Upregulation of CXCR4 favoring neural-like cells migration via AKT activation

Effect of an low-energy Nd: YAG laser on periodontal ligament stem cell homing through the SDF-1/CXCR4 signaling pathway

BACKGROUND

The key to the success of endogenous regeneration is to improve the homing rate of stem cells, and low-energy laser is an effective auxiliary means to promote cell migration and proliferation. The purpose of this study was to observe whether low-energy neodymium (Nd: YAG) laser with appropriate parameters can affect the proliferation and migration of periodontal ligament stem cells (PDLSCs) through SDF-1/CXCR4 pathway.

METHODS

h PDLSCs were cultured and identified. CCK8 assay was used to detect the proliferation of h PDLSCs after different power (0, 0.25, 0.5, 1, and 1.5 W) Nd: YAG laser (MSP, 10 Hz, 30 s, 300 μ m) irradiation at 2th, 3rd,5th, and 7th days, and the optimal laser irradiation parameters were selected for subsequent experiments. Then, the cells were categorized into five groups: control group (C), SDF-1 group (S), AMD3100 group (A), Nd: YAG laser irradiation group (N), and Nd: YAG laser irradiation + AMD3100 group (N + A). the migration of h PDLSCs was observed using Transwell, and the SDF-1 expression was evaluated using ELISA andRT-PCR. The SPSS Statistics 21.0 software was used for statistical analysis.

RESULTS

The fibroblasts cultured were identified as h PDLSCs. Compared with the C, when the power was 1 W, the proliferation rate of h PDLSCs was accelerated (P < 0.05). When the power was 1.5 W, the proliferation rate decreased (P < 0.05). When the power was 0.25 and 0.5 W, no statistically significant difference in the proliferation rate was observed (P > 0.05). The number of cell perforations values as follows: C (956.5 ± 51.74), A (981.5 ± 21.15), S (1253 ± 87.21), N (1336 ± 48.54), and N + A (1044 ± 22.13), that increased significantly in group N (P < 0.05), but decreased in group N + A (P < 0.05). The level of SDF-1 and the expression level of SDF-1 mRNA in groups N and N + A was higher than that in group C (P < 0.05) but lower than that in group A (P < 0.05).

CONCLUSIONS

Nd: YAG laser irradiation with appropriate parameters provides a new method for endogenous regeneration of periodontal tissue. SDF-1/CXCR4 signaling pathway may be the mechanism of LLLT promoting periodontal regeneration.

BKM120 alters the migration of doublecortin-positive cells in the dentate gyrus of mice

BKM120 is an inhibitor of class I phosphoinositide 3-kinases and its anti-cancer effects have been demonstrated in various solid cancer models. BKM120 is highly brain permeable and has been reported to induce mood disturbances in clinical trials. Therefore, we examined whether BKM120 produces anxiety- and depression-like behaviors in mice, as with patients receiving BKM120 in clinical trials. In this study, repeated BKM120 treatment (2.0 or 5.0mg/kg, i.p., five times at 12-h interval) significantly induced anxiety- and depression-like behaviors in mice. Although abnormal changes in hippocampal neurogenesis have been suggested to, at least in part, associated with the pathogenesis of depression and anxiety, BKM120 did not affect the incorporation of 5-bromo-2'-deoxyuridine or the expression of doublecortin (DCX); however, it significantly enhanced the radial migration of DCX-positive cells in the dentate gyrus. BKM120-induced changes in migration were not accompanied by obvious neuronal damage in the hippocampus. Importantly, BKM120-induced anxiety- and depression-like behaviors were positively correlated with the extent of DCX-positive cell migration. Concomitantly, p-Akt expression was significantly decreased in the dentate gyrus. Moreover, the expression of p-c-Jun N-terminal kinase (JNK), p-DCX, and Ras homolog family member A (RhoA)-GTP decreased significantly, particularly in aberrantly migrated DCX-positive cells. Together, the results suggest that repeated BKM120 treatment enhances the radial migration of DCX-positive cells and induces anxiety- and depression-like behaviors by regulating the activity of Akt, JNK, DCX, and RhoA in the dentate gyrus. It also suggests that the altered migration of adult-born neurons in the dentate gyrus plays a role in mood disturbances.

