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.

Transplantation of tissue engineering neural network and formation of neuronal relay into the transected rat spinal cord.

Severe spinal cord injury (SCI) causes loss of neural connectivity and permanent functional deficits. Re-establishment of new neuronal relay circuits after SCI is therefore of paramount importance. The present study tested our hypothesis if co-culture of neurotrophin-3 (NT-3) gene-modified Schwann cells (SCs, NT-3-SCs) and TrkC (NT-3 receptor) gene-modified neural stem cells (NSCs, TrkC-NSCs) in a gelatin sponge scaffold could construct a tissue engineering neural network for re-establishing an anatomical neuronal relay after rat spinal cord transection. Eight weeks after transplantation, the neural network created a favorable microenvironment for axonal regeneration and for survival and synaptogenesis of NSC-derived neurons. Biotin conjugates of cholera toxin B subunit (b-CTB, a transneuronal tracer) was injected into the crushed sciatic nerve to label spinal cord neurons. Remarkably, not only ascending and descending nerve fibers, but also propriospinal neurons, made contacts with b-CTB positive NSC-derived neurons. Moreover, b-CTB positive NSC-derived neurons extended their axons making contacts with the motor neurons located in areas caudal to the injury/graft site of spinal cord. Further study showed that NT-3/TrkC interactions activated the PI3K/AKT/mTOR pathway and PI3K/AKT/CREB pathway affecting synaptogenesis of NSC-derived neurons. Together, our findings suggest that NT-3-mediated TrkC signaling plays an essential role in constructing a tissue engineering neural network thus representing a promising avenue for effective exogenous neuronal relay-based treatment for 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 ß1. 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.

Graft of the NT-3 persistent delivery gelatin sponge scaffold promotes axon regeneration, attenuates inflammation, and induces cell migration in rat and canine with spinal cord injury.

Persistent neurotrophic factor delivery is crucial to create a microenvironment for cell survival and nerve regeneration in spinal cord injury (SCI). This study aimed to develop a NT-3/fibroin coated gelatin sponge scaffold (NF-GS) as a novel controlled artificial release therapy for SCI. In vitro, bone marrow-derived mesenchymal stem cells (MSCs) were planted into the NF-GS and release test showed that NF-GS was capable to generate a sustainable NT-3 release up to 28 days. MSCs in NF-GS had high cell activity with excellent cell distribution and phenotype. Then, the NF-GS was transplanted into the injury site of spinal cord of rat and canine in vivo, which exhibited strong biocompatibility during post-transplantation period. Four weeks following transplantation, the concentration of NT-3 was much higher than that in control groups. Cavity areas in the injury/graft site were significantly reduced due to tissue regeneration and axonal extensions associated with myelin sheath through the glial scar into the NF-GS. Additionally, the NF-GS decreased the inflammation by reducing the CD68 positive cells and TNF-α. A striking feature was the occurrence of some cells and myelin-like structure that appeared to traverse the NF-GS. The present results demonstrate that the NF-GS has the property to control the release of NT-3 from the NT-3/fibroin complex thus facilitating regeneration of injured spinal cord.

Cholera Toxin B Subunit Shows Transneuronal Tracing after Injection in an Injured Sciatic Nerve.

Cholera toxin B subunit (CTB) has been extensively used in the past for monosynaptic mapping. For decades, it was thought to lack the ability of transneuronal tracing. In order to investigate whether biotin conjugates of CTB (b-CTB) would pass through transneurons in the rat spinal cord, it was injected into the crushed left sciatic nerve. For experimental control, the first order afferent neuronal projections were defined by retrograde transport of fluorogold (FG, a non-transneuronal labeling marker as an experimental control) injected into the crushed right sciatic nerve in the same rat. Neurons containing b-CTB or FG were observed in the dorsal root ganglia (DRG) at the L4-L6 levels ipsilateral to the tracer injection. In the spinal cord, b-CTB labeled neurons were distributed in all laminae ipsilaterally between C7 and S1 segments, but labeling of neurons at the cervical segment was abolished when the T10 segment was transected completely. The interneurons, distributed in the intermediate gray matter and identified as gamma-aminobutyric acid-ergic (GABAergic), were labeled by b-CTB. In contrast, FG labeling was confined to the ventral horn neurons at L4-L6 spinal segments ipsilateral to the injection. b-CTB immunoreactivity remained to be restricted to the soma of neurons and often appeared as irregular patches detected by light and electron microscopy. Detection of monosialoganglioside (GM1) in b-CTB labeled neurons suggests that GM1 ganglioside may specifically enhance the uptake and transneuronal passage of b-CTB, thus supporting the notion that it may be used as a novel transneuronal tracer.

