Adoptive transfer of Th1-conditioned lymphocytes promotes axonal remodeling and functional recovery after spinal cord injury

The role of T lymphocytes in central nervous system (CNS) injuries is controversial, with inconsistent results reported concerning the effects of T-lymphocyte transfer on spinal cord injury (SCI). Here, we demonstrate that a specific T-lymphocyte subset enhances functional recovery after contusion SCI in mice. Intraperitoneal adoptive transfer of type 1 helper T (Th1)-conditioned cells 4 days after SCI promoted recovery of locomotor activity and tactile sensation and concomitantly induced regrowth of corticospinal tract and serotonergic fibers. However, neither type 2 helper T (Th2)- nor IL-17-producing helper T (Th17)-conditioned cells had such effects. Activation of microglia and macrophages were observed in the spinal cords of Th1-transfered mice after SCI. Specifically, M2 subtype of microglia/macrophages was upregulated after Th1 cell transfer. Neutralization of interleukin 10 secreted by Th1-conditioned cells significantly attenuated the beneficial effects by Th1-conditioned lymphocytes after SCI. We also found that Th1-conditioned lymphocytes secreted significantly higher levels of neurotrophic factor, neurotrophin 3 (NT-3), than Th2- or Th17-conditioned cells. Thus, adoptive transfer of pro-inflammatory Th1-conditioned cells has neuroprotective effects after SCI, with prospective implications in immunomodulatory treatment of CNS injury.     

Development of protective autoimmunity by immunization with a neural-derived peptide is ineffective in severe spinal cord injury

Protective autoimmunity (PA) is a physiological response to central nervous system trauma that has demonstrated to promote neuroprotection after spinal cord injury (SCI). To reach its beneficial effect, PA should be boosted by immunizing with neural constituents or neural-derived peptides such as A91. Immunizing with A91 has shown to promote neuroprotection after SCI and its use has proven to be feasible in a clinical setting. The broad applications of neural-derived peptides make it important to determine the main features of this anti-A91 response. For this purpose, adult Sprague-Dawley rats were subjected to a spinal cord contusion (SCC; moderate or severe) or a spinal cord transection (SCT; complete or incomplete). Immediately after injury, animals were immunized with PBS or A91. Motor recovery, T cell-specific response against A91 and the levels of IL-4, IFN-γ and brain-derived neurotrophic factor (BDNF) released by A91-specific T (T(A91)) cells were evaluated. Rats with moderate SCC, presented a better motor recovery after A91 immunization. Animals with moderate SCC or incomplete SCT showed significant T cell proliferation against A91 that was characterized chiefly by the predominant production of IL-4 and the release of BDNF. In contrast, immunization with A91 did not promote a better motor recovery in animals with severe SCC or complete SCT. In fact, T cell proliferation against A91 was diminished in these animals. The present results suggest that the effective development of PA and, consequently, the beneficial effects of immunizing with A91 significantly depend on the severity of SCI. This could mainly be attributed to the lack of T(A91) cells which predominantly showed to have a Th2 phenotype capable of producing BDNF, further promoting neuroprotection.     

Central Canal Ependymal Cells Proliferate Extensively in Response to Traumatic Spinal Cord Injury but Not Demyelinating Lesions