Transforming Growth Factor-β Promotes Homing and Therapeutic Efficacy of Human Mesenchymal Stem Cells to Glioblastoma

Human mesenchymal stem cell-based tumor therapeutic gene delivery is regarded as a promising strategy for the treatment of glioblastoma (GBM). However, the efficiency of these stem cells to home to the target sites limits their potential curative effect and clinical application. In this work, we provide a novel pretreatment approach for enhancing the homing capacity of human adipose-derived mesenchymal stem cells (hAMSCs) for stem cell-based tumor gene delivery for GBM therapy. Pre-exposure of these stem cells to TGF-β resulted in enhanced homing ability to GBM through increasing CXC chemokine receptor 4 (CXCR4) expression, as evidenced by a diminishing homing capacity when inhibition of the TGF-β receptor II and CXCR4 was applied. In addition, by pretreating hAMSCs expression of tumor necrosis factor-related apoptosis-inducing ligand with TGF-β, we achieved significant enhancements in the therapeutic efficacy as demonstrated by an increased number of migrated hAMSCs to target sites, decreased tumor volume, and prolonged survival time in a murine model of GBM. These findings highlight a straightforward method in which cell preconditioning methodology is utilized to promote therapeutic efficacy of a biological treatment for GBM.

Nef-M1, a peptide antagonist of CXCR4, inhibits tumor angiogenesis and epithelial‑to‑mesenchymal transition in colon and breast cancers

The Nef-M1 peptide competes effectively with the natural ligand of CXC chemokine receptor 4 (CXCR4), stromal cell-derived factor 1-alpha, to induce apoptosis and inhibit growth in colon cancer (CRC) and breast cancer (BC). Its role in tumor angiogenesis, and epithelial-to-mesenchymal transition (EMT) regulation, key steps involved in tumor growth and metastasis, are unknown. We evaluated the angioinhibitory effect of Nef-M1 peptide and examined its role in the inhibition of EMT in these cancers.

Colon (HT29) and breast (MDA-MB231) cancer cells expressing CXCR4 were studied in vitro and in xenograft tumors propagated in severe combined immunodeficient mice. The mice were treated intraperitoneally with Nef-M1 or scrambled amino acid sequence of Nef-M1 (sNef-M1) peptide, a negative control, starting at the time of tumor implantation. Sections from tumors were evaluated for tumor angiogenesis, as measured by microvessel density (MVD) based on immunostaining of endothelial markers. In vitro tumor angiogenesis was assessed by treating human umbilical vein endothelial cells with conditioned media from the tumor cell lines. A BC cell line (MDA-MB 468) which does not express CXCR4 was used to study the actions of Nef-M1 peptide. Western blot and immunofluorescence analyses assessed the effect of Nef-M1 on tumor angiogenesis and EMT in both tumors and cancer cells.

Metastatic lesions of CRC and BC expressed more CXCR4 than primary lesions. It was also found that tumors from mice treated with sNef-M1 had well established vascularity, while Nef-M1 treated tumors had very poor vascularization. Indeed, the mean MVD was lower in tumors from Nef-M1 treated mice than in sNef-M1 treated tumors. Nef-M1 treated tumor has poor morphology and loss of endothelial integrity. Although conditioned medium from CRC or BC cells supported HUVEC tube formation, the conditioned medium from Nef-M1 treated CRC or BC cells did not support tube formation. Western blot analyses revealed that Nef-M1 effectively suppressed the expression of VEGF-A in CRC and BC cells and tumors. This suggests that Nef-M1 treated CRC and BC cells are more consistent with E-cadherin signature, and thus appears more epithelial in nature.

Our data indicate that Nef-M1 peptide inhibits tumor angiogenesis and the oncogenic EMT process. Targeting the chemokine receptor, CXCR4, mediated pathways using Nef-M1 may prove to be a novel therapeutic approach for CRC and BC.

