A long-term observation of olfactory ensheathing cells transplantation to repair white matter and functional recovery in a focal ischemia model in rat

Magnetic resonance imaging detects cerebral gray and white matter injury correlated with cognitive impairments in diabetic db/db mice

Type-2 diabetes not only causes gray matter injury but also induces widespread white matter damages, which may contribute the cognitive impairments. This study aimed to assess the structural alterations of the gray and white matter in 20-week-old diabetic db/db mice using magnetic resonance imaging including T2-weighted imaging (T2WI) and diffusion tensor imaging (DTI), and to correlate them with the cognitive performance detected by Morris water maze (MWM). The results revealed impaired spatial learning and memory in db/db mice. T2WI detected severe brain atrophy involving the hippocampus and cortex after diabetes. DTI showed reduced fractional anisotropy (FA) in the cortex, hippocampus, corpus callosum/external capsule, and increased radial diffusivity in the corpus callosum/external capsule of the db/db mice. The immunostaining confirmed the MRI findings showing decreased cell density in the cortex, hippocampus, and reduced integrated optical density of Luxol fast blue staining in the corpus callosum/external capsule. The correlational analysis revealed that the T2WI-derived tissue atrophy and DTI-derived FA in the relevant gray matter and white matter significantly correlated with the behavior performance in the MWM test. Collectively, the present in vivo MRI detected varying degrees of structural abnormalities in the gray and white matter of db/db mice, which might be favorable predictors of diabetic cognitive dysfunction. Our findings might provide new clues for identifying gray and white matter damages associated with cognitive decline, which is imperative for the evaluation of potential pharmacological therapies in preclinical phase.

The role of the ATP-Binding Cassette A1 (ABCA1) in neurological disorders: a mechanistic review

INTRODUCTION

Cholesterol homeostasis is critical for normal brain function. It is tightly controlled by various biological elements. ATP-binding cassette transporter A1 (ABCA1) is a membrane transporter that effluxes cholesterol from cells, particularly astrocytes, into the extracellular space. The recent studies pertaining to ABCA1's role in CNS disorders were included in this study.

AREAS COVERED

In this comprehensive literature review, preclinical and human studies showed that ABCA1 has a significant role in the following diseases or disorders: Alzheimer's disease, Parkinson's disease, Huntington's disease, multiple sclerosis, neuropathy, anxiety, depression, psychosis, epilepsy, stroke, and brain ischemia and trauma.

EXPERT OPINION

ABCA1 via modulating normal and aberrant brain functions such as apoptosis, phagocytosis, BBB leakage, neuroinflammation, amyloid β efflux, myelination, synaptogenesis, neurite outgrowth, and neurotransmission promotes beneficial effects in aforementioned diseases. ABCA1 is a key molecule in the CNS. By boosting its expression or function, some CNS disorders may be resolved. In preclinical studies, liver X receptor agonists have shown promise in treating CNS disorders via ABCA1 and apoE enhancement.

Update of application of olfactory ensheathing cells and stem cells/exosomes in the treatment of retinal disorders

Age-related macular degeneration, diabetic retinopathy, retinitis pigmentosa and other retinal disorders are the main causes of visual impairment worldwide. In the past, these retinal diseases, especially dry age-related macular degeneration, proliferative diabetic retinopathy and retinitis pigmentosa, were treated with traditional surgery and drugs. However, the effect was moderate. In recent years, researchers have used embryonic stem cells, induced pluripotent stem cells, mesenchymal stem cells, olfactory ensheathing cells and other stem cells to conduct experiments and found that stem cells can inhibit inflammation, regulate immune response, secrete neurotrophic factors, and differentiate into retinal cells to replace and promote restoration of the damaged parts. These stem cells have the potential to treat retinal diseases. Whether it is in animal experiments or clinical trials, the increase in the number of retinal cells, maintenance of function and improvement of visual function all reflect the advanced of stem cells to treat retinal diseases, but its risk preserves the donor's hidden pathogenic genes, immune rejection and tumorigenicity. With the development of exosomes study, researchers have discovered that exosomes come from a wide range of sources and can be secreted by almost all types of cells. Using exosomes with stem cell to treat retinal diseases is more effective than using stem cells alone. This review article summarizes the recent advances in the application of olfactory ensheathing cells and stem cells/exosomes in the treatment of retinal disorders.

High mobility group box-1 serves a pathogenic role in spinal cord injury via the promotion of pro-inflammatory cytokines

Traumatic spinal cord injury (SCI) is a devastating condition marked by permanent motor, sensory, and autonomic dysfunction, in which the inflammatory response serves an important and preventable role. High mobility group box-1 (HMGB1) is a potent regulator of inflammation in numerous acute and chronic inflammatory conditions.; however, the role of HMGB1 in SCI remains unclear. The present study aimed to characterize the temporal dynamics of HMGB1 release after SCI, to investigate the role of spinal microglia activation in mediating the effects of HMGB1 on SCI, and to explore the therapeutic potential of intrathecal anti-HMGB1 polyclonal antibody on alleviating SCI. The present study demonstrated that HMGB1 expression was increased immediately after traumatic injury of a primary spinal neuron culture. It was found that neutralizing HMGB1 significantly ameliorated SCI pathogenesis and hind limb paralysis. Moreover, the levels of a number of pro-inflammatory cytokines in the SCI lesion were reduced when local HMGB1 was blocked by anti-HMGB1 antibody. In addition, the injured neuron-derived conditioned medium increased TNF-α secretion and the NF-κB pathway in the BV2 microglia cell line via HMGB1. Collectively, these results indicated that HMGB1 served an important role in SCI inflammation and suggested the therapeutic potential of an anti-HMGB1 antibody for SCI.

