Human neural stem cells overexpressing choline acetyltransferase restore cognitive function of kainic acid-induced learning and memory deficit animals

NSPCs-ES: mechanisms and functional impact on central nervous system diseases

Patients with central neuronal damage may suffer severe consequences, but effective therapies remain unclear. Previous research has established the transplantation of neural stem cells that generate new neurons to replace damaged ones. In a new field of scientific research, the extracellular secretion of NPSCs (NSPCs-ES) has been identified as an alternative to current chemical drugs. Many preclinical studies have shown that NSPCs-ES are effective in models of various central nervous system diseases (CNS) injuries, from maintaining functional structures at the cellular level to providing anti-inflammatory functions at the molecular level, as well as improving memory and motor functions, reducing apoptosis in neurons, and mediating multiple signaling pathways. The NSPC-ES can travel to the damaged tissue and exert a broad range of therapeutic effects by supporting and nourishing damaged neurons. However, gene editing and cell engineering techniques have recently improved therapeutic efficacy by modifying NSPCs-ES. Consequently, future research and application of NSPCs-ES may provide a novel strategy for the treatment of CNS diseases in the future. In this review, we summarize the current progress on these aspects.

Protective effect of vitamin D on learning and memory impairment in rats induced by high fructose corn syrup

In our study, we aimed to investigate the negative effects of the prefrontal cortex (PFC)-associated impairment of cholinergic activity on memory and learning caused by high fructose corn syrup (HFCS) and the protective role of vitamin D in adolescent rats. Twenty-four animals were divided into three groups as control, HFCS group (11 % HFCS-55 solution, ad libitum) and HFCS+ Vit D (42 μg/kg/day). Elevated Plus Maze (EPM), Forced Swim Test (FST), and Morris Water Maze (MWM, performed from day 23) tests were applied to all animals. Fluid intake consumption of the rats was measured daily, weight gain and blood glucose were measured weekly. After 31 days of treatment, the rats were sacrificed and PFC tissue was removed for biochemical, histopathological and immunohistochemical analyses. In HFCS group, fluid consumption, blood glucose, malondialdehyde (MDA) levels, degenerative neuron count and choline acetyltransferase (ChAT) expression were significantly increased; superoxide dismutase (SOD), catalase (CAT) enzyme activity and brain-derived neurotrophic factor (BDNF) expression were significantly decreased. In addition, the time spent in the enclosed arm in EPM was increased, the immobility time in FST was, and the time spent in the target quadrant in MWM was significantly decreased. Vitamin D treatment reversed all these parameters. In conclusion, HFCS caused an increase in the number of degenerative neurons in the PFC, disrupted cholinergic activity and negatively affected learning-memory functions. Vitamin D, decreased the number of degenerative neurons, increased cholinergic activity and positively affected learning and memory performance. BRIEF SYNOPSIS: In this study, prefrontal cortex damage was investigated in adolescent rats fed high fructose corn syrup. The effect of vitamin D on prefrontal cortex damage was evaluated.

Repeated Intravenous Administration of Human Neural Stem Cells Producing Choline Acetyltransferase Exerts Anti-Aging Effects in Male F344 Rats

Major features of aging might be progressive decreases in cognitive function and physical activity, in addition to withered appearance. Previously, we reported that the intracerebroventricular injection of human neural stem cells (NSCs named F3) encoded the choline acetyltransferase gene (F3.ChAT). The cells secreted acetylcholine and growth factors (GFs) and neurotrophic factors (NFs), thereby improving learning and memory function as well as the physical activity of aged animals. In this study, F344 rats (10 months old) were intravenously transplanted with F3 or F3.ChAT NSCs (1 × 106 cells) once a month to the 21st month of age. Their physical activity and cognitive function were investigated, and brain acetylcholine (ACh) and cholinergic and dopaminergic system markers were analyzed. Neuroprotective and neuroregenerative activities of stem cells were also confirmed by analyzing oxidative damages, neuronal skeletal protein, angiogenesis, brain and muscle weights, and proliferating host stem cells. Stem cells markedly improved both cognitive and physical functions, in parallel with the elevation in ACh levels in cerebrospinal fluid and muscles, in which F3.ChAT cells were more effective than F3 parental cells. Stem cell transplantation downregulated CCL11 and recovered GFs and NFs in the brain, leading to restoration of microtubule-associated protein 2 as well as functional markers of cholinergic and dopaminergic systems, along with neovascularization. Stem cells also restored muscular GFs and NFs, resulting in increased angiogenesis and muscle mass. In addition, stem cells enhanced antioxidative capacity, attenuating oxidative damage to the brain and muscles. The results indicate that NSCs encoding ChAT improve cognitive function and physical activity of aging animals by protecting and recovering functions of multiple organs, including cholinergic and dopaminergic systems, as well as muscles from oxidative injuries through secretion of ACh and GFs/NFs, increased antioxidant elements, and enhanced blood flow.

Genetically engineered neural stem cells (NSCs) therapy for neurological diseases; state-of-the-art

Neural stem cells (NSCs) are multipotent stem cells with remarkable self-renewal potential and also unique competencies to differentiate into neurons, astrocytes, and oligodendrocytes (ODCs) and improve the cellular microenvironment. In addition, NSCs secret diversity of mediators, including neurotrophic factors (e.g., BDNF, NGF, GDNF, CNTF, and NT-3), pro-angiogenic mediators (e.g., FGF-2 and VEGF), and anti-inflammatory biomolecules. Thereby, NSCs transplantation has become a reasonable and effective treatment for various neurodegenerative disorders by their capacity to induce neurogenesis and vasculogenesis and dampen neuroinflammation and oxidative stress. Nonetheless, various drawbacks such as lower migration and survival and less differential capacity to a particular cell lineage concerning the disease pathogenesis hinder their application. Thus, genetic engineering of NSCs before transplantation is recently regarded as an innovative strategy to bypass these hurdles. Indeed, genetically modified NSCs could bring about more favored therapeutic influences post-transplantation in vivo, making them an excellent option for neurological disease therapy. This review for the first time offers a comprehensive review of the therapeutic capability of genetically modified NSCs rather than naïve NSCs in neurological disease beyond brain tumors and sheds light on the recent progress and prospect in this context.

Effectiveness of Combinational Treatments for Alzheimer's Disease with Human Neural Stem Cells and Microglial Cells Over-Expressing Functional Genes

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases. In AD patients, amyloid-β (Aβ) peptide-mediated degeneration of the cholinergic system utilizing acetylcholine (ACh) for memory acquisition is observed. Since AD therapy using acetylcholinesterase (AChE) inhibitors are only palliative for memory deficits without reversing disease progress, there is a need for effective therapies, and cell-based therapeutic approaches should fulfil this requirement. We established F3.ChAT human neural stem cells (NSCs) encoding the choline acetyltransferase (ChAT) gene, an ACh-synthesizing enzyme, HMO6.NEP human microglial cells encoding the neprilysin (NEP) gene, an Aβ-degrading enzyme, and HMO6.SRA cells encoding the scavenger receptor A (SRA) gene, an Aβ-uptaking receptor. For the efficacy evaluation of the cells, first, we established an appropriate animal model based on Aβ accumulation and cognitive dysfunction. Among various AD models, intracerebroventricular (ICV) injection of ethylcholine mustard azirinium ion (AF64A) induced the most severe Aβ accumulation and memory dysfunction. Established NSCs and HMO6 cells were transplanted ICV to mice showing memory loss induced by AF64A challenge, and brain Aβ accumulation, ACh concentration and cognitive function were analyzed. All the transplanted F3.ChAT, HMO6.NEP and HMO6.SRA cells were found to survive up to 4 weeks in the mouse brain and expressed their functional genes. Combinational treatment with the NSCs (F3.ChAT) and microglial cells encoding each functional gene (HMO6.NEP or HMO6.SRA) synergistically restored the learning and memory function of AF64A-challenged mice by eliminating Aβ deposits and recovering ACh level. The cells also attenuated inflammatory astrocytic (glial fibrillary acidic protein) response by reducing Aβ accumulation. Taken together, it is expected that NSCs and microglial cells over-expressing ChAT, NEP or SRA genes could be strategies for replacement cell therapy of AD.

