Improvement of contusive spinal cord injury in rats by co-transplantation of gamma-aminobutyric acid-ergic cells and bone marrow stromal cells

CREB1 Facilitates GABAergic Neural Differentiation of Human Mesenchymal Stem Cells through BRN2 for Pain Alleviation and Locomotion Recovery after Spinal Cord Injury

The transplantation of GABAergic neuron cells has been reported to alleviate nerve pain and improve motor function after spinal cord injury (SCI). However, human mesenchymal stem cell (hMSC) differentiation into GABAergic neuron cells in a sufficient quantity remains to be accomplished. From a database screening, cAMP-responsive element-binding protein 1 (CREB1) was chosen as a potential modulator due to its critical role in the protein-protein interaction of genes related to GABAergic neural differentiation. Here, CREB1 was overexpressed in transfected hMSCs, where CREB1 could induce differentiation into GABAergic neuron cells with an upregulation of Map2 and GAD1 by 2- and 3.4-fold, respectively. Additionally, GABAergic neural differentiation was enhanced, while Notch signaling was inhibited, and BRN2 transcriptional activation played an important role in neuronal maturation. Moreover, transfected hMSCs injected into immunocompromised mice caused by CsA exhibited the neuronal markers Tuj1 and Map2 via the intraspinal route, suggesting an improvement in survival and neural differentiation. Significantly, improvement in both BMS scores (6.2 ± 1.30 vs. 4 ± 0) and thermal hyperalgesia latency (7.74 ± 2.36 s vs. 4.52 ± 0.39 s) was seen compared with the SCI naïve treatment at 4 weeks post-transplantation. Our study demonstrates that CREB1 is crucial in generating induced GABAergic neuron cells (iGNs) originating from hMSCs. Transplanting iGNs to injured spinal cord provides a promising strategy for alleviating neuropathic pain and locomotion recovery after SCI.

The Role of NMDA Receptor Partial Antagonist, Carbamathione, as a Therapeutic Agent for Transient Global Ischemia

Carbamathione (Carb), an NMDA glutamate receptor partial antagonist, has potent neuroprotective functions against hypoxia- or ischemia-induced neuronal injury in cell- or animal-based stroke models. We used PC-12 cell cultures as a cell-based model and bilateral carotid artery occlusion (BCAO) for stroke. Whole-cell patch clamp recording in the mouse retinal ganglion cells was performed. Key proteins involved in apoptosis, endoplasmic reticulum (ER) stress, and heat shock proteins were analyzed using immunoblotting. Carb is effective in protecting PC12 cells against glutamate- or hypoxia-induced cell injury. Electrophysiological results show that Carb attenuates NMDA-mediated glutamate currents in the retinal ganglion cells, which results in activation of the AKT signaling pathway and increased expression of pro-cell survival biomarkers, e.g., Hsp 27, P-AKT, and Bcl2 and decreased expression of pro-cell death markers, e.g., Beclin 1, Bax, and Cleaved caspase 3, and ER stress markers, e.g., CHOP, IRE1, XBP1, ATF 4, and eIF2α. Using the BCAO animal stroke model, we found that Carb reduced the brain infarct volume and decreased levels of ER stress markers, GRP 78, CHOP, and at the behavioral level, e.g., a decrease in asymmetric turns and an increase in locomotor activity. These findings for Carb provide promising and rational strategies for stroke therapy.

Restoration of spinal cord injury: From endogenous repairing process to cellular therapy

Spinal cord injury (SCI) disrupts neurological pathways and impacts sensory, motor, and autonomic nerve function. There is no effective treatment for SCI currently. Numerous endogenous cells, including astrocytes, macrophages/microglia, and oligodendrocyte, are involved in the histological healing process following SCI. By interfering with cells during the SCI repair process, some advancements in the therapy of SCI have been realized. Nevertheless, the endogenous cell types engaged in SCI repair and the current difficulties these cells confront in the therapy of SCI are poorly defined, and the mechanisms underlying them are little understood. In order to better understand SCI and create new therapeutic strategies and enhance the clinical translation of SCI repair, we have comprehensively listed the endogenous cells involved in SCI repair and summarized the six most common mechanisms involved in SCI repair, including limiting the inflammatory response, protecting the spared spinal cord, enhancing myelination, facilitating neovascularization, producing neurotrophic factors, and differentiating into neural/colloidal cell lines.

