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Enhanced Proliferation (enhanced + proliferation)
Selected AbstractsEnhanced proliferation and differentiation of rat hepatocytes cultured with bone marrow stromal cellsJOURNAL OF CELLULAR PHYSIOLOGY, Issue 1 2001Toru Mizuguchi Liver transplantation is the only clinically effective method of treating acute liver failure. However, wider application of this therapeutic modality is restricted primarily by shortage of donor organs. In the search for alternative methods of liver replacement therapy, investigators have focused on transplantation of normal allogeneic hepatocytes and on the development of liver support systems utilizing isolated hepatocytes. Since all human livers suitable for cell harvest are being used for transplantation, hepatocyte therapy using human tissue would require growing of cells in vitro. Unfortunately, although hepatocytes have tremendous capacity to proliferate in vivo, their ability to grow in culture is severely limited. Stromal cells from bone marrow and other blood-forming organs have been found to support hematopoiesis. In this paper, we show that bone marrow-derived stromal cells (BMSCs) enhance proliferation and support differentiation of rat hepatocytes in culture. Further, we demonstrate that in hepatocyte/BMSC co-cultures, clonal expansion of small hepatocytes (SH) is increased. Using semipermeable membrane cultures, we established that direct cell,cell contact is necessary for stimulation of cell proliferation. We also show that BMSCs which are in direct contact with hepatocytes and SH colonies express Jagged1. This suggests a potential role for Notch signaling in the observed effects. Finally, we present evidence that the expression and activity of liver specific transcirption factors, CCAAT/enhancer binding proteins and liver specific key enzymes such as tryptophan 2,3-dioxygenase, are improved in hepatocyte/BMSC co-cultures. In conclusion, results of this study indicate that BMSCs could facilitate proliferation and differentiation of primary rat hepatocytes and their progenitors (SH) in vitro. © 2001 Wiley-Liss, Inc. [source] Enhanced proliferation of progenitor cells in the subventricular zone and limited neuronal production in the striatum and neocortex of adult macaque monkeys after global cerebral ischemia,JOURNAL OF NEUROSCIENCE RESEARCH, Issue 6 2005Anton B. Tonchev Abstract Cerebral ischemia in adult rodent models increases the proliferation of endogenous neural progenitor cells residing in the subventricular zone along the anterior horn of the lateral ventricle (SVZa) and induces neurogenesis in the postischemic striatum and cortex. Whether the adult primate brain preserves a similar ability in response to an ischemic insult is uncertain. We used the DNA synthesis indicator bromodeoxyuridine (BrdU) to label newly generated cells in adult macaque monkeys and show here that the proliferation of cells with a progenitor phenotype (double positive for BrdU and the markers Musashi1, Nestin, and ,III-tubulin) in SVZa increased during the second week after a 20-min transient global brain ischemia. Subsequent progenitor migration seemed restricted to the rostral migratory stream toward the olfactory bulb and ischemia increased the proportion of adult-generated cells retaining their location in SVZa with a progenitor phenotype. Despite the lack of evidence for progenitor cell migration toward the postischemic striatum or prefrontal neocortex, a small but sustained proportion of BrdU-labeled cells expressed features of postmitotic neurons (positive for the protein NeuN and the transcription factors Tbr1 and Islet1) in these two regions for at least 79 days after ischemia. Taken together, our data suggest an enhanced neurogenic response in the adult primate telencephalon after a cerebral ischemic insult. © 2005 Wiley-Liss, Inc. [source] Enhanced proliferation and efficient transmission of Candidatus Liberibacter asiaticus by adult Diaphorina citri after acquisition feeding in the nymphal stageANNALS OF APPLIED BIOLOGY, Issue 1 2009H. Inoue Abstract We carried out a quantitative detection of Candidatus Liberibacter asiaticus, the bacterium associated with the disease of huanglongbing, in the vector psyllid Diaphorina citri by using a TaqMan real-time PCR assay. The concentration of the bacterium was monitored at 5-day intervals for a period of 20 days after psyllids were exposed as fifth instar nymphs or adults to a Ca. L. asiaticus-infected plant for an acquisition access period of 24 h. When adults fed on Ca. L. asiaticus-infected plant, the concentration of the bacterium did not increase significantly and the pathogen was not transmitted to any citrus seedlings. In contrast, when psyllids fed on infected plant as nymphs, the concentration of the pathogen significantly increased by 25-, 360- and 130-fold from the initial acquisition day to 10, 15 and 20 days, respectively. Additionally, the pathogen was successfully transmitted to 67% of citrus seedlings by emerging adults. Our data suggested that multiplication