The adult mammalian spinal cord has limited regenerative capacity in settings such as spinal cord injury (SCI) and multiple sclerosis (MS). Recent studies have revealed that ependymal cells lining the central canal possess latent neural stem cell potential, undergoing proliferation and multi-lineage differentiation following experimental SCI. To determine whether reactive ependymal cells are a realistic endogenous cell population to target in order to promote spinal cord repair, we assessed the spatiotemporal dynamics of ependymal cell proliferation for up to 35 days in three models of spinal pathologies: contusion SCI using the Infinite Horizon impactor, focal demyelination by intraspinal injection of lysophosphatidylcholine (LPC), and autoimmune-mediated multi-focal demyelination using the active experimental autoimmune encephalomyelitis (EAE) model of MS. Contusion SCI at the T9–10 thoracic level stimulated a robust, long-lasting and long-distance wave of ependymal proliferation that peaked at 3 days in the lesion segment, 14 days in the rostral segment, and was still detectable at the cervical level, where it peaked at 21 days. This proliferative wave was suppressed distal to the contusion. Unlike SCI, neither chemical- nor autoimmune-mediated demyelination triggered ependymal cell proliferation at any time point, despite the occurrence of demyelination (LPC and EAE), remyelination (LPC) and significant locomotor defects (EAE). Thus, traumatic SCI induces widespread and enduring activation of reactive ependymal cells, identifying them as a robust cell population to target for therapeutic manipulation after contusion; conversely, neither demyelination, remyelination nor autoimmunity appears sufficient to trigger proliferation of quiescent ependymal cells in models of MS-like demyelinating diseases.     

Structural and functional regeneration after spinal cord injury in the weakly electric teleost fish, <Emphasis Type="Italic">Apteronotus</Emphasis><Emphasis Type="Italic">leptorhynchus</Emphasis>

In contrast to mammals, teleost fish exhibit an enormous potential to regenerate adult spinal cord tissue after injury. However, the mechanisms mediating this ability are largely unknown. Here, we analyzed the major processes underlying structural and functional regeneration after amputation of the caudal portion of the spinal cord in Apteronotus leptorhynchus, a weakly electric teleost. After a transient wave of apoptotic cell death, cell proliferation started to increase 5 days after the lesion and persisted at high levels for at least 50 days. New cells differentiated into neurons, glia, and ependymal cells. Retrograde tract tracing revealed axonal re-growth and innervation of the regenerate. Functional regeneration was demonstrated by recovery of the amplitude of the electric organ discharge, a behavior generated by spinal motoneurons. Computer simulations indicated that the observed rates of apoptotic cell death and cell proliferation can adequately explain the re-growth of the spinal cord. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Transplantation of D15A-Expressing Glial-Restricted-Precursor-Derived Astrocytes Improves Anatomical and Locomotor Recovery after Spinal Cord Injury

The transplantation of neural stem/progenitor cells is a promising therapeutic strategy for spinal cord injury (SCI). In this study, we tested whether combination of neurotrophic factors and transplantation of glial-restricted precursor (GRPs)-derived astrocytes (GDAs) could decrease the injury and promote functional recovery after SCI. We developed a protocol to quickly produce a sufficiently large, homogenous population of young astrocytes from GRPs, the earliest arising progenitor cell population restricted to the generation of glia. GDAs expressed the axonal regeneration promoting substrates, laminin and fibronectin, but not the inhibitory chondroitin sulfate proteoglycans (CSPGs). Importantly, GDAs or its conditioned medium promoted the neurite outgrowth of dorsal root ganglion neurons in vitro. GDAs were infected with retroviruses expressing EGFP or multi-neurotrophin D15A and transplanted into the contused adult thoracic spinal cord at 8 days post-injury. Eight weeks after transplantation, the grafted GDAs survived and integrated into the injured spinal cord. Grafted GDAs expressed GFAP, suggesting they remained astrocyte lineage in the injured spinal cord. But it did not express CSPG. Robust axonal regeneration along the grafted GDAs was observed. Furthermore, transplantation of D15A-GDAs significantly increased the spared white matter and decreased the injury size compared to other control groups. More importantly, transplantation of D15A-GDAs significantly improved the locomotion function recovery shown by BBB locomotion scores and Tredscan footprint analyses. However, this combinatorial strategy did not enhance the aberrant synaptic connectivity of pain afferents, nor did it exacerbate posttraumatic neuropathic pain. These results demonstrate that transplantation of D15A-expressing GDAs promotes anatomical and locomotion recovery after SCI, suggesting it may be an effective therapeutic approach for SCI.     

