenerative failure, and treatment in an established nonregenerative mammalian system. In a healthy rat spinal cord, ultraperformance liquid chromatography (UPLC) N-glycoprofiling identified complex, hybrid, and oligomannose N-glycans. Following rat SCI, complex and outer-arm fucosylated glycans decreased while oligomannose and hybrid structures increased. Sialic acid was associated with microglia/macrophages following SCI. Treatment with aligned collagen hydrogel had a minimal effect on the glycosylation response. In Xenopus, lectin histochemistry revealed increased levels of N-acetyl-glucosamine (GlcNAc) in premetamorphic animals. The addition of GlcNAc is required for processing complex-type glycans and is a necessary foundation for additional branching. A large increase in sialic acid was observed in nonregenerative animals. This work suggests that glycosylation may influence regenerative success. In particular, loss of complex glycans in rat spinal cord may contribute to regeneration failure. Targeting the glycosylation response may be a promising strategy for future therapies.

Stem cell treatment trials of spinal cord injuries in animals

BACKGROUND

Spinal cord injury (SCI) is a serious neurological spinal cord damage that resulted in the loss of temporary or permanent function. However, there are even now no effective therapies for it. So, a new medical promising therapeutic hotspot over the previous decades appeared which was (Stem cell (SC) cure of SCI). Otherwise, animal models are considered in preclinical research as a model for humans to trial a potential new treatment.

METHODOLOGY

Following articles were saved from different databases (PubMed, Google scholar, Egyptian knowledge bank, Elsevier, Medline, Embase, ProQuest, BMC) on the last two decades, and data were obtained then analyzed.

RESULTS

This review discusses the type and grading of SCI. As well as different types of stem cells therapy for SCI, including mesenchymal stem cells (MSCs), neural stem cells (NSCs), hematopoietic stem cells (HSCs), induced pluripotent stem cells (iPSCs), and embryonic stem cells (ESCs). The review focuses on the transplantation pathways, clinical evaluation, and clinical signs of different types of SC on different animal models which are summarized in tables to give an easy to reach.

CONCLUSION

Pharmacological and physiotherapy have limited regenerative power in comparison with stem cells medication in the treatment of SCI. Among several sources of cell therapies, mesenchymal stromal/stem cell (MSC) one is being progressively developed as a trusted important energetic way to repair and regenerate. Finally, a wide-ranged animal models have been condensed that helped in human clinical trial therapies.

Cell transplantation and secretome based approaches in spinal cord injury regenerative medicine

The axonal growth-restrictive character of traumatic spinal cord injury (SCI) makes finding a therapeutic strategy a very demanding task, due to the postinjury events impeditive to spontaneous axonal outgrowth and regeneration. Considering SCI pathophysiology complexity, it has been suggested that an effective therapy should tackle all the SCI-related aspects and provide sensory and motor improvement to SCI patients. Thus, the current aim of any therapeutic approach for SCI relies in providing neuroprotection and support neuroregeneration. Acknowledging the current SCI treatment paradigm, cell transplantation is one of the most explored approaches for SCI with mesenchymal stem cells (MSCs) being in the forefront of many of these. Studies showing the beneficial effects of MSC transplantation after SCI have been proposing a paracrine action of these cells on the injured tissues, through the secretion of protective and trophic factors, rather than attributing it to the action of cells itself. This manuscript provides detailed information on the most recent data regarding the neuroregenerative effect of the secretome of MSCs as a cell-free based therapy for SCI. The main challenge of any strategy proposed for SCI treatment relies in obtaining robust preclinical evidence from in vitro and in vivo models, before moving to the clinics, so we have specifically focused on the available vertebrate and mammal models of SCI currently used in research and how can SCI field benefit from them.

Pastable, Adhesive, Injectable, Nanofibrous, and Tunable (PAINT) Biphasic Hybrid Matrices as Versatile Therapeutic Carriers

A critical challenge in many pharmaceutical fields is developing versatile adjuvant devices that can reduce the off-target delivery of therapeutic materials to target lesions. Herein, a biphasic hybrid fibrous system that can manipulate the spatial and temporal delivery of various therapeutic agents to target lesions by integrating multiple distinct systems and technologies such as fluffy coaxial electrospun polycaprolactone (PCL)/polystyrene (PS) fibers, cyclohexane-mediated leaching to remove PS layers selectively, amine display on PCL fibers, conjugation of naturally occurring adhesive gallol molecules onto hyaluronic acid (HA-g), and electrostatically complexing the aminated PCL fibers with the gallol-conjugated HA. In the context of "paintable" systems on target lesions, the resulting system is called a PAINT matrix (abbreviated according to the initial letter of its features: pastable, adhesive, injectable, nanofibrous, and tunable). Its viscoelastic property, which was attributed by coalescing aminated PCL fibers with viscous HA-g, enabled it to be noninvasively injected and fit into any cavity in the body with various morphologies, manually pasted on tissue surfaces, and adhered onto moisture-rich surfaces to ensure the secure delivery of therapeutics toward the target lesions. The PAINT matrix efficiently supplied immunomodulatory human neural stem cells (hNSCs) at rat hemisectioned spinal cord injury (SCI) sites and promoted both locomotive and sensory recovery in SCI models, presumably by protecting hNSCs against host immunosurveillance. The PAINT matrix will be broadly utilized for efficiently delivering therapeutics to difficult-to-reach target lesions by direct infusion or conventional biomaterial-mediated approaches due to their locations, wet surfaces, or complicated ambient environments.

3D bioprinted neural tissue constructs for spinal cord injury repair

Three-dimensional (3D) bioprinting has emerged as a promising approach to fabricate living neural constructs with anatomically accurate complex geometries and spatial distributions of neural stem cells (NSCs) for spinal cord injury (SCI) repair. The NSC-laden 3D bioprinting, however, still faces some big challenges, such as cumbersome printing process, poor cell viability, and minimal cell-material interaction. To address these issues, we have fabricated NSC-laden scaffolds by 3D bioprinting and explore for the first time their application for in vivo SCI repair. In our strategy, we have developed a novel biocompatible bioink consisting of functional chitosan, hyaluronic acid derivatives, and matrigel. This bioink shows fast gelation (within 20 s) and spontaneous covalent crosslinking capability, facilitating convenient one-step bioprinting of spinal cord-like constructs. Thus-fabricated scaffolds maintain high NSC viability (about 95%), and offer a benign microenvironment that facilitates cell-material interactions and neuronal differentiation for optimal formation of neural network. The in vivo experiment has further demonstrated that the bioprinted scaffolds promoted the axon regeneration and decreased glial scar deposition, leading to significant locomotor recovery of the SCI model rats, which may represent a general and versatile strategy for precise engineering of central nervous system and other neural organs/tissues for regenerative medicine application.