Advanced molecular therapies for neurological diseases: focus on stroke, alzheimer's disease, and parkinson's disease

Neurological diseases (NDs) are one of the leading causes of disability and the second leading cause of death globally. Among these stroke, Alzheimer's disease (AD), and Parkinson's disease (PD) are the most common NDs. A rise in the absolute number of individuals affected with these diseases indicates that the current treatment strategies in management and prevention of these debilitating diseases are not effective sufficiently. Therefore, novel treatment strategies are being explored to cure these diseases by addressing the causative mechanisms at the molecular level. Advanced therapies like gene therapy (gene editing and gene silencing) and stem cell therapies aim to cure diseases by gene editing, gene silencing and tissue regeneration, respectively. Gene editing results in the deletion of the aberrant gene or insertion of the corrected gene which can be executed using the CRISPR/Cas gene editing tool a promising treatment strategy being explored for many other prevalent diseases. Gene silencing using siRNA silences the gene by inhibiting protein translation, thereby silencing its expression. Stem cell therapy aims to regenerate damaged cells or tissues because of their ability to divide into any type of cell in the human body. Among these approaches, gene editing and gene silencing have currently been applied in vitro and to animal models, while stem cell therapy has reached the clinical trial stage for the treatment of NDs. The current status of these strategies suggests a promising outcome in their clinical translation.

JAK2/STAT3 pathway mediates neuroprotective and pro-angiogenic treatment effects of adult human neural stem cells in middle cerebral artery occlusion stroke animal models

Mismatches between pre-clinical and clinical results of stem cell therapeutics for ischemic stroke limit their clinical applicability. To overcome these discrepancies, precise planning of pre-clinical experiments that can be translated to clinical trials and the scientific elucidation of treatment mechanisms is important. In this study, adult human neural stem cells (ahNSCs) derived from temporal lobe surgical samples were used (to avoid ethical and safety issues), and their therapeutic effects on ischemic stroke were examined using middle cerebral artery occlusion animal models. 5 × 10⁵ ahNSCs was directly injected into the lateral ventricle of contralateral brain hemispheres of immune suppressed rat stroke models at the subacute phase of stroke. Compared with the mock-treated group, ahNSCs reduced brain tissue atrophy and neurological sensorimotor and memory functional loss. Tissue analysis demonstrated that the significant therapeutic effects were mediated by the neuroprotective and pro-angiogenic activities of ahNSCs, which preserved neurons in ischemic brain areas and decreased reactive astrogliosis and microglial activation. The neuroprotective and pro-angiogenic effects of ahNSCs were validated in in vitro stroke models and were induced by paracrine factors excreted by ahNSCs. When the JAK2/STAT3 signaling pathway was inhibited by a specific inhibitor, AG490, the paracrine neuroprotective and pro-angiogenic effects of ahNSCs were reversed. This pre-clinical study that closely simulated clinical settings and provided treatment mechanisms of ahNSCs for ischemic stroke may aid the development of protocols for subsequent clinical trials of ahNSCs and the realization of clinically available stem cell therapeutics for ischemic stroke.

The Neuroprotective Effects of Exosomes Derived from TSG101-Overexpressing Human Neural Stem Cells in a Stroke Model

Although tissue-type plasminogen activator was approved by the FDA for early reperfusion of occluded vessels, there is a need for an effective neuroprotective drug for stroke patients. In this study, we established tumor susceptibility gene (TSG)101-overexpressing human neural stem cells (F3.TSG) and investigated whether they showed enhanced secretion of exosomes and whether treatment with exosomes during reperfusion alleviated ischemia-reperfusion-mediated brain damage. F3.TSG cells secreted higher amounts of exosomes than the parental F3 cells. In N2A cells subjected to oxygen-glucose deprivation (OGD), treatment with exosomes or coculture with F3.TSG cells significantly attenuated lactate dehydrogenase release, the mRNA expression of proinflammatory factors, and the protein expression of DNA-damage-related proteins. In a middle cerebral artery occlusion (MCAO) rat model, treatment with exosomes, F3 cells, or F3.TSG cells after 2 h of occlusion followed by reperfusion reduced the infarction volume and suppressed inflammatory cytokines, DNA-damage-related proteins, and glial fibrillary acidic protein, and upregulated several neurotrophic factors. Thus, TSG101-overexpressing neural stem cells showed enhanced exosome secretion; exosome treatment protected against MCAO-induced brain damage via anti-inflammatory activities, DNA damage pathway inhibition, and growth/trophic factor induction. Therefore, exosomes and F3.TSG cells can affect neuroprotection and functional recovery in acute stroke patients.

Therapeutic Application of Stem Cells in the Repair of Traumatic Brain Injury

Traumatic brain injury is the main cause of injury-related deaths and disabilities throughout the world, which is characterized by a disruption of the normal physiology of the brain following trauma. It can potentially cause severe complications such as physical, cognitive, and emotional impairment. In addition to understanding traumatic brain injury pathophysiology, this review explains the therapeutic potential of stem cells following brain injury in two pathways: response of endogenous neurogenic cells and transplantation of exogenous stem cell therapy. After traumatic brain injuries, clinical evidence indicated that endogenous neural progenitor cells might play an important role in regenerative medicine to treat brain injury. This is due to an increased neurogenic regeneration ability of these cells following brain injury. Besides, exogenous stem cell transplantation has also accelerated immature neuronal development and increased endogenous cellular proliferation in the damaged brain region. Therefore, a better understanding of the endogenous neural stem cell’s regenerative ability and the effect of exogenous stem cells on proliferation and differentiation ability may help researchers to understand how to increase functional recovery and tissue repair following injury.

Neural stem cell therapy for brain disease

Brain diseases, including brain tumors, neurodegenerative disorders, cerebrovascular diseases, and traumatic brain injuries, are among the major disorders influencing human health, currently with no effective therapy. Due to the low regeneration capacity of neurons, insufficient secretion of neurotrophic factors, and the aggravation of ischemia and hypoxia after nerve injury, irreversible loss of functional neurons and nerve tissue damage occurs. This damage is difficult to repair and regenerate the central nervous system after injury. Neural stem cells (NSCs) are pluripotent stem cells that only exist in the central nervous system. They have good self-renewal potential and ability to differentiate into neurons, astrocytes, and oligodendrocytes and improve the cellular microenvironment. NSC transplantation approaches have been made for various neurodegenerative disorders based on their regenerative potential. This review summarizes and discusses the characteristics of NSCs, and the advantages and effects of NSCs in the treatment of brain diseases and limitations of NSC transplantation that need to be addressed for the treatment of brain diseases in the future.

Nerve Growth Factor-Based Therapy in Alzheimer's Disease and Age-Related Macular Degeneration

Alzheimer's disease (AD) is an age-associated neurodegenerative disease which is the most common cause of dementia among the elderly. Imbalance in nerve growth factor (NGF) signaling, metabolism, and/or defect in NGF transport to the basal forebrain cholinergic neurons occurs in patients affected with AD. According to the cholinergic hypothesis, an early and progressive synaptic and neuronal loss in a vulnerable population of basal forebrain involved in memory and learning processes leads to degeneration of cortical and hippocampal projections followed by cognitive impairment with accumulation of misfolded/aggregated Aβ and tau protein. The neuroprotective and regenerative effects of NGF on cholinergic neurons have been largely demonstrated, both in animal models of AD and in living patients. However, the development of this neurotrophin as a disease-modifying therapy in humans is challenged by both delivery limitations (inability to cross the blood-brain barrier (BBB), poor pharmacokinetic profile) and unwanted side effects (pain and weight loss). Age-related macular degeneration (AMD) is a retinal disease which represents the major cause of blindness in developed countries and shares several clinical and pathological features with AD, including alterations in NGF transduction pathways. Interestingly, nerve fiber layer thinning, degeneration of retinal ganglion cells and changes of vascular parameters, aggregation of Aβ and tau protein, and apoptosis also occur in the retina of both AD and AMD. A protective effect of ocular administration of NGF on both photoreceptor and retinal ganglion cell degeneration has been recently described. Besides, the current knowledge about the detection of essential trace metals associated with AD and AMD and their changes depending on the severity of diseases, either systemic or locally detected, further pave the way for a promising diagnostic approach. This review is aimed at describing the employment of NGF as a common therapeutic approach to AMD and AD and the diagnostic power of detection of essential trace metals associated with both diseases. The multiple approaches employed to allow a sustained release/targeting of NGF to the brain and its neurosensorial ocular extensions will be also discussed, highlighting innovative technologies and future translational prospects.

