Mesenchymal Stem Cells Combined With Electroacupuncture Treatment Regulate the Subpopulation of Macrophages and Astrocytes to Facilitate Axonal Regeneration in Transected Spinal Cord

OBJECTIVE

Herein, we investigated whether mesenchymal stem cells (MSCs) transplantation combined with electroacupuncture (EA) treatment could decrease the proportion of proinflammatory microglia/macrophages and neurotoxic A1 reactive astrocytes and inhibit glial scar formation to enhance axonal regeneration after spinal cord injury (SCI).

METHODS

Adult rats were divided into 5 groups after complete transection of the spinal cord at the T10 level: a control group, a nonacupoint EA (NA-EA) group, an EA group, an MSC group, and an MSCs+EA group. Immunofluorescence labeling, quantitative real-time polymerase chain reaction, enzyme-linked immunosorbent assay, and Western blots were performed.

RESULTS

The results showed that MSCs+EA treatment reduced the proportion of proinflammatory M1 subtype microglia/macrophages, but increased the differentiation of anti-inflammatory M2 phenotype cells, thereby suppressing the mRNA and protein expression of proinflammatory cytokines (tumor necrosis factor-α and IL-1β) and increasing the expression of an anti-inflammatory cytokine (interleukin [IL]-10) on days 7 and 14 after SCI. The changes in expression correlated with the attenuated neurotoxic A1 reactive astrocytes and glial scar, which in turn facilitated the axonal regeneration of the injured spinal cord. In vitro, the proinflammatory cytokines increased the level of proliferation of astrocytes and increased the expression levels of C3, glial fibrillary acidic protein, and chondroitin sulfate proteoglycan. These effects were blocked by administering inhibitors of ErbB1 and signal transducer and activator of transcription 3 (STAT3) (AG1478 and AG490) and IL-10.

CONCLUSION

These findings showed that MSCs+EA treatment synergistically regulated the microglia/macrophage subpopulation to reduce inflammation, the formation of neurotoxic A1 astrocytes, and glial scars. This was achieved by downregulating the ErbB1-STAT3 signal pathway, thereby providing a favorable microenvironment conducive to axonal regeneration after SCI.

A biocompatible gelatin sponge scaffold confers robust tissue remodeling after spinal cord injury in a non-human primate model

We previously constructed a three-dimensional gelatin sponge (3D-GS) scaffold as a delivery vehicle for therapeutic cells and trophic factors in the treatment of spinal cord injury (SCI), and this study aimed to assess the biosafety and efficacy of the scaffold in a non-human primate SCI model. However, because it has only been tested in rodent and canine models, the biosafety and efficacy of the scaffold should ideally be assessed in a non-human primate SCI model before its use in the clinic. No adverse reactions were observed over 8 weeks following 3D-GS scaffold implantation into in a Macaca fascicularis with hemisected SCI. Scaffold implantation also did not add to neuroinflammatory or astroglial responses already present at the injured site, suggesting good biocompatibility. Notably, there was a significant reduction in α-smooth muscle actin (αSMA)-positive cells at the injury/implantation interface, leading to alleviation of fibrotic compression of the residual spinal cord tissue. The regenerating tissue in the scaffold showed numerous cells migrating into the implant secreting abundant extracellular matrix, resulting in a pro-regenerative microenvironment. Consequently, nerve fiber regeneration, myelination, vascularization, neurogenesis, and electrophysiological improvements were achieved. These results indicated that the 3D-GS scaffold had good histocompatibility and effectiveness in the structural repair of injured spinal cord tissue in a non-human primate and is suitable for use in the treatment of patients with SCI.

The therapeutic mechanism of transcranial iTBS on nerve regeneration and functional recovery in rats with complete spinal cord transection

Background

After spinal cord transection injury, the inflammatory microenvironment formed at the injury site, and the cascade of effects generated by secondary injury, results in limited regeneration of injured axons and the apoptosis of neurons in the sensorimotor cortex (SMC). It is crucial to reverse these adverse processes for the recovery of voluntary movement. The mechanism of transcranial intermittent theta-burst stimulation (iTBS) as a new non-invasive neural regulation paradigm in promoting axonal regeneration and motor function repair was explored by means of a severe spinal cord transection.

Methods

Rats underwent spinal cord transection and 2 mm resection of spinal cord at T10 level. Four groups were studied: Normal (no lesion), Control (lesion with no treatment), sham iTBS (lesion and no functional treatment) and experimental, exposed to transcranial iTBS, 72 h after spinal lesion. Each rat received treatment once a day for 5 days a week; behavioral tests were administered one a week. Inflammation, neuronal apoptosis, neuroprotective effects, regeneration and synaptic plasticity after spinal cord injury (SCI) were determined by immunofluorescence staining, western blotting and mRNA sequencing. For each rat, anterograde tracings were acquired from the SMC or the long descending propriospinal neurons and tested for cortical motor evoked potentials (CMEPs). Regeneration of the corticospinal tract (CST) and 5-hydroxytryptamine (5-HT) nerve fibers were analyzed 10 weeks after SCI.

Results

When compared to the Control group, the iTBS group showed a reduced inflammatory response and reduced levels of neuronal apoptosis in the SMC when tested 2 weeks after treatment. Four weeks after SCI, the neuroimmune microenvironment at the injury site had improved in the iTBS group, and neuroprotective effects were evident, including the promotion of axonal regeneration and synaptic plasticity. After 8 weeks of iTBS treatment, there was a significant increase in CST regeneration in the region rostral to the site of injury. Furthermore, there was a significant increase in the number of 5-HT nerve fibers at the center of the injury site and the long descending propriospinal tract (LDPT) fibers in the region caudal to the site of injury. Moreover, CMEPs and hindlimb motor function were significantly improved.

Conclusion

Neuronal activation and neural tracing further verified that iTBS had the potential to provide neuroprotective effects during the early stages of SCI and induce regeneration effects related to the descending motor pathways (CST, 5-HT and LDPT). Furthermore, our results revealed key relationships between neural pathway activation, neuroimmune regulation, neuroprotection and axonal regeneration, as well as the interaction network of key genes.

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

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

Transcription Profiling of a Revealed the Potential Molecular Mechanism of Governor Vessel Electroacupuncture for Spinal Cord Injury in Rats

OBJECTIVE

This study aimed to identify differentially expressed genes (DEGs) by transcriptome analysis to elucidate a potential mechanism by which governor vessel electroacupuncture (GV-EA) promotes neuronal survival, axonal regeneration, and functional recovery after complete transection spinal cord injury (SCI).

METHODS

Sham, control, or GV-EA group adult female Sprague Dawley rats underwent a complete transection SCI protocol. SCI area RNA-seq investigated the DEGs of coding and noncoding RNAs 7 days post-SCI. Gene ontology (GO) and kyoto encyclopedia of genes and genomes (KEGG) enrichment analyses were used to classify DEGs functions, to explain a possible molecular mechanism. Immunofluorescence and BBB (Basso, Beattie, and Bresnahan) score were used to verify a GV-EA treatment effect following SCI.

RESULTS

GV-EA treatment could regulate the expression of 173 mRNA, 260 lncRNA, and 153 circRNA genes among these DEGs resulted by SCI. GO enrichment analysis showed that the DEGs were most enriched in membrane, actin binding, and regulation of Toll-like receptor signaling pathway. KEGG pathway analysis showed enriched pathways (e.g. , Toll-like receptors, MAPK, Hippo signaling). According to the ceRNA network, miR-144-3p played a regulatory role by interacting with lncRNA and circRNA. GV-EA also promoted the injured spinal cord neuron survival, axonal regeneration, and functional improvement of hind limb locomotion.

CONCLUSION

Results of our RNA-seq suggest that post-SCI GV-EA may regulate characteristic changes in transcriptome gene expression, potential critical genes, and signaling pathways, providing clear directions for further investigation into the mechanism of GV-EA in subacute SCI treatment. Moreover, we found that GV-EA promotes neuronal survival, nerve fiber extension, and motor function recovery in subacute SCI.