Laminin-coated multifilament entubulation, combined with Schwann cells and glial cell line-derived neurotrophic factor, promotes unidirectional axonal regeneration in a rat model of thoracic spinal cord hemisection

Biomaterial bridging provides physical substrates to guide axonal growth across the lesion. To achieve efficient directional guidance, combinatory strategies using permissive matrix, cells and trophic factors are necessary. In the present study, we evaluated permissive effect of poly (acrylonitrile-co-vinyl chloride) guidance channels filled by different densities of laminin-precoated unidirectional polypropylene filaments combined with Schwann cells, and glial cell line-derived neurotrophic factor for axonal regeneration through a T10 hemisected spinal cord gap in adult rats. We found that channels with filaments significantly reduced the lesion cavity, astrocytic gliosis, and inflammatory responses at the graft-host boundaries. The laminin coated low density filament provided the most favorable directional guidance for axonal regeneration which was enhanced by co-grafting of Schwann cells and glial cell line-derived neurotrophic factor. These results demonstrate that the combinatorial strategy of filament-filled guiding scaffold, adhesive molecular laminin, Schwann cells, and glial cell line-derived neurotrophic factor, provides optimal topographical cues in stimulating directional axonal regeneration following spinal cord injury. This study was approved by Indiana University Institutional Animal Care and Use Committees (IACUC #:11011) on October 29, 2015.

Improved spinal cord gray matter morphology induced by Spirulina platensis following spinal cord injury in rat models

Despite intense preclinical research focusing on developing potential strategies of mitigating spinal cord injury (SCI), SCI still results in permanent, debilitating symptoms for which there are currently no effective pharmacological interventions to improve the recovery of the fine ultrastructure of the spinal cord. Spirulina platensis is thought to have potential neuroprotective effects. We have previously demonstrated its protective potential on the lesioned corticospinal tracts and behavioral recovery. In this study, spirulina, known for its neuroprotective properties was used to further explore its protective effects on spinal cord gray matter ultrastructural. Twenty-four Sprague-Dawley rats were used and divided into sham group (laminectomy without SCI), control group (SCI without S. platensis), and S. platensis group (SCI + 180 mg/kg S. platensis). All animals were anesthetized via intramuscular injection. A partial crush injury was induced at the level of T12. The rats were humanely sacrificed for 28 days postinjury for ultrastructural study. There were significant mean differences with respect to pairwise comparisons between the ultrastructural grading score of neuronal perikarya of control and the S. platensis following injury at day 28, which correlates with the functional locomotor recovery at this timepoint in our previous study. The group supplemented with spirulina, thus, revealed a better improvement in the fine ultrastructure of the spinal cord gray matter when compared to the control group thereby suggesting neuroprotective potentials of spirulina in mitigating the effects of spinal cord injury and inducing functional recovery.

New Model of Ventral Spinal Cord Lesion Induced by Balloon Compression in Rats

Despite the variety of experimental models of spinal cord injury (SCI) currently used, the model of the ventral compression cord injury, which is commonly seen in humans, is very limited. Ventral balloon compression injury reflects the common anatomical mechanism of a human lesion and has the advantage of grading the injury severity by controlling the inflated volume of the balloon. In this study, ventral compression of the SCI was performed by the anterior epidural placement of the balloon of a 2F Fogarty's catheter, via laminectomy, at the level of T10. The balloon was rapidly inflated with 10 or 15 μL of saline and rested in situ for 5 min. The severity of the lesion was assessed by behavioral and immunohistochemical tests. Compression with the volume of 15 μL resulted in severe motor and sensory deficits represented by the complete inability to move across a horizontal ladder, a final Basso, Beattie and Bresnahan (BBB) score of 7.4 and a decreased withdrawal time in the plantar test (11.6 s). Histology and immunohistochemistry revealed a significant loss of white and gray matter with a loss of motoneuron, and an increased size of astrogliosis. An inflation volume of 10 μL resulted in a mild transient deficit. There are no other balloon compression models of ventral spinal cord injury. This study provided and validated a novel, easily replicable model of the ventral compression SCI, introduced by an inflated balloon of Fogarty´s catheter. For a severe incomplete deficit, an inflated volume should be maintained at 15 μL.

Comparison of the anatomical morphology of cervical vertebrae between humans and macaques: related to a spinal cord injury model

Non-human primates are most suitable for generating cervical experimental models, and it is necessary to study the anatomy of the cervical spine in non-human primates when generating the models. The purpose of this study was to provide the anatomical parameters of the cervical spine and spinal cord in long-tailed macaques (Macaca fascicularis) as a basis for cervical spine-related experimental studies. Cervical spine specimens from 8 male adult subjects were scanned by micro-computed tomography, and an additional 10 live male subjects were scanned by magnetic resonance imaging. The measurements and parameters from them were compared to those of 12 male adult human subjects. Additionally, 10 live male subjects were scanned by magnetic resonance imaging, and the width and depth of the spinal cord and spinal canal and the thickness of the anterior and posterior cerebrospinal fluid were measured and compared to the relevant parameters of 10 male adult human subjects. The tendency of cervical parameters to change with segmental changes was similar between species. The vertebral body, spinal canal, and spinal cord were significantly flatter in the human subjects than in the long-tailed macaques. The cerebrospinal fluid space in the long-tailed macaques was smaller than that in the human subjects. The anatomical features of the cervical vertebrae of long-tailed macaques provide a reference for establishing a preclinical model of cervical spinal cord injury.

