SDF-1/CXCR4 Signaling Maintains Stemness Signature in Mouse Neural Stem/Progenitor Cells

Nano-scaffold containing functional motif of stromal cell-derived factor 1 enhances neural stem cell behavior and synaptogenesis in traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of mortality and morbidity worldwide, presenting a significant challenge due to the lack of effective therapies. Neural stem cells (NSCs) have shown promising potential in preclinical studies as a therapy for TBI. However, their application is limited by challenges related to poor survival and integration within the injured brain. This study investigated the effect of a novel nano-scaffold containing stromal cell-derived factor 1 (SDF-1) on NSC behavior and synaptogenesis after TBI. Using an innovative design, we successfully fabricated a nano-scaffold with Young's modulus of approximately 3.21 kPa, which aligns closely with the mechanical properties exhibited by neural tissue. This achievement marks the first time such a scaffold has been created and has promising implications for its potential use in neural tissue engineering applications. Our findings demonstrate that the nano-scaffold enhances NSC proliferation, migration, and differentiation capacity in vitro. Moreover, when transplanted into the injured brain, the nano-scaffold promotes the survival and integration of NSCs, leading to increased synaptogenesis and functional recovery. These findings suggest that using the novel nano-scaffold containing SDF-1 could provide a promising approach to treating TBI by improving NSC behavior and promoting synaptogenesis.

Stromal cell-derived factor-1 downregulation contributes to neuroprotection mediated by CXC chemokine receptor 4 interactions after intracerebral hemorrhage in rats

AIM

Stromal cell-derived factor-1 (SDF-1) and CXC chemokine receptor 4 (CXCR4) have a substantial role in neuronal formation, differentiation, remodeling, and maturation and participate in multiple physiological and pathological events. In this study, we investigated the role of SDF-1/CXCR4 in neural functional injury and neuroprotection after intracerebral hemorrhage (ICH).

METHODS

Western blot, immunofluorescence and immunoprecipitation were used to detect SDF-1/CXCR4 expression and combination respectively after ICH. TUNEL staining, Lactate dehydrogenase assay, Reactive oxygen species assay, and Enzyme-linked immunosorbent assay to study neuronal damage; Brain water content to assay brain edema, Neurological scores to assess short-term neurological deficits. Pharmacological inhibition and genetic intervention of SDF-1/CXCR4 signaling were also used in this study.

RESULTS

ICH induced upregulation of SDF-1/CXCR4 and increased their complex formation, whereas AMD3100 significantly reduced it. The levels of TNF-α and IL-1β were significantly reduced after AMD3100 treatment. Additionally, AMD3100 treatment can alleviate neurobehavioral dysfunction of ICH rats. Conversely, simultaneous SDF-1/CXCR4 overexpression induced the opposite effect. Moreover, immunoprecipitation confirmed that SDF-1/CXCR4 combined to initiate neurodamage effects.

CONCLUSION

This study indicated that inhibition of SDF-1/CXCR4 complex formation can rescue the inflammatory response and alleviate neurobehavioral dysfunction after ICH. SDF-1/CXCR4 may have applications as a therapeutic target after ICH.

Inhibition of PIM Kinases Promotes Neuroblastoma Cell Differentiation to a Neuronal Phenotype

BACKGROUND

Neuroblastoma arises from aberrancies in neural stem cell differentiation. PIM kinases contribute to cancer formation, but their precise role in neuroblastoma tumorigenesis is poorly understood. In the current study, we evaluated the effects of PIM kinase inhibition on neuroblastoma differentiation.

METHODS

Versteeg database query assessed the correlation between PIM gene expression and the expression of neuronal stemness markers and relapse free survival. PIM kinases were inhibited with AZD1208. Viability, proliferation, motility were measured in established neuroblastoma cells lines and high-risk neuroblastoma patient-derived xenografts (PDXs). qPCR and flow cytometry detected changes in neuronal stemness marker expression after AZD1208 treatment.

RESULTS

Database query showed increased levels of PIM1, PIM2, or PIM3 gene expression were associated with higher risk of recurrent or progressive neuroblastoma. Increased levels of PIM1 were associated with lower relapse free survival rates. Higher levels of PIM1 correlated with lower levels of neuronal stemness markers OCT4, NANOG, and SOX2. Treatment with AZD1208 resulted in increased expression of neuronal stemness markers.

CONCLUSIONS

Inhibition of PIM kinases differentiated neuroblastoma cancer cells toward a neuronal phenotype. Differentiation is a key component of preventing neuroblastoma relapse or recurrence and PIM kinase inhibition provides a potential new therapeutic strategy for this disease.

