Neural stem cell transplantation in a model of fetal alcohol effects

Antidepressant activities of escitalopram and blonanserin on prenatal and adolescent combined stress-induced depression model: Possible role of neurotrophic mechanism change in serum and nucleus accumbens

BACKGROUND

There has been number of studies suggesting experiences of adversity in early life interrelated subsequent brain development, however, neurobiological mechanisms confer risk for onset of psychiatric illness remains unclear.

METHODS

In order to elucidate the pathogenic mechanisms underlying early life adversity-induced refractory depression in more detail, we administered corticosterone (CORT) to adolescent rats with or without prenatal ethanol exposure followed by an antidepressant or antipsychotic and examined alterations in depressive and social function behaviors and brain-derived neurotrophic factor (BDNF) levels in serum, the hippocampus, anterior cingulate cortex, and nucleus accumbens.

RESULTS

The combined stress exposure of prenatal ethanol and adolescent CORT prolonged immobility times in the forced swim test (FST), and increased investigation times and numbers in the social interaction test (SIT). A treatment with escitalopram reversed depression-like behavior accompanied by reductions in BDNF levels in serum and the nucleus accumbens, while a treatment with blonanserin ameliorated abnormal social interaction behavior with reductions in serum BDNF levels.

LIMITATIONS

Further studies are needed to clarify the clinical evinces responding to these results, and many questions remain regarding the mechanisms by which refractory depression and antidepressant/antipsychotic treatments cause changes in serum and brain regional BDNF levels.

CONCLUSION

These results strongly implicate changes in BDNF levels in serum and the nucleus accumbens in the pathophysiology and treatment of early life combined stress-induced depression and highlight the therapeutic potential of escitalopram and new generation antipsychotic blonanserin for treatment-resistant refractory depression.

Neural Stem Cells

Neural stem cell (NSC) transplantation has provided the basis for the development of potentially powerful new therapeutic cell-based strategies for a broad spectrum of clinical diseases, including stroke, psychiatric illnesses such as fetal alcohol spectrum disorders, and cancer. Here, we discuss pertinent preclinical investigations involving NSCs, including how NSCs can ameliorate these diseases, the current barriers hindering NSC-based treatments, and future directions for NSC research. There are still many translational requirements to overcome before clinical therapeutic applications, such as establishing optimal dosing, route of delivery, and timing regimens and understanding the exact mechanism by which transplanted NSCs lead to enhanced recovery. Such critical lab-to-clinic investigations will be necessary in order to refine NSC-based therapies for debilitating human disorders.

Harnessing neural stem cells for treating psychiatric symptoms associated with fetal alcohol spectrum disorder and epilepsy

Brain insults with progressive neurodegeneration are inherent in pathological symptoms that represent many psychiatric illnesses. Neural network disruptions characterized by impaired neurogenesis have been recognized to precede, accompany, and possibly even exacerbate the evolution and progression of symptoms of psychiatric disorders. Here, we focus on the neurodegeneration and the resulting psychiatric symptoms observed in fetal alcohol spectrum disorder and epilepsy, in an effort to show that these two diseases are candidate targets for stem cell therapy. In particular, we provide preclinical evidence in the transplantation of neural stem cells (NSCs) in both conditions, highlighting the potential of this cell-based treatment for correcting the psychiatric symptoms that plague these two disorders. Additionally, we discuss the challenges of NSC transplantation and offer insights into the mechanisms that may mediate the therapeutic benefits and can be exploited to overcome the hurdles of translating this therapy from the laboratory to the clinic. Our ultimate goal is to advance stem cell therapy for the treatment of psychiatric disorders.

