Neural Stem Cell Death Research Articles

NRICM101 in combatting COVID-19 induced brain fog: Neuroprotective effects and neurovascular integrity preservation in hACE2 mice

Amidst growing concerns over COVID-19 aftereffects like fatigue and cognitive issues, NRICM101, a traditional Chinese medicine, has shown promise. Used by over 2 million people globally, it notably reduces hospitalizations and intubations in COVID-19 patients. To explore whether NRICM101 could combat COVID-19 brain fog, we tested NRICM101 on hACE2 transgenic mice administered the S1 protein of SARS-CoV-2, aiming to mitigate S1-induced cognitive issues by measuring animal behaviors, immunohistochemistry (IHC) staining, and next-generation sequencing (NGS) analysis. The study revealed that S1 protein-administered mice displayed marked signs of brain fog, characterized by reduced learning, memory, and nesting abilities. However, NRICM101 treatment in these animals ameliorated all these cognitive functions. S1 protein administration in mice induced notable inflammation, leading to the death of neurons (NeuN+) and neural stem cells (DCX+) in hACE2 transgenic mice. This was accompanied by heightened microglia activation (IBA1+/CD68+), increased cytokine production (IL1β, IL6), induction of neutrophil extracellular traps (NET), inflammation (NLRP3, CD11b), and platelet (CD31, vWF) and complement (C3) activation, ultimately damaging neurovasculature and disrupting the blood-brain barrier (B.B.B.). Administration of NRICM101 effectively alleviated all these pathological changes. In conclusion, NRICM101 has the potential to prevent COVID-19-associated brain fog by bolstering neurovascular integrity and protecting neurons and neural stem cells. This is achieved by the inhibition of S1 protein-induced complement activation, which in turn leads to the prevention of damage to the neurovasculature and the subsequent death of neurons.

Retracted: Lead Exposure Induced Neural Stem Cells Death via Notch Signaling Pathway and Gut-Brain Axis.

[This retracts the article DOI: 10.1155/2022/7676872.].

Antioxidant MnO2 nanozymes-encapsulated hydrogel synergistically regulate the spinal ROS microenvironment and promote spinal cord repair

Traumatic spinal cord injury (SCI) usually leads to neuronal death and axon destruction, resulting in long-term dysfunction, permanent functional impairment, significant caregiving demands, and substantial financial burden. Therefore, a crucial aspect of SCI recovery lies in understanding how to inhibit neural stem cell (NSC) death, regulate the spinal microenvironment and promote the regeneration of neurons and axons. Herein, we designed dopamine (DA)-modified hyaluronic acid (HA) with the bridging of CeCl3 molecules, termed the CHD hydrogel. To confer regenerative properties to the hydrogel, we incorporated metformin (Met) and manganese dioxide (MnO2) to form the MnO2/Met@CHD hydrogel. The MnO2/Met@CHD hydrogel could promote the NSC adhesive growth and nerve tissue bridging, and improve neuronal differentiation and neurite outgrowth in a pathological ROS microenvironment, suggesting its excellent effect against oxidative stress. Furthermore, the MnO2/Met@CHD hydrogel can facilitate the migration and accumulation of nestin+ NSCs and inhibit GFAP+ astrocytic scar formation, thereby providing optimized microenvironments for axonal regeneration. Collectively, the MnO2/Met@CHD hydrogel system shows great promise as a novel approach for the treatment of SCI.

DNA damage and repair: underlying mechanisms leading to microcephaly.

DNA-damaging agents and endogenous DNA damage constantly harm genome integrity. Under genotoxic stress conditions, the DNA damage response (DDR) machinery is crucial in repairing lesions and preventing mutations in the basic structure of the DNA. Different repair pathways are implicated in the resolution of such lesions. For instance, the non-homologous DNA end joining and homologous recombination pathways are central cellular mechanisms by which eukaryotic cells maintain genome integrity. However, defects in these pathways are often associated with neurological disorders, indicating the pivotal role of DDR in normal brain development. Moreover, the brain is the most sensitive organ affected by DNA-damaging agents compared to other tissues during the prenatal period. The accumulation of lesions is believed to induce cell death, reduce proliferation and premature differentiation of neural stem and progenitor cells, and reduce brain size (microcephaly). Microcephaly is mainly caused by genetic mutations, especially genes encoding proteins involved in centrosomes and DNA repair pathways. However, it can also be induced by exposure to ionizing radiation and intrauterine infections such as the Zika virus. This review explains mammalian cortical development and the major DNA repair pathways that may lead to microcephaly when impaired. Next, we discuss the mechanisms and possible exposures leading to DNA damage and p53 hyperactivation culminating in microcephaly.

