An improved method for generating human spinal cord neural stem cells.

Neural stem cells have exhibited efficacy in pre-clinical models of spinal cord injury (SCI) and are on a translational path to human testing. We recently reported that neural stem cells must be driven to a spinal cord fate to optimize host axonal regeneration into sites of implantation in the injured spinal cord, where they subsequently form neural relays across the lesion that support significant functional improvement. We also reported methods of deriving and culturing human spinal cord neural stem cells derived from embryonic stem cells that can be sustained over serial high passage numbers in vitro, providing a potentially optimized cell source for human clinical trials.

Alginate hydrogel cross-linked by Ca to promote spinal cord neural stem/progenitor cell differentiation and functional recovery after a spinal cord injuryhh.

Alginate capillary hydrogels seeded with differentiated cells can fill the lesion cavity and promote axonal regeneration after grafting into the injured spinal cord. Neural stem/progenitor cells (NSPCs) can potentially repair the spinal cord; however, effects of alginate hydrogels (AHs) on NSPCs remain unknown. In this study, we fabricated AHs cross-linked by Ca and seeded hydrogels with rat embryonic day 14 NSPCs.

Neural Stem Cells: Promoting Axonal Regeneration and Spinal Cord Connectivity.

Spinal cord injury (SCI) leads to irreversible functional impairment caused by neuronal loss and the disruption of neuronal connections across the injury site. While several experimental strategies have been used to minimize tissue damage and to enhance axonal growth and regeneration, the corticospinal projection, which is the most important voluntary motor system in humans, remains largely refractory to regenerative therapeutic interventions. To date, one of the most promising pre-clinical therapeutic strategies has been neural stem cell (NSC) therapy for SCI.

Anisotropic Alginate Hydrogels Promote Axonal Growth across Chronic Spinal Cord Transections after Scar Removal.

We have previously reported that cell-seeded alginate hydrogels (AHs) with anisotropic capillaries can restore the continuity of the spinal cord and support axonal regeneration in a rat model of acute partial spinal cord transection. Whether similar effects can be found after transplantation into sites of complete chronic spinal cord transections without additional growth-promoting stimuli has not been investigated. We therefore implanted AHs into the cavity of a chronic thoracic transection following scar resection (SR) 4 weeks postinjury and examined electrophysiological and functional recovery as well as regeneration of descending and ascending projections within and beyond the AH scaffold up to 3 months after engraftment.

Peptides and Astroglia Improve the Regenerative Capacity of Alginate Gels in the Injured Spinal Cord.

Axonal bridging across a lesion in the injured spinal cord requires a growth substrate and guidance cues. Using alginate hydrogels with capillary channels we show that poly-l-ornithine and laminin can be stably bound and improve cell adhesion and neurite growth , and axon growth by enhancing host cell infiltration in the injured spinal cord. Filling of coated hydrogels with postnatal astrocytes further increases short-distance axon growth and results in a continuous astroglial substrate across the host/graft interface.

Sensorimotor Activity Partially Ameliorates Pain and Reduces Nociceptive Fiber Density in the Chronically Injured Spinal Cord.

A large proportion of patients suffering from spinal cord injury (SCI) develop chronic central neuropathic pain. Previously, we and others have shown that sensorimotor training early after SCI can prevent the development of mechanical allodynia. To determine whether training initiated in the subchronic/chronic phase remains effective, correlates of below-level neuropathic pain were analyzed in the hindpaws 5-10 weeks after a moderate T11 contusion SCI (50 kDyn) in adult female C57BL/6 mice.

Systemic epothilone D improves hindlimb function after spinal cord contusion injury in rats.

Following a spinal cord injury (SCI) a growth aversive environment forms, consisting of a fibroglial scar and inhibitory factors, further restricting the already low intrinsic growth potential of injured adult central nervous system (CNS) neurons. Previous studies have shown that local administration of the microtubule-stabilizing drug paclitaxel or epothilone B (Epo B) reduce fibrotic scar formation and axonal dieback as well as induce axonal growth/sprouting after SCI. Likewise, systemic administration of Epo B promoted functional recovery.

Cortical electrical stimulation in female rats with a cervical spinal cord injury to promote axonal outgrowth.

