Peripheral blood fibrocytes: new information to explain the dynamics of Leishmania infection

Fibrocytes are important for understanding the progression of many diseases because they are present in areas where pathogenic lesions are generated. However, the morphology of fibrocytes and their interactions with parasites are poorly understood. In this study, we examined the morphology of peripheral blood fibrocytes and their interactions with Leishmania (L.) amazonensis . Through ultrastructural analysis, we describe the details of fibrocyte morphology and how fibrocytes rapidly internalise Leishmania promastigotes. The parasites differentiated into amastigotes after 2 h in phagolysosomes and the infection was completely resolved after 72 h. Early in the infection, we found increased nitric oxide production and large lysosomes with electron-dense material. These factors may regulate the proliferation and death of the parasites. Because fibrocytes are present at the infection site and are directly involved in developing cutaneous leishmaniasis, they are targets for effective, non-toxic cell-based therapies that control and treat leishmaniasis.

Staurosporine and cytochalasin D induce chondrogenesis by regulation of actin dynamics in different way

Actin cytoskeleton has been known to control and/or be associated with chondrogenesis. Staurosporine and cytochalasin D modulate actin cytoskeleton and affect chondrogenesis. However, the underlying mechanisms for actin dynamics regulation by these agents are not known well. In the present study, we investigate the effect of staurosporine and cytochalasin D on the actin dynamics as well as possible regulatory mechanisms of actin cytoskeleton modulation. Staurosporine and cytochalasin D have different effects on actin stress fibers in that staurosporine dissolved actin stress fibers while cytochalasin D disrupted them in both stress forming cells and stress fiber-formed cells. Increase in the G-/F-actin ratio either by dissolution or disruption of actin stress fiber is critical for the chondrogenic differentiation. Cytochalasin D reduced the phosphorylation of cofilin, whereas staurosporine showed little effect on cofilin phosphorylation. Either staurosporine or cytochalasin D had little effect on the phosphorylation of myosin light chain. These results suggest that staurosporine and cytochalasin D employ different mechanisms for the regulation of actin dynamics and provide evidence that removal of actin stress fibers is crucial for the chondrogenic differentiation.

Reactive oxygen species enhance differentiation of human embryonic stem cells into mesendodermal lineage

Recently, reactive oxygen species (ROS) have been studied as a regulator of differentiation into specific cell types in embryonic stem cells (ESCs). However, ROS role in human ESCs (hESCs) is unknown because mouse ESCs have been used mainly for most studies. Herein we suggest that ROS generation may play a critical role in differentiation of hESCs; ROS enhances differentiation of hESCs into bi-potent mesendodermal cell lineage via ROS-involved signaling pathways. In ROS-inducing conditions, expression of pluripotency markers (Oct4, Tra 1-60, Nanog, and Sox2) of hESCs was decreased, while expression of mesodermal and endodermal markers was increased. Moreover, these differentiation events of hESCs in ROS-inducing conditions were decreased by free radical scavenger treatment. hESC-derived embryoid bodies (EBs) also showed similar differentiation patterns by ROS induction. In ROS-related signaling pathway, some of the MAPKs family members in hESCs were also affected by ROS induction. p38 MAPK and AKT (protein kinases B, PKB) were inactivated significantly by buthionine sulfoximine (BSO) treatment. JNK and ERK phosphorylation levels were increased at early time of BSO treatment but not at late time point. Moreover, MAPKs family-specific inhibitors could prevent the mesendodermal differentiation of hESCs by ROS induction. Our results demonstrate that stemness and differentiation of hESCs can be regulated by environmental factors such as ROS.

Stemness Evaluation of Mesenchymal Stem Cells from Placentas According to Developmental Stage: Comparison to Those from Adult Bone Marrow

This study was done to evaluate the stemness of human mesenchymal stem cells (hMSCs) derived from placenta according to the development stage and to compare the results to those from adult bone marrow (BM). Based on the source of hMSCs, three groups were defined: group I included term placentas, group II included first-trimester placentas, and group III included adult BM samples. The stemness was evaluated by the proliferation capacity, immunophenotypic expression, mesoderm differentiation, expression of pluripotency markers including telomerase activity. The cumulative population doubling, indicating the proliferation capacity, was significantly higher in group II (P<0.001, 31.7+/-5.8 vs. 15.7+/-6.2 with group I, 9.2+/-4.9 with group III). The pattern of immunophenotypic expression and mesoderm differentiation into adipocytes and osteocytes were similar in all three groups. The expression of pluripotency markers including ALP, SSEA-4, TRA-1-60, TRA-1-81, Oct-4, and telomerase were strongly positive in group II, but very faint positive in the other groups. In conclusions, hMSCs from placentas have different characteristics according to their developmental stage and express mesenchymal stemness potentials similar to those from adult human BMs.