Microglial regulation of brain function and pathological changes

Microglia are the only immune cells in the central nervous system. It has been shown that microglia actively regulate the number of neurons by participating in the cell death of neural stem cells during development and maturation. In addition, recent optical techniques have enabled in vivo imaging, which has revealed the function of microglia on synapses. Microglia regularly monitor synaptic activity and remove synapses that show abnormal activity in the event of brain infarction or other disorders. During development, microglia contribute to the formation of immature synapses by contacting dendrites during early synapse formation, and they are also involved in the de-synaptic process by selectively removing weakly active synapses through the use of classical complement cascade signaling. Furthermore, these abnormalities are known to contribute to the development of autism during development and to the development of Alzheimer's disease during maturation. In addition to this, microglia also contribute to plastic changes in synapses during the learning process in maturation. Furthermore, by modifying synaptic activity, microglia are known to be involved in changes in the activity of neuronal circuits. In addition to these synaptic functions, microglia are also known to be involved in the permeability of the blood-brain barrier. In this chapter, these functions will be summarized and discussed.

Pharmacology-based molecular docking of 4-methylcatechol and its role in RANKL-mediated ROS/Keap1/Nrf2 signalling axis and osteoclastogenesis

4-Methylcatechol (4-MC) is an agonist of various neurotrophic factors, which can upregulate the expression of Heme oxygenase 1 (HO-1) protein by activating nuclear factor erythroid 2-related factor 2 (Nrf2), thereby inhibiting oxidative stress-induced neural stem cell death. During RANKL-stimulated osteoclast differentiation, intracellular reactive oxygen species (ROS) levels were increased. Nonetheless, the effect of 4-MC on osteoclast formation and bone resorption function has not been researched. In this study, we investigated the effect of HO-1 upregulation by 4-MC on RANKL-induced osteoclastogenesis and explored the molecular mechanism of HO-1 upregulation by 4-MC. We found that the small molecule compound 4-MC could bind to Keap1 amino acid residue of glycine GLY 367, isoleucine ILE 559 and valine VAL 606, with a predicted binding energy of −4.99 kcal/mol. 4-MC was found to inhibit osteoclast differentiation in vitro by activating Nrf2 to scavenge ROS, inhibiting NF-κB phosphorylation, and alleviating osteoporosis in ovariectomized (OVX) mice. Taken together, 4-MC reduces ROS by inhibiting Keap1, thereby preventing OVX-induced bone loss.

Lead Exposure Induced Neural Stem Cells Death via Notch Signaling Pathway and Gut-Brain Axis.

Numerous studies have examined the effects of lead (Pb) on cognitive ability. It is essential for the brain to maintain its functions through the differentiation of neural stem cells into various types of cells. Despite this, it remains unclear how Pb exposure affects neural stem cells and how it does, so the Pb-exposed mice were treated with the Notch inhibitor DAPT after we established the Pb exposure models. Neuronal stem cells and autophagy were assessed by immunofluorescence staining and western blot. The microbiota of the feces was also analyzed using the 16S rRNA amplicon sequencing technique. In this study, we found that Pb exposure caused neural injuries and deficits in neural stem cells, whereas DAPT rescued the damage. With DAPT, Pb-induced autophagy was partially reversed. Exposure to Pb also reduced inflammation and damaged gut barrier function. Furthermore, Pb exposure led to low bacterial diversity, an increase in pathogen abundance, and an unusual mode of interaction. Taken together, this study revealed that damages in neural stem cells contributed largely to cognitive impairment during Pb exposure, and this process was partially dependent on the Notch pathway and gut dysbiosis.