Electro-acupuncture and its combination with adult stem cell transplantation for spinal cord injury treatment: A summary of current laboratory findings and a review of literature

The incidence and disability rate of spinal cord injury (SCI) worldwide are high, imposing a heavy burden on patients. Considerable research efforts have been directed toward identifying new strategies to effectively treat SCI. Governor Vessel electro‐acupuncture (GV‐EA), used in traditional Chinese medicine, combines acupuncture with modern electrical stimulation. It has been shown to improve the microenvironment of injured spinal cord (SC) by increasing levels of endogenous neurotrophic factors and reducing inflammation, thereby protecting injured neurons and promoting myelination. In addition, axons extending from transplanted stem cell‐derived neurons can potentially bridge the two severed ends of tissues in a transected SC to rebuild neuronal circuits and restore motor and sensory functions. However, every single treatment approach to severe SCI has proven unsatisfactory. Combining different treatments—for example, electro‐acupuncture (EA) with adult stem cell transplantation—appears to be a more promising strategy. In this review, we have summarized the recent progress over the past two decades by our team especially in the use of GV‐EA for the repair of SCI. By this strategy, we have shown that EA can stimulate the nerve endings of the meningeal branch. This would elicit the dorsal root ganglion neurons to secrete excess amounts of calcitonin gene‐related peptide centrally in the SC. The neuropeptide then activates the local cells to secrete neurotrophin‐3 (NT‐3), which mediates the survival and differentiation of donor stem cells overexpressing the NT‐3 receptor, at the injury/graft site of the SC. Increased local production of NT‐3 facilitates reconstruction of host neural tissue such as nerve fiber regeneration and myelination. All this events in sequence would ultimately strengthen the cortical motor‐evoked potentials and restore the motor function of paralyzed limbs. The information presented herein provides a basis for future studies on the clinical application of GV‐EA and adult stem cell transplantation for the treatment of SCI.

Construction of a niche-specific spinal white matter-like tissue to promote directional axon regeneration and myelination for rat spinal cord injury repair

Directional axon regeneration and remyelination are crucial for repair of spinal cord injury (SCI), but existing treatments do not effectively promote those processes. Here, we propose a strategy for construction of niche-specific spinal white matter-like tissue (WMLT) using decellularized optic nerve (DON) loaded with neurotrophin-3 (NT-3)-overexpressing oligodendrocyte precursor cells. A rat model with a white matter defect in the dorsal spinal cord of the T10 segment was used. The WMLT transplantation group showed significant improvement in coordinated motor functions compared with the control groups. WMLT transplants integrated well with host spinal cord white matter, effectively addressing several barriers to directional axonal regeneration and myelination during SCI repair. In WMLT, laminin was found to promote development of oligodendroglial lineage (OL) cells by binding to laminin receptors. Interestingly, laminin could also guide linear axon regeneration via interactions with specific integrins on the axon surface. The WMLT developed here utilizes the unique microstructure and bioactive matrix of DON to create a niche rich in laminin, NT-3 and OL cells to achieve significant structural repair of SCI. Our protocol can help to promote research on repair of nerve injury and construction of neural tissues and organoids that form specific cell niches.

Developing a mechanically matched decellularized spinal cord scaffold for the in situ matrix-based neural repair of spinal cord injury

Tissue engineering is a promising strategy to repair spinal cord injury (SCI). However, a bioscaffold with mechanical properties that match those of the pathological spinal cord tissue and a pro-regenerative matrix that allows robust neurogenesis for overcoming post-SCI scar formation has yet to be developed. Here, we report that a mechanically enhanced decellularized spinal cord (DSC) scaffold with a thin poly (lactic-co-glycolic acid) (PLGA) outer shell may fulfill the requirements for effective in situ neuroengineering after SCI. Using chemical extraction and electrospinning methods, we successfully constructed PLGA thin shell-ensheathed DSC scaffolds (PLGA-DSC scaffolds) in a way that removed major inhibitory components while preserving the permissive matrix. The DSCs exhibited good cytocompatibility with neural stem cells (NSCs) and significantly enhanced their differentiation toward neurons in vitro. Due to the mechanical reinforcement, the implanted PLGA-DSC scaffolds showed markedly increased resilience to infiltration by myofibroblasts and the deposition of dense collagen matrix, thereby creating a neurogenic niche favorable for the targeted migration, residence and neuronal differentiation of endogenous NSCs after SCI. Furthermore, PLGA-DSC presented a mild immunogenic property but prominent ability to polarize macrophages from the M1 phenotype to the M2 phenotype, leading to significant tissue regeneration and functional restoration after SCI. Taken together, the results demonstrate that the mechanically matched PLGA-DSC scaffolds show promise for effective tissue repair after SCI.

Stem cell-derived neuronal relay strategies and functional electrical stimulation for treatment of spinal cord injury

The inability of adult mammals to recover function lost after severe spinal cord injury (SCI) has been known for millennia and is mainly attributed to a failure of brain-derived nerve fiber regeneration across the lesion. Potential approaches to re-establishing locomotor function rely on neuronal relays to reconnect the segregated neural networks of the spinal cord. Intense research over the past 30 years has focused on endogenous and exogenous neuronal relays, but progress has been slow and the results often controversial. Treatments with stem cell-derived neuronal relays alone or together with functional electrical stimulation offer the possibility of improved repair of neuronal networks. In this review, we focus on approaches to recovery of motor function in paralyzed patients after severe SCI based on novel therapies such as implantation of stem cell-derived neuronal relays and functional electrical stimulation. Recent research progress offers hope that SCI patients will one day be able to recover motor function and sensory perception.

An NT-3-releasing bioscaffold supports the formation of TrkC-modified neural stem cell-derived neural network tissue with efficacy in repairing spinal cord injury

The mechanism underlying neurogenesis during embryonic spinal cord development involves a specific ligand/receptor interaction, which may be help guide neuroengineering to boost stem cell-based neural regeneration for the structural and functional repair of spinal cord injury. Herein, we hypothesized that supplying spinal cord defects with an exogenous neural network in the NT-3/fibroin-coated gelatin sponge (NF-GS) scaffold might improve tissue repair efficacy. To test this, we engineered tropomyosin receptor kinase C (TrkC)-modified neural stem cell (NSC)-derived neural network tissue with robust viability within an NF-GS scaffold. When NSCs were genetically modified to overexpress TrkC, the NT-3 receptor, a functional neuronal population dominated the neural network tissue. The pro-regenerative niche allowed the long-term survival and phenotypic maintenance of the donor neural network tissue for up to 8 weeks in the injured spinal cord. Additionally, host nerve fibers regenerated into the graft, making synaptic connections with the donor neurons. Accordingly, motor function recovery was significantly improved in rats with spinal cord injury (SCI) that received TrkC-modified NSC-derived neural network tissue transplantation. Together, the results suggested that transplantation of the neural network tissue formed in the 3D bioactive scaffold may represent a valuable approach to study and develop therapies for SCI.

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A NT-3 sustained-release scaffold confers a microenvironment partially simulating the developmental spinal cord.

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The NT-3 microenvironment boosts neuronal differentiation of TrkC-modified NSCs by interactions between ligand and receptor.

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TrkC-NSCs is self-organized into a neural network tissue with typical neural excitability in 3D bioactive scaffold in vitro.

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The grafted neural network tissue can survive and maintain neural property, and improve motor function of paralyzed rats.

Electroacupuncture facilitates the integration of a grafted TrkC-modified mesenchymal stem cell-derived neural network into transected spinal cord in rats via increasing neurotrophin-3

Aims

This study was aimed to investigate whether electroacupuncture (EA) would increase the secretion of neurotrophin‐3 (NT‐3) from injured spinal cord tissue, and, if so, whether the increased NT‐3 would promote the survival, differentiation, and migration of grafted tyrosine kinase C (TrkC)‐modified mesenchymal stem cell (MSC)‐derived neural network cells. We next sought to determine if the latter would integrate with the host spinal cord neural circuit to improve the neurological function of injured spinal cord.