of the bacterium into the psyllids is essential for an efficient transmission and show that it is difficult for adults to transmit the pathogen unless they acquire it as nymphs. [source] Deficient translocation of c-Rel is associated with impaired Th1 cytokine production in T cells from atopic dermatitis patientsEXPERIMENTAL DERMATOLOGY, Issue 1 2005Karsten Dieckhoff Abstract:, Decreased production of T helper type 1 (Th1) cytokines, such as interferon-, (IFN-,) or interleukin-2 (IL-2), is a hallmark of atopic diseases. While accessory signals from antigen-presenting cells may be missing, T cells themselves may be suppressed in their ability to produce substantial amounts of Th1 cytokines. We show, in this study, that T cell receptor (TCR)-activated T cells from atopic dermatitis (AD) patients proliferate less than control T cells and produce lower amounts of IFN-, and IL-2, but comparable amounts of IL-4. Because mice lacking the nuclear factor kappa B (NF-,B) transcription factors , p65 or c-Rel , show reduced Th1, but undisturbed Th2 responses, we investigated the role of c-Rel and p65 for Th1 cytokine production in T cells from healthy and severe AD patients. TCR-activated primary T cells from healthy donors treated with c-Rel antisense oligonucleotides produced lower levels of IL-2 and IFN-, and proliferated less efficiently than the corresponding control T cells. Moreover, transfection of primary T cells with c-Rel or p65 enhanced proliferation and production of IL-2 and IFN-,. Nuclear extracts of activated primary T cells from AD donors bound weakly to NF-,B-specific oligonucleotides, compared to extracts from healthy control T cells. Western blotting studies revealed that nuclear, but not cytosolic, extracts from T cells of AD patients lacked significant amounts of c-Rel and p65. T cell clones derived from AD patients failed to sufficiently translocate c-Rel and p65 into the nucleus following activation. Thus, impaired nuclear translocation of c-Rel and p65 may determine an impaired Th1 cytokine response in AD. [source] HMGA2 and the p19Arf -TP53-CDKN1A axis: A delicate balance in the growth of uterine leiomyomas,GENES, CHROMOSOMES AND CANCER, Issue 8 2010Dominique Nadine Markowski Pathogenetically, uterine leiomyomas (ULs) can be interpreted as the result of a monoclonal abnormal proliferation of myometrial cells. Oncogene-induced senescence (OIS) is a frequent phenomenon in premalignant lesions that leads to a growth arrest mainly by the activation of two potent growth-inhibitory pathways as represented by p16Ink4a and p19Arf. The relevance of OIS for the development of UL has not been addressed, but HMGA2, encoded by a major target gene of recurrent chromosomal abnormalities in UL, has been implicated in the repression of the Ink4a/Arf (CDKN2A) locus. This prompted us to examine if HMGA2 contributes to the growth of leiomyomas by repressing this locus. Contrary to the expectations, we were able to show that generally ULs express significantly higher levels of p19Arf mRNA than myometrium and that UL with 12q14,15 rearrangements showed higher expression levels than UL with other cytogenetic aberrations. Furthermore, the finding of a significant correlation between the expressions of p19Arf and CDKN1A shows that p19Arf triggers senescence rather than apoptosis in UL. Furthermore, the expression levels of HMGA2, p19Arf, and CDKN1A were found to be correlated with the size of the tumors, indicating that an enhanced growth potential is counterbalanced by the p19Arf pathway. Mechanistically, the UL may thus execute a program already present in their cell of origin, where it is activated to protect the genome, for example, in the case of enhanced proliferation. In summary, the results identify the p19Arf -TP53-CDKN1A pathway as a major player in the growth control and genomic stability of uterine fibroids. © 2010 Wiley-Liss, Inc. [source] Formation of three-dimensional cell/polymer constructs for bone tissue engineering in a spinner flask and a rotating wall vessel bioreactorJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2002Vassilios I. Sikavitsas Abstract The aim of this study is to investigate the effect of the cell culture conditions of three-dimensional polymer scaffolds seeded with rat marrow stromal cells (MSCs) cultured in different bioreactors concerning the ability of these cells to proliferate, differentiate towards the osteoblastic lineage, and generate mineralized extracellular matrix. MSCs harvested from male Sprague,Dawley rats were culture expanded, seeded on three-dimensional porous 75:25 poly(D,L -lactic- co -glycolic acid) biodegradable scaffolds, and cultured for 21 days under static conditions or in two model bioreactors (a spinner flask and a rotating wall vessel) that enhance mixing of the media and provide better nutrient transport to the seeded cells. The spinner flask culture demonstrated a 60% enhanced proliferation at the end of the first week when compared to static culture. On day 14, all cell/polymer constructs exhibited their maximum alkaline phosphatase activity (AP). Cell/polymer constructs cultured in the spinner flask had 2.4 times higher AP activity than constructs cultured under static conditions on day 14. The total osteocalcin (OC) secretion in the spinner flask culture was 3.5 times higher than the static culture, with a peak OC secretion occurring on day 18. No considerable AP activity and OC secretion were detected in the rotating wall vessel culture throughout the 21-day culture period. The spinner flask culture had the highest calcium content at day 14. On day 21, the calcium deposition in the spinner flask culture was 6.6 times higher than the static cultured constructs and over 30 times higher than the rotating wall vessel culture. Histological sections showed concentration of cells and mineralization at the exterior of the foams at day 21. This phenomenon may arise from the potential existence of nutrient concentration gradients at the interior of the scaffolds. The better mixing provided in the spinner flask, external to the outer surface of the scaffolds, may explain the accelerated proliferation and differentiation of marrow stromal osteoblasts, and the localization of the enhanced mineralization on the external surface of the scaffolds. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 136,148, 2002 [source] Effect of aging on neurogenesis in the canine brainAGING CELL, Issue 3 2008Anton Pekcec Summary An age-dependent decline in hippocampal neurogenesis has been reported in laboratory rodents. Environmental enrichment proved to be a strong trigger of neurogenesis in young and aged laboratory rodents, which are generally kept in facilities with a paucity of environmental stimuli. These data raise the question whether an age-dependent decline in hippocampal cell proliferation and neurogenesis can also be observed in individuals exposed to diversified and varying surroundings. Therefore, we determined rates of canine hippocampal neurogenesis using post-mortem tissue from 37 nonlaboratory dogs that were exposed to a variety of environmental conditions throughout their life. Expression of the neuronal progenitor cell marker doublecortin clearly correlated with age. The analysis of doublecortin-labeled cells in dogs aged > 133 months indicated a 96% drop in the aged canine brain as compared to young adults. Expression of the proliferation marker Ki-67 in the subgranular zone decreased until dogs were aged 85,132 months. In the aging canine brain amyloid-beta peptide deposits have been described that might resemble an early pathophysiological change in the course of human Alzheimer's disease. Comparison of Ki-67 and doublecortin expression in canine brain tissue with or without diffuse plaques revealed no differences. The data indicate that occurrence of diffuse plaques in the aging brain is not sufficient to trigger enhanced proliferation or enhanced neurogenesis such as described in human Alzheimer's disease. In addition, this study gives first proof that an age-dependent decline also dominates hippocampal neurogenesis rates in individuals living in diversified environments. [source] Induction of cytotoxic T lymphocytes by dendritic cells pulsed with murine leukemic cell RNAAMERICAN JOURNAL OF HEMATOLOGY, Issue 3 2004Chul Won Jung Abstract Peptide-pulsed dendritic cells can stimulate T cells showing specific cytotoxicity in chronic myelogenous leukemia. We tried to induce a specific cytotoxic T-cell response stimulated by RNA-pulsed dendritic cells in acute myelogenous leukemia. The total RNA of WEHI-3BD+, a myelomonocytic leukemia cell line derived from BALB/c mice, was transfected into dendritic cells induced from bone marrow nucleated cells of BALB/c mice with granulocyte macrophage colony-stimulating factor (GM-CSF) and lipopolysaccharide (LPS) using liposome. RNA-pulsed dendritic cells were injected into the peritoneal cavity of BALB/c mice, and splenic T cells were isolated for antigen-stimulated proliferation and leukemia-specific cytotoxicity assay. Cultured bone marrow nucleated cells expressed dendritic cell markers including MHC class II antigen, CD80, CD86, and CD11c. T cells stimulated by RNA-pulsed dendritic cells showed enhanced proliferation than those stimulated by unpulsed dendritic cells (P = 0.05) and showed dose-dependent specific cytotoxicity against WEHI-3BD+ cells. We concluded total RNA-pulsed dendritic cells could induce a specific T-cell cytotoxicity in acute myelogenous leukemia. Am. J. Hematol. 