Research progress on the therapeutic effect of olfactory ensheathing cell transplantation on ischemic stroke

Olfactory ensheathing cells (OECs) are a special type of glial cell in the olfactory system, which exhibit neuroprotective, immunomodulatory, and angiogenic effects. Although many studies have focused on the reversal of demyelination and axonal degeneration (during spinal cord injury) by OECs, few reports have focused on the ability of OECs to repair ischemic nerve injury. This article reviews the protective effects of OEC transplantation in ischemic stroke and provides a theoretical basis and new strategy for OEC transplantation in the treatment of ischemic stroke.

Clinical Trials of Stem Cell Therapy for Cerebral Ischemic Stroke

Despite recent developments in innovative treatment strategies, stroke remains one of the leading causes of death and disability worldwide. Stem cell therapy is currently attracting much attention due to its potential for exerting significant therapeutic effects on stroke patients. Various types of cells, including bone marrow mononuclear cells, bone marrow/adipose-derived stem/stromal cells, umbilical cord blood cells, neural stem cells, and olfactory ensheathing cells have enhanced neurological outcomes in animal stroke models. These stem cells have also been tested via clinical trials involving stroke patients. In this article, the authors review potential molecular mechanisms underlying neural recovery associated with stem cell treatment, as well as recent advances in stem cell therapy, with particular reference to clinical trials and future prospects for such therapy in treating stroke.

ABCA1/ApoE/HDL Signaling Pathway Facilitates Myelination and Oligodendrogenesis after Stroke

ATP-binding cassette transporter A1 (ABCA1) plays an important role in the regulation of apolipoprotein E (ApoE) and the biogenesis of high-density lipoprotein (HDL) cholesterol in the mammalian brain. Cholesterol is a major source for myelination. Here, we investigate whether ABCA1/ApoE/HDL contribute to myelin repair and oligodendrogenesis in the ischemic brain after stroke. Specific brain ABCA1-deficient (ABCA1^-B/-B) and ABCA1-floxed (ABCA1^fl/fl) control mice were subjected to permanent distal middle-cerebral-artery occlusion (dMCAo) and were intracerebrally administered (1) artificial mouse cerebrospinal fluid (CSF) as vehicle control, (2) human plasma HDL3, and (3) recombined human ApoE2 starting 24 h after dMCAo for 14 days. All stroke mice were sacrificed 21 days after dMCAo. The ABCA1^-B/-B–dMCAo mice exhibit significantly reduced myelination and oligodendrogenesis in the ischemic brain as well as decreased functional outcome 21 days after stroke compared with ABCA1^fl/fl mice; administration of human ApoE2 or HDL3 in the ischemic brain significantly attenuates the deficits in myelination and oligodendrogenesis in ABCA1^-B/-B–dMCAo mice ( p < 0.05, n = 9/group). In vitro, ABCA1^-B/-B reduces ApoE expression and decreases primary oligodendrocyte progenitor cell (OPC) migration and oligodendrocyte maturation; HDL3 and ApoE2 treatment significantly reverses ABCA1^-B/-B-induced reduction in OPC migration and oligodendrocyte maturation. Our data indicate that the ABCA1/ApoE/HDL signaling pathway contributes to myelination and oligodendrogenesis in the ischemic brain after stroke.

Olfactory Ensheathing Cells: A Trojan Horse for Glioma Gene Therapy

BACKGROUND

The olfactory ensheathing cells (OECs) migrate from the peripheral nervous system to the central nervous system (CNS), a critical process for the development of the olfactory system and axonal extension after injury in neural regeneration. Because of their ability to migrate to the injury site and anti-inflammatory properties, OECs were tested against different neurological pathologies, but were never studied in the context of cancer. Here, we evaluated OEC tropism to gliomas and their potential as a "Trojan horse" to deliver therapeutic transgenes through the nasal pathway, their natural route to CNS.

METHODS

OECs were purified from the mouse olfactory bulb and engineered to express a fusion protein between cytosine deaminase and uracil phosphoribosyltransferase (CU), which convert the prodrug 5-fluorocytosine (5-FC) into cytotoxic metabolite 5-fluorouracil, leading to a bystander killing of tumor cells. These cells were injected into the nasal cavity of mice bearing glioblastoma tumors and OEC-mediated gene therapy was monitored by bioluminescence imaging and confirmed with survival and ex vivo histological analysis. All statistical tests were two-sided.

RESULTS

OECs migrated from the nasal pathway to the primary glioma site, tracked infiltrative glioma stemlike cells, and delivered therapeutic transgene, leading to a slower tumor growth and increased mice survival. At day 28, bioluminescence imaging revealed that mice treated with a single injection of OEC-expressing CU and 5-FC had tumor-associated photons (mean [SD]) of 1.08E + 08 [9.7E + 07] vs 4.1E + 08 [2.3E + 08] for control group (P < .001), with a median survival of 41 days vs 34 days, respectively (ratio = 0.8293, 95% confidence interval = 0.4323 to 1.226, P <  .001) (n = 9 mice per group).

CONCLUSIONS

We show for the first time that autologous transplantation of OECs can target and deliver therapeutic transgenes to brain tumors upon intranasal delivery, the natural route of OECs to the CNS, which could be extended to other types of cancer.