Upregulated protein O-GlcNAcylation promoted functional and structural recovery of the contused spinal cord injury in rats by Thiamet-G treatment

Objectives-Elevated protein O-GlcNAcylation could benefit cell survival and promote organ functional recovery. Thiamet-G (O-GlcNAcase inhibitor) could upregulate protein O-GlcNAcylation level to improve dyskinesia in models of neurodegenerative diseases without any obvious detrimental side-effects. Therefore, we conducted this study to investigate the effects of protein O-GlcNAcylation upregulation by Thiamet-G on the spinal cord injury (SCI) in rats. Methods-We randomly assigned 74 rats to three groups: sham-operated group (Sham) with no lesion (n = 22), injured control group (SCI+SS) with saline solution (n = 26), and Thiamet-G treated group (SCI+Thiamet-G) (n = 26). We assessed Locomotor behavior using the Basso, Beattice, and Bresnahan (BBB) scale and evaluated histopathological alterations by morphometry and histochemistry. We also assessed potential inflammatory effects by microglia/macrophages immunohistochemistry, and potential apoptosis effects by caspase-3 western blot. Results-Thiamet-G treatment improved hindlimb motor functional recovery by inducing elevated protein O-GlcNAcylation, and mitigated the severity, reduced the lesion size and promoted the structural recovery of the injured spinal cord. Thiamet-G treatment also inhibited microglia/macrophages infiltration at the injury sites and the caspase-3 mediated apoptosis pathway. Discussion-We conclude that Thiamet-G induced elevated protein O-GlcNAcylation to ameliorate acute SCI, which could provide a potential novel therapeutic approach for SCI treatment.

Early intervention for spinal cord injury with human induced pluripotent stem cells oligodendrocyte progenitors

Induced pluripotent stem (iPS) cells are at the forefront of research in regenerative medicine and are envisaged as a source for personalized tissue repair and cell replacement therapy. Here, we demonstrate for the first time that oligodendrocyte progenitors (OPs) can be derived from iPS cells generated using either an episomal, non-integrating plasmid approach or standard integrating retroviruses that survive and differentiate into mature oligodendrocytes after early transplantation into the injured spinal cord. The efficiency of OP differentiation in all 3 lines tested ranged from 40% to 60% of total cells, comparable to those derived from human embryonic stem cells. iPS cell lines derived using episomal vectors or retroviruses generated a similar number of early neural progenitors and glial progenitors while the episomal plasmid-derived iPS line generated more OPs expressing late markers O1 and RIP. Moreover, we discovered that iPS-derived OPs (iPS-OPs) engrafted 24 hours following a moderate contusive spinal cord injury (SCI) in rats survived for approximately two months and that more than 70% of the transplanted cells differentiated into mature oligodendrocytes that expressed myelin associated proteins. Transplanted OPs resulted in a significant increase in the number of myelinated axons in animals that received a transplantation 24 h after injury. In addition, nearly a 5-fold reduction in cavity size and reduced glial scarring was seen in iPS-treated groups compared to the control group, which was injected with heat-killed iPS-OPs. Although further investigation is needed to understand the mechanisms involved, these results provide evidence that patient-specific, iPS-derived OPs can survive for three months and improve behavioral assessment (BBB) after acute transplantation into SCI. This is significant as determining the time in which stem cells are injected after SCI may influence their survival and differentiation capacity.