Inhibition of RhoA/Rho kinase signaling pathway by fasudil protects against kainic acid-induced neurite injury

AIM

RhoA/Rho kinase pathway is essential for regulating cytoskeletal structure. Although its effect on normal neurite outgrowth has been demonstrated, the role of this pathway in seizure-induced neurite injury has not been revealed. The research examined the phosphorylation level of RhoA/Rho kinase signaling pathway and to clarify the effect of fasudil on RhoA/Rho kinase signaling pathway and neurite outgrowth in kainic acid (KA)-treated Neuro-2A cells and hippocampal neurons.

METHOD

Western blotting analysis was used to investigate the expression of key proteins of RhoA/Rho kinase signaling pathway and the depolymerization of actin. After incubated without serum to induce neurite outgrowth, Neuro-2A cells were fixed, and immunofluorescent assay of rhodamine-phalloidin was applied to detect the cellular morphology and neurite length. The influence of KA on neurons was detected in primary hippocampal neurons. Whole-cell patch clamp was conducted in cultured neurons or hippocampal slices to record action potentials.

RESULT

KA at the dose of 100-200 μmol/L induced the increase in phosphorylation of Rho-associated coiled-coil-containing protein kinase and decrease in phosphorylation of Lin11, Isl-1 and Mec-3 kinase and cofilin. The effect of 200 μmol/L KA was peaked at 1-2 hours, and then gradually returned to baseline after 8 hours. Pretreatment with Rho kinase inhibitor fasudil reversed KA-induced activation of RhoA/Rho kinase pathway and increase in phosphorylation of slingshot and 14-3-3, which consequently reduced the ratio of G/F-actin. KA treatment induced inhibition of neurite outgrowth and decrease in spines both in Neuro-2a cells and in cultured hippocampal neurons, and pretreatment with fasudil alleviated KA-induced neurite outgrowth inhibition and spine loss.

CONCLUSION

These data indicate that inhibiting RhoA/Rho kinase pathway might be a potential treatment for seizure-induced injury.

Julian AP, Kopyov O, Kopyov A, Cohen RW. Human neural progenitor cells ameliorate NMDA-induced hippocampal degeneration and related functional deficits

<abstract> <p>It has been established that the CA3 region of the hippocampus is involved in consolidating short-term memory to long-term memory and aids in spatial navigation retention. Seizures and many neurologic diseases induce damage to that region of the hippocampus, resulting in deficits in memory consolidation and spatial navigation. Drug treatments have been proven to have limited effectiveness, but cell replacement therapy has demonstrated to be more promising. Celavie Biosciences have developed a multipotent, nontumorigenic human neural progenitor cell (hNPC) line shown to have the ability to migrate <italic>in situ</italic>, reducing structural and functional deficits in neurodegenerative animal models. Here, we examined whether transplanted hNPCs would reestablish the memories of Han-Wistar rats subjected to hippocampal excitotoxic lesioning. The rats were lesioned in the CA3c regions at 50 days bilaterally with the neurotoxin NMDA (1 µl containing 7.5 mg/ml; −3.5 mm AP; ±2.0 L and −2.5 V). At 54 days of age, live hNPCs (500000 cells in 5 µl cell suspension media), frozen-killed hNPCs (500000 cells/5 µl), HEK293T cells (500000 cells/5 µl) or vehicle (cell suspension media; 5 µl) were bilaterally implanted directly into the NMDA damaged area. The rats were tested two weeks later with three different memory tests: novel and place-object assays and the water-maze task. Results showed that rats receiving live hNPC implantation performed significantly better in the water maze task than control groups; yet, novel and place-object test results showed no significant differences among treatments. Histology confirmed the survival of implanted hNPCs after 28 days post-implantation as well as showing neuroprotective effects. This study showed that Celavie's hNPCs were able to survive and improve some but not all hippocampal functionality, emphasizing the promise for cell replacement therapeutics for neurodegenerative disorders.</p> </abstract>

Nerve growth factor in metabolic complications and Alzheimer's disease: Physiology and therapeutic potential

As the population ages, obesity and metabolic complications as well as neurological disorders are becoming more prevalent, with huge economic burdens on both societies and families. New therapeutics are urgently needed. Nerve growth factor (NGF), first discovered in 1950s, is a neurotrophic factor involved in regulating cell proliferation, growth, survival, and apoptosis in both central and peripheral nervous systems. NGF and its precursor, proNGF, bind to TrkA and p75 receptors and initiate protein phosphorylation cascades, resulting in changes of cellular functions, and are associated with obesity, diabetes and its complications, and Alzheimer's disease. In this article, we summarize changes in NGF levels in metabolic and neuronal disorders, the signal transduction initiated by NGF and proNGF, the physiological and pathophysiological relevance, and therapeutic potential in treating chronic metabolic diseases and cognitive decline.

Human Neural Stem Cells Encoding ChAT Gene Restore Cognitive Function via Acetylcholine Synthesis, Aβ Elimination, and Neuroregeneration in APPswe/PS1dE9 Mice

In Alzheimer disease (AD) patients, degeneration of the cholinergic system utilizing acetylcholine for memory acquisition is observed. Since AD therapy using acetylcholinesterase (AChE) inhibitors are only palliative for memory deficits without slowing or reversing disease progress, there is a need for effective therapies, and stem cell-based therapeutic approaches targeting AD should fulfill this requirement. We established a human neural stem cell (NSC) line encoding choline acetyltransferase (ChAT) gene, an acetylcholine-synthesizing enzyme. APPswe/PS1dE9 AD model mice transplanted with the F3.ChAT NSCs exhibited improved cognitive function and physical activity. Transplanted F3.ChAT NSCs in the AD mice differentiated into neurons and astrocytes, produced ChAT protein, increased the ACh level, and improved the learning and memory function. F3.ChAT cell transplantation reduced Aβ deposits by recovering microglial function; i.e., the down-regulation of β-secretase and inflammatory cytokines and up-regulation of Aβ-degrading enzyme neprilysin. F3.ChAT cells restored growth factors (GFs) and neurotrophic factors (NFs), and they induced the proliferation of NSCs in the host brain. These findings indicate that NSCs overexpressing ChAT can ameliorate complex cognitive and physical deficits of AD animals by releasing ACh, reducing Aβ deposit, and promoting neuroregeneration by the production of GFs/NFs. It is suggested that NSCs overexpressing ChAT could be a candidate for cell therapy in advanced AD therapy.

Neuroprotective effects of human neural stem cells over-expressing choline acetyltransferase in a middle cerebral artery occlusion model

Stroke is one of the most-devastating brain diseases causing acute death or permanent disability. Although tissue-type plasminogen activator was approved by Food and Drug Administration for early reperfusion of the occluded vessels, oxidative injury may cause extensive brain infarction. Accordingly, there is a need for effective neuroprotection during reperfusion, and stem cell-based therapeutic approaches should fulfill this requirement. We established human neural stem cells (NSCs) encoding gene of choline acetyltransferase (F3.ChAT), an acetylcholine-synthesizing enzyme, and investigated whether infusion of the F3.ChAT cells attenuate the ischemia-reperfusion brain damage in a rat model of middle cerebral artery occlusion (MCAO). F3.ChAT cells were found to produce much higher amounts of ChAT as well as neuroprotective and anti-inflammatory neurotrophins than their parental F3 NSCs. After 2-h occlusion, the artery was reperfused, along with intravenous infusion of the stem cells (1 × 106 cells/rat). Administration of the F3.ChAT cells markedly reduced the infarction volume and improved both the cognitive dysfunction and behavioural deficits of MCAO animals, in which F3.ChAT cells were superior to F3 cells. F3.ChAT cells not only restored microtubule-associated protein-2, a neuronal cytoskeletal protein, and preserved microvessels, but also suppressed lipid peroxidation, pro-inflammatory cytokines, glial fibrillary acidic protein, and intercellular adhesion molecule-1 in the brain tissues. The results demonstrate that early intravenous infusion of NSCs expressing ChAT and neurotrophins attenuate brain and capillary injuries and restore neurobehavioural functions via neuroprotective and anti-inflammatory activities, and that F3.ChAT cells could be a candidate for the neuroprotection and functional recovery of acute stroke patients.