MRI Evaluation of Axonal Remodeling After Combination Treatment With Xiaoshuan Enteric-Coated Capsule and Enriched Environment in Rats After Ischemic Stroke

Xiaoshuan enteric-coated capsule (XSEC) is a compound Chinese medicine widely used for the treatment of ischemic stroke. Enriched environment (EE) is a rehabilitative intervention designed to facilitate physical, cognitive, and social activity after brain injury. This study aimed to assess whether the XSEC and EE combination could provide synergistic efficacy in axonal remodeling compared to that with a single treatment after ischemic stroke using magnetic resonance imaging (MRI) followed by histological analysis. Rats were subjected to permanent middle cerebral artery occlusion and treated with XSEC and EE alone or in combination for 30 days. T2-weighted imaging and diffusion tensor imaging (DTI) were performed to examine the infarct volume and axonal remodeling, respectively. The co-localization of Ki67 with NG2 or CNPase was examined by immunofluorescence staining to assess oligodendrogenesis. The expressions of growth associated protein-43 (GAP-43) and growth inhibitors NogoA/Nogo receptor (NgR)/RhoA/Rho-associated kinase2 (ROCK2) were measured using western blot and qRT-PCR. The Morris water maze (MWM) was performed to evaluate the cognitive function. MRI and histological measurements indicated XSEC and EE individually benefited axonal reorganization after stroke. Notably, XSEC + EE decreased infarct volume compared with XSEC or EE monotherapy and increased ipsilateral residual volume compared with vehicle group. DTI showed XSEC + EE robustly increased fractional anisotropy while decreased axial diffusivity and radial diffusivity in the injured cortex, striatum, and external capsule. Meanwhile, diffusion tensor tractography revealed XSEC + EE elevated fiber density in the cortex and external capsule and increased fiber length in the striatum and external capsule compared with the monotherapies. These MRI measurements, confirmed by histology, showed that XSEC + EE promoted axonal restoration. Additionally, XSEC + EE amplified oligodendrogenesis, decreased the expressions of NogoA/NgR/RhoA/ROCK2, and increased the expression of GAP-43 in the peri-infarct tissues. In parallel to these findings, rats treated with XSEC + EE exhibited higher cognitive recovery than those treated with XSEC or EE monotherapy, as evidenced by MWM test. Taken together, our data implicated that XSEC + EE exerted synergistic effects on alleviating atrophy and encouraging axonal reorganization partially by promoting oligodendrogenesis and overcoming intrinsic growth-inhibitory signaling, thereby facilitating higher cognitive recovery.

Olfactory ensheathing cells facilitate neurite sprouting and outgrowth by secreting high levels of hevin

Transplantation of olfactory ensheathing cells (OECs) has been shown to enhance synapse formation. However, the mechanisms underlying this effect are not completely understood. We performed profiling of the OEC and astrocyte secretomes via a proteomics approach, in case hevin secreted by astrocytes might be involved in the formation of synapses. Semi-quantitative proteomic analysis revealed that 25 proteins were highly expressed, and 22 were weakly expressed in OEC conditioned medium compared with astrocyte conditioned medium. These molecules are highly associated with neural differentiation and regeneration, enzyme regulatory activity, and growth factor binding. The quantification data of clusterin, fibronectin, hevin, insulin-like growth factor binding protein 2 and secreted protein acidic and rich in cysteine were further confirmed by western blotting. Moreover, the addition of hevin in the culture medium improved neurite sprouting and outgrowth of differentiated neural stem cells. The greater expression of hevin in OEC conditioned medium than in astrocyte conditioned medium was associated with a greater capacity of synaptic formation. Thus, our results indicate that soluble factors secreted by OECs provide a permissive environment for nerve repair, and hevin is one of the key molecules facilitating neurite sprouting and outgrowth.

MiR-126 Mediates Brain Endothelial Cell Exosome Treatment-Induced Neurorestorative Effects After Stroke in Type 2 Diabetes Mellitus Mice

Background and Purpose- Stroke patients with type 2 diabetes mellitus (T2DM) exhibit increased vascular and white matter damage and have worse prognosis compared with nondiabetic stroke patients. We investigated the neurorestorative effects of exosomes derived from mouse brain endothelial cells (EC-Exo) as treatment for stroke in T2DM mice and investigated the role of miR-126 in mediating EC-Exo-derived therapeutic benefits in T2DM-stroke mice. Methods- Adult, male BKS.Cg-m+/+Lepr^db/J (T2DM) mice were subjected to photothrombotic stroke model. T2DM mice were intravenously injected at 3 days after stroke with (1) PBS; (2) liposome mimic (vehicle control, 3×10¹⁰); (3) EC-Exo (3×10¹⁰); (4) knockdown of miR-126 in EC-Exo (miR-126^-/- EC-Exo, 3×10¹⁰). Behavioral and cognitive tests were performed, and mice were sacrificed at 28 days after stroke. Results- Compared with non-DM stroke mice, T2DM-stroke mice exhibit significantly decreased serum and brain tissue miR-126 expression. Endothelial cells and EC-Exo contain high levels of miR-126 compared with other cell types or exosomes derived from other types of cells, respectively (smooth muscle cells, astrocytes, and marrow stromal cells). Compared with PBS or liposome mimic treatment, EC-Exo treatment of T2DM-stroke mice significantly improves neurological and cognitive function, increases axon density, myelin density, vascular density, arterial diameter, as well as induces M2 macrophage polarization in the ischemic boundary zone. MiR-126^-/- EC-Exo treatment significantly decreases miR-126 expression in serum and brain, as well as attentuates EC-Exo treatment-induced functional improvement and does not significantly increase axon and myelin density, vascular density, arterial diameter or induce M2 macrophage polarization in T2DM-stroke mice. In vitro, EC-Exo treatment significantly increases primary cortical neuron axonal outgrowth and increases endothelial capillary tube formation whereas miR-126^-/- EC-Exo attentuates EC-Exo induced capillary tube formation and axonal outgrowth. Conclusions- EC-Exo treatment of stroke promotes neurorestorative effects in T2DM mice. MiR-126 may mediate EC-Exo-induced neurorestorative effects in T2DM mice. Visual Overview- An online visual overview is available for this article.