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.

Integration of donor mesenchymal stem cell-derived neuron-like cells into host neural network after rat spinal cord transection.

Functional deficits following spinal cord injury (SCI) primarily attribute to loss of neural connectivity. We therefore tested if novel tissue engineering approaches could enable neural network repair that facilitates functional recovery after spinal cord transection (SCT). Rat bone marrow-derived mesenchymal stem cells (MSCs), genetically engineered to overexpress TrkC, receptor of neurotrophin-3 (NT-3), were pre-differentiated into cells carrying neuronal features via co-culture with NT-3 overproducing Schwann cells in 3-dimensional gelatin sponge (GS) scaffold for 14 days in vitro. Intra-GS formation of MSC assemblies emulating neural network (MSC-GS) were verified morphologically via electron microscopy (EM) and functionally by whole-cell patch clamp recording of spontaneous post-synaptic currents. The differentiated MSCs still partially maintained prototypic property with the expression of some mesodermal cytokines. MSC-GS or GS was then grafted acutely into a 2 mm-wide transection gap in the T9-T10 spinal cord segments of adult rats. Eight weeks later, hindlimb function of the MSC-GS-treated SCT rats was significantly improved relative to controls receiving the GS or lesion only as indicated by BBB score. The MSC-GS transplantation also significantly recovered cortical motor evoked potential (CMEP). Histologically, MSC-derived neuron-like cells maintained their synapse-like structures in vivo; they additionally formed similar connections with host neurites (i.e., mostly serotonergic fibers plus a few corticospinal axons; validated by double-labeled immuno-EM). Moreover, motor cortex electrical stimulation triggered c-fos expression in the grafted and lumbar spinal cord cells of the treated rats only. Our data suggest that MSC-derived neuron-like cells resulting from NT-3-TrkC-induced differentiation can partially integrate into transected spinal cord and this strategy should be further investigated for reconstructing disrupted neural circuits.

Combination of electroacupuncture and grafted mesenchymal stem cells overexpressing TrkC improves remyelination and function in demyelinated spinal cord of rats.

This study attempted to graft neurotrophin-3 (NT-3) receptor (TrkC) gene modified mesenchymal stem cells (TrkC-MSCs) into the demyelinated spinal cord and to investigate whether electroacupuncture (EA) treatment could promote NT-3 secretion in the demyelinated spinal cord as well as further enhance grafted TrkC-MSCs to differentiate into oligodendrocytes, remyelination and functional recovery. Ethidium bromide (EB) was microinjected into the spinal cord of rats at T10 to establish a demyelinated model. Six groups of animals were prepared for the experiment: the sham, PBS, MSCs, MSCs+EA, TrkC-MSCs and TrkC-MSCs+EA groups. The results showed that TrkC-MSCs graft combined with EA treatment (TrkC-MSCs+EA group) significantly increased the number of OPCs and oligodendrocyte-like cells differentiated from MSCs. Immunoelectron microscopy showed that the oligodendrocyte-like cells differentiated from TrkC-MSCs formed myelin sheaths. Immunofluorescence histochemistry and Western blot analysis indicated that TrkC-MSCs+EA treatment could promote the myelin basic protein (MBP) expression and Kv1.2 arrangement trending towards the normal level. Furthermore, behavioural test and cortical motor evoked potentials detection demonstrated a significant functional recovery in the TrkC-MSCs+EA group. In conclusion, our results suggest that EA treatment can increase NT-3 expression, promote oligodendrocyte-like cell differentiation from TrkC-MSCs, remyelination and functional improvement of demyelinated spinal cord.