Transplantation of bone marrow mesenchymal stem cells pretreated with valproic acid in rats with an acute spinal cord injury

This study aimed to investigate whether valproic acid (VPA) pretreatment enhances the therapeutic effectiveness of mesenchymal stem cells derived from bone marrow (BMSCs) transplanted into rats with an acute spinal cord injury (SCI). BMSCs were pretreated with VPA before transplantation and then intravenously injected 1 week after SCI. Before transplantation, levels of CXC chemokine receptor 4 (CXCR4) expression in BMSCs were tested using quantitative real-time PCR and Western blotting. Stromal derived factor-1 (SDF-1), the unique ligand of CXCR4, was quantified using RT-PCR and immunofluorescence. The locomotor function of rats with an SCI was evaluated using the Basso, Beattie, and Bresnahan (BBB) locomotor rating scale. Fluorescence microscopy and hematoxylin-eosin (HE) staining were also performed to evaluate pathophysiological changes after transplantation. On day 7 after SCI, the level of SDF-1 expression peaked. CXCR4 expression increased significantly in BMSCs pretreated with VPA. After intravenous transplantation, BrdU-labeled BMSCs were noted at the spinal injury site, and this was especially true for BMSCs pretreated with VPA. More significant functional improvement was observed in rats receiving BMSCs pretreated with VPA than in other groups of rats. AMD3100 partially inhibited improvement. This study demonstrates that pretreatment with VPA before transplantation enhances the therapeutic benefits of BMSCs in terms of greater cell migration and better neurological outcomes after traumatic SCI. The mechanism of this enhancement may be related to the SDF-1/CXCR4 axis. Therefore, pretreatment of BMSCs with VPA warrants further study in relation to the treatment of traumatic SCI.

A prospective randomized double-blind clinical trial using a combination of olfactory ensheathing cells and Schwann cells for the treatment of chronic complete spinal cord injuries

The aim of this prospective randomized double-blind clinical study is to examine the benefits of using olfactory ensheathing cells (OECs) combined with or without Schwann cells (SCs) in treating chronic complete spinal cord injuries (SCIs). This would offer patients a better alternative for neurological functional recovery. According to the initial design, 28 eligible participants with cervical chronic complete SCI were recruited and randomly allocated into four groups of seven participants each. The neurological assessments were to be performed according to the American Spinal Injury Association (ASIA) and International Association of Neurorestoratology (IANR) Functional Rating Scales, in combination with electrophysiological tests, for example, electromyography (EMG) and paraspinal somatosensory evoked potentials (PSSEPs). Here we have summarized the data from seven patients; three patients received an OEC intraspinal transplantation, one underwent SC implantation, and one received a combination of OECs and SCs. The remaining two patients were used as controls. The scores were evaluated independently by at least two neurologists in a blinded fashion for comparing the neurological functional changes during pre- and post-cell transplantation (6-month follow-up). All patients who received OECs, SCs alone, and a combination of them showed functional improvement. Mild fever occurred in one of the patients with OEC transplant that subsided after symptomatic treatments. All treated patients except one showed improvement in the electrophysiological tests. The functional improvement rate comprises 5/5 (100%) in the treated group, but 0/2 (0%) in the control group (p = 0.008). These preliminary findings show that transplanting OECs, SCs, or a combination of them is well tolerated and that they have beneficial effects in patients. Thus, further studies in larger patient cohorts are warranted to assess the benefits and risks of these intervention strategies. This manuscript is published as part of the IANR special issue of Cell Transplantation.

The marginal division of the striatum and hippocampus has different role and mechanism in learning and memory