Transplantation of adult spinal cord grafts into spinal cord transected rats improves their locomotor function

Grafted embryonic central neural tissue pieces can recover function of hemisected spinal cord in neonatal rats and promote axonal growth in adults. However, spinal cord segments from adults have not been used as donor segments for allogeneic transplantation. Here, we utilized adult spinal cord tissue grafts(aSCGs) as donor constructs for repairing complete spinal cord injury(SCI). Moreover, to provide a favourable microenvironment for SCI treatment, a growth factor cocktail containing three growth factors(brain-derived neurotrophic factor, neurotrophin-3 and vascular endothelial growth factor), was applied to the aSCG transplants. We found that the locomotor function was significantly improved 12 weeks after transplantation of aSCGs into the spinal cord lesion site in adult rats. Transplantation of aSCGs combined with these growth factors enhanced neuron and oligodendrocyte survival and functional restoration. These encouraging results indicate that treatment of complete SCI by transplanting aSCGs, especially in the presence of growth factors, has a positive effect on motor functional recovery, and therefore could be considered as a possible therapeutic strategy for SCI.     

Spinal cord injury reveals multilineage differentiation of ependymal cells

Spinal cord injury often results in permanent functional impairment. Neural stem cells present in the adult spinal cord can be expanded in vitro and improve recovery when transplanted to the injured spinal cord, demonstrating the presence of cells that can promote regeneration but that normally fail to do so efficiently. Using genetic fate mapping, we show that close to all in vitro neural stem cell potential in the adult spinal cord resides within the population of ependymal cells lining the central canal. These cells are recruited by spinal cord injury and produce not only scar-forming glial cells, but also, to a lesser degree, oligodendrocytes. Modulating the fate of ependymal progeny after spinal cord injury may offer an alternative to cell transplantation for cell replacement therapies in spinal cord injury.     

Pre-Evaluated Safe Human iPSC-Derived Neural Stem Cells Promote Functional Recovery after Spinal Cord Injury in Common Marmoset without Tumorigenicity

Murine and human iPSC-NS/PCs (induced pluripotent stem cell-derived neural stem/progenitor cells) promote functional recovery following transplantation into the injured spinal cord in rodents. However, for clinical applicability, it is critical to obtain proof of the concept regarding the efficacy of grafted human iPSC-NS/PCs (hiPSC-NS/PCs) for the repair of spinal cord injury (SCI) in a non-human primate model. This study used a pre-evaluated “safe” hiPSC-NS/PC clone and an adult common marmoset (Callithrix jacchus) model of contusive SCI. SCI was induced at the fifth cervical level (C5), followed by transplantation of hiPSC-NS/PCs at 9 days after injury. Behavioral analyses were performed from the time of the initial injury until 12 weeks after SCI. Grafted hiPSC-NS/PCs survived and differentiated into all three neural lineages. Furthermore, transplantation of hiPSC-NS/PCs enhanced axonal sparing/regrowth and angiogenesis, and prevented the demyelination after SCI compared with that in vehicle control animals. Notably, no tumor formation occurred for at least 12 weeks after transplantation. Quantitative RT-PCR showed that mRNA expression levels of human neurotrophic factors were significantly higher in cultured hiPSC-NS/PCs than in human dermal fibroblasts (hDFs). Finally, behavioral tests showed that hiPSC-NS/PCs promoted functional recovery after SCI in the common marmoset. Taken together, these results indicate that pre-evaluated safe hiPSC-NS/PCs are a potential source of cells for the treatment of SCI in the clinic.     

FGF-2 Up-regulation and proliferation of neural progenitors in the regenerating amphibian spinal cord in vivo