Stichopus japonicus Polysaccharide, Fucoidan, or Heparin Enhanced the SDF-1α/CXCR4 Axis and Promoted NSC Migration via Activation of the PI3K/Akt/FOXO3a Signaling Pathway

Stichopus japonicus Polysaccharide (SJP) is a sulfated polysaccharide from the body wall of the sea cucumber, Stichopus japonicus. Fucoidan is a heparinoid compound that belongs to a family of sulfated polyfucose polysaccharides. Heparin is a glycosaminoglycan. SJP, fucoidan, and heparin profoundly promoted stromal cell-derived factor 1 alpha (SDF-1α)-induced neural stem cell (NSC) migration in a concentration-dependent manner. In addition, the basal migration capacity of cells was significantly promoted after incubation with SJP, fucoidan, or heparin. Interaction of SJP, fucoidan, or heparin with SDF-1α efficiently showed additive effects on the promotion of cell migration from the neurosphere. SJP, fucoidan, or heparin interaction with SDF-1α treatment could increase Nestin expression. SDF-1α modulated by SJP, fucoidan, or heparin activated the CXCR4 receptor and directed cellular migration via the activation of the PI3K/Akt/FOXO3a signaling pathway. Moreover, interaction of SJP, fucoidan, or heparin with SDF-1α effectively promoted NSC migration and induced SDF-1α and CXCR4 expressions. Results suggested that SJP, fucoidan, and heparin might be good candidates for alleviating injury-initiated signals to which NSCs respond.

The Role of the PI3K Pathway in the Regeneration of the Damaged Brain by Neural Stem Cells after Cerebral Infarction

Neurologic deficits resulting from stroke remain largely intractable, which has prompted thousands of studies aimed at developing methods for treating these neurologic sequelae. Endogenous neurogenesis is also known to occur after brain damage, including that due to cerebral infarction. Focusing on this process may provide a solution for treating neurologic deficits caused by cerebral infarction. The phosphatidylinositol-3-kinase (PI3K) pathway is known to play important roles in cell survival, and many studies have focused on use of the PI3K pathway to treat brain injury after stroke. Furthermore, since the PI3K pathway may also play key roles in the physiology of neural stem cells (NSCs), eliciting the appropriate activation of the PI3K pathway in NSCs may help to improve the sequelae of cerebral infarction. This review describes the PI3K pathway, its roles in the brain and NSCs after cerebral infarction, and the therapeutic possibility of activating the pathway to improve neurologic deficits after cerebral infarction.

SEMA3F prevents metastasis of colorectal cancer by PI3K-AKT-dependent down-regulation of the ASCL2-CXCR4 axis

Semaphorin-3F (SEMA3F), an axonal repulsant in nerve development, has been shown to inhibit the progression of human colorectal cancer (CRC); however, the underlying mechanism remains elusive. In this study we found a negative correlation between the levels of SEMA3F and CXCR4 in CRC specimens from 85 patients, confirmed by bioinformatics analysis of gene expression in 229 CRC samples from the Cancer Genome Atlas. SEMA3F(high) /CXCR4(low) patients showed the lowest frequency of lymph node and distant metastasis and the longest survival. Mechanistically, SEMA3F inhibited the invasion and metastasis of CRC cells through PI3K-AKT-dependent down-regulation of the ASCL2-CXCR4 axis. Specifically, ASCL2 enhanced the invasion and metastasis of CRC cells in vitro and expression of ASCL2 correlated with distant metastasis, tumour size and poor overall survival in CRC patients. Treatment of CRC cells with the CXCR4 antagonist AMD3100 attenuated SEMA3F knockdown-induced invasion and metastasis of CRC cells in vitro and in vivo. Our study thus demonstrates that SEMA3F functions as a suppressor of CRC metastasis via down-regulating the ASCL2-CXCR4 axis.