Natural-Based Biomaterials for Peripheral Nerve Injury Repair

Peripheral nerve injury treatment is a relevant problem because of nerve lesion high incidence and because of unsatisfactory regeneration after severe injuries, thus resulting in a reduced patient's life quality. To repair severe nerve injuries characterized by substance loss and to improve the regeneration outcome at both motor and sensory level, different strategies have been investigated. Although autograft remains the gold standard technique, a growing number of research articles concerning nerve conduit use has been reported in the last years. Nerve conduits aim to overcome autograft disadvantages, but they must satisfy some requirements to be suitable for nerve repair. A universal ideal conduit does not exist, since conduit properties have to be evaluated case by case; nevertheless, because of their high biocompatibility and biodegradability, natural-based biomaterials have great potentiality to be used to produce nerve guides. Although they share many characteristics with synthetic biomaterials, natural-based biomaterials should also be preferable because of their extraction sources; indeed, these biomaterials are obtained from different renewable sources or food waste, thus reducing environmental impact and enhancing sustainability in comparison to synthetic ones. This review reports the strengths and weaknesses of natural-based biomaterials used for manufacturing peripheral nerve conduits, analyzing the interactions between natural-based biomaterials and biological environment. Particular attention was paid to the description of the preclinical outcome of nerve regeneration in injury repaired with the different natural-based conduits.

Excess administration of miR-340-5p ameliorates spinal cord injury-induced neuroinflammation and apoptosis by modulating the P38-MAPK signaling pathway

Spinal cord injury (SCI) is a destructive polyneuropathy that can result in loss of sensorimotor function and sphincter dysfunction, and even death in critical situations. MicroRNAs (miRs) are a series of non-coding RNA molecules that are involved in transcriptional regulation. Previous studies have demonstrated that modulation of multiple miRs is involved in neurological recovery after SCI. However, the functions of miR-340-5p in SCI remain uncertain. Therefore, we probed the therapeutic effect and mechanism of miR-340-5p in microglia in vitro and in vivo in SCI rats. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting were employed to examine the alterations in miR-340-5p and P38 levels in SCI rats. miR-340-5p targets in microglia were ascertained using luciferase reporter assays, immunofluorescence analyses, and western blotting. We also established an SCI model and administered miR-340-5p. The effects of miR-340-5p on the amelioration of inflammation, oxidative stress, and apoptosis following SCI were assessed using immunofluorescence, immunohistochemistry, and histological analyses. Finally, locomotor function recovery was determined using the Basso, Beattie, Bresnahan rating scale. In our study, the expression profiles and luciferase assay results clarified that P38 was a target of miR-340-5p, which was associated with activation of the P38-MAPK signaling pathway. Elevation of miR-340-5p decreased P38 expression, subsequently inhibiting the inflammatory reaction. SCI-induced secondary neuroinflammation was relieved under miR-340-5p treatment. Moreover, by controlling neuroinflammation, the increased levels of miR-340-5p might counter oxidative stress and reduce the degree of apoptosis. We also observed decreasing gliosis and glial scar formation and increasing neurotrophin expression at the chronic stage of SCI. Together, these potential effects of miR-340-5p treatment ultimately improved locomotor function recovery in SCI rats.

A mouse model of complete-crush transection spinal cord injury made by two operations

Background

More and more studies have focused on the treatment of spinal cord injury (SCI) by tissue engineering, but there is still no ideal animal model that can genuinely and objectively simulate the real pathological process in clinical practice. Also, given the increasing availability and use of genetically modified animals in basic science research, it has become essential to develop clinically related models for SCI for use in mice.

Methods

Forty-eight C57BL/6 mice were divided into three groups (injured/sham/uninjured). We determined the scar range made by the first crush injury by specimen observation, hematoxylin and eosin (HE) staining, and immunofluorescence staining. Transection to completely remove a 2-mm spinal cord segment centered on the lesion core was completed 6 weeks after the first injury in injured groups, whereas the sham group only underwent re-exposure of the spinal cord without transection injury. The characteristics of this SCI model were fully ascertained by specimen observation, HE staining, immunofluorescence staining, and quantitative real-time polymerase chain reaction (qRT-PCR).

Results

No mice died after the first injury. Histopathological findings suggested a scar range of 2 mm. After the second operation, 2 mice of the injured group and 1 mouse of the sham group died. The Basso Mouse Scale (BMS) score and motor evoked potential (MEP) results showed that the neurological function of mice did not recover. Immunostaining showed that there were no neurons or neurofilament residues in the lesion core 4 weeks after the second injury. Astrocytes encapsulated immune cells to form dense glial scars. Most immune cells were confined to the core of the lesion and formed fibrous scars with the fibroblasts. At the same time, there was considerable angiogenesis in the lesion core and around the injury. The results of qRT-PCR showed that Ptprc was highly expressed in the lesion core, while Gfap, nestin, Cnp, and Sv2b were highly expressed in the adjacent region. This suggests that the lesion core is a highly inflammatory zone, but there may be spontaneous neurogenesis adjacent to the lesion core.

Conclusions

The mouse crash-complete transection SCI model made by the two operations has good simulation, high feasibility, and high reproducibility; it will be a useful tool for pre-clinical testing of SCI treatment.

Animal models of spinal injury for studying back pain and SCI

INTRODUCTION

Back pain is a common ailment affecting individuals around the globe. Animal models to understand the back pain mechanism, treatment modalities, and spinal cord injury are widely researched topics worldwide. Despite the presence of several animal models on disc degeneration and Spinal Cord Injury, there is a lack of a comprehensive review.

MATERIAL AND METHOD

A methodological narrative literature review was carried out for the study. A total of 1273 publications were found, out of which 763 were related to spine surgery in animals. The literature with full-text availability was selected for the review. Scale for the Assessment of Narrative Review Articles (SANRA) guidelines was used to assess the studies. Only English language publications were included which were listed on PubMed. A total of 113 studies were shortlisted (1976-2019) after internal validation scoring.

RESULT

The animal models for spine surgery ranged from rodents to primates. These are used to study the mechanisms of back pain as well as spinal cord injuries. The models could either be created surgically or through various means like use of electric cautery, chemicals or trauma. Genetic spine models have also been documented in which the injuries are created by genetic alterations and knock outs. Though the dorsal approach is the most common, the literature also mentions the anterior and lateral approach for spine surgery animal experiments.

CONCLUSION

There are no single perfect animal models to represent and study human models. The selection is based on the application and the methodology. Careful selection is needed to give optimum and appropriate results.