Electrical stimulation (ES) to promote corticospinal tract (CST) repair after spinal cord injury (SCI) is underinvestigated. This study is the first to detail intracortical ES of the injured CST. We hypothesize that cortical ES will promote CST collateralization and regeneration, prevent dieback, and improve recovery in an SCI rat model.

Depolarization and electrical stimulation enhance in vitro and in vivo sensory axon growth after spinal cord injury.

Activity dependent plasticity is a key mechanism for the central nervous system (CNS) to adapt to its environment. Whether neuronal activity also influences axonal regeneration in the injured CNS, and whether electrical stimulation (ES) can activate regenerative programs in the injured CNS remains incompletely understood. Using KCl-induced depolarization, in vivo ES followed by ex-vivo neurite growth assays and ES after spinal cord lesions and cell grafting, we aimed to identify parameters important for ES-enhanced neurite growth and axonal regeneration.

Enhancing excitatory activity of somatosensory cortex alleviates neuropathic pain through regulating homeostatic plasticity.

Central sensitization and network hyperexcitability of the nociceptive system is a basic mechanism of neuropathic pain. We hypothesize that development of cortical hyperexcitability underlying neuropathic pain may involve homeostatic plasticity in response to lesion-induced somatosensory deprivation and activity loss, and can be controlled by enhancing cortical activity. In a mouse model of neuropathic pain, in vivo two-photon imaging and patch clamp recording showed initial loss and subsequent recovery and enhancement of spontaneous firings of somatosensory cortical pyramidal neurons.

Regulated viral BDNF delivery in combination with Schwann cells promotes axonal regeneration through capillary alginate hydrogels after spinal cord injury.

Unlabelled: Grafting of cell-seeded alginate capillary hydrogels into a spinal cord lesion site provides an axonal bridge while physically directing regenerating axonal growth in a linear pattern. However, without an additional growth stimulus, bridging axons fail to extend into the distal host spinal cord. Here we examined whether a combinatory strategy would support regeneration of descending axons across a cervical (C5) lateral hemisection lesion in the rat spinal cord.

Human ESC-Derived Interneurons Improve Major Consequences of Spinal Cord Injury.

Beyond impaired motor and sensory function, neuropathic pain and loss of bladder control caused by spinal cord injuries (SCIs) can severely affect quality of life. In this issue of Cell Stem Cell, Fandel et al. (2016) show that transplanted human ESC-derived cells biased to produce inhibitory interneurons significantly improve pain and bladder function in rodent SCI models.

A Systems-Level Analysis of the Peripheral Nerve Intrinsic Axonal Growth Program.

The regenerative capacity of the injured CNS in adult mammals is severely limited, yet axons in the peripheral nervous system (PNS) regrow, albeit to a limited extent, after injury. We reasoned that coordinate regulation of gene expression in injured neurons involving multiple pathways was central to PNS regenerative capacity. To provide a framework for revealing pathways involved in PNS axon regrowth after injury, we applied a comprehensive systems biology approach, starting with gene expression profiling of dorsal root ganglia (DRGs) combined with multi-level bioinformatic analyses and experimental validation of network predictions.

Early-onset treadmill training reduces mechanical allodynia and modulates calcitonin gene-related peptide fiber density in lamina III/IV in a mouse model of spinal cord contusion injury.

Below-level central neuropathic pain (CNP) affects a large proportion of spinal cord injured individuals. To better define the dynamic changes of the spinal cord neural network contributing to the development of CNP after spinal cord injury (SCI), we characterized the morphological and behavioral correlates of CNP in female C57BL/6 mice after a moderate T11 contusion SCI (50 kdyn) and the influence of moderate physical activity. Compared with sham-operated animals, injured mice developed mechanical allodynia 2 weeks post injury when tested with small-diameter von Frey hair filaments (0.

Cell-seeded alginate hydrogel scaffolds promote directed linear axonal regeneration in the injured rat spinal cord.

Unlabelled: Despite recent progress in enhancing axonal growth in the injured spinal cord, the guidance of regenerating axons across an extended lesion site remains a major challenge. To determine whether regenerating axons can be guided in rostrocaudal direction, we implanted 2mm long alginate-based anisotropic capillary hydrogels seeded with bone marrow stromal cells (BMSCs) expressing brain-derived neurotrophic factor (BDNF) or green fluorescent protein (GFP) as control into a C5 hemisection lesion of the rat spinal cord. Four weeks post-lesion, numerous BMSCs survived inside the scaffold channels, accompanied by macrophages, Schwann cells and blood vessels.