Stem Cell Exosomes Improve Survival of Neural Stem Cells after Radiation Exposure

The death of neural stem cells in the hippocampus during radiation therapy of brain tumors leads to neurogenesis impairment and the development of cognitive dysfunctions at delayed terms after irradiation. Exosomes secreted by stem cells can provide a protective effect on neural stem cells. We isolated and characterized exosomes from the medium conditioned by neural stem cells and mesenchymal stem cells from mouse adipose tissue and studied their efficiency in protecting irradiated neural stem cells. According to dynamic light scattering data, the exosome size varied from 44 to 68 nm for neural stem cells, and from 80 to 130 nm for mesenchymal stem cells. All exosomes carried markers CD9, CD63, and TSG101. The survival rate and clonogenic activity of neural stem cells irradiated in a dose of 1 Gy was found to increase after culturing in the presence of stem cell exosome preparations.

Periostin attenuates oxygen and glucose deprivation-induced death of mouse neural stem cells via inhibition of p38 MAPK activation

Promoting neural stem cells (NSCs) survival in the harsh niche is essential to cell replacement therapy for various central nervous system diseases. As an integral component of the extracellular matrix, Periostin (POSTN) has been shown to protect various cell types from hypoxia-ischemia damage. This study aimed to investigate the neuroprotective effects of POSTN on NSCs injury induced by oxygen and glucose deprivation (OGD). Under challenge with OGD, cell viability significantly decreased in cultured mouse NSCs, and supplement POSTN rescued cell viability in a concentration-dependent manner, as shown by CCK-8. TUNEL and propidium iodide/Hoechst staining showed that POSTN pretreatment protected NSCs against OGD-induced apoptosis. Western blot assay demonstrated that POSTN pretreatment inhibited cleavage of caspase-3 and restored the balance of Bcl-2/Bax. And pretreatment with cilengitide (an inhibitor of POSTN receptors) abolished the protective effect of POSTN. Further investigation demonstrated that supplement POSTN inhibited phosphorylation of p38 in a concentration-dependent manner. Moreover, the neuroprotective effect of POSTN was hampered by anisomycin, an activator of p38. We conclude that POSTN pretreatment in cultured mouse NSCs mitigated OGD-induced cell death, and inhibition of the p38 MAPK pathway might be one of the underlying mechanisms. Our findings may provide a novel strategy for enhancing both endogenous and exogenous NSCs survival after ischemia and hypoxia injury.

Monitoring Autophagy in Neural Stem and Progenitor Cells.

Autophagy is a critical cellular program that is necessary for cellular survival and adaptation to nutrient and metabolic stress. In addition to homeostatic maintenance and adaptive response functions, autophagy also plays an active role during development and tissue regeneration. Within the neural system, autophagy is important for stem cell maintenance and the ability of neural stem cells to undergo self-renewal. Autophagy also contributes toward neurogenesis and provides neural progenitorcells with sufficient energy to mediate cytoskeleton remodeling during the differentiation process. In differentiated neural cells, autophagy maintains neuronal homeostasis and viability by preventing the accumulation of toxic and pathological intracellular aggregates. However, prolonged autophagy or dysregulated upregulation of autophagy can result in autophagic cell death. Moreover, mutations or defects in autophagy that result in neural stem cell instability and cell death underlie many neurodegenerative disorders, such as Parkinson'sdisease. Thus, autophagy plays a multi-faceted role during neurogenesis from the stem cell to the differentiated neural cell. In this chapter, we describe methods to monitor autophagy at the protein and transcript level to evaluate alterations within the autophagy program in neural stem and progenitor cells. We describe immunoblotting and immunocytochemistry approaches for evaluating autophagy-dependent protein modifications, as well as quantitative real-time PCR to assess transcript levels of autophagy genes. As autophagy is a dynamic process, we highlight the importance of using late-stage inhibitors to be able to assess autophagic flux and quantify the level of autophagy occurring within cells.