Regeneration of the spinal cord occurs spontaneously in adult urodele amphibians. The key cells in this regenerative process appear to be the ependymal cells that following injury migrate and proliferate to form the ependymal tube from which the spinal cord regenerates. Very little is known about the signal(s) that initiates and maintains the proliferative response of these cells. Fibroblast growth factor 2 (FGF-2) has been shown to play a role in maintaining neural progenitor cell cycling in vitro and may be important for neuronal survival and axonal growth after injury. We have investigated its role in regeneration of the spinal cord in vivo following tail amputation in the adult salamander, Pleurodeles waltl. We show that only the low-molecular-weight form of FGF-2 is found in Pleurodeles and that in the normal cord it is expressed in a subset of neurons, but is hardly detectable in ependymal cells. Tail amputation results in induction of FGF-2 in the ependymal cells of the regenerating structure, and later in regeneration FGF-2 is up-regulated in some newborn neurons. FGF-2 pattern of expression in the ependymal tube parallels that of proliferation. Furthermore, exogenous FGF-2 significantly increases ependymal cell proliferation in vivo. Overall our results strongly support the view that one important role of FGF-2 during spinal cord regeneration in Pleurodeles is to induce proliferation of neural progenitor cells.     

ifn-γ-dependent secretion of IL-10 from Th1 cells and microglia/macrophages contributes to functional recovery after spinal cord injury

Transfer of type-1 helper T-conditioned (Th1-conditioned) cells promotes functional recovery with enhanced axonal remodeling after spinal cord injury (SCI). This study explored the molecular mechanisms underlying the beneficial effects of pro-inflammatory Th1-conditioned cells after SCI. The effect of Th1-conditioned cells from interferon-γ (ifn-γ) knockout mice (ifn-γ^−/− Th1 cells) on the recovery after SCI was reduced. Transfer of Th1-conditioned cells led to the activation of microglia (MG) and macrophages (MΦs), with interleukin 10 (IL-10) upregulation. This upregulation of IL-10 was reduced when ifn-γ^−/− Th1 cells were transferred. Intrathecal neutralization of IL-10 in the spinal cord attenuated the effects of Th1-conditioned cells. Further, IL-10 is robustly secreted from Th1-conditioned cells in an ifn-γ-dependent manner. Th1-conditioned cells from interleukin 10 knockout (il-10^−/−) mice had no effects on recovery from SCI. These findings demonstrate that ifn-γ-dependent secretion of IL-10 from Th1 cells, as well as native MG/MΦs, is required for the promotion of motor recovery after SCI.     

Application of the sodium hyaluronate-CNTF scaffolds in repairing adult rat spinal cord injury and facilitating neural network formation

The present study aimed to explore the potential of the sodium hyaluronate-CNTF (ciliary neurotrophic factor) scaffold in activating endogenous neurogenesis and facilitating neural network re-formation after the adult rat spinal cord injury (SCI). After completely cutting and removing a 5-mm adult rat T8 segment, a sodium hyaluronate-CNTF scaffold was implanted into the lesion area. Dil tracing and immunofluorescence staining were used to observe the proliferation, differentiation and integration of neural stem cells (NSCs) after SCI. A planar multielectrode dish system (MED64) was used to test the electrophysiological characteristics of the regenerated neural network in the lesioned area. Electrophysiology and behavior evaluation were used to evaluate functional recovery of paraplegic rat hindlimbs. The Dil tracing and immunofluorescence results suggest that the sodium hyaluronate-CNTF scaffold could activate the NSCs originating from the spinal cord ependymal, and facilitate their migration to the lesion area and differentiation into mature neurons, which were capable of forming synaptic contact and receiving glutamatergic excitatory synaptic input. The MED64 results suggest that functional synapsis could be established among regenerated neurons as well as between regenerated neurons and the host tissue, which has been evidenced to be glutamatergic excitatory synapsis. The electrophysiology and behavior evaluation results indicate that the paraplegic rats’ sensory and motor functions were recovered in some degree. Collectively, this study may shed light on paraplegia treatment in clinics.     

