OBJECTIVETo explore the mechanism of Wnt and Notch pathway involved modulating time and spatial restricted hematopoiesis.

METHODSMurine hematopoietic stem and progenitor cells (HSPCs) were isolated from bone marrow (BM) by using c-kit microbeads. E10.5 aorta-gonad-mesonephros (AGM), E12.5, E14.5, E16.5 fetal liver (FL) and adult BM derived stromal cells (StroCs) were isolated and co-cultured with c-kit(+)HSPCs. The floating cells in co-culture system were sorted and counted by FACS. Gene expressions of Wnt and Notch pathway were detected by quantitative PCR and protein expressions by immunostaining.

RESULTSCo-culturing HSPCs with AGM and FL-derived StroCs resulted in an expansion of c-kit(+)population from 0.4 x 10(5)/well to (19.2 +/- 3.2) x 10(5)/well and (26.8 +/- 5.4) x 10(5)/well, respectively, being greater than that with BM-derived StroCs (P < 0.05). The percentage of c-kit(+)cells detected in AGM- and BM- derived StroCs culture system was (75.2 +/- 7.1)%, (74.1 +/- 6.2)% respectively, being higher than FL- derived StroCs culture system (63.4 +/- 5.3)% (P < 0.05). Wnt and Notch pathway genes expression varied at different phases of hematopoiesis. Wnt was highly expressed in AGM and FL derived StroCs, and, Notch did in AGM and BM derived StroCs.

CONCLUSIONWnt and Notch pathway are important modulators in regulating time and spatial restricted hematopoiesis.

Animals ; Aorta ; cytology ; Coculture Techniques ; Hematopoiesis ; Hematopoietic Stem Cells ; cytology ; Humans ; Mesonephros ; cytology ; Stromal Cells

BACKGROUNDTelocytes (TCs) are a novel type of interstitial cells, which have been recently described in a large variety of cavitary and noncavitary organs. TCs have small cell bodies, and remarkably thin, long, and moniliform prolongations called telopodes (Tps). Until now, TCs have been found in various loose connective tissues surrounding the arterioles, venules, and capillaries, but as a histological cellular component, whether TCs exist in large arteries remains unexplored.

METHODSTCs were identified by transmission electron microscope in the aortic arch of male C57BL/6 mice.

RESULTSTCs in aortic arch had small cell bodies (length: 6.06-13.02 μm; width: 1.05-4.25 μm) with characteristics of specific long (7.74-39.05 μm), thin, and moniliform Tps; TCs distributed in the whole connective tissue layer of tunica adventitia: TCs in the innermost layer of tunica adventitia, located at the juncture between media and adventitia, with their long axes oriented parallel to the outer elastic membrane; and TCs in outer layers of tunica adventitia, were embedded among transverse and longitudinal oriented collagen fibers, forming a highly complex three-dimensional meshwork. Moreover, desmosomes were observed, serving as pathways connecting neighboring Tps. In addition, vesicles shed from the surface of TCs into the extracellular matrix, participating in some biological processes.

CONCLUSIONSTCs in aorta arch are a newly recognized complement distinct from other interstitial cells in large arteries, such as fibroblasts. And further biologically functional correlations need to be elucidated.

Adventitia ; cytology ; Animals ; Aorta ; cytology ; Aorta, Thoracic ; cytology ; Cell Communication ; physiology ; Connective Tissue Cells ; cytology ; ultrastructure ; Male ; Mice ; Mice, Inbred C57BL ; Microscopy, Electron, Transmission

This study was purposed to isolate human embryonic AGM derived HSPCs and investigate the effect of AGM stromal cells on AGM-derived HSPCs. Immunohistochemical sections of human AGM tissue were investigated for CD34, Flk-1 and VEGF expression. Human AGM-derived single cells were isolated and seeded onto pre-treated feeder of human AGM stromal cells (hAGMS3 and hAGMS4) by direct contact and non-contact co-culture in Transwell culture system. Growth characteristics of HSPCs with cobblestone area-forming cells (CAFCs) were observed and number of cobblestone area (CA) was counted. Indirect immunofluorescent assay was used to detect CD34 and Flk-1 expression on the surface of suspended cells as well as CAFCs in contact co-culture system. The cells after culture for 2 weeks were collected from both contact and non-contact co-culture systems for CFU assay. The result showed that hematopoietic cells in AGM tissue expressed CD34 and Flk-1. Both of the hematopoietic culture systems could produce CFCs. Nevertheless, direct contact co-culture produced CD34(+)Flk-1(+) CAFC and more CFUs than those from indirect non-contact culture (hAGMS3 system: 1647 +/- 194 vs 389 +/- 31, p < 0.05; hAGMS4 system: 1586 +/- 75 vs 432 +/- 35, p < 0.05). It is concluded that there were CD34(+)Flk-1(+) HSCs in human embryonic AGM region. The hematopoietic co-culture systems composed of AGM-derived HSPCs and AGM stromal cells are successfully established, both direct contact and Transwell non-contact co-culture can expand AGM-derived definitive HSPCs. Cell-cell contact between AGM-derived HSPCs and AGM stromal cells are of most importance to maintain and expand AGM-HSPCs.
Aorta ; cytology ; Cell Culture Techniques ; methods ; Cell Separation ; Cells, Cultured ; Coculture Techniques ; Fetal Blood ; cytology ; Gonads ; cytology ; Hematopoietic Stem Cells ; cytology ; Humans ; Mesonephros ; cytology ; Stromal Cells ; cytology ; physiology