The memory function of the hippocampal formation (Hip) and the marginal division (MrD) of neostriatum was compared. Rats with bilateral lesions of the MrD either immediate or 24 h after training in Y-maze were found to have decrease in correct runs in both groups. However, animals with transected afferent and efferent nerve bundles to isolate the Hip immediately or 24 h after training in Y-maze were found to show a decrease in correct runs only in the group injured immediately after Y-maze training but not in the 24 h group suggesting that MrD is likely involved in the entire process of long-term memory consolidation whereas the Hip only contributes to memory in the early stage. In addition, animals treated with a NMDA receptor (NMDAR) blocker, e.g. MK-801, showed decreased correct runs in Y-maze test and in expression level of phosphorylated CREB (pCREB) in neurons of the MrD but not in the Hip. Furthermore, animals treated with okadaic acid (OA), a potent protein phosphatase 1 inhibitor, showed increased correct runs in the Y-maze test. The expression level of pCREB and c-Fos and c-Jun was found increased in neurons of the MrD and the Hip in response to OA treatment. In conclusion, NMDAR and pCREB are involved in memory functions of both the Hip and the MrD. NMDAR might regulate pCREB level in neurons of the MrD but not in the Hip. Hence, the processes and mechanism of learning and memory involved in the MrD and the Hip may be different.

Prevention of liver fibrosis by intrasplenic injection of high-density cultured bone marrow cells in a rat chronic liver injury model

Endothelial progenitor cells (EPCs) from bone marrow have proven to be functional for the prevention of liver fibrosis in chronic liver injury. However, expansion of EPCs in culture is complicated and expansive. Previously, we have established a simple method that could enrich and expand EPCs by simple seeding bone marrow cells in high density dots. The purpose of this study is to evaluate whether cells derived from high-density (HD) culture of rat bone marrow cells could prevent the liver fibrosis in a chronic liver injury rat model, induced by carbon tetrachloride (CCl₄). Flow cytometric analysis showed that cells from HD culture were enriched for EPCs, expressing high levels of EPC markers. Intrasplenic injection of HD cultured bone marrow cells in the CCl₄-induced liver injury rat showed an enhanced antifibrogenic effect compared with animals treated with cells from regular-density culture. The antifibrogenic effect was demonstrated by biochemical and histological analysis 4 weeks post-transplantation. Furthermore, cells from HD culture likely worked through increasing neovascularization, stimulating liver cell proliferation, and suppressing pro-fibrogenic factor expression. HD culture, which is a simple and cost-effective procedure, could potentially be used to expand bone marrow cells for the treatment of liver fibrosis.

Mode of action of S-methyl-N, N-diethylthiocarbamate sulfoxide (DETC-MeSO) as a novel therapy for stroke in a rat model

One approach for protecting neurons from excitotoxic damage in stroke is to attenuate receptor activity with specific antagonists. S-Methyl-N, N-diethylthiocarbamate sulfoxide (DETC-MeSO), the active metabolite of disulfiram, has been shown to be a partial antagonist of glutamate receptors and effective in reducing seizure. First, we investigated neuroprotective effect of DETC-MeSO on primary cortical neuronal culture under hypoxia/reoxygenation condition in vitro. Then, DETC-MeSO was administered subcutaneously for 4 and 8 days with the first injection occurring 1 h before or 24 h after reperfusion in the rat middle cerebral artery occlusion stroke model. Rats were subjected to the neuroscore test, and the brain was analyzed for infarct size. Monitoring neurotransmitter release was carried out by microdialysis. Heat shock proteins, key proteins involved in apoptosis and endoplasmic reticulum (ER) stress, were analyzed by immunoblotting. DETC-MeSO greatly reduced both cell death following hypoxia/reoxygenation and brain infarct size. It improved performance on the neuroscore test and attenuated proteolysis of αII-spectrin. The level of pro-apoptotic proteins declined, and anti-apoptotic and HSP27 protein expressions were markedly increased. Levels of the ER stress protein markers p-PERK, p-eIF2α, ATF4, JNK, XBP-1, GADD34, and CHOP significantly declined after DETC-MeSO administration. Microdialysis data showed that DETC-MeSO increased high potassium-induced striatal dopamine release indicating that more neurons were protected and survived under ischemic insult in the presence of DETC-MeSO. We also showed that DETC-MeSO can prevent gliosis. DETC-MeSO elicits neuroprotection through the preservation of ER resulting in reduction of apoptosis by increase of anti-apoptotic proteins and decrease of pro-apoptotic proteins.