Epithelial-Mesenchymal Transitions of Bile Duct Epithelial Cells in Primary Hepatolithiasis

The purpose of this study was to explore the role of epithelial-mesenchymal transition in the pathogenesis of hepatolithiasis. Thirty-one patients with primary hepatolithiasis were enrolled in this study. Expressions of E-cadherin, alpha-catenin, alpha-SMA, vimentin, S100A4, TGF-beta1 and P-smad2/3 in hepatolithiasis bile duct epithelial cells were examined by immunohistochemistry staining. The results showed that the expressions of the epithelial markers E-cadherin and alpha-catenin were frequently lost in hepatolithiasis (32.3% and 25.9% of cases, respectively), while the mesenchymal markers vimentin, alpha-SMA and S100A4 were found to be present in hepatolithiasis (35.5%, 29.0%, and 32.3% of cases, respectively). The increased mesenchymal marker expression was correlated with decreased epithelial marker expression. The expressions of TGF-beta1 and P-smad2/3 in hepatolithiasis were correlated with the expression of S100A4. These data indicate that TGF-beta1-mediated epithelial-mesenchymal transition might be involved in the formation of hepatolithiasis.

Cyclooxygenase-2 Expression Is Related to the Epithelial-to-Mesenchymal Transition in Human Colon Cancers

PURPOSE: Down-regulation of E-cadherin is a hallmark of the epithelial-to-mesenchymal transition (EMT). EMT progression in cancer cells is associated with the loss of certain epithelial markers and the acquisition of a mesenchymal phenotype, as well as migratory activities. Cyclooxygenase-2 (COX-2) expression is associated with tumor invasion and metastasis in colon cancer. This study investigated the relationship between E-cadherin and COX-2 in colon cancer cells and human colon tumors. MATERIALS AND METHODS: Colon cancer cell lines and immunohistochemistry were used. RESULTS: E-cadherin expression was inversely related to the expressions of COX-2 and Snail in colon cancer cells. Ectopic expression of COX-2 or Snail reduced E-cadherin and induced a scattered, flattened phenotype with few intercellular contacts in colon cancer cells. Treatment of cancer cells with phorbol 12-myristate 13-acetate increased the expressions of COX-2 and Snail, decreased 15-hydroxyprostaglandin dehydrogenase expression, and increased the cells' motility. In addition, exposure to prostaglandin E2 increased Snail expression and cell motility, and decreased E-cadherin expression. Membranous E-cadherin expression was lower in adenomas and cancers than in the adjacent, non-neoplastic epithelium. In contrast, the expressions of Snail and COX-2 were higher in cancers than in normal tissues and adenomas. The expressions of COX-2 and Snail increased in areas with abnormal E-cadherin expression. Moreover, COX-2 expression was related to higher tumor stages and was significantly higher in nodal metastatic lesions than primary cancers. CONCLUSION: This study suggests that COX-2 may have a role in tumor metastasis via EMT.

Role of nuclear factor kappa B and reactive oxygen species in the tumor necrosis factor-a-induced epithelial-mesenchymal transition of MCF-7 cells