Stem Cell Therapy for Alzheimer's Disease

Alzheimer's disease (AD) is the most common neurodegenerative disease caused by eventually aggregated amyloid β (Aβ) plaques in degenerating neurons of the aging brain. These aggregated protein plaques mainly consist of Aβ fibrils and neurofibrillary tangles (NFTs) of phosphorylated tau protein. Even though some cholinesterase inhibitors, NMDA receptor antagonist, and monoclonal antibodies were developed to inhibit neurodegeneration or activate neural regeneration or clear off the Aβ deposits, none of the treatment is effective in improving the cognitive and memory dysfunctions of the AD patients. Thus, stem cell therapy represents a powerful tool for the treatment of AD. In addition to discussing the advents in molecular pathogenesis and animal models of this disease and the treatment approaches using small molecules and immunoglobulins against AD, we will focus on the stem cell sources for AD using neural stem cells (NSCs); embryonic stem cells (ESCs); and mesenchymal stem cells (MSCs) from bone marrow, umbilical cord, and umbilical cord blood. In particular, patient-specific-induced pluripotent stem cells (iPS cells) are proposed as a future prospective and the challenges for the treatment of AD.

Kainic Acid Impairs the Memory Behavior of APP23 Mice by Increasing Brain Amyloid Load through a Tumor Necrosis Factor-α-Dependent Mechanism

Kainic acid (KA) was recently identified as an epileptogenic and neuroexcitotoxic agent that is responsible for inducing learning and memory deficits in various neurodegenerative diseases, such as Alzheimer's disease (AD). However, the mechanism by which KA acts upon AD remains unclear. To this end, we presently investigated the roles of KA in processing amyloid-β protein precursor (AβPP) and amyloid-β protein (Aβ) loads during the course of AD development and progression. Specifically, KA treatment clearly caused the upregulation of tumor necrosis factor α (TNF-α) via activation of the PI3-K/AKT, ERK1/2, and p65 pathways in glial cells. TNF-α secreted from glial cells was then found to be responsible for stimulating the expression of BACE-1 and PS1/2, which resulted in the production and deposition of Aβ in neurons. Finally, the accumulation and aggregation of Aβ lead to the cognitive decline of APP23 mice. These results indicate that KA accelerates the progression of AD by inducing the crosstalk between glial cells and neurons.

Concise Review: Human-Animal Neurological Chimeras: Humanized Animals or Human Cells in an Animal?

Blastocyst complementation is an emerging methodology in which human stem cells are transferred into genetically engineered preimplantation animal embryos eventually giving rise to fully developed human tissues and organs within the animal host for use in regenerative medicine. The ethical issues surrounding this method have caused the National Institutes of Health to issue a moratorium on funding for blastocyst complementation citing the potential for human cells to substantially contribute to the brain of the chimeric animal. To address this concern, we performed an in-depth review of the neural transplantation literature to determine how the integration of human cells into the nonhuman neural circuitry has altered the behavior of the host. Despite reports of widespread integration of human cell transplants, our review of 150 transplantation studies found no evidence suggestive of humanization of the animal host, and we thus conclude that, at present, concerns over humanization should not prevent research on blastocyst complementation to continue. We suggest proceeding in a controlled and transparent manner, however, and include recommendations for future research with careful consideration for how human cells may contribute to the animal host nervous system. Stem Cells 2019;37:444-452.

Brain-derived neurotrophic factor modified human umbilical cord mesenchymal stem cells-derived cholinergic-like neurons improve spatial learning and memory ability in Alzheimer's disease rats

Alzheimer's disease (AD) is an age-related neurodegenerative disease and the most common type of dementia. Although it is still incurable, stem cell replacement therapy provides new hope for AD. Human umbilical cord mesenchymal stem cells (hUC-MSCs) have multiple differentiation potentials, which can differentiate into cholinergic-like neurons and promote the release of acetylcholine. Brain-derived neurotrophic factor (BDNF) can also promote neurogenesis and synaptic formation, reduce oxidative stress and cell death. Therefore, we investigated the therapeutic effects of BDNF modified hUC-MSCs-derived cholinergic-like neurons in AD rats in this study. To make AD models, 1 μl beta amyloid (Aβ)_1-42 was injected into the right hippocampus of the rats. After two weeks, the hUC-MSCs-derived cholinergic-like neurons null cells or overexpressing BDNF cells delivered by lentiviralvectors were slowly injected into the right hippocampus of the AD rats. After 8 weeks of transplantation, Morris water maze test, Western blotting, Immunohistochemistry, Immunofluorescence assay and TdT mediated dUTP Nick End Labeling (TUNEL) detection were performed. Transplantation of BDNF modified hUC-MSCs-derived cholinergic-like neurons significantly improved spatial learning and memory abilities in the AD rats, increased the release of acetylcholine and ChAT expression in the hippocampus, enhanced the activation of astrocytes and microglia, reduced the expression of Aβ and recombinant human beta-site APP-cleaving enzyme1 (BACE1), inhibited neuronal apoptosis, and promoted neurogenesis. Our results demonstrate that BDNF modified hUC-MSCs-derived cholinergic-like neurons might be a promising therapeutic strategy for AD.

Stem cell therapy in Alzheimer's disease: possible benefits and limiting drawbacks

Alzheimer's disease (AD) is the sixth leading cause of death globally and the main reason for dementia in elderly people. AD is a long-term and progressive neurodegenerative disorder that steadily worsens memory and communicating skills eventually leads to a disabled person of performing simple daily tasks. Unfortunately, numerous clinical trials exploring new therapeutic drugs have encountered disappointing outcomes in terms of improved cognitive performance since they are not capable of halting or stimulating the regeneration of already-damaged neural cells, and merely provide symptomatic relief. Therefore, a deeper understanding of the mechanism of action of stem cell may contribute to the development of novel and effective therapies. The revolutionary discovery of stem cells has cast a new hope for the development of disease-modifying treatments for AD, in terms of their potency in the replenishment of lost cells via differentiating towards specific lineages, stimulating in situ neurogenesis, and delivering the therapeutic agents to the brain. Herein, firstly, we explore the pathophysiology of AD. Next, we summarize the most recent preclinical stem cell reports designed for AD treatment, their benefits and outcomes according to cell type. We briefly review relevant clinical trials and their potential clinical applications in order to find a unique solution to effectively relieve the patients' pain.

Is Alzheimer's Also a Stem Cell Disease? - The Zebrafish Perspective

Alzheimer's disease (AD) is the most common neurodegenerative disease and is the leading form of dementia. AD entails chronic inflammation, impaired synaptic integrity and reduced neurogenesis. The clinical and molecular onsets of the disease do not temporally overlap and the initiation phase of the cellular changes might start with a complex causativeness between chronic inflammation, reduced neural stem cell plasticity and neurogenesis. Although the immune and neuronal aspects in AD are well studied, the neural stem cell-related features are far less investigated. An intriguing question is, therefore, whether a stem cell can ever be made proliferative and neurogenic during the prevalent AD in the brain. Recent findings affirm this hypothesis and thus a plausible way to circumvent the AD phenotypes could be to mobilize the endogenous stem cells by enhancing their proliferative and neurogenic capacity as well as to provide the newborn neurons the potential to survive and integrate into the existing circuitry. To address these questions, zebrafish offers unprecedented information and tools, which can be effectively translated into mammalian experimental systems.