Characterization of transection spinal cord injuries by monitoring somatosensory evoked potentials and motor behavior

Standardization of spinal cord injury (SCI) models is crucial for reproducible injury in research settings and their objective assessments. Basso, Beattie and Bresnahan (BBB) scoring, the traditional behavioral evaluation method, is subjective and susceptible to human error. On the other hand, neuro-electrophysiological monitoring, such as somatosensory evoked potential (SSEP), is an objective assessment method that can be performed continuously for longitudinal studies. We implemented both SSEP and BBB assessments on transection SCI model. Five experimental groups are designed as follows: left hemi-transection at T8, right hemi-transection at T10, double hemi-transection at left T8 and right T10, complete transection at T8 and control group which receives only laminectomy with intact dura and no injury on spinal cord parenchyma. On days 4, 7, 14 and 21 post-injury, first BBB scores in awake and then SSEP signals in anesthetized rats were obtained. Our results show SSEP signals and BBB scores are both closely associated with transection model and injury progression. However, the two assessment modalities demonstrate different sensitivity in measuring injury progression when it comes to late-stage double hemi-transection, complete transection and hemi-transection injury. Furthermore, SSEP amplitudes are found to be distinct in different injury groups and the progress of their attenuation is increasingly rapid with more severe transection injuries. It is evident from our findings that SSEP and BBB methods provide distinctive and valuable information and could be complementary of each other. We propose incorporating both SSEP monitoring and conventional BBB scoring in SCI research to more effectively standardize injury progression.

In situ injectable hydrogels for spinal cord regeneration: advances from the last 10 years

Spinal cord injury (SCI) is a tremendously devastating disorder with no effective therapy. Neuroprotective strategies have been applied aiming to prevent secondary cell death but no successful and robust effects have been observed. Recently, combinatorial approaches using biomaterials with cells and/or growth factors have demonstrated promising therapeutic effects because of the improvement of axonal growth and in vivo functional recovery in model organisms. In situ injectable hydrogels are a particularly attractive neuroregenerative approach to improve spinal cord repair and regeneration since they can be precisely injected into the lesion site filling the space prior to gelification, decrease scarring and promote axon growth due to the hydrogel's soft structure. Important advances regarding the use of hydrogels as potential therapeutic approaches has been reported during the last 10 years. Injectable alginate hydrogel loaded with GDNF, thermoresponsives heparin-poloxamer loaded with NGF and imidazole-poly(organophosphazenes) hydrogels are just three examples of biomaterials that can promote neurite, axon growth and improve functional recovery in hemisected and resected rats. Here we will review the status of in situ injectable hydrogels for spinal cord regeneration with special focus in the advantages of using hydrogel scaffolds, the ideal polymers to be used, the gelification process and the cells or growth factors combined. The in vitro and in vivo results reported for those biomaterials will be presented, compared and discussed.

The advances in nerve tissue engineering: From fabrication of nerve conduit to in vivo nerve regeneration assays

Peripheral nerve damage is a common clinical complication of traumatic injury occurring after accident, tumorous outgrowth, or surgical side effects. Although the new methods and biomaterials have been improved recently, regeneration of peripheral nerve gaps is still a challenge. These injuries affect the quality of life of the patients negatively. In the recent years, many efforts have been made to develop innovative nerve tissue engineering approaches aiming to improve peripheral nerve treatment following nerve injuries. Herein, we will not only outline what we know about the peripheral nerve regeneration but also offer our insight regarding the types of nerve conduits, their fabrication process, and factors associated with conduits as well as types of animal and nerve models for evaluating conduit function. Finally, nerve regeneration in a rat sciatic nerve injury model by nerve conduits has been considered, and the main aspects that may affect the preclinical outcome have been discussed.

Innovative mouse model mimicking human-like features of spinal cord injury: efficacy of Docosahexaenoic acid on acute and chronic phases

Traumatic spinal cord injury has dramatic consequences and a huge social impact. We propose a new mouse model of spinal trauma that induces a complete paralysis of hindlimbs, still observable 30 days after injury. The contusion, performed without laminectomy and deriving from the pressure exerted directly on the bone, mimics more closely many features of spinal injury in humans. Spinal cord was injured at thoracic level 10 (T10) in adult anesthetized female CD1 mice, mounted on stereotaxic apparatus and connected to a precision impactor device. Following severe injury, we evaluated motor and sensory functions, and histological/morphological features of spinal tissue at different time points. Moreover, we studied the effects of early and subchronic administration of Docosahexaenoic acid, investigating functional responses, structural changes proximal and distal to the lesion in primary and secondary injury phases, proteome modulation in injured spinal cord. Docosahexaenoic acid was able i) to restore behavioural responses and ii) to induce pro-regenerative effects and neuroprotective action against demyelination, apoptosis and neuroinflammation. Considering the urgent health challenge represented by spinal injury, this new and reliable mouse model together with the positive effects of docosahexaenoic acid provide important translational implications for promising therapeutic approaches for spinal cord injuries.

Pericytes Act as Key Players in Spinal Cord Injury

Spinal cord injury results in locomotor impairment attributable to the formation of an inhibitory fibrous scar, which prevents axonal regeneration after trauma. The scarcity of knowledge about the molecular and cellular mechanisms involved in scar formation after spinal cord lesion impede the design of effective therapies. Recent studies, by using state-of-the-art technologies, including genetic tracking and blockage of pericytes in combination with optogenetics, reveal that pericyte blockage facilitates axonal regeneration and neuronal integration into the local neural circuitry. Strikingly, a pericyte subset is essential during scarring after spinal cord injury, and its arrest results in motor performance improvement. The arising knowledge from current research will contribute to novel approaches to develop therapies for spinal cord injury. We review novel advances in our understanding of pericyte biology in the spinal cord.

Polymer scaffolds facilitate spinal cord injury repair

During the past decades, improving patient neurological recovery following spinal cord injury (SCI) has remained a challenge. An effective treatment for SCI would not only reduce fractured elements and isolate developing local glial scars to promote axonal regeneration but also ameliorate secondary effects, including inflammation, apoptosis, and necrosis. Three-dimensional (3D) scaffolds provide a platform in which these mechanisms can be addressed in a controlled manner. Polymer scaffolds with favorable biocompatibility and appropriate mechanical properties have been engineered to minimize cicatrization, customize drug release, and ensure an unobstructed space to promote cell growth and differentiation. These properties make polymer scaffolds an important potential therapeutic platform. This review highlights the recent developments in polymer scaffolds for SCI engineering. STATEMENT OF SIGNIFICANCE: How to improve the efficacy of neurological recovery after spinal cord injury (SCI) is always a challenge. Tissue engineering provides a promising strategy for SCI repair, and scaffolds are one of the most important elements in addition to cells and inducing factors. The review highlights recent development and future prospects in polymer scaffolds for SCI therapy. The review will guide future studies by outlining the requirements and characteristics of polymer scaffold technologies employed against SCI. Additionally, the peculiar properties of polymer materials used in the therapeutic process of SCI also have guiding significance to other tissue engineering approaches.

