搜索结果: 'NeuroCult Proliferation'

BACKGROUND: Previous studies have shown that patients with Bcr-Abl-positive acute lymphoblastic leukemia (ALL) either have primary disease that is refractory to imatinib mesylate or develop disease recurrence after an initial response. METHODS: The authors investigated the effects of a newly designed Bcr-Abl inhibitor,AMN107,by comparing its in vitro inhibitory potency on p190 Bcr-Abl ALL cell lines with that of imatinib. RESULTS: In two Philadelphia (Ph)-positive ALL cell lines,AMN107 was found to be 30-40 times more potent than imatinib in inhibiting cellular proliferation. AMN107 was also more effective than imatinib in inhibiting phosphorylation of p190 Bcr-Abl tyrosine kinase in cell lines and primary ALL cells. The inhibition of cellular proliferation was associated with the induction of apoptosis in only one of the cell lines. No activity was observed in cell lines lacking the BCR-ABL genotype. CONCLUSIONS: The results of the current study suggest the superior potency of AMN107 compared with imatinib in Ph-positive ALL and support clinical trials of AMN107 in patients with Ph-positive ALL. View Publication

Recent work investigating exercise induced changes in immunocompetence suggests that some of the ambiguity in the literature is resultant from different cell isolation protocols and mitogen selection. To understand this effect,we compared post-exercise measures of T cell activation and proliferation using two different stimulation methods (costimulation through CD28 or stimulation with phytohaemagglutinin [PHA]). Further,we investigated whether exercise induced changes are maintained when T cell isolation from whole blood is delayed overnight in either a room temperature or chilled (4°C) environment. As expected,an increased proliferation response was observed post-exercise in T cells isolated from whole blood of previously trained individuals immediately after blood collection. Also,cells stimulated with PHA after resting overnight in whole blood were not adversely impacted by the storage conditions. In contrast,allowing cells to rest overnight in whole blood prior to stimulation through CD28,lessened the proliferation observed by cells following exercise rendering both the room temperature and chilled samples closer to the results seen in the control condition. Changes in early markers of activation (CD25),followed a similar pattern,with activation in PHA stimulated cells remaining fairly robust after overnight storage; whereas cell activation following stimulation through CD3+CD28 was disproportionately decreased by the influence of overnight storage. These findings indicate that decisions regarding cell stimulation methods need to be paired with the timeline for T cell isolation from whole blood. These considerations will be especially important for field based studies of immunocompetence where there is a delay in getting whole blood samples to a lab for processing as well as clinical applications where a failure to isolate T cells in a timely manner may result in loss of the response of interest. View Publication

OBJECTIVES: Recent data show that Imatinib mesylate (IM) also affects haematopoietic stem cells (HSC),T lymphocytes and dendritic cells that do not harbour constitutively active tyrosine kinases. MATERIALS AND METHODS: We evaluated possible effects of IM on human bone marrow-derived mesenchymal stem cells (MSC) in vitro. RESULTS: Screening the activity of 42 receptor tyrosine kinases revealed an exclusive inhibition of platelet-derived growth factor receptorbeta (PDGFRbeta). Analysis of downstream targets of PDGFRbeta demonstrated IM-mediated reduction of Akt and Erk1/2 phosphorylation. Culture of MSC with IM led to the reversible development of perinuclear multi-vesicular bodies. The proliferation and clonogenicity of MSC were significantly reduced compared to control cultures. IM favoured adipogenic differentiation of MSC whereas osteogenesis was suppressed. The functional deficits described led to a 50% reduction in the support of clonogenic haematopoietic stem cells,cultured for 1 month on a monolayer of MSC with IM. CONCLUSION: In summary,inhibition of PDGFRbeta and downstream Akt and Erk signalling by IM has a significant impact on proliferation and differentiation of human MSC in vitro. View Publication