3D spheroids of human placenta-derived mesenchymal stem cells attenuate spinal cord injury in mice

Mesenchymal stem cell (MSC) is an absorbing candidate for cell therapy in treating spinal cord injury (SCI) due to its great potential for multiple cell differentiation, mighty paracrine secretion as well as vigorous immunomodulatory effect, of which are beneficial to the improvement of functional recovery post SCI. However, the therapeutic effects of MSC on SCI have been limited because of the gradual loss of MSC stemness in the process of expanding culture. Therefore, in this study, we aimed to maintain those beneficial properties of MSC via three-dimensional spheroid cell culture and then compared them with conventionally-cultured MSCs in the treatment of SCI both in vitro and in vivo with the aid of two-photon microscope. We found that 3D human placenta-derived MSCs (3D-HPMSCs) demonstrated a significant increase in secretion of anti-inflammatory factors and trophic factors like VEGF, PDGF, FGF via QPCR and Bio-Plex assays, and showed great potentials on angiogenesis and neurite morphogenesis when co-cultured with HUVECs or DRGs in vitro. After transplantation into the injured spinal cord, 3D-HPMSCs managed to survive for the entire experiment and retained their advantageous properties in secretion, and exhibited remarkable effects on neuroprotection by minimizing the lesion cavity, inhibiting the inflammation and astrogliosis, and promoting angiogenesis. Further investigation of axonal dieback via two-photon microscope indicated that 3D-HPMSCs could effectively alleviate axonal dieback post injury. Further, mice only treated with 3D-HPMSCs obtained substantial improvement of functional recovery on electrophysiology, BMS score, and Catwalk analysis. RNA sequencing suggested that the 3D-HPMSCs structure organization-related gene was significantly changed, which was likely to potentiate the angiogenesis and inflammation regulation after SCI. These results suggest that 3D-HPMSCs may hold great potential for the treatment of SCI.Subject terms: Spinal cord injury, Mesenchymal stem cells     

β1-Integrin and Integrin Linked Kinase Regulate Astrocytic Differentiation of Neural Stem Cells

Astrogliosis with glial scar formation after damage to the nervous system is a major impediment to axonal regeneration and functional recovery. The present study examined the role of β1-integrin signaling in regulating astrocytic differentiation of neural stem cells. In the adult spinal cord β1-integrin is expressed predominantly in the ependymal region where ependymal stem cells (ESCs) reside. β1-integrin signaling suppressed astrocytic differentiation of both cultured ESCs and subventricular zone (SVZ) progenitor cells. Conditional knockout of β1-integrin enhanced astrogliogenesis both by cultured ESCs and by SVZ progenitor cells. Previous studies have shown that injection into the injured spinal cord of a self-assembling peptide amphiphile that displays an IKVAV epitope (IKVAV-PA) limits glial scar formation and enhances functional recovery. Here we find that injection of IKVAV-PA induced high levels of β1-integrin in ESCs in vivo, and that conditional knockout of β1-integrin abolished the astroglial suppressive effects of IKVAV-PA in vitro. Injection into an injured spinal cord of PAs expressing two other epitopes known to interact with β1-integrin, a Tenascin C epitope and the fibronectin epitope RGD, improved functional recovery comparable to the effects of IKVAV-PA. Finally we found that the effects of β1-integrin signaling on astrogliosis are mediated by integrin linked kinase (ILK). These observations demonstrate an important role for β1-integrin/ILK signaling in regulating astrogliosis from ESCs and suggest ILK as a potential target for limiting glial scar formation after nervous system injury.     

Allografts of the acellular sciatic nerve and brain-derived neurotrophic factor repair spinal cord injury in adult rats

Objective

We aimed to investigate whether an innovative growth factor-laden scaffold composed of acellular sciatic nerve (ASN) and brain-derived neurotrophic factor (BDNF) could promote axonal regeneration and functional recovery after spinal cord injury (SCI).

Methods

Following complete transection at the thoracic level (T9), we immediately transplanted the grafts between the stumps of the severed spinal cords. We evaluated the functional recovery of the hindlimbs of the operated rats using the BBB locomotor rating scale system every week. Eight weeks after surgery, axonal regeneration was examined using the fluorogold (FG) retrograde tracing method. Electrophysiological analysis was carried out to evaluate the improvement in the neuronal circuits. Immunohistochemistry was employed to identify local injuries and recovery.