A new function for Prokineticin 2: Recruitment of SVZ-derived neuroblasts to the injured cortex in a mouse model of traumatic brain injury

Traumatic brain injury is an important cause of global morbidity and mortality. After an initial injury, there is a cascade of cellular and molecular events that ultimately lead to cell death. Therapies aim to both counteract these mechanisms and replenish the lost cell population in order to improve recovery. The adult mammal brain has at least two neurogenic regions that maintain physiological functions: the subgranular zone of the dentate gyrus in the hippocampus, which produces neurons that integrate locally, and the subventricular zone (SVZ) adjacent to the lateral ventricles, which produces neuroblasts that migrate through the rostral migratory stream (RMS) to the olfactory bulbs. Brain injuries, as well as neurodegenerative diseases, induce the SVZ to respond by increasing cell proliferation and migration to the injured areas. Here we report that cells migrate from the SVZ and RMS to the injured cortex after traumatic brain injury in mice, and that the physiological RMS migration is not impaired. We also show that Prokineticin 2 (PROK2), a chemokine important for the olfactory bulb neurogenesis, expressed exclusively by cortical microglia in the cortex as early as 24 h after injury. We then show that administration of a PROK2 receptor antagonist decreases the number of SVZ cells that reach the injured cortex, while injection of recombinant PROK2 into the cortex of uninjured mice attracts SVZ cells. We also demonstrate that cells expressing PROK2 in vitro directionally attract SVZ cells. These data suggest that PROK2 could be utilized in regeneration efforts for the acutely injured mammalian cortex.

The Ethanol Fraction of White Rose Petal Extract Abrogates Excitotoxicity-Induced Neuronal Damage In Vivo and In Vitro through Inhibition of Oxidative Stress and Proinflammation

Since oxidative stress and inflammation are involved in seizure-related neurotoxicity, the neuroprotective effect of a white rose (Rosa hybrida) petal extract (WRPE) in mice that are challenged with kainic acid (KA) were examined using behavioral epileptiform seizures as well as biochemical and morphological parameters of oxidative stress and inflammation. WRPE (50⁻200 mg/kg) was orally administered to male ICR mice for 15 days, and intraperitoneally challenged with KA (30 mg/kg). Seizure activity, lipid peroxidation, inflammatory cytokines, and related enzymes were analyzed in the brain tissue, in addition to the morphological alterations in the hippocampal pyramidal neurons. Separately, antioxidant ingredients in WRPE were analyzed, and antioxidant, anti-inflammatory, and neuroprotective activities of WRPE were investigated in HB1.F3 human neural stem cells (NSCs) to elucidate underlying mechanisms. Total polyphenol and flavonoid contents in WRPE were 303.3 ± 15.3 mg gallic acid equivalent/g extract and 18.5 ± 2.2 mg catechin/g extract, respectively. WRPE exhibited strong radical-scavenging activities and inhibited lipid peroxidation in vitro, and protected glutamate-induced cytotoxicity in NSCs by suppressing inflammatory process. Treatment with WRPE attenuated epileptiform seizure scores to a half level in KA-challenged mice, and decreased hippocampal pyramidal neuronal injury and loss (cresyl violet and DAPI staining) as well as astrocyte activation (GFAP immunostaining). Lipid peroxidation was inhibited, and mRNA expression of antioxidant enzymes (GPx, PHGPx, SOD1, and SOD2) were recovered in the brain tissues. Inflammatory parameters (cytokines and enzymes) including NF-kB, IL-1β, TNF-α, IL-6, HMGB1, TGF-β, iNOS, COX2, and GFAP mRNAs and proteins were also down-regulated by WRPE treatment. Taken together, the results indicate that WRPE could attenuate KA-induced brain injury through antioxidative and anti-inflammatory activities.

Improvement by Human Oligodendrocyte Progenitor Cells of Neurobehavioral Disorders in an Experimental Model of Neonatal Periventricular Leukomalacia

The effects of human oligodendrocyte progenitor (F3.olig2) cells on improving neurobehavioral deficits were investigated in an experimental model of periventricular leukomalacia (PVL). Seven-day-old male rats were subjected to hypoxia-ischemia-lipopolysaccharide injection (HIL), and intracerebroventricularly transplanted with F3.olig2 (4 × 105 cells/rat) once at post-natal day (PND) 10 or repeatedly at PND10, 17, 27, and 37. Neurobehavioral disorders were evaluated at PND14, 20, 30, and 40 via cylinder test, locomotor activity, and rotarod performance, and cognitive function was evaluated at PND41-45 through passive avoidance and Morris water-maze performances. F3.olig2 cells recovered the rate of use of the forelimb contralateral to the injured brain, improved locomotor activity, and restored rotarod performance of PVL animals; in addition, marked improvement of learning and memory function was seen. It was confirmed that transplanted F3·olig2 cells migrated to injured areas, matured to oligodendrocytes expressing myelin basic protein (MBP), and markedly attenuated the loss of host MBP in the corpus callosum. The results indicate that the transplanted F3.olig2 cells restored neurobehavioral functions by preventing axonal demyelination, and that human oligodendrocyte progenitor cells could be a candidate for cell therapy of perinatal hypoxic-ischemic and infectious brain injuries including PVL and cerebral palsy.

FAM19A1 is a new ligand for GPR1 that modulates neural stem-cell proliferation and differentiation

FAM19A1 is a member of the family with sequence similarity 19 with unknown function. FAM19A1 mRNA expression is restricted to the CNS. Here, we report that FAM19A1 is a classic secretory protein, and expression levels correlate with brain development, increasing from embryonic d 12.5, peaking between postnatal d (P)1 and P7 and decreasing at wk 8. The adult hippocampus is a region of FAM19A1 high expression. Recombinant FAM19A1 suppressed the proliferation and self-renewal of neural stem cells (NSCs) and altered the lineage progression of NSCs with promoted neuron differentiation and suppressed astrocyte differentiation. Although GPCR 1 (GPR1) has been reported to be expressed in the CNS, its functions in the brain remain unclear. We identified GPR1 to be a functional receptor for FAM19A1. FAM19A1 interacted with GPR1 via the N-terminal domain (GPR1-ND), and its NSC modulatory functions required the Rho-associated protein kinase (ROCK) /ERK1/2 and ROCK/signal transducer and activator of transcription 3 signaling pathways. GPR1-ND that selectively bound to FAM19A1 neutralized the effects of FAM19A1 on NSC functions. Taken together, our results show, for the first time to our knowledge, that FAM19A1 is a novel regulatory factor of the proliferation and differentiation of NSCs, and identified a novel mechanism by which GPCR mediates the effects of FAM19A1 on NSC functions that may be important for brain development and neurogenesis. Additional exploration of the functions of FAM19A1 and GPR1 in the CNS may broaden the range of therapeutic options available for major brain disorders.-Zheng, C., Chen, D., Zhang, Y., Bai, Y., Huang, S., Zheng, D., Liang, W., She, S., Peng, X., Wang, P., Mo, X., Song, Q., Lv, P., Huang, J., Ye, R. D., Wang, Y. FAM19A1 is a new ligand for GPR1 that modulates neural stem-cell proliferation and differentiation.

Stem Cell Therapy for Alzheimer's Disease: A Review of Recent Clinical Trials

Stem cell therapy has been noted to be a disease-modifying treatment for Alzheimer's disease (AD). After the failure to develop new drugs for AD, the number of studies on stem cells, such as mesenchymal stem cells (MSCs) and neural stem cells (NSCs), has increased from the early 2000 s. Issues pertaining to stem cells have been investigated in many animal studies in terms of stem cell origin, differentiation potency, method of culture, tumor formation, injection route, and mobility. Since 2010, mainly in East Asia, researchers began clinical trials investigating the use of stem cells for AD. Two phase I trials on moderate AD have been completed; though they revealed no severe acute or long-term side effects, no significant clinical efficacy was observed. Several studies, which involve more sophisticated study designs using different injection routes, well-established scales, and biomarkers such as amyloid positron emission tomography, are planned for mild to moderate AD patients. Here, we review the concept of stem cell therapy for AD and the progress of recent clinical trials.