Early wheel-running promotes functional recovery by improving mitochondria metabolism in olfactory ensheathing cells after ischemic stroke in rats

Olfactory ensheathing cells (OECs) has been widely studied in stroke. The present study was aimed at examining the role of wheel-running treatment (WR) on rat olfactory ensheathing cells (rOECs) functions. Thirty adult male Sprague Dawley rats were randomly divided into two groups: the middle cerebral artery occlusion (MCAO) group and WR + MCAO group. Motor behavior was assessed through the footfault test, and the results showed that WR training markedly improved the neurobehavioral outcome. The glucose metabolic status of the brain was assessed with the micro-PET. This training significantly enhanced the glucose uptake of olfactory bulb in the early stage of WR treatment. The function of rOECs mitochondrial was significantly enhanced after 10 days of treatment. Body weight of rats in both of the two groups decreased and then increased slowly following the days. But the growth trend of the WR + MCAO group was no significantly higher than that of the WR group. This training significantly enhanced the glucose uptake, improved the proliferation of rOECs and increased the expression level of cytochrome C (Cyt-c). The mechanism may be associated with the facilitation of mitochondrial function of rOECs cells. Including facilitation of mitochondrial fusion, fission, and accompanying increased quantities of mitochondria. Obtained results indicate that early WR treatment may exert enhanced function on rOECs in vivo and increased mitochondrial amounts, and improved the expression level of Cyt-c after ischemic stroke.

On the Viability and Potential Value of Stem Cells for Repair and Treatment of Central Neurotrauma: Overview and Speculations

Central neurotrauma, such as spinal cord injury or traumatic brain injury, can damage critical axonal pathways and neurons and lead to partial to complete loss of neural function that is difficult to address in the mature central nervous system. Improvement and innovation in the development, manufacture, and delivery of stem-cell based therapies, as well as the continued exploration of newer forms of stem cells, have allowed the professional and public spheres to resolve technical and ethical questions that previously hindered stem cell research for central nervous system injury. Recent in vitro and in vivo models have demonstrated the potential that reprogrammed autologous stem cells, in particular, have to restore functionality and induce regeneration-while potentially mitigating technical issues of immunogenicity, rejection, and ethical issues of embryonic derivation. These newer stem-cell based approaches are not, however, without concerns and problems of safety, efficacy, use and distribution. This review is an assessment of the current state of the science, the potential solutions that have been and are currently being explored, and the problems and questions that arise from what appears to be a promising way forward (i.e., autologous stem cell-based therapies)-for the purpose of advancing the research for much-needed therapeutic interventions for central neurotrauma.

MiR-126 Contributes to Human Umbilical Cord Blood Cell-Induced Neurorestorative Effects After Stroke in Type-2 Diabetic Mice

Diabetes mellitus (DM) is a high risk factor for stroke and leads to more severe vascular and white-matter injury than stroke in non-DM. We tested the neurorestorative effects of delayed human umbilical cord blood cell (HUCBC) treatment of stroke in type-2 diabetes (T2DM). db/db-T2DM and db/+-non-DM mice were subjected to distal middle cerebral artery occlusion (dMCAo) and were treated 3 days after dMCAo with: (a) non-DM + Phosphate buffered saline (PBS); (b) T2DM + PBS; (c) T2DM + naïve-HUCBC; (d) T2DM + miR-126(-/-) HUCBC. Functional evaluation, vascular and white-matter changes, neuroinflammation, and miR-126 effects were measured in vivo and in vitro. T2DM mice exhibited significantly decreased serum and brain tissue miR-126 expression compared with non-DM mice. T2DM + HUCBC mice exhibited increased miR-126 expression, increased tight junction protein expression, axon/myelin, vascular density, and M2-macrophage polarization. However, decreased blood-brain barrier leakage, brain hemorrhage, and miR-126 targeted gene vascular cell adhesion molecule-1 and monocyte chemotactic protein 1 expression in the ischemic brain as well as improved functional outcome were present in HUCBC-treated T2DM mice compared with control T2DM mice. MiR-126(-/-) HUCBC-treatment abolished the benefits of naïve-HUCBC-treatment in T2DM stroke mice. In vitro, knock-in of miR-126 in primary cultured brain endothelial cells (BECs) or treatment of BECs with naïve-HUCBCs significantly increased capillary-like tube formation, and increased axonal outgrowth in primary cultured cortical neurons; whereas treatment of BECs or cortical neurons with miR-126(-/-) HUCBC attenuated HUCBC-treatment-induced capillary tube formation and axonal outgrowth. Our data suggest delayed HUCBC-treatment of stroke increases vascular/white-matter remodeling and anti-inflammatory effects; MiR-126 may contribute to HUCBC-induced neurorestorative effects in T2DM mice.