The microenvironment of the tumor plays an important role in facilitating cancer progression and activating dormant cancer cells. Most tumors are infiltrated with inflammatory cells which secrete cytokines such as tumor necrosis factor-alpha (TNF-alpha). To evaluate the role of TNF-alpha in the development of cancer we studied its effects on cell migration with a migration assay. The migrating cell number in TNF-alpha-treated group is about 2-fold of that of the control group. Accordingly, the expression of E-cadherin was decreased and the expression of vimentin was increased upon TNF-alpha treatment. These results showed that TNF-alpha can promote epithelial-mesenchymal transition (EMT) of MCF-7 cells. Further, we found that the expression of Snail, an important transcription factor in EMT, was increased in this process, which is inhibited by the nuclear factor kappa B (NFkB) inhibitor aspirin while not affected by the reactive oxygen species (ROS) scavenger N-acetyl cysteine. Consistently, specific inhibition of NFkB by the mutant IkBalpha also blocked the TNF-alpha-induced upregulation of Snail promoter activity. Thus, the activation of NFkB, which causes an increase in the expression of the transcription factor Snail is essential in the TNF-alpha-induced EMT. ROS caused by TNF-alpha seemed to play a minor role in the TNF-alpha-induced EMT of MCF-7 cells, though ROS per se can promote EMT. These findings suggest that different mechanisms might be responsible for TNF-alpha - and ROS-induced EMT, indicating the need for different strategies for the prevention of tumor metastasis induced by different stimuli.

Interaction of Mesenchymal Stem Cells and Osteoblasts for in vitro Osteogenesis

It has recently been reported that bone marrow-derived mesenchymal stem cells (MSCs), which are systemically administrated to different species, undergo site-specific differentiation. This suggests that the tissue specific cells may cause or promote the differentiation of the MSCs toward their cell type via a cell-to-cell interaction that is mediated not only by hormones and cytokines, but also by direct cell-to-cell contact. In this study, in order to assess the possible synergistic interactions for osteogenesis between the two types of cells, the MSCs derived from rabbit bone marrow were co-cultured with rat calvarial osteoblasts in direct cell-to-cell contact in a control medium (CM) and in an osteogenic medium (OM). The cell number, alkaline phosphatase activity, and amount of calcium deposition were assayed in the cultures of MSCs, osteoblasts, and co-cultures of them in either OM or CM for up to 40 days. The cell numbers and the alkaline phosphatase activities in the co-culture were somewhere in between those of the osteoblast cultures and the MSC cultures. The amounts of deposited calcium were lower in the co-culture compared to those of the other cultures. This suggests that there are little synergistic interactions during osteogenesis in vitro between the rat osteoblasts and rabbit MSCs.

The Expression of E-cadherin in Human and Rat Hepatic Stellate Cells: Evidence of Epithelial-Mesenchymal Transition / 대한간학회지

BACKGROUND/AIMS: The embryonal origin of hepatic stellate cells (HSCs), the principal cells in hepatic fibrogenesis, is still intriguing. We have previously demonstrated that human HSCs express cytokeratins which suggests the epithelial origin of these cells. To further explore the origin and the differentiation of HSCs we studied the expression of E-cadherin, the specific marker of epithelial cells, in human and rat HSCs. METHODS: We studied the changing pattern of E-cadherin expression during spontaneous activation of primarily isolated human HSCs by immunofluorescence staining and RT-PCR. To confirm the expression of E-cadherin in HSCs in vivo we performed double immunofluorescence staining for E-cadherin and glial fibrillary acidic protein, the specific identification marker of quiescent rat HSCs, in normal rat liver. RESULTS: Quiescent human HSCs were labeled strongly by anti-E-cadherin monoclonal antibody at the first and seventh days after primary culture. Human HSCs, however, did not stain for E-cadherin after the first passage of culture. RT-PCR also confirmed these modulations of E-cadherin expression. Double immunofluorescence staining, performed on rat liver tissue and observed by confocal laser scanning microscopy, unequivocally revealed the membranous expression of E-cadherin in quiescent HSCs labeled by glial fibrillary acidic protein. CONCLUSIONS: Quiescent HSCs of humans and rats express E-cadherin both in vitro and in vivo. The extent of E-cadherin expression rapidly decreases during the process of spontaneous activation. Our results suggest that HSCs may be of epithelial origin and undergo epithelial-mesenchymal transition during activation process.