INTRODUCTION: The physiological signals that direct the division and differentiation of the zygote to form a blastocyst,and subsequent embryonic stem cell division and differentiation during early embryogenesis,are unknown. Although a number of growth factors,including the pregnancy-associated hormone human chorionic gonadotropin (hCG) are secreted by trophoblasts that lie adjacent to the embryoblast in the blastocyst,it is not known whether these growth factors directly signal human embryonic stem cells (hESCs).backslashnbackslashnMETHODS: Here we used hESCs as a model of inner cell mass differentiation to examine the hormonal requirements for the formation of embryoid bodies (EB's; akin to blastulation) and neuroectodermal rosettes (akin to neurulation).backslashnbackslashnRESULTS: We found that hCG promotes the division of hESCs and their differentiation into EB's and neuroectodermal rosettes. Inhibition of luteinizing hormone/chorionic gonadotropin receptor (LHCGR) signaling suppresses hESC proliferation,an effect that is reversed by treatment with hCG. hCG treatment rapidly upregulates steroidogenic acute regulatory protein (StAR)-mediated cholesterol transport and the synthesis of progesterone (P4). hESCs express P4 receptor A,and treatment of hESC colonies with P4 induces neurulation,as demonstrated by the expression of nestin and the formation of columnar neuroectodermal cells that organize into neural tubelike rosettes. Suppression of P4 signaling by withdrawing P4 or treating with the P4-receptor antagonist RU-486 inhibits the differentiation of hESC colonies into EB's and rosettes.backslashnbackslashnCONCLUSIONS: Our findings indicate that hCG signaling via LHCGR on hESC promotes proliferation and differentiation during blastulation and neurulation. These findings suggest that trophoblastic hCG secretion and signaling to the adjacent embryoblast could be the commencement of trophic support by placental tissues in the growth and development of the human embryo. View Publication

Memantine is classified as an NMDA receptor antagonist. We recently reported that memantine promoted the proliferation of neural progenitor cells and the production of mature granule neurons in the adult hippocampus. However,the molecular mechanism responsible for the memantine-induced promotion of cellular proliferation remains unknown. In this study we searched for a factor that mediates memantine-induced cellular proliferation,and found that pigment epithelium-derived factor (PEDF),a broad-acting neurotrophic factor,is up-regulated in the dentate gyrus of adult mice after the injection of memantine. PEDF mRNA expression increased significantly by 3.5-fold at 1 day after the injection of memantine. In addition,the expression level of PEDF protein also increased by 1.8-fold at 2 days after the injection of memantine. Immunohistochemical study using anti-PEDF antibody showed that the majority of the PEDF-expressing cells were protoplasmic and perivascular astrocytes. Using a neurosphere assay,we confirmed that PEDF enhanced cellular proliferation under the presence of fibroblast growth factor-2 (FGF-2) and epidermal growth factor (EGF) but was not involved in the multilineage potency of hippocampal progenitor cells. Over expression of PEDF by adeno-associated virus,however,did not stimulate cellular proliferation,suggesting PEDF per se does not promote cellular proliferation in vivo. These findings suggest that the memantine induced PEDF up-regulation is involved in increased proliferation of hippocampal progenitor cells. View Publication

Virus-specific CD8(+) T cells are associated with declining viremia in acute human immunodeficiency virus (HIV)1 infection,but do not correlate with control of viremia in chronic infection,suggesting a progressive functional defect not measured by interferon gamma assays presently used. Here,we demonstrate that HIV-1-specific CD8(+) T cells proliferate rapidly upon encounter with cognate antigen in acute infection,but lose this capacity with ongoing viral replication. This functional defect can be induced in vitro by depletion of CD4(+) T cells or addition of interleukin 2-neutralizing antibodies,and can be corrected in chronic infection in vitro by addition of autologous CD4(+) T cells isolated during acute infection and in vivo by vaccine-mediated induction of HIV-1-specific CD4(+) T helper cell responses. These data demonstrate a loss of HIV-1-specific CD8(+) T cell function that not only correlates with progressive infection,but also can be restored in chronic infection by augmentation of HIV-1-specific T helper cell function. This identification of a reversible defect in cell-mediated immunity in chronic HIV-1 infection has important implications for immunotherapeutic interventions. View Publication