Traumatic Brain Injury and Stem Cell: Pathophysiology and Update on Recent Treatment Modalities

Traumatic brain injury (TBI) is a complex condition that presents with a wide spectrum of clinical symptoms caused by an initial insult to the brain through an external mechanical force to the skull. In the United States alone, TBI accounts for more than 50,000 deaths per year and is one of the leading causes of mortality among young adults in the developed world. Pathophysiology of TBI is complex and consists of acute and delayed injury. In the acute phase, brain tissue destroyed upon impact includes neurons, glia, and endothelial cells, the latter of which makes up the blood-brain barrier. In the delayed phase, “toxins” released from damaged cells set off cascades in neighboring cells eventually leading to exacerbation of primary injury. As researches further explore pathophysiology and molecular mechanisms underlying this debilitating condition, numerous potential therapeutic strategies, especially those involving stem cells, are emerging to improve recovery and possibly reverse damage. In addition to elucidating the most recent advances in the understanding of TBI pathophysiology, this review explores two primary pathways currently under investigation and are thought to yield the most viable therapeutic approach for treatment of TBI: manipulation of endogenous neural cell response and administration of exogenous stem cell therapy.

Microglia-targeted stem cell therapies for Alzheimer disease: A preclinical data review

Alzheimer disease (AD) is a severe, life-threatening illness characterized by gradual memory loss. The classic histological features of AD include extracellular formation of β-amyloid plaques (Aβ), intracellular neurofibrillary tangles (NFT), and synaptic loss. Recently, accumulated evidence has confirmed the critical role of microglia in the development and exacerbation of AD. When Aβ forms deposits, microglia quickly respond to restore brain physiology by activating a series of repair mechanisms. However, prolonged microglial activation is considered detrimental and may aggravate AD progression. To date, there are no curative therapies for AD. The advent of stem cell transplantation offers novel strategies to treat AD in animal models. Furthermore, studies have reported that transplanted stem cells might ameliorate AD symptoms by regulating microglial functions, from detrimental to protective. This review focuses on the crucial functions of microglia in AD and examines the reactions of microglia to transplanted stem cells.

Combination of RNA Interference and Stem Cells for Treatment of Central Nervous System Diseases

RNA interference (RNAi), including microRNAs, is an important player in the mediation of differentiation and migration of stem cells via target genes. It is used as a potential strategy for gene therapy for central nervous system (CNS) diseases. Stem cells are considered vectors of RNAi due to their capacity to deliver RNAi to other cells. In this review, we discuss the recent advances in studies of RNAi pathways in controlling neuronal differentiation and migration of stem cells. We also highlight the utilization of a combination of RNAi and stem cells in treatment of CNS diseases.

Establishment and Characterization of Immortalized Minipig Neural Stem Cell Line

Despite the increasing importance of minipigs in biomedical research, there has been relatively little research concerning minipig-derived adult stem cells as a promising research tool that could be used to develop stem cell-based therapies. We first generated immortalized neural stem cells (iNSCs) from primary minipig olfactory bulb cells (pmpOBCs) and defined the characteristics of the cell line. Primary neural cells were prepared from minipig neonate olfactory bulbs and immortalized by infection with retrovirus carrying the v-myc gene. The minipig iNSCs (mpiNSCs) had normal karyotypes and expressed NSC-specific markers, including nestin, vimentin, Musashi1, and SOX2, suggesting a similarity to human NSCs. On the basis of the global gene expression profiles from the microarray analysis, neurogenesis-associated transcript levels were predominantly altered in mpiNSCs compared with pmpOBCs. These findings increase our understanding of minipig stem cells and contribute to the utility of mpiNSCs as resources for immortalized stem cell experiments.

Comparative effects of plant oils and trans-fat on blood lipid profiles and ischemic stroke in rats

Since plant oils are believed to be better than animal fats for cerebrovascular and cardiovascular diseases, the effects of various plant oils and trans-fat on blood lipid profiles and ischemic stroke were investigated. Sprague-Dawley rats were fed a diet containing the oils or trans-fat, and then body weights, blood lipids, and effects on brain infarction and physical dysfunction induced by middle cerebral artery occlusion (MCAO) were analyzed. All the oils and trans-fat, except perilla oil, significantly increased body fats and body weight gain. Sesame oil and trans-fat specifically increased blood cholesterols and triglycerides, respectively, while perilla oil decreased both cholesterols and triglycerides. Perilla oil not only attenuated cerebral infarction, but also restored locomotor activity and rota-rod performances of MCAO rats. It is suggested that perilla oil among oils and fats could be the first choice to reduce the risk of metabolic syndrome and ischemic stroke.

A silk peptide fraction restores cognitive function in AF64A-induced Alzheimer disease model rats by increasing expression of choline acetyltransferase gene

This study investigated the effects of a silk peptide fraction obtained by incubating silk proteins with Protease N and Neutrase (SP-NN) on cognitive dysfunction of Alzheimer disease model rats. In order to elucidate underlying mechanisms, the effect of SP-NN on the expression of choline acetyltransferase (ChAT) mRNA was assessed in F3.ChAT neural stem cells and Neuro2a neuroblastoma cells; active amino acid sequence was identified using HPLC-MS. The expression of ChAT mRNA in F3.ChAT cells increased by 3.79-fold of the control level by treatment with SP-NN fraction. The active peptide in SP-NN was identified as tyrosine-glycine with 238.1 of molecular weight. Male rats were orally administered with SP-NN (50 or 300mg/kg) and challenged with a cholinotoxin AF64A. As a result of brain injury and decreased brain acetylcholine level, AF64A induced astrocytic activation, resulting in impairment of learning and memory function. Treatment with SP-NN exerted recovering activities on acetylcholine depletion and brain injury, as well as cognitive deficit induced by AF64A. The results indicate that, in addition to a neuroprotective activity, the SP-NN preparation restores cognitive function of Alzheimer disease model rats by increasing the release of acetylcholine.

Comparative Effects of Human Neural Stem Cells and Oligodendrocyte Progenitor Cells on the Neurobehavioral Disorders of Experimental Autoimmune Encephalomyelitis Mice

Since multiple sclerosis (MS) is featured with widespread demyelination caused by autoimmune response, we investigated the recovery effects of F3.olig2 progenitors, established by transducing human neural stem cells (F3 NSCs) with Olig2 transcription factor, in myelin oligodendrocyte glycoprotein- (MOG-) induced experimental autoimmune encephalomyelitis (EAE) model mice. Six days after EAE induction, F3 or F3.olig2 cells (1 × 10(6)/mouse) were intravenously transplanted. MOG-injected mice displayed severe neurobehavioral deficits which were remarkably attenuated and restored by cell transplantation, in which F3.olig2 cells were superior to its parental F3 cells. Transplanted cells migrated to the injured spinal cord, matured to oligodendrocytes, and produced myelin basic proteins (MBP). The F3.olig2 cells expressed growth and neurotrophic factors including brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), ciliary neurotrophic factor (CNTF), and leukemia inhibitory factor (LIF). In addition, the transplanted cells markedly attenuated inflammatory cell infiltration, reduced cytokine levels in the spinal cord and lymph nodes, and protected host myelins. The results indicate that F3.olig2 cells restore neurobehavioral symptoms of EAE mice by regulating autoimmune inflammatory responses as well as by stimulating remyelination and that F3.olig2 progenitors could be a candidate for the cell therapy of demyelinating diseases including MS.