The Role of Hypoxia and Cancer Stem Cells in Development of Glioblastoma

Glioblastoma multiform (GBM) is recognized as the most malignant brain tumor with a high level of hypoxia, containing a small population of glioblastoma stem like cells (GSCs). These GSCs have the capacity of self-renewal, proliferation, invasion and recapitulating the parent tumor, and are major causes of radio-and chemoresistance of GBM. Upregulated expression of hypoxia inducible factors (HIFs) in hypoxia fundamentally contributes to maintenance and progression of GSCs. Therefore, we thoroughly reviewed the currently acknowledged roles of hypoxia-associated GSCs in development of GBM. In detail, we recapitulated general features of GBM, especially GSC-related features, and delineated essential responses resulted from interactions between GSC and hypoxia, including hypoxia-induced signatures, genes and pathways, and hypoxia-regulated metabolic alterations. Five hypothesized GSC niches are discussed and integrated into one comprehensive concept: hypoxic peri-arteriolar niche of GSCs. Autophagy, another protective mechanism against chemotherapy, is also closely related to hypoxia and is a potential therapeutic target for GBM. In addition, potential causes of therapeutic resistance (chemo-, radio-, surgical-, immuno-), and chemotherapeutic agents which can improve the therapeutic effects of chemo-, radio-, or immunotherapy are introduced and discussed. At last, as a potential approach to reverse the hypoxic microenvironment in GBM, hyperbaric oxygen therapy (HBOT) might be an adjuvant therapy to chemo-and radiotherapy after surgery. In conclusion, we focus on demonstrating the important role of hypoxia on development of GBM, especially by affecting the function of GSCs. Important advantages have been made to understand the complicated responses induced by hypoxia in GBM. Further exploration of targeting hypoxia and GSCs can help to develop novel therapeutic strategies to improve the survival of GBM patients.

CXCR4 enhances the inhibitory effects of bone mesenchymal stem cells on lung cell apoptosis in a rat model of smoking-induced COPD

Chronic obstructive pulmonary disease is the 3rd leading cause of death worldwide, and the available treatments are unsatisfactory, resulting in a major economic burden. As cellular therapy is commonly used for lung disease, we investigated a treatment with CXCR4-overexpressing BMSCs in a COPD model. We extracted and purified Bone marrow mesenchymal stem cells (BMSCs) from SD rats. COPD apoptosis model was established by cigarette smoke exposure. BMSCs (1 × 106 cells per injection)were transplanted in vivo twice a month during model establishment, and alveolar rupture in the lung was assessed. Lung cell apoptosis was assessed by terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL) analysis, and the concentrations of apoptotic proteins in the lungs were detected by Western blotting. We successfully isolated BMSCs and established CXCR4-overexpressing BMSCs. qRT‒PCR and Western blotting detection both reveal that CXCR4 mRNA level and protein both significantly higher expression in CXCR4-BMSCs than the pBABE-BMSCs. Continuous cigarette smoke exposure caused alveolar septal rupture: In the model group, the alveolar mean linear intercept in the first month was significantly lower than that in the third month (p < 0.05). In the third month, the alveolar mean linear intercept values of the control and CXCR4-BMSC groups were lower than those of the model group (control group p < 0.01, CXCR4-BMSC group p < 0.05), and TUNEL staining revealed that the apoptosis rates of the control and CXCR4-BMSC groups were significantly lower than those of the model group (p < 0.01). Furthermore, the levels of the apoptotic proteins cleaved caspase-8, cleaved caspase-3 and cleaved PARP-1 were higher in the model group than in the control group (p < 0.05) and significantly lower in the CXCR4-BMSC group than in the model group (p < 0.05). The transplantation of CXCR4-overexpressing BMSCs during COPD model generation significantly inhibited apoptosis via the extrinsic apoptosis pathway. CXCR4 enhances the inhibitory effects of bone mesenchymal stem cells on lung cell apoptosis in a rat model of smoking-induced COPD.

Upregulating HIF-1α to Boost the Survival of Neural Stem Cells via Functional Peptides-Complexed MRI-Visible Nanomedicine for Stroke Therapy

Neural stem cells (NSCs) transplantation has been considered as a promising strategy for the treatment of ischemic stroke. However, the therapeutic prospect is limited by the poor control over the survival, migration, and maturation of transplanted NSCs. Upregulating hypoxia inducible factor (HIF)-1α expression in stem cells can improve the survival and migration of NSCs grafted for stroke therapy. Functional peptide drugs, which could inhibit endogenous HIF-1α ubiquitination, might be used to effectively upregulate the HIF-1α expression in NSCs, thereby to improve the therapeutic effect in ischemia stroke. Herein, a magnetic resonance imaging (MRI)-visible nanomedicine is developed to codeliver functional peptides and superparamagnetic iron oxide (SPIO) nanoparticles into NSCs. This nanomedicine not only promotes the survival and migration ability of NSCs but also allows an in vivo tracking of transplanted NSCs with MRI. The results demonstrate the great potential of the functional peptides-complexed multifunctional nanomedicine in boosting the therapeutic effect of stem cell-based therapy in stroke.

To Explore the Stem Cells Homing to GBM: The Rise to the Occasion

Multiple efforts are currently underway to develop targeted therapeutic deliveries to the site of glioblastoma progression. The use of carriers represents advancement in the delivery of various therapeutic agents as a new approach in neuro-oncology. Mesenchymal stem cells (MSCs) and neural stem cells (NSCs) are used because of their capability in migrating and delivering therapeutic payloads to tumors. Two of the main properties that carrier cells should possess are their ability to specifically migrate from the bloodstream and low immunogenicity. In this article, we also compared the morphological and molecular features of each type of stem cell that underlie their migration capacity to glioblastoma. Thus, the major focus of the current review is on proteins and lipid molecules that are released by GBM to attract stem cells.