The glycogen synthase kinase 3 (GSK3) inhibitor,6-bromoindirubin-3'-oxime (BIO),is a key regulator of many signaling pathways to maintain pluripotency of human and mouse embryonic stem cells (ESCs). However,the effect of BIO on derivation of dairy goat male germline stem cells (mGSCs) remains unclear. The objectives of this study were to investigate whether BIO influences derivation of dairy goat mGSCs. Dairy goat mGSCs were cultured in mTeSR containing BIO medium and its effects on the proliferation ability of goat mGSCs (derived from goats ≤2 mo of age) were evaluated by 5-Bromo-2-deoxyuridine (BrdU) incorporation and alkaline phosphatase (AP) staining. Furthermore,its effects on maintenance of the undifferentiated state of mGSCs in late passages of cultures,as well as the capacity of mGSCs to differentiate into embryoid bodies (EBs) were examined. The presence of BIO increased the mitosis index and the number of AP positive colonies,as well as expression of pluripotent markers,Oct4,Nanog,Sox2,C-myc,Klf4,E-cadherin,and the proliferative markers,Pcna and C-myc. In contrast,there was no significant change in expression of apoptosis markers,P53,P21 and cyclin-related genes (Cyclin A,CDK2,Cyclin D1),as determined by RT-PCR analysis. When mGSCs were cultured in mTeSR medium containing BIO,EBs were formed,which were capable of further differentiating into various cell types found in the three embryonic germ layers,as determined by immunofluorescence and/or histologic staining. In conclusion,adding BIO to cultures BIO significantly promoted establishment of goat mGSC colonies and maintained their undifferentiated state. View Publication

Cellular damage by reactive oxygen species and altered neurogenesis are implicated in the etiology of AD and the pathogenic actions of amyloid β-peptide (Aβ); the underlying mechanisms and the early oxidative intracellular events triggered by Aβ are not established. In the present study,we found that mouse embryonic cortical neural progenitor cells exhibit intermittent spontaneous mitochondrial superoxide (SO) flashes that require transient opening of mitochondrial permeability transition pores (mPTPs). The incidence of mitochondria SO flash activity in neural progenitor cells (NPCs) increased during the first 6-24 hours of exposure to aggregating amyloid β-peptide (Aβ1-42),indicating an increase in transient mPTP opening. Subsequently,the SO flash frequency progressively decreased and ceased between 48 and 72 hours of exposure to Aβ1-42,during which time global cellular reactive oxygen species increased,mitochondrial membrane potential decreased,cytochrome C was released from mitochondria and the cells degenerated. Inhibition of mPTPs and selective reduction in mitochondrial SO flashes significantly ameliorated the negative effects of Aβ1-42 on NPC proliferation and survival. Our findings suggest that mPTP-mediated bursts of mitochondrial SO production is a relatively early and pivotal event in the adverse effects of Aβ1-42 on NPCs. If Aβ inhibits NPC proliferation in the brains of AD patients by a similar mechanism,then interventions that inhibit mPTP-mediated superoxide flashes would be expected to protect NPCs against the adverse effects of Aβ. View Publication

Effects of lysophosphatidic acid (LPA),an extracellular phospholipid signal,on the proliferation of rat embryonic neural stem cells (NSCs) and their differentiation into microtubule-associated protein 2 (MAP2)-positive and choline acetyltransferase (ChAT)-positive,i.e. cholinergic-committed neurons,were observed in vitro by [(3)H]-thymidine incorporation,immunocytochemistry,Western blot and other techniques. The results showed that: (1) Lower concentrations of LPA (0.01˜1.0 mumol/L) dose-dependently enhanced the uptake of [(3)H]-thymidine by NSCs cultured in specific serum-free medium,indicating a significant promotive action of LPA on the proliferation of NSCs. (2) After fetal bovine serum which induces and commences the differentiation of NSCs,was used in the medium,the lower concentrations of LPA increased the percentages of both MAP2- and ChAT-immunoreactive neurons,with a peak at 0.1 mumol/L LPA in two cases. (3) The promotive effects of LPA on the differentiation of MAP2- and ChAT-positive neurons were also supported by the up-regulation of the expressions of both MAP2 and ChAT proteins detected by Western blot. (4) At the early phase of differentiation of NSCs,the cell migration and neurite extension were enhanced significantly by lower dosages of LPA under phase-contrast microscope. These results suggest that LPA within certain lower range of concentrations promotes the proliferation of NSCs and their differentiation into unspecific MAP2-positive and specific cholinergic-committed neurons,and also strengthens the migration and neurite extension of the newly-generated neuronal (and also glial as reported elsewhere) progenitors. View Publication