Cochlear Implant-Based Electric-Acoustic Stimulation Modulates Neural Stem Cell-Derived Neural Regeneration

Cochlear implantation is considered to be the best therapeutic method for profound sensorineural hearing loss, but insufficient numbers of functional spiral ganglion neurons hinder the clinical effects of cochlear implantation. Stem cell transplantation has the potential to provide novel strategies for spiral ganglion neuron regeneration after injury. However, some obstacles still need to be overcome, such as low survival and uncontrolled differentiation. Several novel technologies show promise for modulating neural stem cell behaviors to address these issues. Here, a device capable of electrical stimulation was designed by combining a cochlear implant with a graphene substrate. Neural stem cells (NSCs) were cultured on the graphene substrate and subjected to electrical stimulation transduced from sound waves detected by the cochlear implant. Cell behaviors were studied, and this device showed good biocompatibility for NSCs. More importantly, electric-acoustic stimulation with higher frequencies and amplitudes induced NSC death and apoptosis, and electric-acoustic stimulation could promote NSCs to proliferate and differentiate into neurons only when low-frequency stimulation was supplied. The present study provides experimental evidence for understanding the regulatory role of electric-acoustic stimulation on NSCs and highlights the potentials of the above-mentioned device in stem cell therapy for hearing loss treatment.

Glial cell diversity and methamphetamine-induced neuroinflammation in human cerebral organoids

Methamphetamine (METH) is a potent stimulant that induces a euphoric state but also causes cognitive impairment, neurotoxicity and neurodevelopmental deficits. Yet, the molecular mechanisms by which METH causes neurodevelopmental defects have remained elusive. Here we utilized human cerebral organoids and single-cell RNA sequencing (scRNA-seq) to study the effects of prenatal METH exposure on fetal brain development. We analyzed 20,758 cells from eight untreated and six METH-treated cerebral organoids and found that the organoids developed from embryonic stem cells contained a diverse array of glial and neuronal cell types. We further identified transcriptionally distinct populations of astrocytes and oligodendrocytes within cerebral organoids. Treatment of organoids with METH-induced marked changes in transcription in multiple cell types, including astrocytes and neural progenitor cells. METH also elicited novel astrocyte-specific gene expression networks regulating responses to cytokines, and inflammasome. Moreover, upregulation of immediate early genes, complement factors, apoptosis, and immune response genes suggests a neuroinflammatory program induced by METH regulating neural stem cell proliferation, differentiation, and cell death. Finally, we observed marked METH-induced changes in neuroinflammatory and cytokine gene expression at the RNA and protein levels. Our data suggest that human cerebral organoids represent a model system to study drug-induced neuroinflammation at single-cell resolution.

Autophagic death of neural stem cells mediates chronic stress-induced decline of adult hippocampal neurogenesis and cognitive deficits

Autophagic death of neural stem cells mediates chronic stress-induced decline of adult hippocampal neurogenesis and cognitive deficits

Presenilin 2 (PS2) N141I mutation mediates corticosterone-induced autophagic cell death of adult hippocampal neural stem cells

Presenilin 2 (PS2) N141I mutation mediates corticosterone-induced autophagic cell death of adult hippocampal neural stem cells

Autophagic death of neural stem cells mediates chronic stress-induced decline of adult hippocampal neurogenesis and cognitive deficits

ABSTRACT Macroautophagy/autophagy is generally regarded as a cytoprotective mechanism, and it remains a matter of controversy whether autophagy can cause cell death in mammals. Here, we show that chronic restraint stress suppresses adult hippocampal neurogenesis in mice by inducing autophagic cell death (ACD) of hippocampal neural stem cells (NSCs). We generated NSC-specific, inducible Atg7 conditional knockout mice and found that they had an intact number of NSCs and neurogenesis level under chronic restraint stress and were resilient to stress- or corticosterone-induced cognitive and mood deficits. Corticosterone treatment of adult hippocampal NSC cultures induced ACD via SGK3 (serum/glucocorticoid regulated kinase 3) without signs of apoptosis. Our results demonstrate that ACD is biologically important in a mammalian system in vivo and would be an attractive target for therapeutic intervention for psychological stress-induced disorders. Abbreviations AAV: adeno-associated virus; ACD: autophagic cell death; ACTB: actin, beta; Atg: autophagy-related; ASCL1/MASH1: achaete-scute family bHLH transcription factor 1; BafA1: bafilomycin A1; BrdU: Bromodeoxyuridine/5-bromo-2ʹ-deoxyuridine; CASP3: caspase 3; cKO: conditional knockout; CLEM: correlative light and electron microscopy; CORT: corticosterone; CRS: chronic restraint stress; DAB: 3,3ʹ–diaminobenzidine; DCX: doublecortin; DG: dentate gyrus; GC: glucocorticoid; GFAP: glial fibrillary acidic protein; HCN: hippocampal neural stem; i.p.: intraperitoneal; MAP1LC3B: microtubule-associated protein 1 light chain 3 beta; MKI67/Ki67: antigen identified by monoclonal antibody Ki 67; MWM: Morris water maze; Nec-1: necrostatin-1; NES: nestin; NR3C1/GR: nuclear receptor subfamily 3, group C, member 1; NSC: neural stem cell; PCD: programmed cell death; PFA: paraformaldehyde; PX: Phox homology; PtdIns3P: phosphatidylinositol-3-phosphate; RBFOX3/NeuN: RNA binding protein, fox-1 homolog (C. elegans) 3; SGK: serum/glucocorticoid-regulated kinases; SGZ: subgranular zone; SOX2: SRY (sex determining region Y)-box 2; SQSTM1: sequestosome 1; STS: staurosporine; TAM: tamoxifen; Ulk1: unc-51 like kinase 1; TUNEL: terminal deoxynucleotidyl transferase dUTP nick end labeling; VIM: vimentin; WT: wild type; ZFYVE1: zinc finger, FYVE domain containing 1; Z-VAD/Z-VAD-FMK: pan-caspase inhibitor