Methods

After NT‐3‐modified Schwann cells (SCs) and TrkC‐modified MSCs were co‐cultured in a gelatin sponge scaffold for 14 days, the MSCs differentiated into neuron‐like cells that formed a MSC‐derived neural network (MN) implant. On this basis, we combined the MN implantation with EA in a rat model of spinal cord injury (SCI) and performed immunohistochemical staining, neural tracing, electrophysiology, and behavioral testing after 8 weeks.

Results

Electroacupuncture application enhanced the production of endogenous NT‐3 in damaged spinal cord tissues. The increase in local NT‐3 production promoted the survival, migration, and maintenance of the grafted MN, which expressed NT‐3 high‐affinity TrkC. The combination of MN implantation and EA application improved cortical motor‐evoked potential relay and facilitated the locomotor performance of the paralyzed hindlimb compared with those of controls. These results suggest that the MN was better integrated into the host spinal cord neural network after EA treatment compared with control treatment.

Conclusions

Electroacupuncture as an adjuvant therapy for TrkC‐modified MSC‐derived MN, acted by increasing the local production of NT‐3, which accelerated neural network reconstruction and restoration of spinal cord function following SCI.

Decellularized optic nerve functional scaffold transplant facilitates directional axon regeneration and remyelination in the injured white matter of the rat spinal cord

Axon regeneration and remyelination of the damaged region is the most common repair strategy for spinal cord injury. However, achieving good outcome remains difficult. Our previous study showed that porcine decellularized optic nerve better mimics the extracellular matrix of the embryonic porcine optic nerve and promotes the directional growth of dorsal root ganglion neurites. However, it has not been reported whether this material promotes axonal regeneration in vivo. In the present study, a porcine decellularized optic nerve was seeded with neurotrophin-3-overexpressing Schwann cells. This functional scaffold promoted the directional growth and remyelination of regenerating axons. In vitro, the porcine decellularized optic nerve contained many straight, longitudinal channels with a uniform distribution, and microscopic pores were present in the channel wall. The spatial micro topological structure and extracellular matrix were conducive to the adhesion, survival and migration of neural stem cells. The scaffold promoted the directional growth of dorsal root ganglion neurites, and showed strong potential for myelin regeneration. Furthermore, we transplanted the porcine decellularized optic nerve containing neurotrophin-3-overexpressing Schwann cells in a rat model of T10 spinal cord defect in vivo. Four weeks later, the regenerating axons grew straight, the myelin sheath in the injured/transplanted area recovered its structure, and simultaneously, the number of inflammatory cells and the expression of chondroitin sulfate proteoglycans were reduced. Together, these findings suggest that porcine decellularized optic nerve loaded with Schwann cells overexpressing neurotrophin-3 promotes the directional growth of regenerating spinal cord axons as well as myelin regeneration. All procedures involving animals were conducted in accordance with the ethical standards of the Institutional Animal Care and Use Committee of Sun Yat-sen University (approval No. SYSU-IACUC-2019-B034) on February 28, 2019.

Governor Vessel Electro-Acupuncture Promotes the Intrinsic Growth Ability of Spinal Neurons through Activating Calcitonin Gene-Related Peptide/α-Calcium/Calmodulin-Dependent Protein Kinase/Neurotrophin-3 Pathway after Spinal Cord Injury

Spinal cord injury (SCI) invariably results in neuronal death and failure of axonal regeneration. This is attributed mainly to the hostile microenvironment and the poor intrinsic regrowth capacity of the injured spinal neurons. We have reported previously that electro-acupuncture on Governor Vessel acupoints (GV-EA) can promote neuronal survival and axonal regeneration of injured spinal cord. However, the underlying mechanism for this has remained uncertain. The present study aimed to explore the neural afferent pathway of GV-EA stimulation and the possible mechanism by which GV-EA can activate the intrinsic growth ability of injured spinal neurons. By cholera toxin B (CTB) retrograde labeling, immunostaining, and enzyme-linked immunosorbent assay (ELISA), we showed here that GV-EA could stimulate the spinal nerve branches of the dorsal root ganglion cells. This would then increase the release of calcitonin gene-related peptide (CGRP) from the afferent terminals in the spinal cord. It is of note that the effect was abrogated after dorsal rhizotomy. Additionally, both in vivo and in vitro results showed that CGRP would act on the post-synaptic spinal cord neurons and triggered the synthesis and secretion of neurotrophin-3 (NT-3) by activating the calcitonin gene-related peptide (CGRP)/ receptor activity-modifying protein (RAMP)1/calcium/calmodulin-dependent protein kinase (αCaMKII) pathway. Remarkably, the observed effect was prevented by the dorsal rhizotomy and the blockers of the CGRP/RAMP1/αCaMKII pathway. More importantly, increase in NT-3 promoted the survival, axonal regrowth, and synaptic maintenance of spinal cord neurons in the injured spinal cord. Therefore, it is concluded that increase in NT-3 production is one of the mechanisms by which GV-EA can activate the intrinsic growth ability of spinal neurons after SCI. The experimental results have reinforced the theoretical basis of GV-EA for its clinical efficacy in patients with SCI.

Decellularization optimizes the inhibitory microenvironment of the optic nerve to support neurite growth

Allogeneic or homologous tissue transplantation is an effective strategy to repair tissue injury. However, the central nervous tissues like the brain, spinal cord, and optic nerve are not ideal materials for nervous tissue regeneration due to the excessive axonal inhibitor cues in their microenvironments. In the present study, we found that decellularization optimizes the function of the adult optic nerve in supporting the oriented outgrowth of dorsal root ganglion (DRG) neurites. The neurites growing on the decellularized optic nerve (DON) showed longer extension distances than those growing on the normal optic nerve (ON). Neurite branching was also significantly increased on the DON compared to on the ON. Decellularization selectively removed some axon-inhibitory molecules such as myelin-associated glycoprotein (basically not detected in DON) and chondroitin sulfate proteoglycans (detected in DON at a level less than 0.3 fold that in ON) and preserved some axon-promoted extracellular matrix (ECM) proteins, including collagen IV and laminin (detected at levels 6.0-fold higher in DON than in ON). Furthermore, collagen IV and laminin were shown to be preserved in DON, and their binding activities with integrin α1 were retained to promote the extension of DRG neurites. Together, the findings provide a feasible way to optimize the axon-inhibited microenvironment of central nervous tissues and establish a theoretical basis for the application of DON scaffolds in repairing central nervous injury.

Polarization-division and spatial-division shared-aperture nanopatch antenna arrays for wide-angle optical beam scanning

Chip-based optical beam scanners hold promise for future compact high-speed light detection and ranging (LIDAR) systems. Many of the demonstrated chip-based optical beam scanners are designed based on diffraction-based waveguide gratings as on-chip antennas. The waveguide grating antenna, however, only provides a typical field-of-view (FOV) of roughly 10° by tuning the input light wavelength. In this paper, polarization-division and spatial-division multiplexed nanoantenna arrays are proposed to expand the FOV of on-chip antennas. The proposed device, based on silicon-on-insulator (SOI) platform, consists of three nanoantenna groups which are densely packed and fed by a common silicon nanostrip. It is demonstrated that the combination of the optical mode-multiplexing technique and the antenna engineering allows independent controls over the interactions between multiple nanoantenna groups and the waveguide. By proper engineering of the antenna dimensions, the proposed device achieves a FOV of over 40° within a 100 nm wavelength tuning range, almost tripling that of the conventional waveguide grating antenna.