Cell-based therapy approaches: the hope for incurable diseases

Cell therapies aim to repair the mechanisms underlying disease initiation and progression, achieved through trophic effect or by cell replacement. Multiple cell types can be utilized in such therapies, including stem, progenitor or primary cells. This review covers the current state of cell therapies designed for the prominent disorders, including cardiovascular, neurological (Parkinson's disease, amyotrophic lateral sclerosis, stroke, spinal cord injury), autoimmune (Type 1 diabetes, multiple sclerosis, Crohn's disease), ophthalmologic, renal, liver and skeletal (osteoarthritis) diseases. Various cell therapies have reached advanced clinical trial phases with potential marketing approvals in the near future, many of which are based on mesenchymal stem cells. Advances in pluripotent stem cell research hold great promise for regenerative medicine. The information presented in this review is based on the analysis of the cell therapy collection detailed in LifeMap Discovery(®) (LifeMap Sciences Inc., USA) the database of embryonic development, stem cell research and regenerative medicine.

A microarray study of middle cerebral occlusion rat brain with acupuncture intervention

Microarray analysis was used to investigate the changes of gene expression of ischemic stroke and acupuncture intervention in middle cerebral artery occlusion (MCAo) rat brain. Results showed that acupuncture intervention had a remarkable improvement in neural deficit score, cerebral blood flow, and cerebral infarction volume of MCAo rats. Microarray analysis showed that a total of 627 different expression genes were regulated in ischemic stroke. 417 genes were upregulated and 210 genes were downregulated. A total of 361 different expression genes were regulated after acupuncture intervention. Three genes were upregulated and 358 genes were downregulated. The expression of novel genes after acupuncture intervention, including Tph1 and Olr883, was further analyzed by Real-Time Quantitative Polymerase Chain Reaction (RT-PCR). Upregulation of Tph1 and downregulation of Olr883 indicated that the therapeutic effect of acupuncture for ischemic stroke may be closely related to the suppression of poststroke depression and regulation of olfactory transduction. In conclusion, the present study may enrich our understanding of the multiple pathological process of ischemic brain injury and indicate possible mechanisms of acupuncture on ischemic stroke.

Recombinant human erythropoietin increases cerebral cortical width index and neurogenesis following ischemic stroke

The cerebral cortical expansion index refers to the ratio between left and right cortex width and is recognized as an indicator for cortical hyperplasia. Cerebral ischemia was established in CB-17 mice in the present study, and the mice were subsequently treated with recombinant human erythropoietin via subcutaneous injection. Results demonstrated that cerebral cortical width index significantly increased. Immunofluorescence detection showed that the number of nuclear antigen antibody/5-bromodeoxyuridine-positive cells at the infarction edge significantly increased. Correlation analysis revealed a negative correlation between neurological scores and cortical width indices in rats following ischemic stroke. These experimental findings suggested that recombinant human erythropoietin promoted cerebral cortical hyperplasia, increased cortical neurogenesis, and enhanced functional recovery following ischemic stroke.

The potential therapeutic applications of olfactory ensheathing cells in regenerative medicine

Olfactory ensheathing cells (OECs) are unique glia cells restricted to the primary olfactory system including the olfactory mucosa, olfactory nerve, and the outer nerve layer of the olfactory bulb. OECs guide growing olfactory axons from the neurons of the nasal cavity olfactory mucosa to the olfactory bulb to connect both the peripheral nervous system (PNS) and central nervous system (CNS). Based on these specialized abilities of OECs, transplantation of OECs to injury sites has been widely investigated for their potential therapeutic applications in neural repair in different injuries. In this article, we reviewed the properties of OECs and their roles in olfactory regeneration and in treatment of different injuries including spinal cord injury, PNS injury, and stroke and neurodegenerative diseases.

Transplantation of olfactory ensheathing cells attenuates acute carbon monoxide poisoning-induced brain damages in rats

In this study, the therapeutic effect of olfactory ensheathing cells (OEC) transplantation on brain damage was evaluated on acute carbon monoxide (CO) poisoning rat model. Two weeks after primary culture, OECs were microinjected into hippocampus of CO poisoning rats. Survival of OECs in the host was observed and quantified. OECs survived at 2 weeks, but surviving cell number was found sharply decreased at 6 weeks and reduced to less than 10(3) at 8 weeks after transplantation. At 2 weeks after transplantation, motor function test and cerebral edema assay were performed and followed by pathological examination including hematoxylin and eosin and immunohistochemistry staining to observe the neuron injury and synapsin I and growth associated protein-43 (GAP-43) expression. Furthermore, biomarkers of oxidative stress and apoptosis related proteins in the hippocampus were detected. The results showed that CO exposure led to neurological dysfunction and cerebral edema in rats. After OEC transplantation, neurological function was significantly improved and the cerebral edema was alleviated. In addition, the numbers of neurons and Nissl bodies were increased and synapsin I and GAP-43 protein expressions were upregulated in the hippocampus. Compared with CO poisoned rats, superoxide dismutase activity and glutathione content were both increased and methane dicarboxylic aldehyde level was decreased in the hippocampus of OEC transplanted rats. Moreover, OEC transplantation reduced apoptosis induced by CO exposure. The Bcl-2 expression was significantly upregulated and Bax expression was significantly downregulated. The activity of caspase-3 and the cleaved-poly ADP-ribose polymerase expression were decreased. Taken together, our data suggest that OEC attenuates brain damages induced by acute CO poisoning within 2 weeks after transplantation.

The potential for cell-based therapy in perinatal brain injuries

Perinatal brain injuries are a leading cause of cerebral palsy worldwide. The potential of stem cell therapy to prevent or reduce these impairments has been widely discussed within the medical and scientific communities and an increasing amount of research is being conducted in this field. Animal studies support the idea that a number of stem cells types, including cord blood and mesenchymal stem cells have a neuroprotective effect in neonatal hypoxia-ischemia. Both these cell types are readily available in a clinical setting. The mechanisms of action appear to be diverse, including immunomodulation, activation of endogenous stem cells, release of growth factors, and anti-apoptotic effects. Here, we review the different types of stem cells and progenitor cells that are potential candidates for therapeutic strategies in perinatal brain injuries, and summarize recent preclinical and clinical studies.