Propofol induces the apoptosis of neural stem cells via microRNA-9-5p / chemokine CXC receptor 4 signaling pathway

Recent studies suggested that propofol, one of the most widely used anesthetics, may cause neurotoxicity in the developing brain, leading to cognitive deficits in adults. However, the underlying mechanisms remain unclear. In this study, we aimed to evaluate the mechanisms of propofol neurotoxicity in the neural stem cells (NSCs). The mRNA and protein expression levels of microRNA-9-5p (miR-9-5p) and chemokine CXC receptor 4 (CXCR4) were determined by quantitative reverse transcription-polymerase chain reaction and Western blotting analyses. Cell viability and apoptosis were evaluated using the cell counting kit-8 and Hoechst staining kits. The levels of apoptosis-related proteins B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein, and caspase-3 were detected by Western blotting analysis. These results confirmed that propofol activated cell apoptosis in a dose-dependent manner. A significant increase in the miR-9-5p and CXCR4 expression was observed in the propofol-treated cells. The overexpression of miR-9-5p induced apoptosis in NSCs, accompanied by elevated apoptosis-related protein activity. Furthermore, mitigated CXCR4 expression reduced propofol-induced cell apoptosis. We conclude that propofol induces cell death in NSCs, and overexpression of miR-9-5p/CXCR4 contributes to propofol-induced cell apoptosis, which might be a target for developing novel strategies to treat propofol neurotoxicity.

Co-culture of mesenchymal stem cell spheres with hematopoietic stem cells under hypoxia: a cost-effective method to maintain self-renewal and homing marker expression

BACKGROUND

Hematopoietic stem cell (HSC) transplantation is considered a possible treatment option capable of curing various diseases. The aim of this study was the co-culturing of mesenchymal stem cell (MSC) spheres with HSCs under hypoxic condition to enhance the proliferation, self-renewal, stemness, and homing capacities of HSCs.

METHODS AND RESULTS

HSCs were expanded after being subjected to different conditions including cytokines without feeder (Cyto), co-culturing with adherent MSCs (MSC), co-culturing with adherent MSCs + hypoxia (MSC + Hyp), co-culturing with MSCs spheres (Sph-MSC), co-culturing with MSCs spheres + hypoxia (Sph-MSC + Hyp), co-culturing with MSC spheres + cytokines (Sph-MSC + Cyto). After 10 days, total nucleated cell (TNC) and CD34⁺/CD38^- cell counts, colony-forming unit assay (CFU), long-term culture initiating cell (LTC-IC), the expression of endothelial protein C receptor (EPCR), nucleostemin (NS), nuclear factor I/X (Nfix) CXCR4, and VLA-4 were evaluated. The TNC, CD34⁺/CD38^- cell count, CFU, and LTC-IC were higher in the Sph-MSC + Hyp and Sph-MSC + Cyto groups as compared with those of the MSC + Hyp group (P < 0.001). The expanded HSCs co-cultured with MSC spheres in combination with hypoxia expressed more EPCR, CXCR4, VLA-4, NS, and Nfix mRNA. The protein expression was also more up-regulated in the Sph-MSC + Cyto and Sph-MSC + Hyp groups.

CONCLUSION

Co-culturing HSCs with MSC spheres under hypoxic condition not only leads to higher cellular yield but also increases the expression of self-renewal and homing genes. Therefore, we suggest this approach as a simple and non-expensive strategy that might improve the transplantation efficiency of HSCs.

Insulin growth factor-1 enhances proliferation and inhibits apoptosis of neural progenitor cells by phosphorylation of Akt/mTOR/p70S6K molecules and triggering intrinsic apoptosis signaling pathway

Neural progenitor cells (NPCs) transplantation is known as a potential strategy for treating spinal cord injury (SCI). This study aimed to investigate effects of insulin growth factor-1 (IGF-I) on NPCs proliferation and clarify associated mechanisms. NPCs isolated from T8-T10 segmental spinal cord tissues of rats were cultured and identification. Then, lentivirus packing plasmids containing IGF-I was constructed and used for NPCs infection. Cell proliferation was evaluated by detecting 5-Bromodeoxyuridine (BrdU) expression in NPCs, cell differentiation was detected using double-labeling immunofluorescence staining while cell apoptosis was detected using TUNEL assay. In addition, the signal expression of Akt/mTOR/p70S6K in NPCs cells were investigated using immunofluorescence staining and western blot assay. The experimental group was defined as pCMV-IGF-I group, while the negative control group was defined as pCMV-LacZ group. Cells infected with pCMV-IGF-I lentivirus followed by addition of 100 mg/ml rapamycin were defined as pCMV-IGF-I + Rapa group. NPCs were successfully isolated, identified and cultured. IGF-I overexpression significantly inhibited cell apoptosis and enhanced cell migration. Akt/mTOR/ p70S6K signaling cascade was proved to be present in NPCs, IGF-I overexpression significantly activated Akt/mTOR/p70S6K signaling cascade, while rapamycin addition inhibited its expression. Also, the activated Akt/mTOR/p70S6K signal cascade induced by IGF-I significantly enhanced BrdU expression and inhibited cell apoptosis, and promoted the differentiation of NPC into the neuronal system. However, the rapamycin addition inhibited the cell response induced by IGF-I overexpression. IGF-I overexpression could enhance cell proliferation, inhibit cell apoptosis and promote their differentiation into neuronal systems by activating Akt/mTOR/p70S6K signaling cascade in vitro, indicating that the Akt/mTOR/p70S6K signaling cascade may be the potentially mechanism for the endogenous repair and remodeling of spinal cord after injury.