Beneficial effect of diosgenin as a stimulator of NGF on the brain with neuronal damage induced by Aβ-42 accumulation and neurotoxicant injection

To investigate the beneficial effects of diosgenin (DG) on the multiple types of brain damage induced by Aβ-42 peptides and neurotoxicants, alterations in the specific aspects of brain functions were measured in trimethyltin (TMT)-injected transgenic 2576 (TG) mice that had been pretreated with DG for 21 days. Multiple types of damage were successfully induced by Aβ-42 accumulation and TMT injection into the brains of TG mice. However, DG treatment significantly reduced the number of Aβ-stained plaques and dead cells in the granule cells layer of the dentate gyrus. Significant suppression of acetylcholinesterase (AChE) activity and Bax/Bcl-2 expression was also observed in the DG treated TG mice (TG+DG group) when compared with those of the vehicle (VC) treated TG mice (TG+VC group). Additionally, the concentration of nerve growth factor (NGF) was dramatically enhanced in TG+DG group, although it was lower in the TG+VC group than the non-transgenic (nTG) group. Furthermore, the decreased phosphorylation of downstream members in the TrkA high affinity receptor signaling pathway in the TG+VC group was significantly recovered in the TG+DG group. A similar pattern was observed in p75^NTR expression and JNK phosphorylation in the NGF low affinity receptor signaling pathway. Moreover, superoxide dismutase (SOD) activity was enhanced in the TG+DG group, while the level of malondialdehyde (MDA), a marker of lipid peroxidation, was lower in the TG+DG group than the TG+VC group. These results suggest that DG could exert a wide range of beneficial activities for multiple types of brain damage through stimulation of NGF biosynthesis.

Human Neural Stem Cells Overexpressing Choline Acetyltransferase Restore Unconditioned Fear in Rats with Amygdala Injury

Amygdala is involved in the fear memory that recognizes certain environmental cues predicting threatening events. Manipulation of neurotransmission within the amygdala affects the expression of conditioned and unconditioned emotional memories such as fear freezing behaviour. We previously demonstrated that F3.ChAT human neural stem cells (NSCs) overexpressing choline acetyltransferase (ChAT) improve cognitive function of Alzheimer's disease model rats with hippocampal or cholinergic nerve injuries by increasing acetylcholine (ACh) level. In the present study, we examined the effect of F3.ChAT cells on the deficit of unconditioned fear freezing. Rats given N-methyl-d-aspartate (NMDA) in their amygdala 2 weeks prior to cat odor exposure displayed very short resting (freezing) time compared to normal animals. NMDA induced neuronal degeneration in the amygdala, leading to a decreased ACh concentration in cerebrospinal fluid. However, intracerebroventricular transplantation of F3.ChAT cells attenuated amygdala lesions 4 weeks after transplantation. The transplanted cells were found in the NMDA-injury sites and produced ChAT protein. In addition, F3.ChAT-receiving rats recuperated freezing time staying remote from the cat odor source, according to the recovery of brain ACh concentration. The results indicate that human NSCs overexpressing ChAT may facilitate retrieval of unconditioned fear memory by increasing ACh level.

Alpha-lipoic acid-mediated activation of muscarinic receptors improves hippocampus- and amygdala-dependent memory

Aluminum (Al) is a neurotoxic agent which readily crosses the blood-brain-barrier (BBB) and accumulates in the brain leading to neurodegenerative disorders, characterised by cognitive impairment. Alpha-lipoic acid (ALA) is an antioxidant and has a potential to improve cognitive functions. This study aimed to evaluate the neuroprotective effect of ALA in AlCl3-induced neurotoxicity mouse model. Effect of ALA (25mg/kg/day) was evaluated in the AlCl3-induced neurotoxicity (AlCl3 150 mg/kg/day) mouse model on learning and memory using behaviour tests and on the expression of muscarinic receptor genes (using RT-PCR), in hippocampus and amygdala. Following ALA treatment, the expression of muscarinic receptor genes M1, M2 and choline acetyltransferase (ChaT) were significantly improved (p<0.05) relative to AlCl3-treated group. ALA enhanced fear memory (p<0.01) and social novelty preference (p<0.001) comparative to the AlCl3-treated group. Fear extinction memory was remarkably restored (p<0.001) in ALA-treated group demonstrated by reduced freezing response as compared to the AlCl3-treated group which showed higher freezing. In-silico analysis showed that racemic mixture of ALA has higher binding affinity for M1 and M2 compared to acetylcholine. These novel findings highlight the potential role of ALA in cognitive functions and cholinergic system enhancement thus presenting it an enviable therapeutic candidate for the treatment of neurodegenerative disorders.

Potential of Neural Stem Cell-Based Therapy for Parkinson's Disease

Neural stem cell (NSC) transplantation is an emerging strategy for restoring neuronal function in neurological disorders, such as Parkinson's disease (PD), which is characterized by a profound and selective loss of nigrostriatal dopaminergic (DA) neurons. Adult neurogenesis generates newborn neurons that can be observed at specialized niches where endothelial cells (ECs) play a significant role in regulating the behavior of NSCs, including self-renewal and differentiating into all neural lineage cells. In this minireview, we highlight the importance of establishing an appropriate microenvironment at the target site of NSC transplantation, where grafted cells integrate into the surroundings in order to enhance DA neurotransmission. Using a novel model of NSC-EC coculture, it is possible to combine ECs with NSCs, to generate such a neurovascular microenvironment. With appropriate NSCs selected, the composition of the transplant can be investigated through paracrine and juxtacrine signaling within the neurovascular unit (NVU). With target site cellular and acellular compartments of the microenvironment recognized, guided DA differentiation of NSCs can be achieved. As differentiated DA neurons integrate into the existing nigrostriatal DA pathway, the symptoms of PD can potentially be alleviated by reversing characteristic neurodegeneration.

The anti-aging properties of a human placental hydrolysate combined with dieckol isolated from Ecklonia cava

BACKGROUNDS

In the present study, we aimed to examine the anti-aging properties of human placental hydrolysate (HPE) and dieckol (DE) from Ecklonia cava against free radical scavenging, muscle hypertrophy-related follistatin mRNA expression, amelioration of cognition-related genes and proteins, inhibition of collagenase-regulating genes, and elastinase activity.

METHODS

The anti-aging effects were examined in human fibroblast (CCD986sk), mouse myoblast (C2C12), and neuroblastoma (N2a) cell models, by employing various assays such as 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH) scavenging, hydroxyl radical-mediated oxidation, quantitative real-time polymerase chain reaction, enzyme activity, and immunocytochemistry observation.

RESULTS

Our results show that HPE combined with DE (HPE:DE) strongly scavenged DPPH radicals and protected proteins against degradation by hydroxyl radical attack. HPE:DE effectively inhibited matrix metalloproteinase-1 expression, protein kinase C alpha expression, and elastinase activity. Furthermore, HPE:DE improved the expression of cognition-related genes (choline acetyltransferase and vesicular acetylcholine transporter). These events may proactively contribute to retard the aging processes and the abrupt physiological changes probably induced by mitochondrial dysfunction with aging.

CONCLUSIONS

Based on these findings, we conclude that the combined treatment of HPE:DE may be useful for anti-aging therapy in which the accumulation of oxidative damage is the main driving force.

Health Span-Extending Activity of Human Amniotic Membrane- and Adipose Tissue-Derived Stem Cells in F344 Rats

Aging brings about the progressive decline in cognitive function and physical activity, along with losses of stem cell population and function. Although transplantation of muscle-derived stem/progenitor cells extended the health span and life span of progeria mice, such effects in normal animals were not confirmed. Human amniotic membrane-derived mesenchymal stem cells (AMMSCs) or adipose tissue-derived mesenchymal stem cells (ADMSCs) (1×10(6) cells per rat) were intravenously transplanted to 10-month-old male F344 rats once a month throughout their lives. Transplantation of AMMSCs and ADMSCs improved cognitive and physical functions of naturally aging rats, extending life span by 23.4% and 31.3%, respectively. The stem cell therapy increased the concentration of acetylcholine and recovered neurotrophic factors in the brain and muscles, leading to restoration of microtubule-associated protein 2, cholinergic and dopaminergic nervous systems, microvessels, muscle mass, and antioxidative capacity. The results indicate that repeated transplantation of AMMSCs and ADMSCs elongate both health span and life span, which could be a starting point for antiaging or rejuvenation effects of allogeneic or autologous stem cells with minimum immune rejection.

SIGNIFICANCE

This study demonstrates that repeated treatment with stem cells in normal animals has antiaging potential, extending health span and life span. Because antiaging and prolonged life span are issues currently of interest, these results are significant for readers and investigators.