An Update on Fetal Alcohol Syndrome-Pathogenesis, Risks, and Treatment

Alcohol is a well-established teratogen that can cause variable physical and behavioral effects on the fetus. The most severe condition in this spectrum of diseases is known as fetal alcohol syndrome (FAS). The differences in maternal and fetal enzymes, in terms of abundance and efficiency, in addition to reduced elimination, allow for alcohol to have a prolonged effect on the fetus. This can act as a teratogen through numerous methods including reactive oxygen species (generated as by products of CYP2E1), decreased endogenous antioxidant levels, mitochondrial damage, lipid peroxidation, disrupted neuronal cell-cell adhesion, placental vasoconstriction, and inhibition of cofactors required for fetal growth and development. More recently, alcohol has also been shown to have epigenetic effects. Increased fetal exposure to alcohol and sustained alcohol intake during any trimester of pregnancy is associated with an increased risk of FAS. Other risk factors include genetic influences, maternal characteristics, for example, lower socioeconomic statuses and smoking, and paternal chronic alcohol use. The treatment options for FAS have recently started to be explored although none are currently approved clinically. These include prenatal antioxidant administration food supplements, folic acid, choline, neuroactive peptides, and neurotrophic growth factors. Tackling the wider impacts of FAS, such as comorbidities, and the family system have been shown to improve the quality of life of FAS patients. This review aimed to focus on the pathogenesis, especially mechanisms of alcohol teratogenicity, and risks of developing FAS. Recent developments in potential management strategies, including prenatal interventions, are discussed.

Potential of GABA-ergic cell therapy for schizophrenia, neuropathic pain, and Alzheimer's and Parkinson's diseases

Several neurological and psychiatric disorders present hyperexcitability of neurons in specific regions of the brain or spinal cord, partly because of some loss and/or dysfunction of gamma-amino butyric acid positive (GABA-ergic) inhibitory interneurons. Strategies that enhance inhibitory neurotransmission in the affected brain regions may therefore ease several or most deficits linked to these disorders. This perception has incited a huge interest in testing the efficacy of GABA-ergic interneuron cell grafting into regions of the brain or spinal cord exhibiting hyperexcitability, dearth of GABA-ergic interneurons or impaired inhibitory neurotransmission, using preclinical models of neurological and psychiatric disorders. Interneuron progenitors from the embryonic ventral telencephalon capable of differentiating into diverse subclasses of interneurons have particularly received much consideration because of their ability for dispersion, migration and integration with the host neural circuitry after grafting. The goal of this review is to discuss the premise, scope and advancement of GABA-ergic cell therapy for easing neurological deficits in preclinical models of schizophrenia, chronic neuropathic pain, Alzheimer's disease and Parkinson's disease. As grafting studies in these prototypes have so far utilized either primary cells from the embryonic medial and lateral ganglionic eminences or neural progenitor cells expanded from these eminences as donor material, the proficiency of these cell types is highlighted. Moreover, future studies that are essential prior to considering the possible clinical application of these cells for the above neurological conditions are proposed. Particularly, the need for grafting studies utilizing medial ganglionic eminence-like progenitors generated from human pluripotent stem cells via directed differentiation approaches or somatic cells through direct reprogramming methods are emphasized. This article is part of a Special Issue entitled SI: PSC and the brain.

The potential of neural stem cell transplantation for the treatment of fetal alcohol spectrum disorder

Fetal alcohol spectrum disorder (FASD) is caused by intrauterine exposure to alcohol and can cause a full range of abnormalities to brain development, as well as long-term sequelae of cognitive, sensory and motor impairments. The incidence is estimated to be as high as 2% to 5% in children born within the US, however the prevalence is even higher in low socioeconomic populations. Despite the various mechanisms thought to explain the etiology of FASD, molecular targets of ethanol toxicity during development are not completely understood. More recent findings explore the role of GABA-A and GABA-B mechanisms, as well as cell death, cell signaling and gene expression malfunctions. Stem cell based therapies have grown exponentially over the last decade, which have lead to novel clinical interventions across many disciplines. Thus, early detailed understanding of the therapeutic potential of stem cell research has provided promising applications across a wide range of illnesses. Consequently, these potential benefits may ultimately lead to a reduced incidence and severity of this highly preventable and prevalent birth defect. It is recognized that stem cell derivations provide unique difficulties and limitations of therapeutic applications. This review will outline the current knowledge, along with the benefits and challenges of stem cell therapy for FASD.