LINGO-1 deficiency promotes nerve regeneration through reduction of cell apoptosis, inflammation, and glial scar after spinal cord injury in mice

Leucine-rich repeat and immunoglobulin domain-containing protein 1 (LINGO-1) is a transmembrane protein that negatively regulates neural regeneration in the central nervous system. LINGO-1 expression is up-regulated after central nerve injury, and is accompanied by cell death. Both LINGO-1 and cell death in the injury microenvironment are thought to limit neural regeneration, but the relationship between LINGO-1 and cell death has not been characterized. To investigate whether LINGO-1 deletion improves the spinal cord microenvironment after spinal cord injury (SCI) and contributes to cell survival, we generated LINGO-1 knockout (KO) mice. These mice and wild-type control mice were subjected to spinal cord transection. Fourteen days after spinal cord transection, cell apoptosis, inflammation, glial scar, and growth of nerve fibers were evaluated by immunostaining. The results showed that LINGO-1 KO mice demonstrated a profound reduction in expression of caspase-3, transferase-mediated deoxyuridine triphosphate biotin nick end labeling (TUNEL), ionized calcium binding adapter molecule 1 (IBA1), glial fibrillary acidic protein (GFAP), and chondroitin sulfate proteoglycans (CSPGs) compared to controls. In contrast, expression of neurofilament (NF) at the SCI site in LINGO-1 KO mice was markedly increased compared to that in wild-type mice. These results suggested that LINGO-1 plays a critical role in the injury microenvironment in processes such as cell death, inflammatory response, and glial scar formation. Importantly, LINGO-1 deletion and a positive microenvironment may exert synergistic effects to promote nerve fiber regeneration. Therefore, inhibition of LINGO-1 may be a therapeutic strategy to promote neural regeneration following SCI.

Efficient unidirectional and broadband vertical-emitting optical coupler assisted by aperture-coupled nanopatch antenna array

Vertical-emitting optical couplers that convert in-plane guided light to out-of-plane emission are crucial elements for future photonic integrated circuits. However, traditional vertical-coupling elements, such as grating couplers, by default radiate light in both upward and downward directions, leading to a significant reduction of device efficiency. In this paper, we propose to solve this problem using a novel nanopatch antenna array, inspired by patch antenna theories commonly deployed in microwave circuits. The proposed nanopatch array features an up-to-down emission directionality up to 12.91 dBc and a wide operating bandwidth of over 400 nm simultaneously. Compared with a typical waveguide grating antenna, our design shows a significantly higher free-space gain of 24.27 dBi. The unidirectional, efficient, and broadband antenna arrays presented here are promising for a range of integrated photonics applications, including inter-chip photonic interconnects, light ranging and detection, optical communications, and biological imaging.

Electroacupuncture Facilitates the Integration of Neural Stem Cell-Derived Neural Network with Transected Rat Spinal Cord

The hostile environment of an injured spinal cord makes it challenging to achieve higher viability in a grafted tissue-engineered neural network used to reconstruct the spinal cord circuit. Here, we investigate whether cell survival and synaptic transmission within an NT-3 and TRKC gene-overexpressing neural stem cell-derived neural network scaffold (NN) transplanted into transected spinal cord could be promoted by electroacupuncture (EA) through improving the microenvironment. Our results showed that EA facilitated the cell survival, neuronal differentiation, and synapse formation of a transplanted NN. Pseudorabies virus tracing demonstrated that EA strengthened synaptic integration of the transplanted NN with the host neural circuit. The combination therapy also promoted axonal regeneration, spinal conductivity, and functional recovery. The findings highlight EA as a potential and safe supplementary therapeutic strategy to reinforce the survival and synaptogenesis of a transplanted NN as a neuronal relay to bridge the two severed ends of an injured spinal cord.

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EA promotes the survival and synapse formation of NSC-derived neurons in grafted NN

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EA strengthens synaptic integration of grafted NN with the spinal cord neural circuit

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EA enhances NT-3 level and activates NT-3/TRKC/AKT pathway in the injury/graft site

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The combination therapy increases axonal regeneration and spinal functional recovery

Recovery of paralyzed limb motor function in canine with complete spinal cord injury following implantation of MSC-derived neural network tissue

We have reported previously that bone marrow mesenchymal stem cell (MSC)-derived neural network scaffold not only survived in the injury/graft site of spinal cord but also served as a "neuronal relay" that was capable of improving the limb motor function in a complete spinal cord injury (SCI) rat model. It remained to be explored whether such a strategy was effective for repairing the large spinal cord tissue loss as well as restoring motor function in larger animals. We have therefore extended in this study to construct a canine MSC-derived neural network tissue in vitro with the aim to evaluate its efficacy in treating adult beagle dog subjected to a complete transection of the spinal cord. The results showed that after co-culturing with neurotropin-3 overexpressing Schwann cells in a gelatin sponge scaffold for 14 days, TrkC overexpressing MSCs differentiated into neuron-like cells. In the latter, some cells appeared to make contacts with each other through synapse-like structures with trans-synaptic electrical activities. Remarkably, the SCI canines receiving the transplantation of the MSC-derived neural network tissue demonstrated a gradual restoration of paralyzed limb motor function, along with improved electrophysiological presentation when compared with the control group. Magnetic resonance imaging and diffusion tensor imaging showed that the canines receiving the MSC-derived neural network tissue exhibited robust nerve tract regeneration in the injury/graft site. Histological analysis showed that some of the MSC-derived neuron-like cells had survived in the injury/graft site up to 6.5 months. Implantation of MSC-derived neural network tissue significantly improved the microenvironment of the injury/graft site. It is noteworthy that a variable number of them had integrated with the regenerating corticospinal tract nerve fibers and 5-HT nerve fibers through formation of synapse-like contacts. The results suggest that the transplanted MSC-derived neural network tissue may serve as a structural and functional "neuronal relay" to restore the paralyzed limb motor function in the canine with complete SCI.

Spatial distribution affects the role of CSPGs in nerve regeneration via the actin filament-mediated pathway

CSPGs are components of the extracellular matrix in the nervous system, where they serve as cues for axon guidance during development. After a peripheral nerve injury, CSPGs switch roles and become axon inhibitors and become diffusely distributed at the injury site. To investigate whether the spatial distribution of CSPGs affects their role, we combined in vitro DRG cultures with CSPG stripe or coverage assays to simulate the effect of a patterned substrate or dispersive distribution of CSPGs on growing neurites. We observed neurite steering at linear CSPG interfaces and neurite inhibition when diffused CSPGs covered the distal but not the proximal segment of the neurite. The repellent and inhibitory effects of CSPGs on neurite outgrowth were associated with the disappearance of focal actin filaments on growth cones. The application of an actin polymerization inducer, jasplakinolide, allowed neurites to break through the CSPG boundary and grow on CSPG-coated surfaces. The results of our study collectively reveal a novel mechanism that explains how the spatial distribution of CSPGs determines whether they act as a cue for axon guidance or as an axon-inhibiting factor. Increasing our understanding of this issue may promote the development of novel therapeutic strategies that regulate the spatial distributions of CSPGs to use them as an axon guidance cue.

Neurotrophin-3 released from implant of tissue-engineered fibroin scaffolds inhibits inflammation, enhances nerve fiber regeneration, and improves motor function in canine spinal cord injury

Spinal cord injury (SCI) normally results in cell death, scarring, cavitation, inhibitory molecules release, etc., which are regarded as a huge obstacle to reconnect the injured neuronal circuits because of the lack of effective stimulus. In this study, a functional gelatin sponge scaffold was used to inhibit local inflammation, enhance nerve fiber regeneration, and improve neural conduction in the canine. This scaffold had good porosity and modified with neurotrophin‐3 (NT‐3)/fibroin complex, which showed sustained release in vitro. After the scaffold was transplanted into canine spinal cord hemisection model, hindlimb movement, and neural conduction were improved evidently. Migrating host cells, newly formed neurons with associated synaptic structures together with functional blood vessels with intact endothelium in the regenerating tissue were identified. Taken together, the results demonstrated that using bioactive scaffold could establish effective microenvironment stimuli for endogenous regeneration, providing a potential and practical strategy for treatment of spinal cord injury. © 2018 The Authors Journal of Biomedical Materials Research Part A Published by Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2158‐2170, 2018.