Experimental spinal cord injury and behavioral tests in laboratory rats

Traumatic spinal cord injury (SCI) results in some serious neurophysiological consequences that alter healthy body functions and devastate the quality of living of individuals. To find a cure for SCI, researchers around the world are working on different neurorepair and neurorehabilitation modalities. To test a new treatment for SCI as well as to understand the mechanism of recovery, animal models are being widely used. Among them, SCI rat models are arguably the most prominent. Furthermore, it is important to select a suitable behavioral test to evaluate both the motor and sensory recovery following any therapeutic intervention. In this paper, we review the rat models of spinal injury and commonly used behavioral tests to serve as a useful guideline for neuroscientists in the field of SCI research.

The Hemisection Approach in Large Animal Models of Spinal Cord Injury: Overview of Methods and Applications

Introduction: Translating basic science research into a safe and effective therapy for spinal cord injury (SCI) requires suitable large animal models for testing both implantable devices and biologic approaches to better approximate human anatomy and function. Hemisection lesions, routinely used for investigational purposes in small animals, are less frequently described in large animals that might be appropriate for translational studies. Size constraints of small animals (mice and rats) limits the predictability of the findings when scaled up. Our goal is to review the status of hemisection SCI in large animals across species and time to prepare for the testing of a novel intradural spinal cord stimulation device for control of spasticity in an ovine model. Methods and Results: We surveyed the literature on hemisection in quadrupeds and nonhuman primates, and catalogued the species, protocols and outcomes of the experimental work in this field. Feline, lapine, canine, simian, porcine, ovine and bovine models were the primary focal points. There is a consistent body of literature reporting use of the hemisection approach in large animals, but with differences in surgical technique depending on the goals and nature of the individual studies. While the injuries are not always consistent, the experimental variability is generally lower than that of the contusion-based approach. In general, as the body size of the animal increases, animal care requirements and the associated costs follow. In most cases, this is inversely correlated with the number of animals used in hemisection models. Conclusions: The hemisection approach to modeling SCI is straightforward compared with other methods such as the contusive impact and enables the transection of isolated ascending and descending tracts and segment specific cell bodies. This has certain advantages in models investigating post-injury axonal regrowth. However, this approach is not generally in line with the patho-physiologies encountered in SCI patients. Even so, the ability to achieve more control over the level of injury makes it a useful adjunct to contusive and ischemic approaches, and suggests a useful role in future translational studies.

Melanin incorporated electroactive and antioxidant silk fibroin nanofibrous scaffolds for nerve tissue engineering

Nerve restoration and repair in the central nervous system is complicated and requires several factors to be considered while designing the scaffolds like being bioactive as well as having neuroinductive, neuroconductive and antioxidant properties. Aligned electrospun nanofibers provide necessary guidance and topographical cues required for directing the axonal and neurite outgrowth during regeneration. Conduction of nerve impulses is a mandatory feature of a typical nerve. The neuro-conductive property can be imparted by blending the biodegradable, bioactive polymers with conductive polymers. This will provide additional features, i.e., electrical cues to the already existing topographical and bioactive cues in order to make it a more multifaceted neuroregenerative approach. Hence in the present study, we used a combination of silk fibroin and melanin for the fabrication of random and aligned electrospun nanofibrous composite scaffolds. We performed the physico-chemical characterization and also assessed their antioxidant properties. We also evaluated their neurogenic potential using human neuroblastoma cells (SH-SY5Y) for their cellular viability, proliferation, adhesion and differentiation levels. Designed nanofibrous scaffolds had adequate physical properties suitable as neural substrates to promote neuronal growth and regeneration. They stimulated the neuroblastoma cell attachment and viability indicating their biocompatible nature. Silk/melanin composite scaffolds have specifically exhibited high antioxidant nature proven by the radical scavenging activity. Additionally, the melanin incorporated aligned silk fibroin scaffolds promoted the cell differentiation into neurons and orientation along their axis. Our results confirmed the potential of melanin incorporated aligned silk fibroin scaffolds as the promising candidates for effective nerve regeneration and recovery.

The Dorsal Column Lesion Model of Spinal Cord Injury and Its Use in Deciphering the Neuron-Intrinsic Injury Response

The neuron‐intrinsic response to axonal injury differs markedly between neurons of the peripheral and central nervous system. Following a peripheral lesion, a robust axonal growth program is initiated, whereas neurons of the central nervous system do not mount an effective regenerative response. Increasing the neuron‐intrinsic regenerative response would therefore be one way to promote axonal regeneration in the injured central nervous system. The large‐diameter sensory neurons located in the dorsal root ganglia are pseudo‐unipolar neurons that project one axon branch into the spinal cord, and, via the dorsal column to the brain stem, and a peripheral process to the muscles and skin. Dorsal root ganglion neurons are ideally suited to study the neuron‐intrinsic injury response because they exhibit a successful growth response following peripheral axotomy, while they fail to do so after a lesion of the central branch in the dorsal column. The dorsal column injury model allows the neuron‐intrinsic regeneration response to be studied in the context of a spinal cord injury. Here we will discuss the advantages and disadvantages of this model. We describe the surgical methods used to implement a lesion of the ascending fibers, the anatomy of the sensory afferent pathways and anatomical, electrophysiological, and behavioral techniques to quantify regeneration and functional recovery. Subsequently we review the results of experimental interventions in the dorsal column lesion model, with an emphasis on the molecular mechanisms that govern the neuron‐intrinsic injury response and manipulations of these after central axotomy. Finally, we highlight a number of recent advances that will have an impact on the design of future studies in this spinal cord injury model, including the continued development of adeno‐associated viral vectors likely to improve the genetic manipulation of dorsal root ganglion neurons and the use of tissue clearing techniques enabling 3D reconstruction of regenerating axon tracts. © 2018 The Authors. Developmental Neurobiology Published by Wiley Periodicals, Inc. Develop Neurobiol 00: 000–000, 2018

Implantation of 3D Constructs Embedded with Oral Mucosa-Derived Cells Induces Functional Recovery in Rats with Complete Spinal Cord Transection

Spinal cord injury (SCI), involving damaged axons and glial scar tissue, often culminates in irreversible impairments. Achieving substantial recovery following complete spinal cord transection remains an unmet challenge. Here, we report of implantation of an engineered 3D construct embedded with human oral mucosa stem cells (hOMSC) induced to secrete neuroprotective, immunomodulatory, and axonal elongation-associated factors, in a complete spinal cord transection rat model. Rats implanted with induced tissue engineering constructs regained fine motor control, coordination and walking pattern in sharp contrast to the untreated group that remained paralyzed (42 vs. 0%). Immunofluorescence, CLARITY, MRI, and electrophysiological assessments demonstrated a reconnection bridging the injured area, as well as presence of increased number of myelinated axons, neural precursors, and reduced glial scar tissue in recovered animals treated with the induced cell-embedded constructs. Finally, this construct is made of bio-compatible, clinically approved materials and utilizes a safe and easily extractable cell population. The results warrant further research with regards to the effectiveness of this treatment in addressing spinal cord injury.