Autologous chondrocyte implantation is the current gold standard cell therapy for cartilage lesions. However,in some instances,the heavily compromised health of the patient can either impair or limit the recovery of the autologous chondrocytes and a satisfactory outcome of the implant. Allogeneic human articular chondrocytes (hAC) could be a good alternative,but the possible immunological incompatibility between recipient and hAC donor should be considered. Herein,we report that allogeneic hAC inhibited T lymphocyte response to antigen-dependent and -independent proliferative stimuli. This effect was maximal when T cells and hAC were in contact and it was not relieved by the addition of exogenous lymphocyte growth factor interleukin (IL)-2. More important,hAC impaired the differentiation of peripheral blood monocytes induced with granulocyte monocyte colony-stimulating factor and IL-4 (Mo) to professional antigen-presenting cells,such as dendritic cells (DC). Indeed,a marked inhibition of the onset of the CD1a expression and an ineffective downregulation of CD14 antigens was observed in Mo-hAC co-cultures. Furthermore,compared to immature or mature DC,Mo from Mo-hAC co-cultures did not trigger an efficacious allo-response. The prostaglandin (PG) E2 present in the Mo-hAC co-culture conditioned media is a putative candidate of the hAC-mediated inhibition of Mo maturation. Altogether,these findings indicate that allogeneic hAC inhibit,rather than trigger,immune response and strongly suggest that an efficient chondrocyte implantation could be possible also in an allogeneic setting. View Publication

We examined the effects of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3],25-hydroxyvitamin D3 (25OHD3),and vitamin D3 on human keratinocyte proliferation and differentiation in a serum-free or defined culture system. Concentrations greater than 10(-8) M 1,25-(OH)2D3 or 10(-7) M 25(OH)2D3 caused marked inhibition of cell growth. Growth inhibition with high doses of 1,25-(OH)2D3 was not stringent,but was mainly exerted in the G1 phase of the cell cycle. Early release from the cell cycle block restored the proliferation of human keratinocytes. The calcium concentration in the medium had no significant effect on the antiproliferative action of 1,25-(OH)2D3,25OHD3,and vitamin D3. We also show that human keratinocyte proliferation is enhanced at doses of 1,25-(OH)2D3 and 25OH2D3 of 10(-9) M or less. Enhanced proliferation of human keratinocytes with physiological concentrations of 1,25-(OH)2D3 could only be shown in fully defined medium that contained no vitamin D3,related sterols,or bovine pituitary extract. Human keratinocyte differentiation was enhanced with higher doses of 1,25-(OH)2D3 when cells were grown in the presence of high calcium concentrations. These studies demonstrate that the lower,physiological concentrations of vitamin D3 metabolites are capable of stimulating the proliferation of epidermal keratinocytes grown under selected conditions that eliminate confounding or unidentified medium culture factors. Vitamin D3 metabolites are shown to exert mitogenic trophic effects in cultured human epithelial cells similar to their established activities in vivo. View Publication

FOXM1 is an important cell cycle regulator and regulates cell proliferation. In addition,FOXM1 has been reported to contribute to oncogenesis in various cancers. However,it is not clearly understood how FOXM1 contributes to acute myeloid leukemia (AML) cell proliferation. In this study,we investigated the cellular and molecular function of FOXM1 in AML cells. The FOXM1 messenger RNA (mRNA) expressed in AML cell lines was predominantly the FOXM1B isoform,and its levels were significantly higher than in normal high aldehyde dehydrogenase activity (ALDH(hi)) cells. Reduction of FOXM1 expression in AML cells inhibited cell proliferation compared with control cells,through induction of G(2)/M cell cycle arrest,a decrease in the protein expression of Aurora kinase B,Survivin,Cyclin B1,S-phase kinase-associated protein 2 and Cdc25B and an increase in the protein expression of p21(Cip1) and p27(Kip1). FOXM1 messenger RNA (mRNA) was overexpressed in all 127 AML clinical specimens tested (n = 21,56,32 and 18 for M1,M2,M4 and M5 subtypes,respectively). Compared with normal ALDH(hi) cells,FOXM1 gene expression was 1.65- to 2.26-fold higher in AML cells. Moreover,the FOXM1 protein was more strongly expressed in AML-derived ALDH(hi) cells compared with normal ALDH(hi) cells. In addition,depletion of FOXM1 reduced colony formation of AML-derived ALDH(hi) cells due to inhibition of Cdc25B and Cyclin B1 expression. In summary,we found that FOXM1B mRNA is predominantly expressed in AML cells and that aberrant expression of FOXM1 induces AML cell proliferation through modulation of cell cycle progression. Thus,inhibition of FOXM1 expression represents an attractive target for AML therapy. View Publication