Perineurium-like sheath derived from long-term surviving mesenchymal stem cells confers nerve protection to the injured spinal cord

The functional multipotency enables mesenchymal stem cells (MSCs) promising translational potentials in treating spinal cord injury (SCI). Yet the fate of MSCs grafted into the injured spinal cord has not been fully elucidated even in preclinical studies, rendering concerns of their safety and genuine efficacy. Here we used a rat spinal cord transection model to evaluate the cell fate of allograft bone marrow derived MSCs. With the application of immunosuppressant, donor cells, delivered by biocompatible scaffold, survived up to 8 weeks post-grafting. Discernible tubes formed by MSCs were observed beginning 2 weeks after transplantation and they dominated the morphological features of implanted MSCs at 8 weeks post-grafting. The results of immunocytochemistry and transmission electron microscopy displayed the formation of perineurium-like sheath by donor cells, which, in a manner comparable to the perineurium in peripheral nerve, enwrapped host myelins and axons. The MSC-derived perineurium-like sheath secreted a group of trophic factors and permissive extracellular matrix, and served as a physical and chemical barrier to insulate the inner nerve fibers from ambient oxidative insults by the secretion of soluble antioxidant, superoxide dismutase-3 (SOD3). As a result, many intact regenerating axons were preserved in the injury/graft site following the forming of perineurium-like sheath. A parallel study utilizing a good manufacturing practice (GMP) grade human umbilical cord-derived MSCs or allogenic MSCs in an acute contusive/compressive SCI model exhibited a similar perineurium-like sheath formed by surviving donor cells in rat spinal cord at 3 weeks post-grafting. The present study for the first time provides an unambiguous morphological evidence of perineurium-like sheath formed by transplanted MSCs and a novel therapeutic mechanism of MSCs in treating SCI.

Mitochondrial protective and anti-apoptotic effects of Rhodiola crenulata extract on hippocampal neurons in a rat model of Alzheimer's disease

In our previous study, we found that the edible alcohol extract of the root of the medicinal plant Rhodiola crenulata (RCE) improved spatial cognition in a rat model of Alzheimer's disease. Another study from our laboratory showed that RCE enhanced neural cell proliferation in the dentate gyrus of the hippocampus and prevented damage to hippocampal neurons in a rat model of chronic stress-induced depression. However, the mechanisms underlying the neuroprotective effects of RCE are unclear. In the present study, we investigated the anti-apoptotic effect of RCE and its neuroprotective mechanism of action in a rat model of Alzheimer's disease established by intracerebroventricular injection of streptozotocin. The rats were pre-administered RCE at doses of 1.5, 3.0 or 6.0 g/kg for 21 days before model establishment. ATP and cytochrome c oxidase levels were significantly decreased in rats with Alzheimer's disease. Furthermore, neuronal injury was obvious in the hippocampus, with the presence of a large number of apoptotic neurons. In comparison, in rats given RCE pretreatment, ATP and cytochrome c oxidase levels were markedly increased, the number of apoptotic neurons was reduced, and mitochondrial injury was mitigated. The 3.0 g/kg dose of RCE had the optimal effect. These findings suggest that pretreatment with RCE prevents mitochondrial dysfunction and protects hippocampal neurons from apoptosis in rats with Alzheimer's disease.

Effects of electroacupuncture and the retinoid X receptor (RXR) signalling pathway on oligodendrocyte differentiation in the demyelinated spinal cord of rats

Objectives

In spinal cord demyelination, some oligodendrocyte precursor cells (OPCs) remain in the demyelinated region but have a reduced capacity to differentiate into oligodendrocytes. This study investigated whether ‘Governor Vessel’ (GV) electroacupuncture (EA) would promote the differentiation of endogenous OPCs into oligodendrocytes by activating the retinoid X receptor γ (RXR-γ)-mediated signalling pathway.

Methods

Adult rats were microinjected with ethidium bromide (EB) into the T10 spinal cord to establish a model of spinal cord demyelination. EB-injected rats remained untreated (EB group, n=26) or received EA treatment (EB+EA group, n=26). A control group (n=26) was also included that underwent dural exposure without EB injection. After euthanasia at 7 days (n=5 per group), 15 days (n=8 per group) or 30 days (n=13 per group), protein expression of RXR-γ in the demyelinated spinal cord was evaluated by immunohistochemistry and Western blotting. In addition, OPCs derived from rat embryonic spinal cord were cultured in vitro, and exogenous 9-cis-RA (retinoic acid) and RXR-γ antagonist HX531 were administered to determine whether RA could activate RXR-γ and promote OPC differentiation.

Results

EA was found to increase the numbers of both OPCs and oligodendrocytes expressing RXR-γ and RALDH2, and promote remyelination in the remyelinated spinal cord. Exogenous 9-cis-RA enhanced the differentiation of OPCs into mature oligodendrocytes by activating RXR-γ.

Conclusions

The results suggest that EA may activate RXR signalling to promote the differentiation of OPCs into oligodendrocytes in spinal cord demyelination.

Cell Transplantation and Neuroengineering Approach for Spinal Cord Injury Treatment: A Summary of Current Laboratory Findings and Review of Literature

Spinal cord injury (SCI) can cause severe traumatic injury to the central nervous system (CNS). Current therapeutic effects achieved for SCI in clinical medicine show that there is still a long way to go to reach the desired goal of full or significant functional recovery. In basic medical research, however, cell transplantation, gene therapy, application of cytokines, and biomaterial scaffolds have been widely used and investigated as treatments for SCI. All of these strategies when used separately would help rebuild, to some extent, the neural circuits in the lesion area of the spinal cord. In light of this, it is generally accepted that a combined treatment may be a more effective strategy. This review focuses primarily on our recent series of work on transplantation of Schwann cells and adult stem cells, and transplantation of stem cell-derived neural network scaffolds with functional synapses. Arising from this, an artificial neural network (an exogenous neuronal relay) has been designed and fabricated by us—a biomaterial scaffold implanted with Schwann cells modified by the neurotrophin-3 (NT-3) gene and adult stem cells modified with the TrkC (receptor of NT-3) gene. More importantly, experimental evidence suggests that the novel artificial network can integrate with the host tissue and serve as an exogenous neuronal relay for signal transfer and functional improvement of SCI.

Autocrine fibronectin from differentiating mesenchymal stem cells induces the neurite elongation in vitro and promotes nerve fiber regeneration in transected spinal cord injury

Extracellular matrix (ECM) expression is temporally and spatially regulated during the development of stem cells. We reported previously that fibronectin (FN) secreted by bone marrow mesenchymal stem cells (MSCs) was deposited on the surface of gelatin sponge (GS) soon after culture. In this study, we aimed to assess the function of accumulated FN on neuronal differentiating MSCs as induced by Schwann cells (SCs) in three dimensional transwell co‐culture system. The expression pattern and amount of FN of differentiating MSCs was examined by immunofluorescence, Western blot and immunoelectron microscopy. The results showed that FN accumulated inside GS scaffold, although its mRNA expression in MSCs was progressively decreased during neural induction. MSC‐derived neuron‐like cells showed spindle‐shaped cell body and long extending processes on FN‐decorated scaffold surface. However, after blocking of FN function by application of monoclonal antibodies, neuron‐like cells showed flattened cell body with short and thick neurites, together with decreased expression of integrin β1. In vivo transplantation study revealed that autocrine FN significantly facilitated endogenous nerve fiber regeneration in spinal cord transection model. Taken together, the present results showed that FN secreted by MSCs in the early stage accumulated on the GS scaffold and promoted the neurite elongation of neuronal differentiating MSCs as well as nerve fiber regeneration after spinal cord injury. This suggests that autocrine FN has a dynamic influence on MSCs in a three dimensional culture system and its potential application for treatment of traumatic spinal cord injury. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1902–1911, 2016.

Nanofiber scaffolds for treatment of spinal cord injury

Spinal cord injury (SCI) is a common neurologic disorder that results in loss of sensory function and mobility. It is well documented that tissue engineering is a potential therapeutic strategy for treatment of SCI. In this connection, various biomaterials have been explored to meet the needs of SCI tissue engineering and these include natural materials, synthetic biodegradable polymers and synthetic non- degradable polymers. Nanofiber scaffolds are newly emerging biomaterials that have been widely utilized in tissue engineering recently. In comparison to the traditional biomaterials, nanofibers have advantages in topography and porosity, thus mimicking the naturally occurring extracellular matrix. Besides, they exhibit excellent biocompatibility with low immunogenicity, and furthermore they are endowed with properties that help to bridge the lesion cavity or gap, and serve as an effective delivery system for graft cells or therapeutic drugs. This review summarizes some of the unique properties of nanofiber scaffolds which are critical to their potential application in treatment of injured spinal cord.