Promotion of neurological recovery in rat spinal cord injury by mesenchymal stem cells loaded on nerve-guided collagen scaffold through increasing alternatively activated macrophage polarization

Mesenchymal stem cells (MSCs) are characterized by multidifferentiation and immunoregulatory potential and have been used in the treatment of spinal cord injury (SCI), but direct transplantation may limit effectiveness due to their quick diffusion. The role of macrophages in healing is being increasingly recognized because of their ability to polarize into pro- and anti-inflammatory phenotypes. In the present study, nerve-guide collagen scaffold (CS) combined with rat MSCs was developed. After CS was confirmed to minimize MSC distribution in vivo by positron emission tomography (PET) imaging, the repair capacity of combined implantation of CS and MSCs and the effect on classically activated macrophage/alternatively activated macrophage (M2) polarization was assessed in a hemisected SCI rat model. In vivo studies showed that, compared to the control group, the rats in the combined implantation group exhibited more significant recovery of nerve function evidenced by the 21-point Basso-Beattie-Bresnahan score and footprint analysis. Morphological staining showed less macrophage infiltration, apoptosis and glial fibrillary acidic protein, and more neurofilaments, and the fibres were guided to grow through the implant. More M2 were observed in the combined implantation group. The data suggest that the combined implantation could support MSCs to play a protective role of SCI, not only through inhibiting chronic scar formation and providing linear guidance for the nerve, but also benefitting M2 polarization to form an anti-inflammatory environment. Thus, the combination of biomaterial and MSCs might be a prominent therapeutic treatment for SCI. Copyright © 2016 John Wiley & Sons, Ltd.

Glial Cell Line-Derived Neurotrophic Factor-Transfected Placenta-Derived Versus Bone Marrow-Derived Mesenchymal Cells for Treating Spinal Cord Injury

Background

Placenta-derived mesenchymal stem cells (PMSCs) were isolated from placenta and had differentiation and self-renewal potential. We transfected PMSCs with glial cell line-derived neurotrophic factor (GDNF) and compared their effect for repairing spinal cord injury (SCI) with that of GDNF-transfected bone marrow-derived mesenchymal stem cell (BMSC).

Material/Methods

The PMSCs were isolated from Sprague-Dawley rat placenta; BMSCs were isolated from Sprague-Dawley rat thigh bone marrow. Primary cultured BMSCs and PMSCs were uniformly spindle-shaped. Flow cytometry indicated that both cell types were CD29- and CD90-positive and CD34- and CD45-negative, confirming that they were MSCs. The PMSCs and BMSCs were transfected with recombinant lentivirus containing the GDNF gene in vitro. PMSC and BMSC viability was increased after transfection, and GDNF expression was increased until 10 d after transfection. SCI was created in the rats (n=64) and was repaired using transfected PMSCs and BMSCs or untransfected PMSCs and BMSCs.

Results

The transfected PMSCs and BMSCs repaired the SCI. Flow cytometry, histology, immunohistochemical, kinesiology properties, and Basso-Beattie-Bresnahan locomotion score measurements determined no significant difference between transfected PMSCs and BMSCs at 7, 14, and 21 d post-transplantation (P>0.05); the injury healed better in transfected PMSCs and BMSCs than in untransfected PMSCs and BMSCs (P<0.05).

Conclusions

MSCs have similar biology characteristics and capacity for SCI repair to BMSCs and can be used as a new resource for treating SCI.

Chronic administration of [Pyr1] apelin-13 attenuates neuropathic pain after compression spinal cord injury in rats

Apelin is an endogenous ligand for apelin receptor (APJ) with analgesic effect on visceral, analgesic and proanalgesic influences on acute pains in animal models. The purpose of this study was to determine the possible analgesic effects of [Pyr¹] apelin-13 on chronic pain after spinal cord injury (SCI) in rats. Animals were randomly divided into three major groups as intact, sham and SCI. The SCI group randomly allocated to four subgroups as no treatment, vehicle-treatment (normal saline: 10μl, intrathecally) and two subgroups with intrathecal injection (i.t) of 1μg and 5μg of [Pyr¹] apelin-13. After laminectomy at T6-T8 level, spinal cord compression injury was induced using an aneurysm clip. Vehicle or [Pyr¹] apelin-13 injected from day1 post SCI and continued for a week on a daily basis. Pain behaviors and locomotor activity were monitored up to 8weeks. At the end of the experiments, intracardial paraformaldehyde perfusion was made under deep anesthesia in some animals for histological and immunohistochemistry evaluations. Western blot technique was also done to detect caspase-3 in fresh spinal cord tissues. SCI decreased nociceptive thresholds and locomotor scores. Administration of [Pyr¹] apelin-13 (1μg and 5μg) improved locomotor activity and reduced pain symptoms, cavity size and caspase-3 levels. Results showed long-term beneficial effects of [Pyr¹] apelin-13 on neuropathic pain and locomotion. Therefore, we may suggest [Pyr¹] apelin-13 as a new option for further neuropathic pain research and a suitable candidate for ensuing clinical trials in spinal cord injury arena.

Animal models of spinal cord injury: a systematic review

STUDY DESIGN

PRISMA-guided systematic review.

OBJECTIVES

To provide a comprehensive framework of the current animal models for investigating spinal cord injury (SCI) and categorize them based on the aims, patterns and levels of injury, and outcome measurements as well as animal species.

SETTING

Sina Trauma and Surgery Research Center, Tehran University of Medical Sciences, Tehran, Iran.

