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Wen Jie Zhang

Publications and source records attributed to Wen Jie Zhang.

15 recordsLinked to original sources
PubMed2006

Repair of canine mandibular bone defects with bone marrow stromal cells and porous beta-tricalcium phosphate.

Tissue engineering has become a new approach for repairing bone defects. Previous studies have been limited to the use of slow-degradable scaffolds with bone marrow stromal cells (BMSCs) in mandibular reconstruction. In this study, a 30 mm long mandibular segmental defect was repaired by engineered bone graft using osteogenically induced autologous BMSCs seeded on porous beta-tricalcium phosphate (beta-TCP, n=5). The repair of defects was compared with those treated with beta-TCP alone (n=6) or with autologous mandibular segment (n=4). In the BMSCs/beta-TCP group, new bone formation was observed from 4 weeks post-operation, and bony-union was achieved after 32 weeks, which was detected by radiographic and histological examination. In contrast, minimal bone formation with almost fibrous connection was observed in the group treated with beta-TCP alone. More importantly, the engineered bone with BMSCs/beta-TCP achieved a satisfactory biomechanical property in terms of bending load strength, bending displacement, bending stress and Young's modulus at 32 weeks post-operation, which was very close to those of contralateral edentulous mandible and autograft bone (p>0.05). Based on these results, we conclude that engineered bone from osteogenically induced BMSCs and biodegradable beta-TCP can well repair the critical-sized segmental mandibular defects in canines.

Animals↗
PubMed2006

STAT6 specific shRNA inhibits proliferation and induces apoptosis in colon cancer HT-29 cells.

RNA interference (RNAi) has been employed as an effective tool for studying gene functions. Here, we have demonstrated that different short hairpin RNAs (shRNAs) can specifically knock-down the transcription of STAT6, resulting in the inhibition of cell proliferation, G1/S phase arrest and apoptotic death in colon cancer HT-29 cells. These findings suggest that Stat6 signaling pathway plays a role in the regulation of cell proliferation and apoptosis in colon cancer cells, which promises further investigation for targeted cancer therapy.

Apoptosis↗
PubMed2006

Angelica sinensis down-regulates hydroxyproline and Tgfb1 and provides protection in mice with radiation-induced pulmonary fibrosis.

Pulmonary fibrosis is a common delayed side effect of radiation therapy, and it has a poor prognosis. Tgfb1 is a potent chemoattractant for fibroblasts and stimulates the production of collagen, the protein that contains hydroxyproline. Since collagen is by far the most abundant protein in the lung, comprising 60-70% of the tissue mass, analysis of the hydroxyproline content in lung tissues provides a reliable quantitative index for pulmonary fibrosis. Thus hydroxyproline and Tgfb1 may be involved in the development of fibrosis. In this study, we investigated radiation-induced pulmonary fibrosis in a mouse model. C57BL/6 mice were assigned into four groups: no treatment, treated with Angelica sinensis treated only, X-irradiated only (a single fraction of 12 Gy to the thorax), and Angelica sinensis treatment plus radiation. We assayed expression of hydroxyproline and the mRNA and protein of Tgfb1 in the four groups. We found that Angelica sinensis down-regulated the production of Tgfb1 and hydroxyproline in mice with radiation-induced pulmonary fibrosis. This study has demonstrated for the first time that Angelica sinensis inhibits the progress of radiation-induced pulmonary fibrosis, possibly by down-regulating the expression of the proinflammatory cytokine Tgfb1. These data suggest that Angelica sinensis may be useful in preventing and/or treating radiation-induced pulmonary fibrosis in the clinic.

Angelica sinensis↗
PubMed2006

Chinese medicine Angelica sinensis suppresses radiation-induced expression of TNF-alpha and TGF-beta1 in mice.