Understanding the neural repair-promoting properties of olfactory ensheathing cells

Olfactory ensheathing glial cells (OECs) are a specialized type of glia that form a continuously aligned cellular pathway that actively supports unprecedented regeneration of primary olfactory axons from the periphery into the central nervous system. Implantation of OECs stimulates neural repair in experimental models of spinal cord, brain and peripheral nerve injury and delays disease progression in animal models for neurodegenerative diseases like amyotrophic lateral sclerosis. OECs implanted in the injured spinal cord display a plethora of pro-regenerative effects; they promote axonal regeneration, reorganize the glial scar, remyelinate axons, stimulate blood vessel formation, have phagocytic properties and modulate the immune response. Recently genome wide transcriptional profiling and proteomics analysis combined with classical or larger scale "medium-throughput" bioassays have provided novel insights into the molecular mechanism that endow OECs with their pro-regenerative properties. Here we review these studies and show that the gaps that existed in our understanding of the molecular basis of the reparative properties of OECs are narrowing. OECs express functionally connected sets of genes that can be linked to at least 10 distinct processes directly relevant to neural repair. The data indicate that OECs exhibit a range of synergistic cellular activities, including active and passive stimulation of axon regeneration (by secretion of growth factors, axon guidance molecules and basement membrane components) and critical aspects of tissue repair (by structural remodeling and support, modulation of the immune system, enhancement of neurotrophic and antigenic stimuli and by metabolizing toxic macromolecules). Future experimentation will have to further explore the newly acquired knowledge to enhance the therapeutic potential of OECs.

A synthetic oxygen carrier-olfactory ensheathing cell composition system for the promotion of sciatic nerve regeneration

The treatment of lengthy peripheral nerve defects is challenging in the field of the regenerative medicine. Thus far, many nerve scaffolds with seeded cells have been developed, which hold great potential to replace nerve autograft in bridging lengthy nerve defects by providing guiding and bioactive cues. However, low oxygen status has been found within nerve scaffolds after their implantation in vivo, which has been shown to result in death or loss of function of supportive cells, and significantly limit nerve regeneration and functional recovery after nerve injury. In the present study, perfluorotributylamine (PFTBA) was introduced into a collagen-chitosan conduit within which olfactory ensheathing cells (OECs) were seeded to increase oxygen supply to OECs, as well as regenerating axons. The "PFTBA-OECs" enriched scaffolds were then used to bridge a 15-mm-long sciatic nerve defect in rats. Both nerve regeneration and functional recovery were examined at pre-defined time points after surgery. We found that the number of GFP-labeled OECs was significantly higher in the "PFTBA-OECs" scaffold than that in the single OECs scaffold. In addition, PFTBA was found to enhance the beneficial effect of OECs-enriched scaffold on axonal regeneration and functional recovery. All these findings indicate that the "PFTBA-OECs" enriched scaffolds are capable of promoting nerve regeneration and functional recovery, which might be attributable, at least in part, to their beneficial effect on the survival of OECs after their implantation in vivo.

Endothelial nitric oxide synthase regulates white matter changes via the BDNF/TrkB pathway after stroke in mice

Stroke induced white matter (WM) damage is associated with neurological functional deficits, but the underlying mechanisms are not well understood. In this study, we investigate whether endothelial nitric oxide synthase (eNOS) affects WM-damage post-stroke. Adult male wild-type (WT) and eNOS knockout (eNOS(-/-)) mice were subjected to middle cerebral artery occlusion. Functional evaluation, infarct volume measurement, immunostaining and primary cortical cell culture were performed. To obtain insight into the mechanisms underlying the effects of eNOS(-/-) on WM-damage, measurement of eNOS, brain-derived neurotrophic factor (BDNF) and its receptor TrkB in vivo and in vitro were also performed. No significant differences were detected in the infarction volume, myelin density in the ipsilateral striatal WM-bundles and myelin-based protein expression in the cerebral ischemic border between WT and eNOS(-/-) mice. However, eNOS(-/-) mice showed significantly: 1) decreased functional outcome, concurrent with decreases of total axon density and phosphorylated high-molecular weight neurofilament density in the ipsilateral striatal WM-bundles. Correlation analysis showed that axon density is significantly positive correlated with neurological functional outcome; 2) decreased numbers of oligodendrocytes / oligodendrocyte progenitor cells in the ipsilateral striatum; 3) decreased synaptophysin, BDNF and TrkB expression in the ischemic border compared with WT mice after stroke (n = 12/group, p<0.05). Primary cortical cell culture confirmed that the decrease of neuronal neurite outgrowth in the neurons derived from eNOS(-/-) mice is mediated by the reduction of BDNF/TrkB (n = 6/group, p<0.05). Our data show that eNOS plays a critical role in WM-damage after stroke, and eNOS(-/-)-induced decreases in the BDNF/TrkB pathway may contribute to increased WM-damage, and thereby decrease functional outcome.