METHODS

An electronic search of the Medline database for literature describing animal models of SCI was performed on 1 January 2016 using the following keywords: 'spinal cord injuries' and 'animal models'. The search retrieved 2870 articles. Reviews and non-original articles were excluded. Data extraction was independently performed by two reviewers.

RESULTS

Among the 2209 included studies, testing the effects of drug's or growth factor's interventions was the most common aim (36.6%) followed by surveying pathophysiologic changes (30.2%). The most common spinal region involved was thoracic (81%). Contusion was the most common pattern of injury (41%) followed by transection (32.5%) and compression (19.4%). The most common species involved in animal models of SCI was the rat (72.4%). Two or more types of outcome assessments were used in the majority of the studies, and the most common assessment method was biological plus behavioral (50.8%).

CONCLUSIONS

Prior to choosing an animal model, the objectives of the proposed study must precisely be defined. Contusion and compression models better simulate the biomechanics and neuropathology of human injury, whereas transection models are valuable to study anatomic regeneration. Rodents are the most common and probably best-suited species for preliminary SCI studies.

Expression of fibrosis-related molecules in the oral mucosa of six animal species: A reference for selecting animal models

Several animal models have been used in studies associated with oral submucous fibrosis (OSF); however, an appropriate model based on the histopathological characteristics of OSF is still needed. This study aimed to provide histological references for selecting a potential model. The expression intensities of collagen type I (Col I), type III (Col III), type IV (Col IV), fibronectin (FN), transforming growth factors β (TGF-β), and connective tissue growth factor (CCN2) in the oral mucosa of the human and six non-human animal species were measured by immunohistochemistry. There was little variation in the expression intensity of Col I while the expression of Col III, Col IV, and FN showed differences. The expression intensities of TGF-β in dog, rat, sheep, and pig oral mucosae, and those of CCN2 in dog, minipig, rat, and buffalo oral mucosae were equivalent to the expression intensities in human mucosa. The expression of fibrosis-related molecules in the dog oral mucosa optimally mimics the human condition, suggesting its suitability with regard to histopathology as an animal model for the study of OSF.

Neural stem cell transplantation combined with erythropoietin for the treatment of spinal cord injury in rats

Spinal cord injury (SCI) comprises nerve and motor function disorders that may be caused by a variety of damaging factors and is challenging to treat. The aim of the present study was to investigate the regenerative effects of neural stem cell (NSC) transplantation combined with intraperitoneal injection of erythropoietin (EPO) on cross-sectional SCI in rats. A model of SCI was induced in 40 adult Wistar rats via the complete transection of the 10th thoracic vertebra (T10). The rats were allocated at random into 4 groups: Control, NSC, EPO and NSC + EPO groups (n=10 per group). Morphological alterations associated with axonal regeneration were detected using neurofilament (NF)-200 immunohistochemistry and immunofluorescence staining after 8 weeks. Basso, Beattie and Bresnahan (BBB) scoring was used to evaluate the recovery of hindlimb function. A total of 5 rats died following surgery, including 2 control rats and 1 rat each in the EPO, NSC and NSC + EPO groups. NSCs labeled with bromodeoxyuridine were observed to have survived and migrated in the spinal cord tissue after 8 weeks. Significant histomorphological differences were observed in the NSC and NSC + EPO groups compared with the EPO and control groups. Furthermore, the rats of the NSC + EPO group exhibited significantly enhanced axonal regeneration in the SCI area compared with the NSC group rats. The rats of the NSC and NSC + EPO groups exhibited significantly improved BBB scores compared with the EPO and control group rats at 7 days after treatment (P<0.05). In addition, the BBB scores of the NSC + EPO group were significantly improved compared with those of the three other groups at 7 days after surgery (P<0.05). Therefore, the results of the present study suggest that NSC transplantation combined with intraperitoneal injection of EPO may benefit the survival and regeneration of injured axons, and accelerate the repair of injured spinal cord tissue, thus facilitating the functional recovery of hindlimb locomotor function in rats.

Co-effects of matrix low elasticity and aligned topography on stem cell neurogenic differentiation and rapid neurite outgrowth

The development of novel biomaterials that deliver precise regulatory signals to direct stem cell fate for nerve regeneration is the focus of current intensive research efforts. In this study, a hierarchically aligned fibrillar fibrin hydrogel (AFG) that was fabricated through electrospinning and the concurrent molecular self-assembly process mimics both the soft and oriented features of nerve tissue, thus providing hybrid biophysical cues to instruct cell behavior in vitro and in vivo. The electrospun hydrogels were examined by scanning electron microscopy (SEM), polarized light microscopy, small angle X-ray scattering assay and atomic force microscopy (AFM), showing a hierarchically linear-ordered structure from the nanoscale to the macroscale with a soft elastic character (elasticity ∼1 kPa). We found that this low elasticity and aligned topography of AFG exhibit co-effects on promoting the neurogenic differentiation of human umbilical cord mesenchymal stem cells (hUMSCs) in comparison to random fibrin hydrogel (RFG) and tissue culture plate (TCP) control after two week cell culture in growth medium lacking supplementation with soluble neurogenic induction factors. In addition, AFG also induces dorsal root ganglion (DRG) neurons to rapidly project numerous long neurite outgrowths longitudinally along the AFG fibers for a total neurite extension distance of 1.96 mm in three days in the absence of neurotrophic factor supplementation. Moreover, the AFG implanted in a rat T9 dorsal hemisection spinal cord injury model was found to promote endogenous neural cell fast migration and axonal invasion along AFG fibers, resulting in aligned tissue cables in vivo. Our results suggest that matrix stiffness and aligned topography may instruct stem cell neurogenic differentiation and rapid neurite outgrowth, providing great promise for biomaterial design for applications in nerve regeneration.

Comparative assessment of phototherapy protocols for reduction of oxidative stress in partially transected spinal cord slices undergoing secondary degeneration

BACKGROUND

Red/near-infrared light therapy (R/NIR-LT) has been developed as a treatment for a range of conditions, including injury to the central nervous system (CNS). However, clinical trials have reported variable or sub-optimal outcomes, possibly because there are few optimized treatment protocols for the different target tissues. Moreover, the low absolute, and wavelength dependent, transmission of light by tissues overlying the target site make accurate dosing problematic.