Effects of stem cell transplantation on cognitive decline in animal models of Alzheimer's disease: A systematic review and meta-analysis

Alzheimer’s disease (AD), an irreversible progressive neurodegenerative disease, causes characteristic cognitive impairment, and no curative treatments are currently available. Stem cell transplantation offers a powerful tool for the treatment of AD. We conducted a systematic review and meta-analysis of data from controlled studies to study the impact of stem cell biology and experimental design on learning and memory function following stem cell transplantation in animal models of AD. A total of 58 eligible controlled studies were included by searching PubMed, EMBASE, and Web of Science up to April 13, 2015. Meta-analysis showed that stem cell transplantation could promote both learning and memory recovery. Stratified meta-analysis was used to explore the influence of the potential factors on the estimated effect size, and meta-regression analyses were undertaken to explore the sources of heterogeneity for learning and memory function. Publication bias was assessed using funnel plots and Egger’s test. The present review reinforces the evidence supporting stem cell transplantation in experimental AD. However, it highlights areas that require well-designed and well-reported animal studies.

Direct reprogramming of induced neural progenitors: a new promising strategy for AD treatment

Alzheimer's disease (AD) is a prominent form of dementia, characterized by aggregation of the amyloid β-peptide (Aβ) plaques and neurofibrillary tangles, loss of synapses and neurons, and degeneration of cognitive functions. Currently, although a variety of medications can relieve some of the symptoms, there is no cure for AD. Recent breakthroughs in the stem cell field provide promising strategies for AD treatment. Stem cells including embryonic stem cells (ESCs), neural stem cells (NSCs), mesenchymal stem cells (MSCs), and induced pluripotent stem cells (iPSCs) are potentials for AD treatment. However, the limitation of cell sources, safety issues, and ethical issues restrict their applications in AD. Recently, the direct reprogramming of induced neural progenitor cells (iNPCs) has shed light on the treatment of AD. In this review, we will discuss the latest progress, challenges, and potential applications of direct reprogramming in AD treatment.

Neural stem cells could serve as a therapeutic material for age-related neurodegenerative diseases

Progressively loss of neural and glial cells is the key event that leads to nervous system dysfunctions and diseases. Several neurodegenerative diseases, for instance Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease, are associated to aging and suggested to be a consequence of deficiency of neural stem cell pool in the affected brain regions. Endogenous neural stem cells exist throughout life and are found in specific niches of human brain. These neural stem cells are responsible for the regeneration of new neurons to restore, in the normal circumstance, the functions of the brain. Endogenous neural stem cells can be isolated, propagated, and, notably, differentiated to most cell types of the brain. On the other hand, other types of stem cells, such as mesenchymal stem cells, embryonic stem cells, and induced pluripotent stem cells can also serve as a source for neural stem cell production, that hold a great promise for regeneration of the brain. The replacement of neural stem cells, either endogenous or stem cell-derived neural stem cells, into impaired brain is highly expected as a possible therapeutic mean for neurodegenerative diseases. In this review, clinical features and current routinely treatments of age-related neurodegenerative diseases are documented. Noteworthy, we presented the promising evidence of neural stem cells and their derivatives in curing such diseases, together with the remaining challenges to achieve the best outcome for patients.

Potential of neural stem cell-based therapies for Alzheimer's disease

Alzheimer's disease (AD), known to be a leading cause of dementia that causes heavy social and financial burdens worldwide, is characterized by progressive loss of neurons and synaptic connectivity after depositions of amyloid-β (Aβ) protein. Current therapies for AD patients can only alleviate symptoms but cannot deter the neural degeneration, thus providing no long-term recovery. Neural stem cells (NSCs), capable of self-renewal and of differentiation into functional neurons and glia, have been shown to repair damaged networks and reverse memory and learning deficits in animal studies, providing new hope for curing AD patients by cell transplantation. Under AD pathology, the microenvironment also undergoes great alterations that affect the propagation of NSCs and subsequent therapeutic efficiency, calling for measures to improve the hostile environment for cell transplantation. This article reviews the therapeutic potential of both endogenous and exogenous NSCs in the treatment of AD and the challenges to application of stem cells in AD treatment, particularly those from the microenvironmental alterations, in the hope of providing more information for future research in exploiting stem cell-based therapies for AD. © 2015 Wiley Periodicals, Inc.

Neural cell injury microenvironment induces neural differentiation of human umbilical cord mesenchymal stem cells

This study aimed to investigate the neural differentiation of human umbilical cord mesenchymal stem cells (hUCMSCs) under the induction of injured neural cells. After in vitro isolation and culture, passage 5 hUCMSCs were used for experimentation. hUCMSCs were co-cultured with normal or Aβ_1-40-injured PC12 cells, PC12 cell supernatant or PC12 cell lysate in a Transwell co-culture system. Western blot analysis and flow cytometry results showed that choline acetyltransferase and microtubule-associated protein 2, a specific marker for neural cells, were expressed in hUCMSCs under various culture conditions, and highest expression was observed in the hUCMSCs co-cultured with injured PC12 cells. Choline acetyltransferase and microtubule-associated protein 2 were not expressed in hUCMSCs cultured alone (no treatment). Cell Counting Kit-8 assay results showed that hUCMSCs under co-culture conditions promoted the proliferation of injured PC12 cells. These findings suggest that the microenvironment during neural tissue injury can effectively induce neural cell differentiation of hUCMSCs. These differentiated hUCMSCs likely accelerate the repair of injured neural cells.

Targeting β-secretase with RNAi in neural stem cells for Alzheimer's disease therapy

There are several major pathological changes in Alzheimer's disease, including apoptosis of cholinergic neurons, overactivity or overexpression of β-site amyloid precursor protein cleaving enzyme 1 (BACE1) and inflammation. In this study, we synthesized a 19-nt oligonucleotide targeting BACE1, the key enzyme in amyloid beta protein (Aβ) production, and introduced it into the pSilenCircle vector to construct a short hairpin (shRNA) expression plasmid against the BACE1 gene. We transfected this vector into C17.2 neural stem cells and primary neural stem cells, resulting in downregulation of the BACE1 gene, which in turn induced a considerable reduction in reducing Aβ protein production. We anticipate that this technique combining cell transplantation and gene therapy will open up novel therapeutic avenues for Alzheimer's disease, particularly because it can be used to simultaneously target several pathogenetic changes in the disease.

Hippocampal injury-induced cognitive and mood dysfunction, altered neurogenesis, and epilepsy: can early neural stem cell grafting intervention provide protection?

Damage to the hippocampus can occur through many causes including head trauma, ischemia, stroke, status epilepticus, and Alzheimer's disease. Certain changes such as increased levels of neurogenesis and elevated concentrations of multiple neurotrophic factors that ensue in the acute phase after injury seem beneficial for restraining hippocampal dysfunction. However, many alterations that arise in the intermediate to chronic phase after injury such as abnormal migration of newly born neurons, aberrant synaptic reorganization, progressive loss of inhibitory gamma-amino butyric acid positive interneurons including those expressing reelin, greatly declined neurogenesis, and sustained inflammation are detrimental. Consequently, the net effect of postinjury plasticity in the hippocampus remains inadequate for promoting significant functional recovery. Hence, ideal therapeutic interventions ought to be efficient for restraining these detrimental changes in order to block the propensity of most hippocampal injuries to evolve into learning deficits, memory dysfunction, depression, and temporal lobe epilepsy. Neural stem cell (NSC) grafting into the hippocampus early after injury appears alluring from this perspective because several recent studies have demonstrated the therapeutic value of this intervention, especially for preventing/easing memory dysfunction, depression, and temporal lobe epilepsy development in the chronic phase after injury. These beneficial effects of NSC grafting appeared to be mediated through considerable modulation of aberrant hippocampal postinjury plasticity with additions of new inhibitory gamma-amino butyric acid positive interneurons and astrocytes secreting a variety of neurotrophic factors and anticonvulsant proteins. This review presents advancements made in NSC grafting therapy for treating hippocampal injury in animal models of excitotoxic injury, traumatic brain injury, Alzheimer's disease, and status epilepticus; potential mechanisms of functional recovery mediated by NSC grafts placed early after hippocampal injury; and issues that need to be resolved prior to considering clinical application of NSC grafting for hippocampal injury.