Multiple cell transplantation based on an intraparenchymal approach for patients with chronic phase stroke

Stroke is the third leading cause of death worldwide and a huge perpetrator in adult disability. This pilot clinical study investigates the possible benefits of transplanting multiple cells in chronic stroke. A total of 10 consecutive stroke patients were treated by combination cell transplantation on the basis of an intraparenchymal approach from November 2003 to April 2011. There were six males and four females. Their age ranged from 42 to 87 years, and the course of disease varied from 6 months to 20 years. Six patients suffered cerebral infarction, and four patients suffered a brain hemorrhage. The olfactory ensheathing cells, neural progenitor cells, umbilical cord mesenchymal cells, and Schwann cells were injected through selected routes including intracranial parenchymal implantation, intrathecal implantation, and intravenous administration, respectively. The clinical neurological function was assessed carefully and independently before treatment and during a long-term follow-up using the Clinic Neurologic Impairment Scale and the Barthel index. All patients were followed up successfully from 6 months to 2 years after cell transplantation. Every subject achieved neurological function amelioration including improved speech, muscle strength, muscular tension, balance, pain, and breathing; most patients had an increased Barthel index score and Clinic Neurologic Impairment Scale score. These preliminary results demonstrate the novel strategy of combined multiple cell therapy based on intraparenchymal delivery: it appears to be relatively clinically safe and at least initially beneficial for chronic stroke patients. This manuscript is published as part of the International Association of Neurorestoratology (IANR) supplement issue of Cell Transplantation.

Long-term and spatial memory effects of selective β1-antagonists after transient focal ischaemia in rats

BACKGROUND

Although various reports have shown that β-antagonists provide neuroprotective effects after cerebral ischaemia, their effect on spatial memory after transient focal ischaemia is not known. We investigated the treatment of β1-antagonists on neurological outcome spatial memory for 1 month after focal cerebral ischaemia in rats.

METHODS

Male rats randomly received an i.v. infusion of saline 0.5 ml h(-1), esmolol 200 μg kg(-1) min(-1), or landiolol 50 μg kg(-1) min(-1). Infusion was initiated 30 min before middle cerebral artery occlusion and continued for 24 h. The infarct areas in the hippocampus and striatum were measured after the final retention trial and neurological examinations.

RESULTS

Neurological deficit scores in the landiolol- and esmolol-treated rats were significantly lower than in the control rats at 1, 4, 7, and 11 days after ischaemia (P<0.05). Using the Morris water maze to assess spatial memory, we found that escape latency and swimming path length to the platform were significantly shorter in the landiolol-treated rats, compared with the saline-treated rats at 4 and 11 days after ischaemia (P<0.05). The mean (SD) infarct area was 19.1 (8.0)% in the striatum and 18.6 (10.0)% in the hippocampus of the landiolol-treated rats, and 16.8 (14.0)% and 16.8 (15.0)% in the striatum and hippocampus, respectively, of esmolol-treated rats. This was significantly less than in control rats [striatum 31.7 (14.0)% and hippocampus 29.8 (13.0)%, P<0.05].

CONCLUSIONS

The current study indicates that although esmolol and landiolol provided long-term neuroprotection in terms of histological outcome, they had no effect on neurological outcome and spatial memory retention.

Noninvasive monitoring of immunosuppressive drug efficacy to prevent rejection of intracerebral glial precursor allografts

The development of cell-based therapies opens up new avenues for treating a myriad of diseases of the central nervous system (CNS). While significant effort is being directed toward development of patient-specific, autologous transplantable cells, at present, the majority of cell transplantation studies performed clinically utilize allografts. In this context, the issue of graft rejection and immunoprotection is of key importance. In this study, we transplanted mouse glial-restricted progenitors into immunodeficient, immunocompetent, and immunosuppressed mice and monitored their survival noninvasively using bioluminescence imaging (BLI). With the use of serial BLI, we evaluated both the prevalence and dynamics of cell rejection. We demonstrate that allografts in immunocompetent mice were rejected at a rate of 69.2% (n = 13) indicating that graft tolerance is possible even without immunosuppression. Immunosuppression using a combination of rapamycin and FK506 or cyclosporin failed to fully protect the grafts. FK506 and rapamycin treatment resulted in a slight improvement of immunoprotection (22.2% rejected, n = 9) compared to cyclosporin A (55.6% rejected, n = 9); however, the difference was not significant. Notably, immunohistochemistry revealed leukocytes infiltrating the graft area in both rejecting and nonrejecting immunocompetent animals, but not in immunodeficient animals. The induction of an inflammatory process, even in surviving allografts, has implications for their long-term survival and functionality.

Apoptosis of neurons and oligodendrocytes in the spinal cord of spinal hyperostotic mouse (twy/twy): possible pathomechanism of human cervical compressive myelopathy

Introduction

Cervical compressive myelopathy is the most serious complication of cervical spondylosis or ossification of the posterior longitudinal ligament (OPLL) and the most frequent cause of spinal cord dysfunction. There is little information on the exact pathophysiological mechanism responsible for the progressive loss of neural tissue in the spinal cord of such patients. In this study, we used the spinal hyperostotic mouse (twy/twy) as a suitable model of human spondylosis, and OPLL to investigate the cellular and molecular changes in the spinal cord. Mutant twy/twy mouse developed ossification of the ligamentum flavum at C2–C3 and exhibited progressive paralysis.

Materials and methods

The mutant twy/twy mice, aged 16 and 24 weeks, were used in the present study. The cervical spinal cord was analyzed histologically and immunohistochemically.

Results

We observed that a significant correlation between the proportion of apoptotic oligodendrocytes in the compressed area of the spinal cord and the magnitude of cord compression. Immunohistochemical analysis indicated overexpression of TNFR1, CD95, and p75^NTR in the twy/twy mice, which was localized by the immunofluorescence in the neurons and oligodendrocytes.

Conclusion

The expression of such factors seems to play at least some role in the apoptotic process, which probably contributes to axonal degeneration and demyelination in the twy/twy mice spinal cords with severe compression.