75:121,127, 2004. © 2004 Wiley-Liss, Inc. [source] Smad3 signalling plays an important role in keloid pathogenesis via epithelial,mesenchymal interactionsTHE JOURNAL OF PATHOLOGY, Issue 2 2005TT Phan Abstract Smad signalling plays important roles in developmental and cancer biology as well as in fibropathogenesis. Its role in keloid biology is not known. Epithelial,mesenchymal interactions, originally described in normal skin, have recently been established to play a significant role in keloid pathogenesis, and demonstrate the important influence of keratinocyte paracrine factor signalling on fibroblast behaviour. The present study investigated the role of downstream Smad cascade induction in this interaction. Normal fibroblasts (NF) and keloid fibroblasts (KF) were co-cultured in serum-free medium with normal keratinocytes (NK) or keloid keratinocytes (KK) for 5 days, after which fibroblast cell lysates were subjected to western blot and immunoprecipitation analysis to quantify the levels of Smad and Smad2/3/4 binding complex. In another set of experiments, wild-type (wt), Smad2-null (Smad2,/,) and Smad3-null (Smad3,/,) mouse embryonic fibroblasts (MEF) were assayed for cell proliferation and collagen production after serum-free co-culture with KK or exposure to conditioned media collected from serum-free KK/KF co-culture. Compared to normal skin, keloids expressed high basal levels of TGF,R1 and TGF,R2, Smad2, 3 and 4 and phospho-Smad2. Upregulation of TGF,R1 and TGF,R2, Smad3 and p-Smad2 was observed in KF co-cultured with KK, together with enhanced Smad3 phosphorylation and Smad2/3/4 binding complex production. When MEF-wt, MEF-Smad2,/, or MEF-Smad3,/, were co-cultured with KK or exposed to KK/KF co-culture conditioned media, enhanced proliferation and collagen production were seen in MEF-wt and MEF-Smad2,/, but not in MEF-Smad3,/, cells. The activation of Smad signalling, importantly that of Smad3, appears to be one facet of the complex epithelial,mesenchymal interactions in keloid pathogenesis, resulting in active KF proliferation and collagen-ECM production in co-culture with KK. This finding suggests the suppression of Smad signalling as a novel approach in keloid therapy. Copyright © 2005 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source] Enhancement of immunogenicity of JEG-3 Cells by ectopic expression of HLA-A*0201 and CD80AMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 3 2002Serpil Koc The chorioncarcinoma cell line JEG-3 escapes immunity by secretion of leukocyte inhibitory factor suppressing leukocyte proliferation. The cells lack expression of classical HLA alleles but express nonclassical HLA-G, which binds to killer inhibitory receptor of natural killer cells, preventing cytolysis. We investigated whether JEG-3 cells are capable of immune stimulation after introduction of classical HLA and T-cell costimulatory signals. JEG-3 cells were transduced with vectors for HLA-A*0201 and/or CD80. Parental JEG-3, or JEG-3/A2, JEG-3/CD80, or JEG-3/A2/CD80 were used to stimulate allogeneic T cells. While parental JEG-3 cells induced only marginal proliferation of resting T cells, HLA-A2 or CD80 expressing JEG-3 induced enhanced proliferation. Double transfectants were most efficient. This difference was more obvious when T cells were preactivated by PHA. T cell lines restimulated with JEG-3 transfectants were characterized for expansion, phenotypes, and cytolytic activity. HLA-A2 matched and nonmatched donors were compared. T cells stimulated with JEG-3/A2 or JEG-3/CD80 were cytolytic towards parental JEG-3 cells. Again double positive JEG-3/A2/CD80 induced highest cytolytic activity, most obvious in HLA-nonmatched donors suggesting alloreactivity to HLA. Our data suggest that, in spite of immunosuppressive mechanisms, proliferative and cytolytic T cell responses are induced by JEG-3 cells when classical HLA and/or costimulatory signals are present on the cells. [source] Heparin-binding epidermal growth factor-like growth factor functionally antagonizes interstitial cystitis antiproliferative factor via mitogen-activated protein kinase pathway activationBJU INTERNATIONAL, Issue 4 2009Jayoung Kim OBJECTIVE To delineate the mechanism underlying the potential functional relationship between interstitial cystitis antiproliferative factor (APF) and heparin-binding epidermal growth factor-like growth factor (HB-EGF), as APF has previously been shown to decrease the proliferation rate of normal bladder epithelial cells and the amount of HB-EGF produced by these cells. MATERIALS AND METHODS APF-responsive T24 transitional carcinoma bladder cells were treated with high-pressure liquid chromatography-purified native APF with or without HB-EGF to determine the involvement of signalling pathways and proliferation by Western blot analysis, p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (Erk)/MAPK assays, and 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) assay. RESULTS Cyclic stretch induced the secretion of HB-EGF from T24 cells overexpressing the HB-EGF precursor, resulting in enhanced proliferation. T24 cells treated with APF had increased p38MAPK activity and suppressed cell growth, events that were both reversed by treatment with a p38MAPK-selective inhibitor. Activation of Erk/MAPK by HB-EGF was inhibited by APF, and APF did not stimulate p38MAPK in the presence of soluble HB-EGF or when cells overexpressed constitutively secreted HB-EGF. Lastly, APF inhibitory effects on cell growth were attenuated by HB-EGF. CONCLUSIONS These results indicate that HB-EGF and APF are functionally antagonistic and signal through parallel MAPK signalling pathways in bladder cells. [source] | |||||||||||||