Nanogold-Carried Graphene Oxide: Anti-Inflammation and Increased Differentiation Capacity of Mesenchymal Stem Cells

Graphene-based nanocomposites such as graphene oxide (GO) and nanoparticle-decorated graphene with demonstrated excellent physicochemical properties have worthwhile applications in biomedicine and bioengineering such as tissue engineering. In this study, we fabricated gold nanoparticle-decorated GO (GO-Au) nanocomposites and characterized their physicochemical properties using UV-Vis absorption spectra, FTIR spectra, contact angle analyses, and free radical scavenging potential. Moreover, we investigated the potent applications of GO-Au nanocomposites on directing mesenchymal stem cells (MSCs) for tissue regeneration. We compared the efficacy of as-prepared GO-derived nanocomposites including GO, GO-Au, and GO-Au (×2) on the biocompatibility of MSCs, immune cell identification, anti-inflammatory effects, differentiation capacity, as well as animal immune compatibility. Our results showed that Au-deposited GO nanocomposites, especially GO-Au (×2), significantly exhibited increased cell viability of MSCs, had good anti-oxidative ability, sponged the immune response toward monocyte-macrophage transition, as well as inhibited the activity of platelets. Moreover, we also validated the superior efficacy of Au-deposited GO nanocomposites on the enhancement of cell motility and various MSCs-derived cell types of differentiation including neuron cells, adipocytes, osteocytes, and endothelial cells. Additionally, the lower induction of fibrotic formation, reduced M1 macrophage polarization, and higher induction of M2 macrophage, as well as promotion of the endothelialization, were also found in the Au-deposited GO nanocomposites implanted animal model. These results suggest that the Au-deposited GO nanocomposites have excellent immune compatibility and anti-inflammatory effects in vivo and in vitro. Altogether, our findings indicate that Au-decorated GO nanocomposites, especially GO-Au (×2), can be a potent nanocarrier for tissue engineering and an effective clinical strategy for anti-inflammation.

Repetitive transcranial magnetic stimulation increases neurological function and endogenous neural stem cell migration via the SDF-1α/CXCR4 axis after cerebral infarction in rats

Neural stem cell (NSC) migration is closely associated with brain development and is reportedly involved during recovery from ischaemic stroke. Chemokine signalling mediated by stromal cell-derived factor 1α (SDF-1α) and its receptor CXC chemokine receptor 4 (CXCR4) has been previously documented to guide the migration of NSCs. Although repetitive transcranial magnetic stimulation (rTMS) can increase neurological function in a rat stroke model, its effects on the migration of NSCs and associated underlying mechanism remain unclear. Therefore, the present study investigated the effects of rTMS on ischaemic stroke following middle cerebral artery occlusion (MCAO). All rats underwent rTMS treatment 24 h after MCAO. Neurological function, using modified Neurological Severity Scores and grip strength test and NSC migration, which were measured using immunofluorescence staining, were analysed at 7 and 14 days after MCAO, before the protein expression levels of the SDF-1α/CXCR4 axis was evaluated using western blot analysis. AMD3100, a CXCR4 inhibitor, was used to assess the effects of SDF-1α/CXCR4 signalling. In addition, neuronal survival was investigated using Nissl staining at 14 days after MCAO. It was revealed that rTMS increased the neurological recovery of rats with MCAO, facilitated the migration of NSC, augmented the expression levels of the SDF-1α/CXCR4 axis and decreased neuronal loss. Furthermore, the rTMS-induced positive responses were significantly abolished by AMD3100. Overall, these results indicated that rTMS conferred therapeutic neuroprotective properties, which can restore neurological function after ischaemic stroke, in a manner that may be associated with the activation of the SDF-1α/CXCR4 axis.

Immunohistochemical Detection of Neural Stem Cells and Glioblastoma Stem Cells in the Subventricular Zone of Glioblastoma Patients

Glioblastoma usually recurs after therapy consisting of surgery, radiotherapy, and chemotherapy. Recurrence is at least partly caused by glioblastoma stem cells (GSCs) that are maintained in intratumoral hypoxic peri-arteriolar microenvironments, or niches, in a slowly dividing state that renders GSCs resistant to radiotherapy and chemotherapy. Because the subventricular zone (SVZ) is a major niche for neural stem cells (NSCs) in the brain, we investigated whether GSCs are present in the SVZ at distance from the glioblastoma tumor. We characterized the SVZ of brains of seven glioblastoma patients using fluorescence immunohistochemistry and image analysis. NSCs were identified by CD133 and SOX2 but not CD9 expression, whereas GSCs were positive for all three biomarkers. NSCs were present in all seven samples and GSCs in six out of seven samples. The SVZ in all samples were hypoxic and expressed the same relevant chemokines and their receptors as GSC niches in glioblastoma tumors: stromal-derived factor-1α (SDF-1α), C-X-C receptor type 4 (CXCR4), osteopontin, and CD44. In conclusion, in glioblastoma patients, GSCs are present at distance from the glioblastoma tumor in the SVZ. These findings suggest that GSCs in the SVZ niche are protected against radiotherapy and chemotherapy and protected against surgical resection due to their distant localization and thus may contribute to tumor recurrence after therapy.