Results

The results of the Basso-Beattie-Bresnahan (BBB) scale indicated that there was no significant difference between the individual groups. The FG retrograde tracing and electrophysiological analyses indicated that the transplantation of ASN-BDNF provided a permissive environment to support neuron regeneration.

Conclusion

The ASN-BDNF transplantation provided a promising therapeutic approach to promote axonal regeneration and recovery after SCI, and can be used as part of a combinatory treatment strategy for SCI management.     

Neurotrophic factor gene delivery supports axonal regeneration after injury

A successful treatment for spinal cord injury (SCI) must include means to induce axonal regeneration and synaptogenesis. Though much research has demonstrated the effectiveness of neurotrophic factors (NFs) in supporting axonal regeneration, systemic delivery of doses sufficient to reach therapeutic concentrations and overcome their short half‐lives has caused adverse effects. Local expression of NFs would overcome these limitations. We tested whether local expression of NFs would induce axonal regeneration without adverse effects in two models of neural injury. In a chemical injury model the rat serotonergic system was lesioned with p‐chloroamphetamine. When an adenoviral vector carrying the gene for brain‐derived neurotrophic factor (BDNF) was injected into the denervated cortex BDNF expressed by the transfected cells induced serotonergic axon reinnervation only in area around the injection site. In a mechanical injury model the cortical spinal tract (CST) in rats was lesioned unilaterally at the level of the hindbrain. Neurotorphin‐3 (NT‐3) was expressed locally in the spinal cord either by direct injection of an adenoviral vector carrying the gene for NT‐3 or by retrograde delivery of the vector from the sciatic nerve. Axons were observed growing from the unlesioned CST across the midline to the denervated side. These data demonstrate that local expression of NFs will induce and support axonal regeneration in a circumscribed area after injury without adverse effects and suggest that a therapy for SCI based upon this strategy may include NF gene delivery. Acknowledgements: Supported by NIH grant NS35280 and Mission Connect of the TIRR Foundation.     

More attention on glial cells to have better recovery after spinal cord injury

Functional improvement after spinal cord injury remains an unsolved difficulty. Glial scars, a major component of SCI lesions, are very effective in improving the rate of this recovery. Such scars are a result of complex interaction mechanisms involving three major cells, namely, astrocytes, oligodendrocytes, and microglia. In recent years, scientists have identified two subtypes of reactive astrocytes, namely, A1 astrocytes that induce the rapid death of neurons and oligodendrocytes, and A2 astrocytes that promote neuronal survival. Moreover, recent studies have suggested that the macrophage polarization state is more of a continuum between M1 and M2 macrophages. M1 macrophages that encourage the inflammation process kill their surrounding cells and inhibit cellular proliferation. In contrast, M2 macrophages promote cell proliferation, tissue growth, and regeneration. Furthermore, the ability of oligodendrocyte precursor cells to differentiate into adult oligodendrocytes or even neurons has been reviewed. Here, we first scrutinize recent findings on glial cell subtypes and their beneficial or detrimental effects after spinal cord injury. Second, we discuss how we may be able to help the functional recovery process after injury.     

Neurotrophic factor gene delivery supports axonal regeneration after injury

A successful treatment for spinal cord injury (SCI) must include means to induce axonal regeneration and synaptogenesis. Though much research has demonstrated the effectiveness of neurotrophic factors (NFs) in supporting axonal regeneration, systemic delivery of doses sufficient to reach therapeutic concentrations and overcome their short half-lives has caused adverse effects. Local expression of NFs would overcome these limitations. We tested whether local expression of NFs would induce axonal regeneration without adverse effects in two models of neural injury. In a chemical injury model the rat serotonergic system was lesioned with p-chloroamphetamine. When an adenoviral vector carrying the gene for brain-derived neurotrophic factor (BDNF) was injected into the denervated cortex BDNF expressed by the transfected cells induced serotonergic axon reinnervation only in area around the injection site. In a mechanical injury model the cortical spinal tract (CST) in rats was lesioned unilaterally at the level of the hindbrain. Neurotorphin-3 (NT-3) was expressed locally in the spinal cord either by direct injection of an adenoviral vector carrying the gene for NT-3 or by retrograde delivery of the vector from the sciatic nerve. Axons were observed growing from the unlesioned CST across the midline to the denervated side. These data demonstrate that local expression of NFs will induce and support axonal regeneration in a circumscribed area after injury without adverse effects and suggest that a therapy for SCI based upon this strategy may include NF gene delivery.
Acknowledgements:   Supported by NIH grant NS35280 and Mission Connect of the TIRR Foundation.     