Donor mesenchymal stem cell-derived neural-like cells transdifferentiate into myelin-forming cells and promote axon regeneration in rat spinal cord transection

Introduction

Severe spinal cord injury often causes temporary or permanent damages in strength, sensation, or autonomic functions below the site of the injury. So far, there is still no effective treatment for spinal cord injury. Mesenchymal stem cells (MSCs) have been used to repair injured spinal cord as an effective strategy. However, the low neural differentiation frequency of MSCs has limited its application. The present study attempted to explore whether the grafted MSC-derived neural-like cells in a gelatin sponge (GS) scaffold could maintain neural features or transdifferentiate into myelin-forming cells in the transected spinal cord.

Methods

We constructed an engineered tissue by co-seeding of MSCs with genetically enhanced expression of neurotrophin-3 (NT-3) and its high-affinity receptor tropomyosin receptor kinase C (TrkC) separately into a three-dimensional GS scaffold to promote the MSCs differentiating into neural-like cells and transplanted it into the gap of a completely transected rat spinal cord. The rats received extensive post-operation care, including cyclosporin A administrated once daily for 2 months.

Results

MSCs modified genetically could differentiate into neural-like cells in the MN + MT (NT-3-MSCs + TrKC-MSCs) group 14 days after culture in the GS scaffold. However, after the MSC-derived neural-like cells were transplanted into the injury site of spinal cord, some of them appeared to lose the neural phenotypes and instead transdifferentiated into myelin-forming cells at 8 weeks. In the latter, the MSC-derived myelin-forming cells established myelin sheaths associated with the host regenerating axons. And the injured host neurons were rescued, and axon regeneration was induced by grafted MSCs modified genetically. In addition, the cortical motor evoked potential and hindlimb locomotion were significantly ameliorated in the rat spinal cord transected in the MN + MT group compared with the GS and MSC groups.

Conclusion

Grafted MSC-derived neural-like cells in the GS scaffold can transdifferentiate into myelin-forming cells in the completely transected rat spinal cord.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0100-7) contains supplementary material, which is available to authorized users.

Improvement in acupoint selection for acupuncture of nerves surrounding the injury site: electro-acupuncture with Governor vessel with local meridian acupoints

Peripheral nerve injury not only affects the site of the injury, but can also induce neuronal apoptosis at the spinal cord. However, many acupuncture clinicians still focus only on the injury site, selecting acupoints entirely along the injured nerve trunk and neglecting other regions; this may delay onset of treatment efficacy and rehabilitation. Therefore, in the present study, we compared the clinical efficacy of acupuncture at Governor vessel and local meridian acupoints combined (GV/LM group) with acupuncture at local meridian acupoints alone (LM group) in the treatment of patients with peripheral nerve injury. In the GV/LM group (n = 15), in addition to meridian acupoints at the injury site, the following acupoints on the Governor vessel were stimulated: Baihui (GV20), Fengfu (GV16), Dazhui (GV14), and Shenzhu (GV12), selected to treat nerve injury of the upper limb, and Jizhong (GV6), Mingmen (GV4), Yaoyangguan (GV3), and Yaoshu (GV2) to treat nerve injury of the lower limb. In the LM group (n = 15), only meridian acupoints along the injured nerve were selected. Both groups had electroacupuncture treatment for 30 minutes, once a day, 5 times per week, for 6 weeks. Two cases dropped out of the LM group. A good or excellent clinical response was obtained in 80% of the patients in the GV/LM group and 38.5% of the LM group. In a second study, an additional 20 patients underwent acupuncture with the same prescription as the GV/LM group. Electomyographic nerve conduction tests were performed before and after acupuncture to explore the mechanism of action of the treatment. An effective response was observed in 80.0% of the patients, with greater motor nerve conduction velocity and amplitude after treatment, indicating that electroacupuncture on specific Governor vessel acupoints promotes functional motor nerve repair after peripheral nerve injury. In addition, electromyography was performed before, during and after electroacupuncture in one patient with radial nerve injury. After a single session, the patient's motor nerve conduction velocity increased by 23.2%, indicating that electroacupuncture at Governor vessel acupoints has an immediate therapeutic effect on peripheral nerve injury. Our results indicate that Governor vessel and local meridian acupoints used simultaneously promote functional repair after peripheral nerve injury. The mechanism of action may arise from an improvement of the local microenvironment in injured nervous tissue, as well as immediate effects of Governor vessel and local meridian acupoint stimulation to ensure the continuity between the peripheral and central nervous systems.

First Report of Anthracnose Disease on Young Stems of Bawanghua (Hylocereus undatus) Caused by Colletotrichum gloeosporioides in China

Hylocereus undatus widely grows in southern China. Some varieties are planted for their fruits, known as dragon fruits or Pitaya, while some varieties for their flowers known as Bawanghua. Fresh or dried flowers of Bawanghua are used as routine Chinese medicinal food. Since 2008, a serious anthracnose disease has led to great losses on Bawanghua flower production farms in the Baiyun district of Guangzhou city in China. Anthracnose symptoms on young stems of Bawanghua are reddish-brown, sunken lesions with pink masses of spores in the center. The lesions expand rapidly in the field or in storage, and may coalesce in the warm and wet environment in spring and summer in Guangzhou. Fewer flowers develop on infected stems than on healthy ones. The fungus overwinters in infected debris in the soil. The disease caused a loss of up to 50% on Bawanghua. Putative pathogenic fungi with whitish-orange colonies were isolated from a small piece of tissue (3 × 3 mm) cut from a lesion margin and cultured on potato dextrose agar in a growth chamber at 25°C, 80% RH. Dark colonies with acervuli bearing pinkish conidial masses formed 14 days later. Single celled conidia were 11 to 18 × 4 to 6 μm. Based on these morphological characteristics, the fungi were identified as Colletotrichum gloeosporioides (Penz.) Penz. & Sacc (2). To confirm this, DNA was extracted from isolate BWH1 and multilocus analyses were completed with DNA sequence data generated from partial ITS region of nrDNA, actin (ACT) and glutamine synthetase (GS) nucleotide sequences by PCR, with C. gloeosporioides specific primers as ITS4 (5'-TCCTCCGCTTATTGATATGC-3') / CgInt (5'-GGCCTCCCGCCTCCGGGCGG-3'), GS-F (5'-ATGGCCGAGTACATCTGG-3') / GS-R (5'-GAACCGTCGAAGTTCCAC-3') and actin-R (5'-ATGTGCAAGGCCGGTTTCGC-3') / actin-F (5'-TACGAGTCCTTCTGGCCCAT-3'). The sequence alignment results indicated that the obtained partial ITS sequence of 468 bp (GenBank Accession No. KF051997), actin sequence of 282 bp (KF712382), and GS sequence of 1,021 bp (KF719176) are 99%, 96%, and 95% identical to JQ676185.1 for partial ITS, FJ907430 for ACT, and FJ972589 for GS of C. gloeosporioides previously deposited, respectively. For testing its pathogenicity, 20 μl of conidia suspension (1 × 10⁶ conidia/ml) using sterile distilled water (SDW) was inoculated into artificial wounds on six healthy young stems of Bawanghua using sterile fine-syringe needle. Meanwhile, 20 μl of SDW was inoculated on six healthy stems as a control. The inoculated stems were kept at 25°C, about 90% relative humidity. Three independent experiments were carried out. Reddish-brown lesions formed after 10 days, on 100% stems (18 in total) inoculated by C. gloeosporioides, while no lesion formed on any control. The pathogen was successfully re-isolated from the inoculated stem lesions on Bawanghua. Thus, Koch's postulates were fulfilled. Colletotrichum anthracnose has been reported on Pitaya in Japan (3), Malaysia (1) and in Brazil (4). To our knowledge, this is the first report of anthracnose disease caused by C. gloeosporioides on young stems of Bawanghua (H. undatus) in China. References: (1) M. Masyahit et al. Am. J. Appl. Sci. 6:902, 2009. (2) B. C. Sutton. Page 402 in: Colletotrichum Biology, Pathology and Control. J. A. Bailey and M. J. Jeger, eds. CAB International, Wallingford, UK, 1992. (3) S. Taba et al. Jpn. J. Phytopathol. 72:25, 2006. (4) L. M. Takahashi et al. Australas. Plant Dis. Notes 3:96, 2008.