Graft of the gelatin sponge scaffold containing genetically-modified neural stem cells promotes cell differentiation, axon regeneration, and functional recovery in rat with spinal cord transection.

Biological materials combined with genetically-modified neural stem cells (NSCs) are candidate therapy targeting spinal cord injury (SCI). Based on our previous studies, here we performed gelatin sponge (GS) scaffold seeded with neurotrophin-3 (NT-3) and its receptor TrkC gene modifying NSCs for repairing SCI. Eight weeks later, compared with other groups, neurofilament-200 and 5-hydroxytryptamine positive nerve fibers were more in the injury site of the N+T-NSCs group. Immunofluorescence staining showed the grafted NSCs could differentiate into microtubule associated protein (Map2), postsynaptic density (PSD95), and mouse oligodendrocyte special protein (MOSP) positive cells. The percentage of the Map2, PSD95, and MOSP positive cells in the N+T-NSCs group was higher than the other groups. Immuno-electron microscopy showed the grafted NSCs making contact with each other in the injury site. Behavioral analysis indicated the recovery of hindlimbs locomotion was better in the groups receiving cell transplant, the best recovery was found in the N+T-NSCs group. Electrophysiology revealed the amplitude of cortical motor evoked potentials was increased significantly in the N+T-NSCs group, but the latency remained long. These findings suggest the GS scaffold containing genetically-modified NSCs may bridge the injury site, promote axon regeneration and partial functional recovery in SCI rats.

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.

The integration of NSC-derived and host neural networks after rat spinal cord transection.

Rebuilding structures that can bridge the injury gap and enable signal connection remains a challenging issue in spinal cord injury. We sought to determine if genetically enhanced expression of TrkC in neural stem cells (NSCs) and neurotrophin-3 in Schwann cells (SCs) co-cultured in a gelatin sponge scaffold could constitute a neural network, and whether it could act as a relay to rebuilt signal connection after spinal cord transection. Indeed, many NSCs in the scaffold assumed neuronal features including formation of synapses. By whole-cell patch clamp, the synapses associated with NSC-derived neurons were excitable. Grafting of the scaffold with differentiating NSCs + SCs into rats with a segment of the spinal cord removed had resulted in a significant functional recovery of the paralyzed hind-limbs. Remarkably, the NSC-derived neurons formed new synaptic contacts suggesting that the scaffold can form a relay for conduction of signals through the injury gap of spinal cord.

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.

Peri-sciatic administration of recombinant rat IL-1ß induces mechanical allodynia by activation of src-family kinases in spinal microglia in rats.

Previous studies have shown that Interleukin-1 beta (IL-1ß) is implicated in the modulation of pain sensitivity. In the present study, we found that a single peri-sciatic administration of rat recombinant IL-1ß (rrIL-1ß) at doses of 20 and 200 pg (100, 1000 ng/l, in 200 µl volume) induced mechanical allodynia in bilateral hindpaws in rats, lasting for about 50 days. No axonal or Schwann cell damage at the drug administration site was found following 1000 ng/l rrIL-1ß administration. The results of immunofluorescence showed that microglial cells in bilateral spinal dorsal horn were activated after peri-sciatic administration of rrIL-1ß (1000 ng/l). The immunoreactivity (IR) of Iba1 (a marker for microglia) and phosphorylated src-family kinases (p-SFKs) increased significantly in the ipsilateral and contralateral lumbar spinal dorsal horn on day 1 and day 3 after rrIL-1ß administration, respectively. Double immunofluorescence staining revealed that the increased p-SFKs-IR was almost restricted within the microglia. Intrathecal delivery of minocycline (100 µg in 10 µl volume), a selective inhibitor of microglia, started 30 min before rrIL-1ß administration and once daily thereafter for 7 days, blocked mechanical allodynia induced by rrIL-1ß completely and inhibited the upregulation of p-SFKs. Intrathecal delivery of SFKs inhibitor PP2 (12 µg in 10 µl volume) also blocked mechanical allodynia induced by rrIL-1ß completely. These data suggest that activation of SFKs in spinal microglia mediates mechanical allodynia induced by peri-sciatic administration of rrIL-1ß.