Effects of chlorpyrifos on cell death and cellular phenotypic specification of human neural stem cells

Chlorpyrifos (CPF) is an organophosphate pesticide widely used in agriculture, whose traditional and well-known mechanism of action is the inhibition of the enzyme Acetylcholinesterase (AChE). Subacute exposures to CPF have been associated with alterations different from the inhibition of AChE. Because of the vulnerability of the developing nervous system, prenatal and early postnatal exposures are of special concern. Human neural stem cells (hNSC) provide the opportunity to study early stages of neural development and may be a valuable tool for developmental neurotoxicology (DNT). In the current work, the cell line hNS1 was used as a model system with the aim of validating this cell line as a reliable testing method. To evaluate the effects of CPF on early developmental stages, hNS1 cells were exposed to different concentrations of the pesticide and cell death, proliferation and cell fate specification were analyzed under differentiation conditions. Since hNS1 cells responded to CPF in a similar way to other human cell lines, we consider it may be a valid model for DNT chemical assessment. CPF induced apoptotic cell death only at the highest doses tested, suggesting that it is not toxic for the specific developmental stage here addressed under short term exposure. In addition, the higher doses of CPF promoted the generation of astroglial cells, without affecting neurogenesis.

Parkin Promotes Mitophagic Cell Death in Adult Hippocampal Neural Stem Cells Following Insulin Withdrawal.

Regulated cell death (RCD) plays a fundamental role in human health and disease. Apoptosis is the best-studied mode of RCD, but the importance of other modes has recently been gaining attention. We have previously demonstrated that adult rat hippocampal neural stem (HCN) cells undergo autophagy-dependent cell death (ADCD) following insulin withdrawal. Here, we show that Parkin mediates mitophagy and ADCD in insulin-deprived HCN cells. Insulin withdrawal increased the amount of depolarized mitochondria and their colocalization with autophagosomes. Insulin withdrawal also upregulated both mRNA and protein levels of Parkin, gene knockout of which prevented mitophagy and ADCD. c-Jun is a transcriptional repressor of Parkin and is degraded by the proteasome following insulin withdrawal. In insulin-deprived HCN cells, Parkin is required for Ca2+ accumulation and depolarization of mitochondria at the early stages of mitophagy as well as for recognition and removal of depolarized mitochondria at later stages. In contrast to the pro-death role of Parkin during mitophagy, Parkin deletion rendered HCN cells susceptible to apoptosis, revealing distinct roles of Parkin depending on different modes of RCD. Taken together, these results indicate that Parkin is required for the induction of ADCD accompanying mitochondrial dysfunction in HCN cells following insulin withdrawal. Since impaired insulin signaling is implicated in hippocampal deficits in various neurodegenerative diseases and psychological disorders, these findings may help to understand the mechanisms underlying death of neural stem cells and develop novel therapeutic strategies aiming to improve neurogenesis and survival of neural stem cells.