Electronic supplementary material

The online version of this article (doi:10.1007/s00586-011-2025-x) contains supplementary material, which is available to authorized users.

Tumor necrosis factor-α antagonist reduces apoptosis of neurons and oligodendroglia in rat spinal cord injury

STUDY DESIGN

To examine the effects of a tumor necrosis factor (TNF)-α antagonist (etanercept) on rat spinal cord injury and identify a possible mechanism for its action.

OBJECTIVE

To elucidate the contribution of etanercept to the pathologic cascade in spinal cord injury and its possible suppression of neuronal and oligodendroglial apoptosis.

SUMMARY OF BACKGROUND DATA

Etanercept has been recently used successfully for treatment of inflammatory disorders. However, only a few studies have examined its role in suppressing neuronal and oligodendroglial apoptosis in spinal cord injury.

METHODS

Etanercept or saline (control) was administered by intraperitoneal injection 1 hour after thoracic spinal cord injury in rats. The expressions and localizations of TNF-α, TNF receptor 1 (TNFR1), and TNF receptor 2 (TNFR2) were examined by immunoblot and immunohistochemical analyses. Spinal cord tissue damage between saline- and etanercept-treated groups was also compared after hematoxylin-eosin and luxol fast blue (LFB) staining. The Basso-Beattie-Bresnahan (BBB) scale was used to evaluate rat locomotor function after etanercept administration. Terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL)-positive cells were counted and the immunoreactivity to active caspase-3 and caspase-8 was examined after etanercept administration.

RESULTS

Immunoblot and double immunofluorescence staining revealed suppression of TNF-α, TNFR1, and TNFR2 expression after administration of etanercept in the acute phase of spinal cord injury. LFB staining demonstrated potential myelination in the etanercept-treated group from 2 week after spinal cord injury, together with an increased BBB locomotor score. Double immunofluorescence staining showed a significant decrease in TUNEL-positive neurons and oligodendroglia from 12 hour to 1 week in the gray and white matters after etanercept administration. Immunoblot analysis demonstrated overexpression of activated caspase-3 and caspase-8 after spinal cord injury, which was markedly inhibited by etanercept.

CONCLUSION

Our results indicated that etanercept reduces the associated tissue damage of spinal cord injury, improves hindlimb locomotor function, and facilitates myelin regeneration. This positive effect of etanercept on spinal cord injury is probably attributable to the suppression of TNF-α, TNFR1, TNFR2, and activated caspase-3 and caspase-8 overexpressions, and the inhibition of neuronal and oligodendroglial apoptosis.

Intracranial transplant of olfactory ensheathing cells in children and adolescents with cerebral palsy: a randomized controlled clinical trial

Successful repair of damage in cerebral palsy (CP) needs effective clinical interventions other than simply symptomatic treatments. To elucidate the feasibility of using olfactory ensheathing cells (OECs) to treat CP in children and adolescents, we conducted a randomized controlled clinical trial (RCT) on 33 patients. The patients were randomly assigned into two groups (treatment group, n = 18; control group, n = 15), and OECs derived from aborted fetal tissue were injected into the bilateral corona radiata in the frontal lobes (a key point for neural network restoration, KPNNR). The Gross Motor Function Measure (GMFM-66) and the Caregiver Questionnaire Scale were used to evaluate the patients' neurological function and overall health status. Among the 14 patients who completed the 6-month study, six received the cell transplantation and the other eight served as controls. In OEC treatment group, GMFM-66 scores were 26.67 +/- 25.33 compared with 19.00 +/- 20.00 for the control group. Concurrently, the Caregiver Questionnaire Scale score decreased to 77.83 +/- 15.99 in the treatment group in comparison to 138.66 +/- 64.06 of the control group. This trial, albeit small in sample size, indicates OEC KPNNR transplantation is effective for functional improvement in children and adolescents with CP, yet without obvious side effects. This small-scale study suggests that the procedure may be a plausible alternative method to treat this not yet curable disorder, and we urge further evaluation with a large-scale RCT.

Cell Therapy From Bench to Bedside Translation in CNS Neurorestoratology Era

Recent advances in cell biology, neural injury and repair, and the progress towards development of neurorestorative interventions are the basis for increased optimism. Based on the complexity of the processes of demyelination and remyelination, degeneration and regeneration, damage and repair, functional loss and recovery, it would be expected that effective therapeutic approaches will require a combination of strategies encompassing neuroplasticity, immunomodulation, neuroprotection, neurorepair, neuroreplacement, and neuromodulation. Cell-based restorative treatment has become a new trend, and increasing data worldwide have strongly proven that it has a pivotal therapeutic value in CNS disease. Moreover, functional neurorestoration has been achieved to a certain extent in the CNS clinically. Up to now, the cells successfully used in preclinical experiments and/or clinical trial/treatment include fetal/embryonic brain and spinal cord tissue, stem cells (embryonic stem cells, neural stem/progenitor cells, hematopoietic stem cells, adipose-derived adult stem/precursor cells, skin-derived precursor, induced pluripotent stem cells), glial cells (Schwann cells, oligodendrocyte, olfactory ensheathing cells, astrocytes, microglia, tanycytes), neuronal cells (various phenotypic neurons and Purkinje cells), mesenchymal stromal cells originating from bone marrow, umbilical cord, and umbilical cord blood, epithelial cells derived from the layer of retina and amnion, menstrual blood-derived stem cells, Sertoli cells, and active macrophages, etc. Proof-of-concept indicates that we have now entered a new era in neurorestoratology.