Electroacupuncture Promotes the Differentiation of Transplanted Bone Marrow Mesenchymal Stem Cells Preinduced With Neurotrophin-3 and Retinoic Acid Into Oligodendrocyte-Like Cells in Demyelinated Spinal Cord of Rats

Transplantation of bone marrow mesenchymal stem cells (MSCs) promotes functional recovery in multiple sclerosis (MS) patients and in a murine model of MS. However, there is only a modicum of information on differentiation of grafted MSCs into oligodendrocyte-like cells in MS. The purpose of this study was to transplant neurotrophin-3 (NT-3) and retinoic acid (RA) preinduced MSCs (NR-MSCs) into a demyelinated spinal cord induced by ethidium bromide and to investigate whether EA treatment could promote NT-3 secretion in the demyelinated spinal cord. We also sought to determine whether increased NT-3 could further enhance NR-MSCs overexpressing the tyrosine receptor kinase C (TrkC) to differentiate into more oligodendrocyte-like cells, resulting in increased remyelination and nerve conduction in the spinal cord. Our results showed that NT-3 and RA increased transcription of TrkC mRNA in cultured MSCs. EA increased NT-3 levels and promoted differentiation of oligodendrocyte-like cells from grafted NR-MSCs in the demyelinated spinal cord. There was evidence of myelin formation by grafted NR-MSCs. In addition, NR-MSC transplantation combined with EA treatment (the NR-MSCs + EA group) reduced demyelination and promoted remyelination. Furthermore, the conduction of cortical motor-evoked potentials has improved compared to controls. Together, our data suggest that preinduced MSC transplantation combined with EA treatment not only increased MSC differentiation into oligodendrocyte-like cells forming myelin sheaths, but also promoted remyelination and functional improvement of nerve conduction in the demyelinated spinal cord.

Graft of a tissue-engineered neural scaffold serves as a promising strategy to restore myelination after rat spinal cord transection

Remyelination remains a challenging issue in spinal cord injury (SCI). In the present study, we cocultured Schwann cells (SCs) and neural stem cells (NSCs) with overexpression of neurotrophin-3 (NT-3) and its high affinity receptor tyrosine kinase receptor type 3 (TrkC), respectively, in a gelatin sponge (GS) scaffold. This was aimed to generate a tissue-engineered neural scaffold and to investigate whether it could enhance myelination after a complete T10 spinal cord transection in adult rats. Indeed, many NT-3 overexpressing SCs (NT-3-SCs) in the GS scaffold assumed the formation of myelin. More strikingly, a higher incidence of NSCs overexpressing TrkC differentiating toward myelinating cells was induced by NT-3-SCs. By transmission electron microscopy, the myelin sheath showed distinct multilayered lamellae formed by the seeded cells. Eighth week after the scaffold was transplanted, some myelin basic protein (MBP)-positive processes were observed within the transplantation area. Remarkably, certain segments of myelin derived from NSC-derived myelinating cells and NT-3-SCs were found to ensheath axons. In conclusion, we show here that transplantation of the GS scaffold promotes exogenous NSC-derived myelinating cells and SCs to form myelins in the injury/transplantation area of spinal cord. These findings thus provide a neurohistological basis for the future application or transplantation using GS neural scaffold to repair SCI.

Electroacupuncture Promotes the Differentiation of Transplanted Bone Marrow Mesenchymal Stem Cells Overexpressing TrkC into Neuron-Like Cells in Transected Spinal Cord of Rats

Our previous study indicated that electroacupuncture (EA) could increase neurotrophin-3 (NT-3) levels in the injured spinal cord, stimulate the differentiation of transplanted bone marrow mesenchymal stem cells (MSCs), and improve functional recovery in the injured spinal cord of rats. However, the number of neuron-like cells derived from the MSCs is limited. It is known that NT-3 promotes the survival and differentiation of neurons by preferentially binding to its receptor TrkC. In this study, we attempted to transplant TrkC gene-modified MSCs (TrkC-MSCs) into the spinal cord with transection to investigate whether EA treatment could promote NT-3 secretion in the injured spinal cord and to determine whether increased NT-3 could further enhance transplanted MSCs overexpressing TrkC to differentiate into neuron-like cells, resulting in increased axonal regeneration and functional improvement in the injured spinal cord. Our results showed that EA increased NT-3 levels; furthermore, it promoted neuron-phenotype differentiation, synaptogenesis, and myelin formation of transplanted TrkC-MSCs. In addition, TrkC-MSC transplantation combined with EA (the TrkC-MSCs + EA group) treatment promoted the growth of the descending BDA-labeled corticospinal tracts (CSTs) and 5-HT-positive axonal regeneration across the lesion site into the caudal cord. In addition, the conduction of cortical motor-evoked potentials (MEPs) and hindlimb locomotor function increased as compared to controls (treated with the LacZ-MSCs, TrkC-MSCs, and LacZ-MSCs + EA groups). In the TrkC-MSCs + EA group, the injured spinal cord also showed upregulated expression of the proneurogenic factors laminin and GAP-43 and downregulated GFAP and chondroitin sulfate proteoglycans (CSPGs), major inhibitors of axonal growth. Together, our data suggest that TrkC-MSC transplantation combined with EA treatment spinal cord injury not only increased MSC survival and differentiation into neuron-like cells but also promoted CST regeneration across injured sites to the caudal cord and functional improvement, perhaps due to increase of NT-3 levels, upregulation of laminin and GAP-43, and downregulation of GFAP and CSPG proteins.

Bone Marrow Mesenchymal Stem Cells and Electroacupuncture Downregulate the Inhibitor Molecules and Promote the Axonal Regeneration in the Transected Spinal Cord of Rats

Our previous study has reported that electroacupuncture (EA) promotes survival, differentiation of bone marrow mesenchymal stem cells (MSCs), and functional improvement in spinal cord-transected rats. In this study, we further investigated the structural bases of this functional improvement and the potential mechanisms of axonal regeneration in injured spinal cord after MSCs and EA treatment. Five experimental groups, 1) sham control (Sham-control); 2) operated control (Op-control); 3) electroacupuncture treatment (EA); 4) MSCs transplantation (MSCs), and 5) MSCs transplantation combined with electroacupuncture (MSCs + EA), were designed for this study. Western blots and immunohistochemical staining were used to assess the fibrillary acidic protein (GFAP) and chondroitin sulfate proteoglycans (CSPGs) proteins expression. Basso, Beattie, Bresnahan (BBB) locomotion test, cortical motor evoked potentials (MEPs), and anterograde and retrograde tracing were utilized to assess cortical-spinal neuronal projection regeneration and functional recovery. In the MSCs + EA group, increased labeling descending corticospinal tract (CST) projections into the lesion site showed significantly improved BBB scales and enhanced motor evoked potentials after 10 weeks of MSCs transplant and EA treatment. The structural and functional recovery after MSCs + EA treatment may be due to downregulated GFAP and CSPGs protein expression, which prevented axonal degeneration as well as improved axonal regeneration.