Neurotrophin-3 gene modified mesenchymal stem cells promote remyelination and functional recovery in the demyelinated spinal cord of rats.

Multiple sclerosis (MS) is a debilitating neurodegenerative disease characterized by axonal/neuronal damage that may be caused by defective remyelination. Current therapies aim to slow the rate of degeneration, however there are no treatment options that can stop or reverse the myelin sheath damage. Bone marrow mesenchymal stem cells (MSCs) are a potential candidate for the cell implantation-targeted therapeutic strategies, but the pro-remyelination effects of MSCs when directly injected into a demyelinated cord lesion have been questioned. Neurotrophin-3 (NT-3) has been shown to serve a crucial role in the proliferation, differentiation and maturation of oligodendrocyte lineages. Here, we showed that implantation of NT-3 gene-modified MSCs via a recombinant adenoviral vector (Adv) into a region of ethidium bromide (EB)-induced demyelination in the spinal cord resulted in significant improvement of locomotor function and restoration of electrophysiological properties in rats. The morphological basis of this recovery was evidenced by robust myelin basic protein (MBP) expression and the extensive remyelination. AdvNT-3-MSC implants promote the endogenous remyelinating cells to participate directly in myelination, which was confirmed under light and electron microscopy. Our study suggested that genetically modified MSCs could be a potential therapeutic avenue for improving the efficacy of stem cell treatment for neurodegenerative diseases such as MS.

Fig4 expression in the rodent nervous system and its potential role in preventing abnormal lysosomal accumulation.

The phosphatase FIG4 regulates the concentration of phosphatidylinositol 3,5-diphosphate (PI3,5P2), a molecule critical for endosomal/lysosomal membrane trafficking and neuron function. We investigated Fig4 expression in the developing CNS of mice and rats using Western blot, real-time polymerase chain reaction, and morphological techniques in situ and in vitro and after spinal cord injury. Fig4 was expressed at a high levels throughout development in myelinating cells, particularly Schwann cells, and dorsal root ganglia sensory neurons. Fig4 protein and mRNA in CNS neurons were markedly diminished in adult versus embryonal animals. Spinal cord hemisection induced upregulation of Fig4 in adult spinal cord tissues that was associated with accumulation of lysosomes in neurons and glia. This accumulation appeared similar to the abnormal lysosomal storage observed in dorsal root ganglia of young fig4-null mice. The results suggest that Fig4 is involved in normal neural development and the maintenance of peripheral nervous system myelin. We speculate that adequate levels of Fig4 may be required to prevent neurons and glia from excessive lysosomal accumulation after injury and in neurodegeneration.

Cograft of neural stem cells and schwann cells overexpressing TrkC and neurotrophin-3 respectively after rat spinal cord transection.