Chemotactic responses of neural stem cells to SDF-1α correlate closely with their differentiation status

Chemotaxis of neural stem/progenitor cells (NSCs) is regulated by a variety of factors, and much effort has been devoted to the delineation of factors that are involved in NSC migration. However, the relationship between NSC chemotactic migration and differentiation remains uncharacterized. In the present study, by comparing the transfilter migration rate, single-cell migration speed, and directional efficiency of NSCs in stromal cell-derived factor-1 alpha (SDF-1α)-induced Boyden chamber and Dunn chamber chemotaxis assays, we demonstrate that NSCs in varying differentiation stages possess different migratory capacity. Furthermore, F-actin microfilament reorganization upon stimulation varies greatly among separate differentiation states. We show that signaling pathways involved in NSC migration, such as PI3K/Akt and mitogen-activated protein kinase (MAPK) (ERK1/2, JNK, and p38 MAPK) pathways, are differentially activated by SDF-1α among each NSC differentiation stages, and the extent to which these pathways participate in cell chemotaxis exhibits a differentiation stage-dependent manner. Taken together, these results suggest that the differentiation of NSCs influences their chemotactic responses to SDF-1α, providing new insight into the optimization of the therapeutic efficacy of NSCs for neural regeneration and nerve repair after injury.

Preconditioning of stem cells by oxytocin to improve their therapeutic potential

Principal limitation of cell therapy is cell loss after transplantation because of the interplay between ischemia, inflammation, and apoptosis. We investigated the mechanism of preconditioning of mesenchymal stem cells (MSCs) with oxytocin (OT), which has been proposed as a novel strategy for enhancing therapeutic potential of these cells in ischemic heart. In this study, we demonstrate that rat MSCs express binding sites for OT receptor and OT receptor transcript and protein as detected by RT-PCR and immunofluorescence, respectively. In response to OT (10(-10) to 10(-6) M) treatment, MSCs respond with rapid calcium mobilization and up-regulation of the protective protein kinase B (PKB or Akt) and phospho-ERK1/2 proteins. In OT-stimulated cells, phospho-Akt accumulates intracellularly close to the mitochondrial marker cytochrome c oxidase subunit 4. Functional analyses reveal the involvement of Akt/ERK1/2 pathways in cell proliferation, migration, and protection against the cytotoxic and apoptotic effects of hypoxia and serum deprivation. In addition, OT preconditioning increases MSC glucose uptake. Genes with angiogenic, antiapoptotic, and cardiac antiremodeling properties, such as heat shock proteins (hsps) HSP27, HSP32, HSP70, vascular endothelial growth factor, thrombospondin, tissue inhibitor of metalloproteinase (TIMP)-1, TIMP-2, TIMP-3, and matrix metalloproteinase-2, were also up-regulated upon OT exposure. Moreover, coculture with OT-preconditioned MSC reduces apoptosis, as measured using terminal transferase dUTP nick end labeling assay in newborn rat cardiomyocytes exposed to hypoxia and reoxygenation. In conclusion, these results indicate that OT treatment evokes MSC protection through both intrinsic pathways and secretion of cytoprotective factors. Ex vivo cellular treatment with OT represents an attractive strategy aimed to maximize the biological and functional properties of effector cells.