Implantation of adult bone marrow-derived mesenchymal stem cells transfected with the neurotrophin-3 gene and pretreated with retinoic acid in completely transected spinal cord

Implantation of marrow-derived mesenchymal stem cells (MSCs) is the most promising therapeutic strategy for the treatment of spinal cord injury (SCI), especially because of their potential for clinical application, such as the avoidance of immunologic rejection, their strong secretory properties, and their plasticity for developing into neural cells. However, the recovery from SCI after MSC implantation is minimal due to their limited capacity for the reduction of cystic cavitation, for the axonal regeneration and their uncertain neural plasticity in the spinal cord. We previously pretreated MSCs with all-trans retinoic acid (RA) in vitro. Then we genetically modified them to overexpress neurotrophin-3 (NT-3) via a recombinant adenoviral vector (Adv). This combined treatment not only permitted more neuronal differentiation of MSCs, but stimulated more NT-3 secretion prior to grafting, according to our previous and present results. When these cells were implanted into the transected spinal cord of rats, the animals had some improvement (both functionally and structurally), including the recovery of hindlimb locomotor function, shown by the highest Basso, Beattie, and Bresnahan (BBB) scores, as well as dramatically reduced cavity volume, clear axonal regeneration and more neuronal survival. In contrast, simple MSC implantation is not a very effective therapy for spinal transection. However, the neuronal differentiation of MSCs after treatment with a combination of Adv-mediated NT-3 gene transfer and RA was only mildly improved in vivo.

[Effects of Rhodiola rosea on body weight and intake of sucrose and water in depressive rats induced by chronic mild stress]

OBJECTIVE

To explore the effects of Rhodiola rosea on the body weight and the intake of sucrose and water in depressive rats induced by chronic mild stress.dz

METHODS

A total of 70 male SD rats were divided into seven groups, including normal control group (treated with 0.5% sodium carboxymethycellulose), untreated group, negative control group (treated with 0.5% sodium carboxymethycellulose), positive control group (treated with fluoxetine), low-, medium- and high-dose Rhodiola rosea group (treated with 1.5, 3, 6 g/kg Rhodiola rosea respectively). Except for rats in normal control group, the other sixty rats endured chronic stress for 4 weeks to establish the depression model. After that, rats were administered Rhodiola rosea for 3 weeks. During the whole experiment, the body weight, and sucrose intake, tap water intake of all rats were examined once a week.

RESULTS

After the termination of the stress regime, compared with the normal control group, the body weight and 1% sucrose intake in depressive rats were decreased. After 3-week Rhodiola rosea treatment, the body weight and 1% sucrose intake increased in rats of the low-dose Rhodiola rosea group and recovered to the level of the normal control group.

CONCLUSION

Low-dose Rhodiola rosea can increase the body weight and sucrose intake of depressive rats, making them recover to normal status.

The effects of Rhodiola rosea extract on 5-HT level, cell proliferation and quantity of neurons at cerebral hippocampus of depressive rats

The purpose of this study was to investigate the effects of Rhodiola rosea extract and depression on the serotonin (5-HT) level, cell proliferation and quantity of neurons at cerebral hippocampus of depressive rats induced by Chronic Mild Stress (CMS). Seventy male Sprague-Dawley rats were divided into seven groups (10 per group): normal control group, untreated depressive rat model group, negative control group, positive control group, low dosage Rhodiola rosea extract (1.5g/kg) group, medium dosage Rhodiola rosea extract (3g/kg) group and high dosage Rhodiola rosea extract (6g/kg) group. After the depressive rats induced by CMS had received Rhodiola rosea extract for 3 weeks, the 5-HT levels at cerebral hippocampus were detected by high performance liquid chromatography. Bromodeoxyuridine (BrdU) was injected in vivo to label the proliferating cells at hippocampus, and morphometry was used to count the hippocampal neurons. The results showed that the 5-HT level of the three experimental groups had recovered to normal status. The immunohistochemistry of hippocampus BrdU positive cells had returned to the normal level in the group of depressive rats with low dosage Rhodiola rosea extract. In conclusion the results demonstrated that Rhodiola rosea extract could improve 5-HT level in hippocampus in depressive rats, and low dosage Rhodiola rosea could induce neural stem cell proliferation at hippocampus to return to normal level, repairing the injured neurons at hippocampus.

Pretreatment with Rhodiola rosea extract reduces cognitive impairment induced by intracerebroventricular streptozotocin in rats: implication of anti-oxidative and neuroprotective effects

OBJECTIVE

To investigate the pretreatment effects of Rhodiola rosea (R. rosea) extract on cognitive dysfunction, oxidative stress in hippocampus and hippocampal neuron injury in a rat model of Alzheimer's disease (AD).

METHODS

Male Sprague-Dawley rats were pretreated with R. rosea extract at doses of 1.5, 3.0, and 6.0 g/kg for 3 weeks, followed by bilateral intracerebroventricular injection with streptozotocin (1.5 mg/kg) on days 1 and 3. Behavioral alterations were monitored after 2 weeks from the lesion using Morris water maze task. Three weeks after the lesion, the rats were sacrificed for measuring the malondialdehyde (MDA), glutathione reductase (GR) and reduced glutathione (GSH) levels in hippocampus and histopathology of hippocampal neurons.

RESULTS

The MDA level was significantly increased while the GR and GSH levels were significantly decreased with striking impairments in spatial learning and memory and severe damage to hippocampal neurons in the model rat induced by intracerebroventricular injection of streptozotocin. These abnormalities were significantly improved by pretreatment with R. rosea extract (3.0 g/kg).

CONCLUSION

R. rosea extract can protect rats against cognitive deficits, neuronal injury and oxidative stress induced by intracerebroventricular injection of streptozotocin, and may be used as a potential agent in treatment of neurodegenerative diseases such as AD.

Electro-acupuncture promotes survival, differentiation of the bone marrow mesenchymal stem cells as well as functional recovery in the spinal cord-transected rats

Background

Bone marrow mesenchymal stem cells (MSCs) are one of the potential tools for treatment of the spinal cord injury; however, the survival and differentiation of MSCs in an injured spinal cord still need to be improved. In the present study, we investigated whether Governor Vessel electro-acupuncture (EA) could efficiently promote bone marrow mesenchymal stem cells (MSCs) survival and differentiation, axonal regeneration and finally, functional recovery in the transected spinal cord.

Results

The spinal cords of adult Sprague-Dawley (SD) rats were completely transected at T10, five experimental groups were performed: 1. sham operated control (Sham-control); 2. operated control (Op-control); 3. electro-acupuncture treatment (EA); 4. MSCs transplantation (MSCs); and 5. MSCs transplantation combined with electro-acupuncture (MSCs+EA). After 2-8 weeks of MSCs transplantation plus EA treatment, we found that the neurotrophin-3 (NT-3), cAMP level, the differentiation of MSCs, the 5-HT positive and CGRP positive nerve fibers in the lesion site and nearby tissue of injured spinal cord were significantly increased in the MSCs+EA group as compared to the group of the MSCs transplantation or the EA treated alone. Furthermore, behavioral test and spinal cord evoked potentials detection demonstrated a significantly functional recovery in the MSCs +EA group.

Conclusion

These results suggest that EA treatment may promote grafted MSCs survival and differentiation; MSCs transplantation combined with EA treatment could promote axonal regeneration and partial locomotor functional recovery in the transected spinal cord in rats and indicate a promising avenue of treatment of spinal cord injury.

Neurotrophin-3 improves retinoic acid-induced neural differentiation of skin-derived precursors through a p75NTR-dependent signaling pathway

Skin-derived precursors (SKPs) are derived from mesoblast and can differentiate into smooth muscle cells, adipocytes, and less neuronal phenotypes. This study demonstrates that retinoic acid (RA) improves SKPs exit from self-proliferation to neural differentiation through up-regulating of NeuroD and cell-cycle regulatory protein p21, meanwhile RA also induces p75 neurotrophin receptor (p75NTR) up-regulation and apoptosis of SKPs. When treated sequentially with neurotrophin-3 (NT-3) after RA induction, the survival and neural differentiation of SKPs were enhanced significantly, and cell apoptosis induced by RA was decreased. These effects could be reversed by p75NTR inhibitor Pep5 instead of Trk receptor inhibitor K252a. The results indicate that NT-3 improves the neural differentiation of SKPs induced by RA through a p75NTR-dependent signaling pathway.