Inhibition of CXCR4 ameliorates hypoxia-induced pulmonary arterial hypertension in rats

Pulmonary vascular remodeling due to aberrant proliferation and migration of pulmonary artery smooth muscle cells (PASMCs) is the main characteristic of pulmonary arterial hypertension (PAH). CXCR4 is a specific stem cell surface receptor of cytokine CXCL12 which could regulate homing of hematopoietic progenitor cells and their mobilization. There is evidence that bone marrow-derived CXCR4 proangiogenic cell accumulation take an important part in the development of pulmonary arterial hypertension; however, the underlying mechanisms still remain unknown. Here, we explored the expression profile of CXCR4 both in hypoxia rats and PAH patients by measuring proliferation and migration of PASMCs. We performed western blot analysis to detect downstream molecules. We demonstrated that CXCR4 expression level was increased in both rats exposed to chronic hypoxia and PAH patients in reconstructed pulmonary arterioles. The inhibition of CXCR4 expression slowed down the process of hypoxic-PAH by reducing the mean right ventricular systolic pressure, right ventricular hypertrophy, and pulmonary vascular remodeling in vivo experimental mode. CXCR4 overexpression and inhibition regulated the cell growth of PASMCs in hypoxia condition, which are the critical cellular events in vascular disease. Furthermore, activation of β-catenin signaling and upregulation of CXCR4 could be blocked by AMD3100 both in vivo and vitro. Taken together, inhibition of CXCR4 expression could downregulate β-catenin, reduced pulmonary artery smooth muscle cell proliferation, and ameliorated pulmonary vascular remodeling in hypoxia rats. These findings suggest that CXCL12/CXCR4 is critical in driving PAH and uncover a correlation between β-catenin dependent signaling.

Chemokine signaling is required for homeostatic and injury-induced neurogenesis in the olfactory epithelium

The olfactory epithelium (OE) possesses unique lifelong neuroregenerative capacities and undergoes constitutive neurogenesis throughout mammalian lifespan. Two populations of stem cells, frequently dividing globose basal cells (GBCs) and quiescent horizontal basal cells (HBCs), readily replace olfactory neurons throughout lifetime. Although lineage commitment and neuronal differentiation of stem cells has already been described in terms of transcription factor expression, little is known about external factors balancing between differentiation and self-renewal. We show here that expression of the CXC-motif chemokine receptor 4 (CXCR4) distinguishes both types of stem cells. Extensive colocalization analysis revealed exclusive expression of CXCR4 in proliferating GBCs and their neuronal progenies. Moreover, only neuronal lineage cells were derived from CXCR4-CreER-tdTomato reporter mice in the OE. Furthermore, Cre-tdTomato mice specific for HBCs (Nestin+ and Cytokeratin14+) did not reduce CXCR4 expression when bred to mice bearing floxed CXCR4 alleles, and did not show labeling of the neuronal cells. CXCR4 and its ligand CXCL12 were markedly upregulated upon induction of GBC proliferation during injury-induced regeneration. in vivo overexpression of CXCL12 did downregulate CXCR4 levels, which results in reduced GBC maintenance and neuronal differentiation. We proved that these effects were caused by CXCR4 downregulation rather than over-activation by showing that the phenotypes of CXCL12-overexpressing mice were highly similar to the phenotypes of CXCR4 knockout mice. Our results demonstrate functional CXCR4 signaling in GBCs regulates cell cycle exit and neural differentiation. We propose that CXCR4/CXCL12 signaling is an essential regulator of olfactory neurogenesis and provide new insights into the dynamics of neurogenesis in the OE.

Oxidative Stress Impact on the Transcriptome of Differentiating Neuroblastoma Cells: Implication for Psychiatric Disorders

Prenatal environmental exposures that have been shown to induce oxidative stress (OS) during pregnancy, such as smoking and alcohol consumption, are risk factors for the onset of schizophrenia and other neurodevelopmental disorders (NDDs). While the OS role in the etiology of neurodegenerative diseases is well known, its contribution to the genomic dysregulation associated with psychiatric disorders is less well defined. In this study we used the SH-SY5Y cell line and applied RNA-sequencing to explore transcriptomic changes in response to OS before or during neural differentiation. We observed differential expression of many genes, most of which localised to the synapse and were involved in neuronal differentiation. These genes were enriched in schizophrenia-associated signalling pathways, including PI3K/Akt, axon guidance, and signalling by retinoic acid. Interestingly, circulatory system development was affected by both treatments, which is concordant with observations of increased prevalence of cardiovascular disease in patients with NDDs. We also observed a very significant increase in the expression of immunity-related genes, supporting current hypotheses of immune system involvement in psychiatric disorders. While further investigation of this influence in other cell and animal models is warranted, our data suggest that early life exposure to OS has a disruptive influence on neuronal gene expression that may perturb normal differentiation and neurodevelopment, thereby contributing towards overall risk for developing psychiatric diseases.

Is There Such a Thing as a Genuine Cancer Stem Cell Marker? Perspectives from the Gut, the Brain and the Dental Pulp

The conversion of healthy stem cells into cancer stem cells (CSCs) is believed to underlie tumor relapse after surgical removal and fuel tumor growth and invasiveness. CSCs often arise from the malignant transformation of resident multipotent stem cells, which are present in most human tissues. Some organs, such as the gut and the brain, can give rise to very aggressive types of cancers, contrary to the dental pulp, which is a tissue with a very remarkable resistance to oncogenesis. In this review, we focus on the similarities and differences between gut, brain and dental pulp stem cells and their related CSCs, placing a particular emphasis on both their shared and distinctive cell markers, including the expression of pluripotency core factors. We discuss some of their similarities and differences with regard to oncogenic signaling, telomerase activity and their intrinsic propensity to degenerate to CSCs. We also explore the characteristics of the events and mutations leading to malignant transformation in each case. Importantly, healthy dental pulp stem cells (DPSCs) share a great deal of features with many of the so far reported CSC phenotypes found in malignant neoplasms. However, there exist literally no reports about the contribution of DPSCs to malignant tumors. This raises the question about the particularities of the dental pulp and what specific barriers to malignancy might be present in the case of this tissue. These notable differences warrant further research to decipher the singular properties of DPSCs that make them resistant to transformation, and to unravel new therapeutic targets to treat deadly tumors.