Effectively bridging the lesion gap is still an unmet demand for spinal cord repair. In the present study, we tested our hypothesis if cograft of Schwann cells (SCs) and neural stem cells (NSCs) with genetically enhanced expression of neurotrophin-3 (NT-3) and its high affinity receptor TrkC, respectively, could strengthen neural repair through increased NSC survival and neuronal differentiation at the epicenter after complete T10 spinal cord transection in adult rats. Transplantation of NT-3-SCs + TrkC-NSCs in Gelfoam (1 × 10(6)/implant/rat; n = 10) into the lesion gap immediately following injury results in significantly improved relay of the cortical motor evoked potential (CMEP) and cortical somatosensory evoked potential (CSEP) as well as ameliorated hindlimb deficits, relative to controls (treated with LacZ-SCs + LacZ-NSCs, NT-3-SCs + NSCs, NSCs alone, or lesion only; n = 10/group). Further analyses demonstrate that NT-3-SCs + TrkC-NSCs cografting augments levels of neuronal differentiation of NSCs, synaptogenesis (including inhibitory/type II-like synapses) and myelin formation of SCs, in addition to neuroprotection and outgrowth of serotonergic fibers in the lesioned spinal cord. Compared with controls, the treated spinal cords also show elevated expression of laminin, a pro-neurogenic factor, and decreased presence of chondroitin sulfate proteoglycans, major inhibitors of axonal growth and neuroplasticity. Together, our data suggests that coimplantation of neurologically compatible cells with compensatorily overexpressed therapeutic genes may constitute a valuable approach to study, and/or develop therapies for spinal cord injury (SCI).

Transplantation of artificial neural construct partly improved spinal tissue repair and functional recovery in rats with spinal cord transection.

Delivery of cellular and/or trophic factors to the site of injury may promote neural repair or axonal regeneration and return of function after spinal cord injury. Engineered scaffolds provide a platform to deliver therapeutic cells and neurotrophic molecules. To explore therapeutic potential of engineered neural tissue, we generated an artificial neural construct in vitro, and transplanted this construct into a completely transected spinal cord of adult rats. Two months later, behavioral analysis showed that the locomotion recovery was significantly improved compared with control animals. Immunoreactivity against microtubule associated protein 2 (Map2) and postsynaptic density 95 (PSD95) demonstrated that grafted cells had a higher survival rate and were able to differentiate toward neuronal phenotype with ability to form synapse-like structure at the injury site; this was also observed under the electron microscope. Immunostaining of neurofilament-200 (NF-200) showed that the number of nerve fibers regrowing into the injury site in full treatment group was much higher than that seen in other groups. Furthermore, Nissl staining revealed that host neuron survival rate was significantly increased in rats with full treatments. However, there were no biotin dextran amine (BDA) anterograde tracing fibers crossing through the injury site, suggesting the limited ability of corticospinal tract axonal regeneration. Taken together, although our artificial neural construct permits grafted cells to differentiate into neuronal phenotype, synaptogenesis, axonal regeneration and partial locomotor function recovery, the limited capacity for corticospinal tract axonal regeneration may affect its potential therapy in spinal cord injury.

An experimental electro-acupuncture study in treatment of the rat demyelinated spinal cord injury induced by ethidium bromide.

Oligodendrocyte precursor cells (OPCs) are one of the potential treating tools for multiple sclerosis (MS). Therefore, the cell number and differentiation of OPCs in a demyelinated spinal cord are crucial for improvement of reparative process. In the present study, we investigated whether "Governor Vessel (GV)" electro-acupuncture (EA) could efficiently promote increase in cell number and differentiation of OPCs into oligodendrocytes, remyelination and functional recovery in the demyelinated spinal cord. The spinal cord of adult Sprague-Dawley rats was microinjected with ethidium bromide (EB) at T10, to establish a demyelinated model. Six groups of animals were performed for the experiment. After 15 days EA treatment, neurotrophin-3 (NT-3) level and number of NG2-positive OPCs were significantly increased. Compared with the sham group, more NG2-positive OPCs were distributed between neurofilament (NF)-positive nerve fibres or closely associated with them in the lesion site and nearby tissue. In rats given longer EA treatment for 30 days, the number of adenomatous polyposis coli (APC)-positive oligodendrocytes was increased. Concomitantly, the number of newly formed myelins was increased. This was coupled by increase in endogenous oligodendrocyte involved in myelin formation. Furthermore, behavioural test and spinal cord evoked potential detection demonstrated a significant functional recovery in the EA+EB day 30 group. Our results suggest EA treatment can promote NT-3 expression, increase the cell number and differentiation of endogenous OPCs, and remyelination in the demyelinated spinal cord as well as the functional improvement of demyelinated spinal cord.