Stem cell therapy: a new approach to the treatment of refractory depression

To better understand the relationship of repeated exposure to adversity during early development as a risk factor for refractory depression, we exposed pregnant female rats to ethanol and the resulting pups to corticosterone during adolescence. A stressful forced swim test was then used to induce depression-like behavior. The adolescent rat brains were examined for the possible therapeutic benefit of a combination of sertraline, an antidepressant, and neural stem cells (NSCs) complexed with atelocollagen in relation to the level of GABAergic interneuron and synaptic protein density in different brain regions. The combined exposures of prenatal and adolescent stress resulted in a reduction in parvalbumin (PV)-positive phenotype of GABAergic interneurons and reduced postsynaptic density protein 95 (PSD-95) levels in the anterior cingulate cortex, amygdala, and hippocampus. Treatments with sertraline and NSCs reversed the reductions in PV-positive cells and PSD-95 levels. Furthermore, the combined treatment of sertraline and NSCs resulted in reduced depressive-like behaviors. These experiments underscore a potentially important role for synaptic remodeling and GABAergic interneuron genesis in the treatment of refractory depression and highlight the therapeutic potential of stem cell and pharmacological combination treatments for refractory depression.

Effects of atelocollagen on neural stem cell function and its migrating capacity into brain in psychiatric disease model

Stem cell therapy is well proposed as a potential method for the improvement of neurodegenerative damage in the brain. Among several different procedures to reach the cells into the injured lesion, the intravenous (IV) injection has benefit as a minimally invasive approach. However, for the brain disease, prompt development of the effective treatment way of cellular biodistribution of stem cells into the brain after IV injection is needed. Atelocollagen has been used as an adjunctive material in a gene, drug and cell delivery system because of its extremely low antigenicity and bioabsorbability to protect these transplants from intrabody environment. However, there is little work about the direct effect of atelocollagen on stem cells, we examined the functional change of survival, proliferation, migration and differentiation of cultured neural stem cells (NSCs) induced by atelocollagen in vitro. By 72-h treatment 0.01-0.05% atelocollagen showed no significant effects on survival, proliferation and migration of NSCs, while 0.03-0.05% atelocollagen induced significant reduction of neuronal differentiation and increase of astrocytic differentiation. Furthermore, IV treated NSCs complexed with atelocollagen (0.02%) could effectively migrate into the brain rather than NSC treated alone using chronic alcohol binge model rat. These experiments suggested that high dose of atelocollagen exerts direct influence on NSC function but under 0.03% of atelocollagen induces beneficial effect on regenerative approach of IV administration of NSCs for CNS disease.

Stem cell therapy: social recognition recovery in a FASD model

To better understand the cellular pathogenetic mechanisms of fetal alcohol spectrum disorder (FASD) and the therapeutic benefit of stem cell treatment, we exposed pregnant rats to ethanol followed by intravenous administration of neural stem cells (NSCs) complexed with atelocollagen to the new born rats and studied recovery of GABAergic interneuron numbers and synaptic protein density in the anterior cingulate cortex, hippocampus and amygdala. Prenatal ethanol exposure reduced both parvalbumin-positive phenotype of GABAergic interneurons and postsynaptic density protein 95 levels in these areas. Intravenous NSC treatment reversed these reductions. Furthermore, treatment with NSCs reversed impaired memory/cognitive function and social interaction behavior. These experiments underscore an important role for synaptic remodeling and GABAergic interneuron genesis in the pathophysiology and treatment of FASD and highlight the therapeutic potential for intravenous NSC administration in FASD utilizing atelocollagen.

The role of neural stem cells for in vitro models of schizophrenia: neuroprotection via Akt/ERK signal regulation

Recent neuroimaging studies have revealed progressive morphological brain changes during the course of schizophrenia, and the neurotrophic and neurogenetic effects of atypical antipsychotics are believed to prevent or retard these brain volume reductions. In addition to drug-induced neural stem cell (NSC) activation, transplantation of exogenous NSCs has been proposed as a possible approach to repair the damaged brain in psychiatric disease. NSC transplantation embraces not only neuron replacement but also enhanced neuroprotection of existing neurons with the goal of restoring the impaired brain. However, little is known about the cell-cell interactions of exogenous NSCs with existing neurons, or about their neuroprotective actions especially in psychiatric diseases. In the present study, we used cortical neuron cultures to examine the neurotrophism and neuroprotection of exogenous NSCs against the neuronal damage induced by exposure to the NMDA receptor antagonist, MK-801. We also investigated their role in serum/nutrient deprivation stress. The exogenous NSCs exerted neuroprotective effects against both types of apoptotic injuries considered as in vitro schizophrenic disease models. Exogenous NSCs also altered cellular survival signaling in injured neurons by indirect cell-cell contact in an injury-dependent manner. In MK-801 exposure, NSCs increased phosphorylated Akt (p-Akt) and ERK (p-ERK), both of which were reduced by this stress. While, in serum/nutrient deprivation, NSCs increased p-Akt, but decreased p-ERK which was increased by this damage. Our results demonstrate that exogenous NSCs have anti-apoptotic activities and can rescue cortical neurons by directing cellular survival signaling of neurons into the proper direction, without cell contact.