Mitochondrial transfer from mesenchymal stem cells to neural stem cells protects against the neurotoxic effects of cisplatin

Mesenchymal stem cells (MSCs) transfer healthy mitochondria to damaged acceptor cells via actin-based intercellular structures. In this study, we tested the hypothesis that MSCs transfer mitochondria to neural stem cells (NSCs) to protect NSCs against the neurotoxic effects of cisplatin treatment. Our results show that MSCs donate mitochondria to NSCs damaged in vitro by cisplatin. Transfer of healthy MSC-derived mitochondria decreases cisplatin-induced NSC death. Moreover, mitochondrial transfer from MSCs to NSCs reverses the cisplatin-induced decrease in mitochondrial membrane potential. Blocking the formation of actin-based intercellular structures inhibited the transfer of mitochondria to NSCs and abrogated the positive effects of MSCs on NSC survival. Conversely, overexpression of the mitochondrial motor protein Rho-GTPase 1 (Miro1) in MSCs increased mitochondrial transfer and further improved survival of cisplatin-treated NSCs.In vivo, MSC administration prevented the loss of DCX+ neural progenitor cells in the subventricular zone and hippocampal dentate gyrus which occurs as a result of cisplatin treatment. We propose mitochondrial transfer as one of the mechanisms via which MSCs exert their therapeutic regenerative effects after cisplatin treatment.

P53 deletion rescues lethal microcephaly in a mouse model with neural stem cell abscission defects.

Building a cerebral cortex of the proper size involves balancing rates and timing of neural stem cell (NSC) proliferation, neurogenesis and cell death. The cellular mechanisms connecting genetic mutations to brain malformation phenotypes are still poorly understood. Microcephaly may result when NSC divisions are too slow, produce neurons too early or undergo apoptosis but the relative contributions of these cellular mechanisms to various types of microcephaly are not understood. We previously showed that mouse mutants in Kif20b (formerly called Mphosph1, Mpp1 or KRMP1) have small cortices that show elevated apoptosis and defects in maturation of NSC midbodies, which mediate cytokinetic abscission. Here we test the contribution of intrinsic NSC apoptosis to brain size reduction in this lethal microcephaly model. By making double mutants with the pro-apoptotic genes Bax and Trp53 (p53), we find that p53-dependent apoptosis of cortical NSCs accounts for most of the microcephaly, but that there is a significant apoptosis-independent contribution as well. Remarkably, heterozygous p53 deletion is sufficient to fully rescue survival of the Kif20b mutant into adulthood. In addition, the NSC midbody maturation defects are not rescued by p53 deletion, showing that they are either upstream of p53 activation, or in a parallel pathway. Accumulation of p53 in the nucleus of mutant NSCs at midbody stage suggests the possibility of a novel midbody-mediated pathway for p53 activation. This work elucidates both NSC apoptosis and abscission mechanisms that could underlie human microcephaly or other brain malformations.

Aβ42 Peptide Promotes Proliferation and Gliogenesis in Human Neural Stem Cells.

Amyloid-β 42 [Aβ1-42 (Aβ42)] is one of the main Aβ peptide isoforms found in amyloid plaques of brains with Alzheimer's disease (AD). Although Aβ42 is associated with neurotoxicity, it might mediate several normal physiological processes during embryonic brain development and in the adult brain. However, due to the controversy that exists in the field, relatively little is known about its physiological function. In the present work, we have analyzed the effects of different concentrations of monomeric Aβ42 on cell death, proliferation, and cell fate specification of human neural stem cells (hNSCs), specifically the hNS1 cell line, undergoing differentiation. Our results demonstrate that at higher concentrations (1μM), Aβ42 increases apoptotic cell death and DNA damage, indicating that prolonged exposure of hNS1 cells to higher concentrations of Aβ42 is neurotoxic. However, at lower concentrations, Aβ42 significantly promotes cell proliferation and glial cell specification of hNS1 cells by increasing the pool of proliferating glial precursors, without affecting neuronal differentiation, in a concentration-dependent manner. At the molecular level, these effects could be mediated, at least in part, by GSK3β, whose expression is increased by treatment with Aβ42 and whose inhibition prevents the glial specification induced by Aβ42. Since the cellular and molecular effects are known to appear decades before the first clinical symptoms, these types of studies are important in discovering the underlying pathophysiological processes involved in the development of AD. This knowledge could then be used in diagnosing the disease at early stages and be applied to the development of new treatment options.