Embryonic periventricular endothelial cells demonstrate a unique pro-neurodevelopment and anti-inflammatory gene signature

Brain embryonic periventricular endothelial cells (PVEC) crosstalk with neural progenitor cells (NPC) promoting mutual proliferation, formation of tubular-like structures in the former and maintenance of stemness in the latter. To better characterize this interaction, we conducted a comparative transcriptome analysis of mouse PVEC vs. adult brain endothelial cells (ABEC) in mono-culture or NPC co-culture. We identified > 6000 differentially expressed genes (DEG), regardless of culture condition. PVEC exhibited a 30-fold greater response to NPC than ABEC (411 vs. 13 DEG). Gene Ontology (GO) analysis of DEG that were higher or lower in PVEC vs. ABEC identified "Nervous system development" and "Response to Stress" as the top significantly different biological process, respectively. Enrichment in canonical pathways included HIF1A, FGF/stemness, WNT signaling, interferon signaling and complement. Solute carriers (SLC) and ABC transporters represented an important subset of DEG, underscoring PVEC's implication in blood-brain barrier formation and maintenance of nutrient-rich/non-toxic environment. Our work characterizes the gene signature of PVEC and their important partnership with NPC, underpinning their unique role in maintaining a healthy neurovascular niche, and in supporting brain development. This information may pave the way for additional studies to explore their therapeutic potential in neuro-degenerative diseases, such as Alzheimer's and Parkinson's disease.

Common and Distinct Features of Adult Neurogenesis and Regeneration in the Telencephalon of Zebrafish and Mammals

In contrast to mammals, the adult zebrafish brain shows neurogenic activity in a multitude of niches present in almost all brain subdivisions. Irrespectively, constitutive neurogenesis in the adult zebrafish and mouse telencephalon share many similarities at the cellular and molecular level. However, upon injury during tissue repair, the situation is entirely different. In zebrafish, inflammation caused by traumatic brain injury or by induced neurodegeneration initiates specific and distinct neurogenic programs that, in combination with signaling pathways implicated in constitutive neurogenesis, quickly, and efficiently overcome the loss of neurons. In the mouse brain, injury-induced inflammation promotes gliosis leading to glial scar formation and inhibition of regeneration. A better understanding of the regenerative mechanisms occurring in the zebrafish brain could help to develop new therapies to combat the debilitating consequences of brain injury, stroke, and neurodegeneration. The aim of this review is to compare the properties of neural progenitors and the signaling pathways, which control adult neurogenesis and regeneration in the zebrafish and mammalian telencephalon.

The Chemokine Receptor CXCR4 in Cell Proliferation and Tissue Regeneration

The CXCR4 receptor upon binding its ligands triggers multiple signaling pathways that orchestrate cell migration, hematopoiesis and cell homing, and retention in the bone marrow. However, CXCR4 also directly controls cell proliferation of non-hematopoietic cells. This review focuses on recent reports pointing to its pivotal role in tissue regeneration and stem cell activation, and discusses the connection to the known role of CXCR4 in promoting tumor growth. The mechanisms may be similar in all cases, since regeneration often recapitulates developmental processes, and cancer often exploits developmental pathways. Moreover, cell migration and cell proliferation appear to be downstream of the same signaling pathways. A deeper understanding of the complex signaling originating from CXCR4 is needed to exploit the opportunities to repair damaged organs safely and effectively.

Interaction between SDF1 and CXCR4 Promotes Photoreceptor Differentiation via Upregulation of NFκB Pathway Signaling Activity in Pax6 Gene-Transfected Photoreceptor Precursors

BACKGROUND

CCL2 (also known as monocyte chemoattractant protein 1) and CX3CR1 (also known as Fractalkine receptor)-deficient mice have damaged photoreceptors.

OBJECTIVES

We examined the interaction of SDF1 and CXCR4 on the differentiation of retinal progenitors into rhodopsin-positive photoreceptors.

METHODS

Cloned retinal progenitors were obtained by Pax6 gene transfection of mouse iPS cells followed by serial dilution. Clones were selected by expression of nestin, Musashi1, Six3, and Chx10 mRNA. Cell surface protein expression was analyzed by flow cytometry. The levels of mRNA and intracellular protein were examined by real-time PCR and immunochemistry, respectively. Transient transfection experiments of retinal progenitors were conducted using a human rhodopsin promoter luciferase plasmid.

RESULTS

We selected 10 clones that expressed Six3, Chx10, Crx, Rx1, Nrl, CD73, and rhodopsin mRNA, which, except for rhodopsin, are photoreceptor precursor markers. Clones expressed both CD73 and CXCR4 on the cell surface and differentiated into rhodopsin-positive photoreceptors, which was reinforced by the addition of exogenous SDF1. A CXCR4 inhibitor AMD3100 blocked SDF1-mediated differentiation of progenitors into photoreceptors. SDF1 enhanced human rhodopsin promoter transcription activity, possibly via the NFκB pathway. Addition of SDF1 to the cell culture induced nuclear translocation of NFκB on retinal progenitor cell clones. Neonatal and newborn mouse retinas expressed SDF1 and CXCR4. Cells in the outer nuclear layer where photoreceptors are located expressed CXCR4 at P14 and P56. Cells in the inner nuclear layer expressed SDF1.