Functional recovery after spinal cord injury in dogs treated with a combination of Matrigel and neural-induced adipose-derived mesenchymal Stem cells

Background aimsPrevious studies have reported that scaffold or cell-based transplantation may improve functional recovery following spinal cord injury (SCI), but these results were based on neuronal regeneration and cell replacement. In this study, we investigated whether a combination of Matrigel and neural-induced mesenchymal stem cells (NMSC) improved hindlimb function in dogs with SCI, and what mechanisms were involved.MethodsWe pre-differentiated canine adipose-derived mesenchymal stem cells into NMSC. A total of 12 dogs subjected to SCI procedures were assigned to one of the following three transplantation treatment groups: phosphate-buffered saline (PBS); Matrigel; or Matrigel seeded with NMSC. Treatment occurred 1 week after SCI. Basso, Beattie and Bresnahan (B.B.B.) and Tarlov scores, histopathology, immunofluorescence staining and Western blot analysis were used to evaluate the treatment effects.ResultsCompared with dogs administered PBS or Matrigel alone, dogs treated with Matrigel + NMSC showed significantly better functional recovery 8 weeks after transplantation. Histology and immunochemical analysis revealed that the combination of Matrigel + NMSC reduced fibrosis from secondary injury processes and improved neuronal regeneration more than the other treatments. In addition, the combination of Matrigel + NMSC decreased the expression of inflammation and/or astrogliosis markers. Increased expressions of intracellular molecules related to neuronal extension, neuronal markers and neurotrophic factors were also found in the Matrigel + NMSC group. However, the expression of nestin as a neural stem cell marker was increased with Matrigel aloneConclusionsThe combination of Matrigel + NMSC produced beneficial effects in dogs with regard to functional recovery following SCI through enhancement of anti-inflammation, anti-astrogliosis, neuronal extension and neuronal regeneration effects.     

The regenerative effects of electromagnetic field on spinal cord injury

Traumatic spinal cord injury (SCI) is typically the result of direct mechanical impact to the spine, leading to fracture and/or dislocation of the vertebrae along with damage to the surrounding soft tissues. Injury to the spinal cord results in disruption of axonal transmission of signals. This primary trauma causes secondary injuries that produce immunological responses such as neuroinflammation, which perpetuates neurodegeneration and cytotoxicity within the injured spinal cord. To date there is no FDA-approved pharmacological agent to prevent the development of secondary SCI and induce regenerative processes aimed at healing the spinal cord and restoring neurological function. An alternative method to electrically activate spinal circuits is the application of a noninvasive electromagnetic field (EMF) over intact vertebrae. The EMF method of modulating molecular signaling of inflammatory cells emitted in the extra-low frequency range of <100 Hz, and field strengths of <5 mT, has been reported to decrease inflammatory markers in macrophages, and increase endogenous mesenchymal stem cell (MSC) proliferation and differentiation rates. EMF has been reported to promote osteogenesis by improving the effects of osteogenic media, and increasing the proliferation of osteoblasts, while inhibiting osteoclast formation and increasing bone matrix in vitro. EMF has also been shown to increase chondrogenic markers and collagen and induce neural differentiation, while increasing cell viability by over 50%. As advances are made in stem cell technologies, stabilizing the cell line after differentiation is crucial to SCI repair. Once cell-seeded scaffolds are implanted, EMF may be applied outside the wound for potential continued adjunct treatment during recovery.