Radiotherapy of thoracic cancer often causes pulmonary inflammation leading to pneumonitis and fibrosis. We favor the hypothesis that cytokine-mediated multicellular interactions may result in the overexpression of proinflammatory cytokines such as TNF-alpha and TGF-beta1, which promotes progressive radiation-induced lung injury. The root of Angelica sinensis, known as 'Danggui' in Chinese medicine, is widely used to treat radiation-induced pneumonitis in humans and shows clinical efficacy and low/no toxicity with an unclear mechanism. Using quantitative RT-PCR and immunohistochemistry (IHC) methods, we investigated radiation-induced lung injury in a mouse model. C57BL/6 mice were assigned to 4 groups: no treatment (NT), Angelica Sinensis treatment only (AS), X-ray irradiation only (XRT, single fraction of 12 Gy irradiation to the thoraces) and AS treatment plus XRT (AS/XRT). Mice in NT and AS groups exhibited low TNF-alpha and TGF-beta1 mRNA levels and few positive cell counts for TNF-alpha (8-17 cells per field, x400 magnification) and TGF-beta1 (9-31 cells per field), respectively. In XRT mice, there were increased inflammatory cells positive for TNF-alpha and TGF-beta1 in lung tissue compared with NT mice (P<0.01). However, when XRT mice received AS treatment (AS/XRT), the number of inflammatory cells in lung tissue positive for both TNF-alpha and TGF-beta1 was decreased compared with XRT-only mice (P<0.01) accompanied by moderately decreased mRNA levels of TNF-alpha and TGF-beta1. We conclude that radiation induces expression of TNF-alpha and TGF-beta1 in the inflammatory cells of irradiated lung tissue during the pneumonic phase. The predominant localization of TNF-alpha and TGF-beta1 in inflammatory cell infiltrates suggests these cytokines' involvement in the process of radiation-induced pneumonitis. Moreover, effective down-regulation of TNF-alpha and TGF-beta1 in irradiated lung tissue by Angelica Sinensis is, at least in part, indicative of its clinical efficacy in treating radiation-induced pneumonitis.

Angelica sinensis↗
PubMed2005

Improved cryopreservation of human embryonic stem cells with trehalose.

Human embryonic stem (ES) cells have been established either from fresh or frozen embryos. The recovery rates of undifferentiated human ES cells after cryopreservation with conventional slow-rate freezing and rapid-thawing methods are relatively low. The purpose of this study was to improve cryopreservation efficiency by modifying conventional methods with addition of trehalose. Immature oocytes donated from patients undergoing IVF treatment were utilized to generate blastocysts. One human ES cell line (named hES1) was established and characterized in detail. The hES1 cells expressed regular human ES cell markers, including stage-specific embryonic antigens SSEA-3, SSEA-4, tumour rejection antigens TRA-1-60, TRA-1-81 and octamer-binding transcription factor Oct-4 with high levels of alkaline phosphatase and telomerase activities. Cells could be differentiated to form teratomas in vivo. With slow-rate freezing and rapid-thawing methods modified by adding trehalose, the recovery rate of undifferentiated hES1 cells has been greatly improved from 15 to 48%. Cells retained pluripotency with normal karyotype after thawing. The results indicated that the use of trehalose is efficient and convenient for cryopreservation of human ES cells.

Animals↗
PubMed2004

Modulation of hematopoietic and endothelial cell differentiation from mouse embryonic stem cells by different culture conditions.

Embryonic stem (ES) cells can differentiate into many different somatic cells in culture. To better correlate hematopoietic and endothelial cell differentiation of ES cells in currently available protocols, we compared fetal liver kinase-1 (Flk-1)-, stem cell leukemia (Scl)-, and vascular endothelial-cadherin (VE-cadherin)-expressing cells generated in embryoid bodies (EBs) and on OP9 cells. We report that the kinetics of Scl and Flk-1 expression were similar in EBs and OP9 cells, although Flk-1 expression was extended on OP9 cells. CD45+ and Ter-119+ cells developed more efficiently in EBs, whereas VE-cadherin+ cells developed largely on OP9 cells. Cell sorting and replating studies showed that Scl+ cells, not Flk-1+ or VE-cadherin+ cells, were enriched for primitive and definitive hematopoietic progenitors. Our studies indicate that optimal hematopoietic and endothelial cell differentiation occur in EBs and on OP9 cells, respectively. Regardless of the culture systems used, Scl is the most relevant marker for enriching primitive and definitive hematopoietic progenitors.