CONCLUSIONS

These findings suggest that retinal progenitor cell differentiation was at least partly regulated by SDF1 and CXCR4 via upregulation of NFκB activity.

Static Magnetic Field Induced Neural Stem/Progenitor Cell Early Differentiation and Promotes Maturation

The potential impacts of magnetic field exposures on brain development have raised public concern. In the present study, we aimed to investigate the biophysical effects of moderate-intensity (0.5 T, Tesla) static magnetic field (SMF) on mice neural progenitor cells (mNPCs). Our results showed that the SMF exposure increased the number of neurosphere formation and enhanced proliferative activity in mNPCs. In addition, our flow cytometry data demonstrated that the proportions of S phase and G2/M phase mNPCs were remarkably increased following 5 days of SMF exposure. Moreover, the level of a mitotic regulatory protein, cyclin B, was upregulated after SMF exposure. Furthermore, the mNPCs exposed to SMF exhibited a significant increase in Sox2 expression. When mNPCs were induced to differentiation, our immunofluorescence assay revealed that the percentage of neurons (Tuj-1-positive cells) but not astrocyte (s100β-positive cells) was significantly higher and displayed morphological complexity in the SMF group. Finally, our electrophysiological results demonstrated the mNPC-derived neurons from the SMF group showing a significantly increased in input resistance, which indicated more functional maturation. Based on these findings, it appears reasonable to suggest that SMF exposure could affect normal neurogenesis and promote neural lineage differentiation as well as neuronal maturation.

Effects of high glucose on proliferation and function of circulating fibrocytes: Involvement of CXCR4/SDF‑1 axis

The present study aimed to further investigate the effects of high glucose on the function of circulating fibrocytes and its underlying mechanisms. The total peripheral blood mononuclear cells were obtained from normal glucose tolerance patients and type 2 diabetic mellitus patients. Circulating fibrocytes were stimulated with different glucose concentrations for different time periods (24, 48 and 72 h). Cell proliferation was determined by Cell Counting Kit-8 assay. The expression of connective tissue growth factor (CTGF) was detected by western blotting. The expression of COL-I was detected by flow cytometry. The apoptotic bodies of cells were detected by fluorescence microscopy after Hoechst33258 staining. The invasive and migration abilities of fibrocytes were detected by Transwell chamber assay. Secretion of stromal cell-derived factor 1 (SDF-1) was measured by ELISA. The circulating fibrocytes showed a typical spindle-shape and were double-positive for cluster of differentiation 45 (green) and COL-I (red). Compared with the 5.5 mmol/l glucose group, a high glucose concentration significantly promoted the proliferation of circulating fibrocytes and showed the most significant effects at 30 mmol/l after treatment for 48 h. AMD3100 showed no effects on the proliferation of circulating fibrocytes. Flow cytometry revealed that 30 mmol/l glucose significantly promoted the expression of COL-I vs. 5.5 mmol/l glucose group (P<0.01), while AMD3100 reversed this (P<0.05). Hoechst33258 staining showed no differences in the apoptotic bodies between experimental groups (P>0.05). Western blotting revealed that the expression of CTGF was decreased significantly by AMD3100 pretreatment (P<0.01). Transwell chamber assay showed that 30 mmol/l glucose significantly promoted the invasive and transfer abilities (P<0.01) of fibrocytes when compared with the 5.5 mmol/l glucose group. While AMD3100 reversed the cell migratory effects induced by high glucose (P<0.01). In addition, the secretion of SDF-1 stimulated by 30 mmol/l glucose DMEM showed no differences compared with 5.5 mmol/l glucose DMEM (P>0.05). High glucose stimulated the expressions of CTGF and COL-I, and promoted migration of circulating fibrocytes via the CXC chemokine receptor 4/SDF-1 axis.

IGF-1 overexpression improves mesenchymal stem cell survival and promotes neurological recovery after spinal cord injury

BACKGROUND

Survival and therapeutic actions of bone marrow-derived mesenchymal stem cells (BMMSCs) can be limited by the hostile microenvironment present during acute spinal cord injury (SCI). Here, we investigated whether BMMSCs overexpressing insulin-like growth factor 1 (IGF-1), a cytokine involved in neural development and injury repair, improved the therapeutic effects of BMMSCs in SCI.

METHODS

Using a SCI contusion model in C57Bl/6 mice, we transplanted IGF-1 overexpressing or wild-type BMMSCs into the lesion site following SCI and evaluated cell survival, proliferation, immunomodulation, oxidative stress, myelination, and functional outcomes.

RESULTS

BMMSC-IGF1 transplantation was associated with increased cell survival and recruitment of endogenous neural progenitor cells compared to BMMSC- or saline-treated controls. Modulation of gene expression of pro- and anti-inflammatory mediators was observed after BMMSC-IGF1 and compared to saline- and BMMSC-treated mice. Treatment with BMMSC-IGF1 restored spinal cord redox homeostasis by upregulating antioxidant defense genes. BMMSC-IGF1 protected against SCI-induced myelin loss, showing more compact myelin 28 days after SCI. Functional analyses demonstrated significant gains in BMS score and gait analysis in BMMSC-IGF1, compared to BMMSC or saline treatment.

CONCLUSIONS

Overexpression of IGF-1 in BMMSC resulted in increased cell survival, immunomodulation, myelination, and functional improvements, suggesting that IGF-1 facilitates the regenerative actions of BMMSC in acute SCI.