The biological behavior of SDF-1/CXCR4 in patients with myelodysplastic syndrome

The purpose of this investigation is to evaluate the biological behavior of stromal cell-derived factor-l (SDF-1) in migration, adhesion, and apoptosis as well as the related signaling transduction pathways in patients with myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). We chose 22 patients with MDS, 7 patients with de novo AML, and 8 patients with non-clonal cytopenia diseases. We performed flow cytometric analysis of CD34(+) cells apoptosis using annexinV-FITC, which binds to exposed phosphatidylserine on apoptotic cells. The cell adhesion capability was detected by CCK-8 assay. The migration ability of the cell was checked by transwell assay. Furthermore, we measured SDF-1 levels in BM plasma from patients by enzyme-linked immunosorbent assay (ELISA). Our results indicated that the apoptosis of CD34(+) cell was significantly increased in the Low-grade MDS (IPSS score ≤ 1.0) patients compared with the high-grade MDS (IPSS score ≥ 1.5) (21.33% vs. 7.27%, P < 0.001) and patients with de novo AML (21.33% vs. 7.53%, P < 0.001). SDF-1 promoted CXCR4 high expression cells adhesion to the stroma cells (MSC) and induced these cells migration. SDF-1 could trigger the occurrence of polarized morphology of the cells that expressed CXCR4 high. After addition of wortmannin or PTX, the ability of adhesion and migration of the cells that expressed CXCR4 high decreased. But in the patient's cells that expressed CXCR4 low, there was no above-mentioned phenomenon. So we can suppose that the signaling pathway of SDF-1/CXCR4 axis is PI3K pathway, and we should do more things about this pathway and may find out the target treatment of MDS.

Inflammatory regulators of redirected neural migration in the injured brain

Brain injury following stroke or trauma induces the migration of neuroblasts derived from subventricular zone neural precursor cells (NPCs) towards the damaged tissue, where they then have the potential to contribute to repair. Enhancing the recruitment of new cells thus presents an enticing prospect for the development of new therapeutic approaches to treat brain injury; to this end, an understanding of the factors regulating this process is required. During the neuroinflammatory response to ischemic and traumatic brain injuries, a plethora of pro- and anti-inflammatory cytokines, chemokines and growth factors are released in the damaged tissue, and recent work indicates that a variety of these are able to influence injury-induced migration. In this review, we will discuss the contribution of specific chemokines and growth factors towards stimulating NPC migration in the injured brain.

Stromal cell-derived factor-1 (SDF-1): homing factor for engineered regenerative medicine

INTRODUCTION

Stromal cell-derived factor-1α (SDF-1) is a chemokine that plays a major role in cell trafficking and homing of CD34(+) stem cells. Studies employing SDF-1/CXCR4 have demonstrated its therapeutic potential in tissue engineering. During injury, cells from the injured organ highly express SDF-1, which causes an elevation of localized SDF-1 levels. This leads to recruitment and retention of circulating CD34(+) progenitor cells at the injury site via chemotactic attraction toward a gradient of SDF-1. The general approaches for SDF-1 introduction in tissue engineering are direct protein incorporation into scaffolds and transplantation of SDF-1-overexpressing cells and both methods are successful in improving the regeneration of the damaged tissue/organ.

AREAS COVERED

The mechanisms of SDF-1-mediated homing via CXCR4 receptor and the success of SDF-1-based medical applications in mesenchymal stem cell (MSC) homing as well as areas such as therapeutic angiogenesis, wound healing and neuronal and liver regeneration.

EXPERT OPINION

Current SDF-1 delivery designs and platforms hold much room for improvement. Regardless of the different techniques of SDF-1 introduction, they have proved to be effective in recruitment of various stem/progenitor cells. The pursuit of SDF-1-related regenerative medicine has already begun. It is thus conceivable that its usage in the clinical setting will be a reality in the near future.

Regulation of stem cell pluripotency and differentiation by G protein coupled receptors

Stem cell-based therapeutics have the potential to effectively treat many terminal and debilitating human diseases, but the mechanisms by which their growth and differentiation are regulated are incompletely defined. Recent data from multiple systems suggest major roles for G protein coupled receptor (GPCR) pathways in regulating stem cell function in vivo and in vitro. The goal of this review is to illustrate common ground between the growing field of stem cell therapeutics and the long-established field of G protein coupled receptor signaling. Herein, we briefly introduce basic stem cell biology and discuss how several conserved pathways regulate pluripotency and differentiation in mouse and human stem cells. We further discuss general mechanisms by which GPCR signaling may impact these pluripotency and differentiation pathways, and summarize specific examples of receptors from each of the major GPCR subfamilies that have been shown to regulate stem cell function. Finally, we discuss possible therapeutic implications of GPCR regulation of stem cell function.