RESULTS

In order to optimize light therapy treatment parameters, we adapted a mouse spinal cord organotypic culture model to the rat, and characterized myelination and oxidative stress following a partial transection injury. The ex vivo model allows a more accurate assessment of the relative effect of different illumination wavelengths (adjusted for equal quantal intensity) on the target tissue. Using this model, we assessed oxidative stress following treatment with four different wavelengths of light: 450 nm (blue); 510 nm (green); 660 nm (red) or 860 nm (infrared) at three different intensities: 1.93 × 10(16) (low); 3.85 × 10(16) (intermediate) and 7.70 × 10(16) (high) photons/cm(2)/s. We demonstrate that the most effective of the tested wavelengths to reduce immunoreactivity of the oxidative stress indicator 3-nitrotyrosine (3NT) was 660 nm. 860 nm also provided beneficial effects at all tested intensities, significantly reducing oxidative stress levels relative to control (p ≤ 0.05).

CONCLUSIONS

Our results indicate that R/NIR-LT is an effective antioxidant therapy, and indicate that effective wavelengths and ranges of intensities of treatment can be adapted for a variety of CNS injuries and conditions, depending upon the transmission properties of the tissue to be treated.

Oct4-induced oligodendrocyte progenitor cells enhance functional recovery in spinal cord injury model

The generation of patient-specific oligodendrocyte progenitor cells (OPCs) holds great potential as an expandable cell source for cell replacement therapy as well as drug screening in spinal cord injury or demyelinating diseases. Here, we demonstrate that induced OPCs (iOPCs) can be directly derived from adult mouse fibroblasts by Oct4-mediated direct reprogramming, using anchorage-independent growth to ensure high purity. Homogeneous iOPCs exhibit typical small-bipolar morphology, maintain their self-renewal capacity and OPC marker expression for more than 31 passages, share high similarity in the global gene expression profile to wild-type OPCs, and give rise to mature oligodendrocytes and astrocytes in vitro and in vivo. Notably, transplanted iOPCs contribute to functional recovery in a spinal cord injury (SCI) model without tumor formation. This study provides a simple strategy to generate functional self-renewing iOPCs and yields insights for the in-depth study of demyelination and regenerative medicine.

Relevant Anatomic and Morphological Measurements of the Rat Spine: Considerations for Rodent Models of Human Spine Trauma

STUDY DESIGN

Basic science study measuring anatomical features of the cervical and lumbar spine in rat with normalized comparison with the human.

OBJECTIVE

The goal of this study is to comprehensively compare the rat and human cervical and lumbar spines to investigate whether the rat is an appropriate model for spine biomechanics investigations.

SUMMARY OF BACKGROUND DATA

Animal models have been used for a long time to investigate the effects of trauma, degenerative changes, and mechanical loading on the structure and function of the spine. Comparative studies have reported some mechanical properties and/or anatomical dimensions of the spine to be similar between various species. However, those studies are largely limited to the lumbar spine, and a comprehensive comparison of the rat and human spines is lacking.

METHODS

Spines were harvested from male Holtzman rats (n = 5) and were scanned using micro- computed tomography and digitally rendered in 3 dimensions to quantify the spinal bony anatomy, including the lateral width and anteroposterior depth of the vertebra, vertebral body, and spinal canal, as well as the vertebral body and intervertebral disc heights. Normalized measurements of the vertebra, vertebral body, and spinal canal of the rat were computed and compared with corresponding measurements from the literature for the human in the cervical and lumbar spinal regions.

RESULTS

The vertebral dimensions of the rat spine vary more between spinal levels than in humans. Rat vertebrae are more slender than human vertebrae, but the width-to-depth axial aspect ratios are very similar in both species in both the cervical and lumbar regions, especially for the spinal canal.

CONCLUSION

The similar spinal morphology in the axial plane between rats and humans supports using the rat spine as an appropriate surrogate for modeling axial and shear loading of the human spine.

Clinical Trials With Mesenchymal Stem Cells: An Update

In the last year, the promising features of mesenchymal stem cells (MSCs), including their regenerative properties and ability to differentiate into diverse cell lineages, have generated great interest among researchers whose work has offered intriguing perspectives on cell-based therapies for various diseases. Currently the most commonly used adult stem cells in regenerative medicine, MSCs, can be isolated from several tissues, exhibit a strong capacity for replication in vitro, and can differentiate into osteoblasts, chondrocytes, and adipocytes. However, heterogeneous procedures for isolating and cultivating MSCs among laboratories have prompted the International Society for Cellular Therapy (ISCT) to issue criteria for identifying unique populations of these cells. Consequently, the isolation of MSCs according to ISCT criteria has produced heterogeneous, nonclonal cultures of stromal cells containing stem cells with different multipotent properties, committed progenitors, and differentiated cells. Though the nature and functions of MSCs remain unclear, nonclonal stromal cultures obtained from bone marrow and other tissues currently serve as sources of putative MSCs for therapeutic purposes, and several findings underscore their effectiveness in treating different diseases. To date, 493 MSC-based clinical trials, either complete or ongoing, appear in the database of the US National Institutes of Health. In the present article, we provide a comprehensive review of MSC-based clinical trials conducted worldwide that scrutinizes biological properties of MSCs, elucidates recent clinical findings and clinical trial phases of investigation, highlights therapeutic effects of MSCs, and identifies principal criticisms of the use of these cells. In particular, we analyze clinical trials using MSCs for representative diseases, including hematological disease, graft-versus-host disease, organ transplantation, diabetes, inflammatory diseases, and diseases in the liver, kidney, and lung, as well as cardiovascular, bone and cartilage, neurological, and autoimmune diseases.

Organotypic Spinal Cord Culture: a Proper Platform for the Functional Screening

Recent improvements in organotypic slice culturing and its accompanying technological innovations have made this biological preparation increasingly useful ex vivo experimental model. Among organotypic slice cultures obtained from various central nervous regions, spinal cord slice culture is an absorbing model that represents several unique advantages over other current in vitro and in vivo models. The culture of developing spinal cord slices, as allows real-time observation of embryonic cells behaviors, is an instrumental platform for developmental investigation. Importantly, due to the ability of ex vivo models to recapitulate different aspects of corresponding in vivo conditions, these models have been subject of various manipulations to derive disease-relevant slice models. Moreover spinal cord slice cultures represent a potential platform for screening of different pharmacological agents and evaluation of cell transplantation and neuroregenerative materials. In this review, we will focus on studies carried out using the ex vivo model of spinal cord slice cultures and main advantages linked to practicality of these slices in both normal and neuropathological diseases and summarize them in different categories based on application.