Animals↗
PubMed2004

Stat6(null phenotype) human lymphocytes exhibit increased apoptosis.

BACKGROUND: Inflammatory bowel disease (IBD) is associated with altered apoptosis and increased levels of Th1 cytokines (IL-12, TNF-alpha, and IFN-gamma). These proinflammatory events may result from dysfunctional IL-4/Stat6 signal transduction that normally promotes Th2 lymphocyte differentiation and consequential down-regulation of the immune response. The goal of the present study was to measure apoptosis, levels of relevant cytokines, and the effects of cytokine manipulation on apoptosis in cell lines derived from IBD patients that express dysfunctional Stat6 (Stat6(null phenotype)) and wild-type Stat6 (Stat6(high phenotype)). MATERIALS AND METHODS: Lymphocytes with Stat6(null phenotype) (n = 5) or wild-type (n = 5) status were cultured with and without the addition of exogenous cytokines or neutralizing antibodies (IL-12, TNF-alpha, and IFN-gamma). Apoptosis was determined by flow cytometry using Annexin V-PE dual staining. Cytokine levels were determined by ELISA. RESULTS: Stat6(null phenotype) cells exhibited increased apoptosis compared with wild-type cell lines (13.3% +/- 2.9 versus 4.5% +/- 0.4, P < 0.0001). Four of five Stat6(null phenotype) cell lines expressed 5- to 10-fold elevations in IL-12 and IFN-gamma. Addition of exogenous cytokines or neutralizing antibodies had no effect on apoptosis. CONCLUSIONS: Apoptotic cell death is elevated in Stat6(null phenotype) cell lines suggesting a role for Stat6 in apoptosis regulation, a previously unrecognized observation. Increased levels of IL-12 and IFN-gamma were found in the Stat6(null phenotype) cell lines; however, the apoptosis observed is not the consequence of increased IL-12, IFN-gamma, or TNF-alpha. Stat6(null phenotype) cell lines exhibit variably increased levels of these Th1 cytokines, consistent with their human source, and may be a valid source for investigations into IBD pathophysiology.

Antibodies↗
PubMed2004

A hierarchical order of factors in the generation of FLK1- and SCL-expressing hematopoietic and endothelial progenitors from embryonic stem cells.

The receptor tyrosine kinase FLK1 and the transcription factor SCL play crucial roles in the establishment of hematopoietic and endothelial cell lineages in mice. We have previously used an in vitro differentiation model of embryonic stem (ES) cells and demonstrated that hematopoietic and endothelial cells develop via sequentially generated FLK1(+) and SCL(+) cells. To gain a better understanding of cellular and molecular events leading to hematopoietic specification, we examined factors necessary for FLK1(+) and SCL(+) cell induction in serum-free conditions. We demonstrate that bone morphogenetic protein (BMP) 4 was required for the generation of FLK1(+) and SCL(+) cells, and that vascular endothelial growth factor (VEGF) was necessary for the expansion and differentiation of SCL-expressing hematopoietic progenitors. Consistently, Flk1-deficient ES cells responded to BMP4 and generated TER119(+) and CD31(+) cells, but they failed to expand in response to VEGF. The Smad1/5 and map kinase pathways were activated by BMP4 and VEGF, respectively. The overexpression of SMAD6 in ES cells resulted in a reduction of FLK1(+) cells. In addition, a MAP kinase kinase 1 specific inhibitor blocked the expansion of SCL(+) cells in response to VEGF. Finally, VEGF mediated expansion of hematopoietic and endothelial cell progenitors was inhibited by TGFbeta1, but was augmented by activin A. Our studies suggest that hematopoietic and endothelial commitment from the mesoderm occurs via BMP4-mediated signals and that expansion and/or differentiation of such progenitors is achieved by an interplay of VEGF, TGFbeta1 and activin A signaling.