TGF-betas Synthesized by RPE Cells Have Autocrine Activity on Mesenchymal Transformation and Cell Proliferation

The present study investigated the effects of transforming growth factor (TGF)-beta on retinal pigment epithelial (RPE) transformation in a simplified model and also whether or not TGF-beta exhibits similar proliferation effects on transformed RPE cells that it has on primary RPE cells. Furthermore, we examined the cell proliferation effects of RPE-conditioned medium (CM). A vertical wound measuring 2 mm in diameter was made on primary RPE monolayers. The expression of alpha- smooth muscle actin (SMA) by the cells located at the wound edges was observed using a confocal microscope under immunofluorescent staining. Cell proliferation was measured by incorporating 3H-thymidine into DNA. The presence of alpha- SMA was observed in the cells within the wound after treatment with TGF-beta2, while negative expression was observed in control cells. TGF-betas inhibited the proliferation of the primary cultures of RPE cells in a dose-dependent manner, but the spindle-shaped late-passaged RPE cells were not inhibited by these growth factors. The medium conditioned by RPE cells stimulated the proliferation of subconjunctival fibroblasts and inhibited the proliferation of primary RPE cells, in a manner similar to TGF-beta. These findings demonstrate that TGF-beta-stimulated RPE cells may evoke proliferative vitreoretinopathy through mesenchymal transformation and cell proliferation.

Biology and clinical utilization of mesenchymal progenitor cells

Within the complex cellular arrangement found in the bone marrow stroma there exists a subset of nonhematopoietic cells referred to as mesenchymal progenitor cells (MPC). These cells can be expanded ex vivo and induced, either in vitro or in vivo, to terminally differentiate into at least seven types of cells: osteocytes, chondrocytes, adipocytes, tenocytes, myotubes, astrocytes and hematopoietic-supporting stroma. This broad multipotentiality, the feasibility to obtain MPC from bone marrow, cord and peripheral blood and their transplantability support the impact that the use of MPC will have in clinical settings. However, a number of fundamental questions about the cellular and molecular biology of MPC still need to be resolved before these cells can be used for safe and effective cell and gene therapies intended to replace, repair or enhance the physiological function of the mesenchymal and/or hematopoietic systems

Organogenesis and tissue regeneration of fallopian tube: a desired metaplastic transformation of mesodermal stem cells in live animal models (dogs).

The capacity of stem cells of peritonium of mesodermal origin to undergo metaplastic transformation and form different tissues developed from mesoderm germ layer is exploited with ulterior motive to use it in the management of human diseases. The excised fallopian tube was replaced with a tube on a stent constructed from autogenous peritoneum from a suitable donor site. The effect of the surroundings environment of the new tissue system to which the peritoneum stem cells are now exposed was studied for 3, 6 and 12 months period in live animal models. The gross and histological studies revealed development of all the component of the wall of the fallopian tube. The lumen of the constructed peritoneal tube was well preserved in its whole length including the anastomotic sites. The scientific rationale of the working hypothesis on which the work is based, is discussed.

Reconocimiento de residuos glicosídicos mediante lectinas conjugadas en esbozos de miembros de ave / Detection of glycoside residues in chicken limb bud using conjugate lecitines

El esbozo de miembro cuenta con un núcleo mesenquimático cubierto por un epitelio ectodérmico, los que experimentan interacciones, durante el desarrollo, conducentes a la formación de una extremidad normal. En los últimos años, utilizando la técnica de lectinas-HRP, se han estudiado la distribución y el significado de residuos glicosídicos en las interacciones epitelio-mesenquimáticas que ocurren durante la organogénesis. Así, se han identificado y caracterizado los cambios que experimentan diversos glicoconjugados en la diferenciación, reconocimiento e interacciones celulares en diversos sistemas embrionarios. Para conocer estos aspectos, hemos utilizado embriones de pollo con diferentes edades (72, 92, 120 y 168 horas), que sirvieron como dadores de los esbozos de miembros. Este material fue sometido a técnica histológica corriente y a la técnica lectinas, utilizando las siguientes lectinas-HRP:UEA (ulex europaeus agglutinin), DBA (dolichos biflorus agglutinin), ECL (erithyna cristagalli lectin), RCA (ricinus communis agglutinin), LTA (lotus tetragonolobus agglutinin), BSL (Bandeiraea simplicifolia lectin), SBA (glycine max agglutinin), además, sus respectivos inhibidores, para verificar la específidad de cada lectina. Los resultados mostraron existencia de varios residuos glicosídicos, siguiendo un patrón cambiante a lo largo, tantro a nivel del epitelio, como del mesénquima. Se analiza el siginificado de los resultados y se concluye que los patrones glicosídicos detectados peden tener algún significado en el proceso de diferenciación del esbozo en estudio.