Mesenchymal stem cells inhibition of chronic ethanol-induced oxidative damage via upregulation of phosphatidylinositol-3-kinase/Akt and modulation of extracellular signal-regulated kinase 1/2 activation in PC12 cells and neurons

It is well known that chronic ethanol consumption damages CNS through oxidative stress which results in many dysfunctions. Recently, it has been demonstrated that as a promising strategy to treat several neurological diseases, transplanted bone marrow-derived mesenchymal stem cells (MSCs) can secrete lots of protective factors that in turn promote function recovery. In the present study, we assessed the potential effects of MSCs conditioned medium (MSC-CM) against chronic ethanol-associated damage on PC12 cells and primary cortical neurons. We found that pretreatment with MSC-CM notably improved cell survival, prevented chronic ethanol-associated apoptosis and abolished the robust deterioration in oxidative status. In addition, we also discovered that chronic ethanol exposure induced an inactivation of phosphatidylinositol-3-kinase (PI3K)/Akt and a lasting activation of extracellular signal-regulated kinase 1/2 (ERK1/2) in both PC12 cells and primary cortical neurons which were able to be reversed by MSC-CM. The PI3K inhibitor (LY294002) was able to reduce the antioxidative and cytoprotective effects conferred by MSC-CM, in part, and the ERK1/2 inhibitor (PD98059) was able to elicit significant protection from chronic ethanol cytotoxicity but not rescue the deterioration in oxidative status induced by chronic ethanol. Taken together, these findings provide the first evidence that MSCs might have potent antioxidant action to shield the apoptotic impairment from chronic ethanol exposure in PC12 cells and neurons, which is involved in upregulation of PI3K/Akt and modulation of ERK1/2 activation, at least partially.

Biological studies on alcohol-induced neuronal damage

Alcohol is a well-known cytotoxic agent which causes various kinds of neuronal damage. In spite of thousands of published studies, the true mechanism of alcohol-induced neuronal damage remains unclear. Neurogenesis is the generation of neurons from neural stem cells (NSCs) and occurs in predominantly two regions of the brain, the subventricular zone and the dentate gyrus of the hippocampus. NSCs are the self-renewing, multipotent precursor cells of neurons, astrocytes, and oligodendrocytes in the central nervous system. Recent studies have begun to illuminate the role of neurogenesis in the biological and cellular basis of psychiatric disorders and several clinical symptoms seen in alcoholism such as depression, cognitive impairment, underlying stress and brain atrophy have been linked to impaired neurogenesis. Heavy alcohol consumption decreases neurogenesis in animals, while in vitro studies have shown decreased generation of new neurons after alcohol exposure. These findings suggest that decreased neurogenesis is important in the pathophysiology of alcoholism. Neurogenesis can be divided into four stages; proliferation, migration, differentiation and survival. Our in vitro studies on NSCs showed that alcohol decreased neuronal differentiation at doses lower than those that affected cell survival and suggested that neuron-restrictive silencer factor, or repressor element-1 silencing transcription factor (NRSF/REST) could be involved in alcohol-induced inhibition of neuronal differentiation. In an animal model of fetal alcohol effects behavioral symptoms improved after NSC transplantation. Neurogenesis could be the target for new strategies to treat alcohol related disorders.

Embryonic stem cell biology

ES cell research represents an exploding field of exploration. Initially predicted to provide rapid cures for numerous human diseases, the clinical usefulness of ES cell-derived cells remains untested in humans. However, ES cells have rapidly expanded our knowledge of human development and the molecular details of differentiation. Our ability to generate relatively pure populations of specifically differentiated cells for transplantation has markedly improved. It is hoped that soon researchers will overcome the biologic impediments to successful treatment of human disease with ES cell-derived cells.