Animals↗
PubMed2004

Human B lymphoblast cell lines defective of Stat6 signaling produce high levels of proinflammatory cytokines IL-12, TNFalpha and IFNgamma.

Based on Stat6 gene knockout animal models, the Stat6 signaling pathway has been suggested to play a role in carcinogenesis and Th1/Th2 cytokine balance. Using a semiquantitative EMSA assay and EBV-transformed human B lymphoblast cell lines, we have previously identified three Stat6 activational phenotypes, termed as Stat6high, Stat6low, and Stat6null. A genetic mechanism has been proposed which determines the IL-4-induced activation of the human Stat6 signaling. With respect to the contribution of variant phenotypes to human disease, we further hypothesize that the Stat6null phenotype may result from a partial defect in Stat6 signaling which resembles Stat6 knockout animals in several functional aspects. The characterization of the human Stat6null phenotype stably displayed by the EBV-B cell lines is easily assailable and possesses important implications with respect to Th1/Th2 cytokine imbalance in diseases such as cancer development/metastasis and inflammatory diseases. In this study, we have extended our investigation to the downstream regulatory consequences associated with these Stat6 phenotypes. Production of three important proinflammatory cytokines, IL-12, TNFalpha and IFNgamma was examined in spontaneous EBV-B cell culture using ELISA methodology. Individual cell lines defined as Stat6null produced significantly higher levels of IL-12, TNFalpha and IFNgamma on day 4 in spontaneous culture in comparison with cell lines characterized as Stat6high and Stat6low. These observations of the human Stat6null phenotype, together with those accruing from Stat6 knockout mouse model studies, suggest that the Stat6 signaling pathway may play a role in maintaining the Th1/Th2 cytokine balance by directly and indirectly down-regulating the production of proinflammatory cytokines, a regulatory process which appears to go awry in inflammatory diseases. Moreover, observations from signal transduction studies in our human B lymphocyte model may be compatible with those in the chosen mouse B lymphocyte for establishing signaling networks by the Alliance for Cellular Signaling (AfCS).

Animals↗
PubMed2003

Combinatorial effects of Flk1 and Tal1 on vascular and hematopoietic development in the mouse.

Mouse embryos mutant for the VEGF receptor, VEGFR2, Flk-1, or Kdr, fail to form both endothelial and hematopoietic cells, suggesting a possible role in a common progenitor to both lineages. The transcription factor Tal1 (Scl), is not expressed in Flk1(-/-) embryos, consistent with a downstream role in the Flk1 pathway. We tested whether expression of Tal1 under the Flk1 promoter was sufficient to rescue the loss of endothelial and hematopoietic cells in Flk1 mutants. Only partial rescue of hematopoiesis and endothelial development was observed in vivo. However, Flk1(-/Tal1) embryonic stem (ES) cells were capable of blast colony formation in vitro at levels equivalent to Flk1(+/-) heterozygotes. Ectopic expression of Tal1 under the Flk1 promoter in Flk1(+/-) mouse embryos or ES cells caused no obvious pathology but increased the number of blast colony forming cells (BL-CFCs) and enhanced their hematopoietic potential. These single-cell-derived BL-CFCs also produced smooth muscle cells in vitro. Increased Tal1 expression inhibited smooth muscle differentiation in this assay, whereas loss of Tal1 promoted smooth muscle formation. We propose a model in which the combinatorial effects of Flk1 and Tal1 act to regulate cell fate choice in early development into hematopoietic, endothelial, and smooth muscle lineages.

Animals↗
PubMed2003

Genetic control of interleukin-4-induced activation of the human signal transducer and activator of transcription 6 signaling pathway.