Involvement of CXCR4 in Normal and Abnormal Development

CXC motif chemokine receptor type 4 (CXCR4) is associated with normal and abnormal development, including oncogenesis. The ligand of CXCR4 is stromal cell-derived factor (SDF), also known as CXC motif ligand (CXCL) 12. Through the SDF-1/CXCR4 axis, both homing and migration of hematopoietic (stem) cells are regulated through niches in the bone marrow. Outside of the bone marrow, however, SDF-1 can recruit CXCR4-positive cells from the bone marrow. SDF/CXCR4 has been implicated in the maintenance and/or differentiation of stemness, and tissue-derived stem cells can be associated with SDF-1 and CXCR4 activity. CXCR4 plays a role in multiple pathways involved in carcinogenesis and other pathologies. Here, we summarize reports detailing the functions of CXCR4. We address the molecular signature of CXCR4 and how this molecule and cells expressing it are involved in either normal (maintaining stemness or inducing differentiation) or abnormal (developing cancer and other pathologies) events. As a constituent of stem cells, the SDF-1/CXCR4 axis influences downstream signal transduction and the cell microenvironment.

A new role for Notch in the control of polarity and asymmetric cell division of developing T cells

A fundamental question in biology is how single cells can reliably produce progeny of different cell types. Notch signalling frequently facilitates fate determination. Asymmetric cell division (ACD) often controls segregation of Notch signalling by imposing unequal inheritance of regulators of Notch. Here, we assessed the functional relationship between Notch and ACD in mouse T cell development. To attain immunological specificity, developing T cells must pass through a pivotal stage termed β-selection, which involves Notch signalling and ACD. We assessed functional interactions between Notch1 and ACD during β-selection using direct presentation of Notch ligands, DL1 and DL4, and pharmacological inhibition of Notch signalling. Contrary to prevailing models, we demonstrate that Notch controls the distribution of Notch1 itself and cell fate determinants, α-Adaptin and Numb. Further, Notch and CXCR4 signalling cooperated to drive polarity during division. Thus, Notch signalling directly orchestrates ACD, and Notch1 is differentially inherited by sibling cells.

Glioma Cell Secretion: A Driver of Tumor Progression and a Potential Therapeutic Target

Cellular secretion is an important mediator of cancer progression. Secreted molecules in glioma are key components of complex autocrine and paracrine pathways that mediate multiple oncogenic pathologies. In this review, we describe tumor cell secretion in high-grade glioma and highlight potential novel therapeutic opportunities. Cancer Res; 78(21); 6031-9. ©2018 AACR.

Bioinformatic analyses reveal the key pathways and genes in the CXCR4 mediated mesenchymal subtype of glioblastoma

Glioblastoma multiforme (GBM) is one of the most lethal types of tumour, despite severe treatment methods. The Cancer Genome Atlas has categorised GBMs into proneural, neural, classical and mesenchymal subtypes; the mesenchymal subgroup has the worst prognosis. CXCR4 has been reported as selectively overexpressed in the mesenchymal subtype and positively associated with MES markers. However, to the best of our knowledge the underlying mechanisms regarding how CXCR4 may regulate mesenchymal GBM are still unknown. The present study aimed to investigate the critical pathways mediated by CXCR4 in mesenchymal GBM using bioinformatic analyses. The results suggested that CXCR4 is a predictor of poor prognosis and may serve as a biomarker of the mesenchymal subtype in patients with GBM. In addition, CXCR4 mediated the mitogen‑activated protein kinase signaling pathway, which was identified specifically in patients with mesenchymal GBM. CXCR4 associated genes or pathways may be a 'basket trial' option for the management of melanoma, prostate cancer and mesenchymal GBM.

The hypoxic peri-arteriolar glioma stem cell niche, an integrated concept of five types of niches in human glioblastoma

Glioblastoma is the most lethal primary brain tumor and poor survival of glioblastoma patients is attributed to the presence of glioma stem cells (GSCs). These therapy-resistant, quiescent and pluripotent cells reside in GSC niches, which are specific microenvironments that protect GSCs against radiotherapy and chemotherapy. We previously showed the existence of hypoxic peri-arteriolar GSC niches in glioblastoma tumor samples. However, other studies have described peri-vascular niches, peri-hypoxic niches, peri-immune niches and extracellular matrix niches of GSCs. The aim of this review was to critically evaluate the literature on these five different types of GSC niches. In the present review, we describe that the five niche types are not distinct from one another, but should be considered to be parts of one integral GSC niche model, the hypoxic peri-arteriolar GSC niche. Moreover, hypoxic peri-arteriolar GSC niches are structural and functional look-alikes of hematopoietic stem cell (HSC) niches in the bone marrow. GSCs are maintained in peri-arteriolar niches by the same receptor-ligand interactions as HSCs in bone marrow. Our concept should be rigidly tested in the near future and applied to develop therapies to expel and keep GSCs out of their protective niches to render them more vulnerable to standard therapies.

Brain injury and neural stem cells

Many therapies with potential for treatment of brain injury have been investigated. Few types of cells have spurred as much interest and excitement as stem cells over the past few decades. The multipotentiality and self-renewing characteristics of stem cells confer upon them the capability to regenerate lost tissue in ischemic or degenerative conditions as well as trauma. While stem cells have not yet proven to be clinically effective in many such conditions as was once hoped, they have demonstrated some effects that could be manipulated for clinical benefit. The various types of stem cells have similar characteristics, and largely differ in terms of origin; those that have differentiated to some extent may exhibit limited capability in differentiation potential. Stem cells can aid in decreasing lesion size and improving function following brain injury.