AngleJ: A new tool for the automated measurement of neurite growth orientation in tissue sections.

Background: Regeneration of axons is one means to restore function after central nervous system and peripheral nervous system injury. Besides increasing the number of regenerating axons, guidance of axons over long distances into and across a lesion site are important determinants for efficient functional restoration. Quantification of axon growth directions is therefore an important measure for the efficacy of neuroregenerative approaches.

Large animal and primate models of spinal cord injury for the testing of novel therapies.

Large animal and primate models of spinal cord injury (SCI) are being increasingly utilized for the testing of novel therapies. While these represent intermediary animal species between rodents and humans and offer the opportunity to pose unique research questions prior to clinical trials, the role that such large animal and primate models should play in the translational pipeline is unclear. In this initiative we engaged members of the SCI research community in a questionnaire and round-table focus group discussion around the use of such models.

Axonal amphoterin mRNA is regulated by translational control and enhances axon outgrowth.

High mobility group (HMG) proteins concentrate in the nucleus, interacting with chromatin. Amphoterin is an HMG protein (HMGB1) that has been shown to have extranuclear functions and can be secreted from some cell types. Exogenous amphoterin can increase neurite growth, suggesting that the secreted protein may have growth promoting activities in neurons.

Limited Functional Effects of Subacute Syngeneic Bone Marrow Stromal Cell Transplantation After Rat Spinal Cord Contusion Injury.

Cell transplantation might be one means to improve motor, sensory, or autonomic recovery after traumatic spinal cord injury (SCI). Among the different cell types evaluated to date, bone marrow stromal cells (BMSCs) have received considerable interest due to their potential neuroprotective properties. However, uncertainty exists whether the efficacy of BMSCs after intraspinal transplantation justifies an invasive procedure.

Axonal regeneration. Systemic administration of epothilone B promotes axon regeneration after spinal cord injury.

After central nervous system (CNS) injury, inhibitory factors in the lesion scar and poor axon growth potential prevent axon regeneration. Microtubule stabilization reduces scarring and promotes axon growth. However, the cellular mechanisms of this dual effect remain unclear.

A radio-telemetric system to monitor cardiovascular function in rats with spinal cord transection and embryonic neural stem cell grafts.

High thoracic or cervical spinal cord injury (SCI) can lead to cardiovascular dysfunction. To monitor cardiovascular parameters, we implanted a catheter connected to a radio transmitter into the femoral artery of rats that underwent a T4 spinal cord transection with or without grafting of embryonic brainstem-derived neural stem cells expressing green fluorescent protein. Compared to other methods such as cannula insertion or tail-cuff, telemetry is advantageous to continuously monitor blood pressure and heart rate in freely moving animals.

Neural stem cells in models of spinal cord injury.

Replication of published studies is an important and respected aspect of the conduct of science. Most would argue that the interpretation of "negative" outcomes is still more challenging than the interpretation of "positive" findings, however, due to uncertainty in knowing precisely why a hypothesized outcome was not observed: in particular, are "negative" findings in replication studies a result of invalidity of the original experimental hypothesis, or due to a methodological failure, insensitivity of the applied instruments of analysis, or other factors? These points must be carefully considered. Steward and colleagues report findings of a study in which multipotent neural progenitor cells were grafted to sites of T3 complete transection.

Thoracic rat spinal cord contusion injury induces remote spinal gliogenesis but not neurogenesis or gliogenesis in the brain.

After spinal cord injury, transected axons fail to regenerate, yet significant, spontaneous functional improvement can be observed over time. Distinct central nervous system regions retain the capacity to generate new neurons and glia from an endogenous pool of progenitor cells and to compensate neural cell loss following certain lesions. The aim of the present study was to investigate whether endogenous cell replacement (neurogenesis or gliogenesis) in the brain (subventricular zone, SVZ; corpus callosum, CC; hippocampus, HC; and motor cortex, MC) or cervical spinal cord might represent a structural correlate for spontaneous locomotor recovery after a thoracic spinal cord injury.