The interleukin (IL)-4-induced Stat6 signaling pathway is active in a variety of cell types, including immune cells and cancer cells, and plays an important role in the regulation of gene expression, such as CD23 and major histocompatibility complex class II. Using a semiquantitative gel shift assay in which nuclear Stat6 activities were scored, three Stat6 activation phenotypes were defined as Stat6(high) (intense banding), Stat6(low) (medium intensity banding), and Stat6(null) (very low to no discernible banding). These Stat6 phenotypes correlated well with levels of CD23 expression, but not with those of human leukocyte antigen-DR cell-surface display. Pedigree analyses revealed a Mendelian inheritance pattern that can be explained by two STAT6 Pathway (STAT6P) activation genotypes, which we term A and a, where STAT6P*A determines an active Stat6 signaling and STAT6P*a determines an inactive Stat6 signaling, with incomplete dominance. Total Stat6 protein levels failed to correlate with the above Stat6 phenotypes allowing us to propose that IL-4-induced Stat6 signaling is a polygenic quantitative trait regulated by a collection of several contributing genetic loci that functionally interact. The Stat6(null) phenotype may result from a defect in Stat6 signaling, which has important implications with respect to the pathogenesis of cancer and Th1/Th2 cytokine imbalance in autoimmune diseases in general.

Cell Line, Transformed↗
PubMed2002

Lineage analysis of the hemangioblast as defined by FLK1 and SCL expression.

Accumulating studies support the idea that a common progenitor, termed the hemangioblast, generates both hematopoietic and endothelial cell lineages. To better define the relationship between these cell lineages, we have generated knock-in embryonic stem (ES) cells carrying a non-functional human CD4 at the Scl locus. By using in vitro differentiated Scl(+/CD4) ES cells, we demonstrate that FLK1 and SCL are molecular determinants of the hemangioblast. Furthermore, our studies demonstrate that hematopoietic and endothelial cells develop via distinct, sequential generation of FLK1 and SCL-expressing cells. FLK1(+)CD4(-) cells first arise in developing embryoid bodies. The Scl gene is turned on within FLK1(+)CD4(-) cells to give rise to FLK1(+)CD4(+) cells. Alternatively, a subpopulation of the initial FLK1(+)CD4(-) cells remains as SCL negative. Within the FLK1(+)CD4(+) cells, FLK1 is down regulated to generate FILK1(-)CD4(+) cells. Replating studies demonstrate that hematopoietic progenitors are enriched within FLK1(+)CD4(+) and FLK1(-)CD4(+) cells, while endothelial cells develop from FLK1(+)CD4(+) and FLK1(+)CD4(-) cell populations.

Animals↗
PubMedDate not supplied

Phenotyping of IL4-induced nuclear Stat6 activity in humans: quantitation after gel shift assay using immortalized cell lines.

The IL4-induced Stat6 signaling pathway is active in a variety of cell types, including different cancer cells, and plays an important role in the regulation of gene expression, such as CD23. There are large quantitative differences in DNA-binding activity of IL4-induced Stat6, which are useful for phenotyping activated Stat6 in normal and disease status. However, quantitation of activated Stat6 is challenging and a standardized methodology is needed. Here we have developed a semi-quantitative methodology using gel shift assay in which IL4-induced nuclear Stat6 activities are measured in human EBV-transformed lymphoblastoid cell lines. Using a DNA probe with high affinity Stat6-binding N4 motif and a specific antibody to Stat6, autoradiographs of EMSA gels are recorded by a scan imager and OD readings of antibody super-shifted Stat6 complex bands are obtained. OD readings of all test cell lines are referenced to that of a standard cell line placed in every single experiment and an OD ratio is obtained for each test cell, which allows assignment of Stat6 activational phenotypes. Using this methodology, we have been able to define three Stat6 activational phenotypes termed as Stat6high (intense banding), Stat6low (medium intensity banding), and Stat6null (very low to no discernible banding). These Stat6 phenotypes correlate well with levels of CD23 expression, but not with those of HLA-DR. Pedigree analysis has revealed a Mendelian inheritance pattern for Stat6 phenotypes. The methodology is useful in association studies in human cancer and autoimmune diseases. The Stat6null phenotype may result from a defect in Stat6 signaling which has important implications with respect to the pathogenesis of cancer and Th1/Th2 cytokine imbalance in general. In addition, the defective Stat6null lines discovered here may serve as a natural human model for comprehensive study in the same way as a Stat6 knockout null animal model does.

Amino Acid Motifs↗