The coupling between the endothelium and blood flow is an important biomedical problem and has drawn extensive research. Endothelial cells are known to adapt their shapes and functions in response to applied shear flow. Shear Stress being regarded as a primary triggering signal for cellular remodeling, it is important to understand the interaction mechanism between applied shear flow and endothelial cells. In present study we have established a theoretical model to simulate the coupling between the deformation of an endothelial cell and applied shear flow. A two dimensional computational fluid dynamic (CFD) is conducted to determine the local distributions of mechanical stress and pressure on cell surface. Our results show that: (1) the deformation of endothelial cell changes with alpha (corresponding to the shear stress imposed on cell surface by flow fluid). When alpha is greater than 0.021, the cell deformability increases greatly; (2) the distributions of stress and pressure on cell surface are not uniform, but the maximal shear stress and displacement are always at the top point of the cell. Meanwhile, we have measured the deformation of cultured human aortic endothelial cells (HAECs) exposed to shear flow by using a flow chamber. We found that the numerical results are well consistent with those of experiment. These results suggest that the non-uniformity distributions of mechanical stress and pressure on cell surface may play a particular role in the mechanism of cell activation and in the regulation of endothelial cells functions (modification of cytoskeleton, distributions of adhesion molecules, etc.). The present study offers a framework to facilitate the development of a comprehensive dynamic model for endothelial cells.
Aorta ; cytology ; Cells, Cultured ; Endothelium, Vascular ; cytology ; physiology ; Humans ; Models, Cardiovascular ; Stress, Mechanical

AIMIn order to establish a coculture system of ECs and SMCs and by which further study can be done.

METHODSECs in primary culture were grown on a side of Transwell membrane, and SMCs were grown on an other side of it or the bottom of culture well, so that two kinds of coculture systems were established, and detail observation on the coculture systems was carried out by transmission and scanning electron microscope.

RESULTSECs in primary culture were positive of VI factor by immunocytochemistry staining. ECs and SMCs were grown well on both sides of Transwell membrane, relative to ECs monolayer of "cobblestone appearance", SMCs were multilayer of "hills and valleys appearance". ECs and SMCs on both sides of Transwell membrane could form the gap junctions by micropores.

CONCLUSIONThe coculture systems of ECs and SMCs were established successfully by modeling the structural relationship of vascular wall.

Animals ; Aorta ; cytology ; Cell Communication ; Coculture Techniques ; Endothelial Cells ; cytology ; Endothelium, Vascular ; cytology ; Male ; Muscle, Smooth, Vascular ; cytology ; Myocytes, Smooth Muscle ; cytology ; Rabbits

During mammalian ontogeny, hematopoietic activity can be found in distinct anatomical sites, which con-tribute to primitive or definite hematopoiesis. The origin of the hematopoietic stem cell (HSC) has been a controversial issue in the field of hematopoiesis. It has long been believed that the origin derives from the extra-embryonic yolk sac. However, there is now considerable evidence that the first adult repopulating HSC is autonomously generated from a distinct region within the embryonic mesoderm, the aorta-gonad-mesonephros (AGM) region. This review describes the origin and precise location of HSC in the embryo and in AGM region, the hematopoietic microenvironment and the hematopoietic regulatory mechanisms in AGM region.
Animals ; Aorta ; cytology ; embryology ; Gonads ; cytology ; embryology ; Hematopoiesis ; physiology ; Hematopoietic Stem Cells ; cytology ; physiology ; Hematopoietic System ; cytology ; embryology ; Humans ; Mesonephros ; cytology ; embryology

OBJECTIVETo explore the supportive effects of stromal cells from human aorta-gonad-mesonephros (AGM) region on umbilical cord blood CD34+ cells.

METHODSStromal cells derived from human AGM region (hAGMS1-S5) and fetal trunk fibroblasts (hFf) were cultured on the bottom of 24-well plates as feeder cells. CD34+ cells positively selected from human umbilical cord blood through immunomagnetic beads selection method, were seeded into 24-well plates, and co-cultured for 28d. The number of total nucleated cells (TNC), CD34+ cells, CD34+ CD38- cells, and CFC were counted every week.

RESULTSStromal cells from human AGM region significantly supported proliferation of the TNC, CD34+ cells, CD34+ CD38- cells and CFC, when compared with hFT and controls without feeder cells (P < 0.05). The TNC increased (25.13 +/- 4.83)-fold (peak value) at day 21 in group of co-culture with AGM stromal cells. CD34 and CD34+ CD38- cells increased (2.68 +/- 0.51)- and (2. 38 +/- 0.45)-fold respectively at day 14 of co-culture. In colony analysis, HPP-CFU increased (2.62 +/- 0.85)-fold at day 14 of co-culture. The supportive effects of human AGM S1-S5 were significantly different, hAGM S3 and S4 were better than hAGM SI, S2, and S5 (P < 0.05).

CONCLUSIONSHuman AGM stromal cells S1-S5 could support the maintenance and expansion of umbilical cord blood CD34+ cells in vitro. hAGMS3, S4 cell had better effects on maintaining HSC activity, which would provide model cells and basic data for researches on hematopoiesis mechanism and hematopoietic differentiation of embryonic stem cells.

Antigens, CD34 ; analysis ; Aorta ; cytology ; Cell Line ; Embryo, Mammalian ; Fetal Blood ; cytology ; Gonads ; cytology ; Hematopoietic Stem Cells ; Humans ; Mesonephros ; cytology ; Stromal Cells

Our previous study demonstrated that TGF-beta1 could induce the differentiation of vascular adventitial fibroblasts (AFs) to myofibroblasts (MFs). The aim of this study was to identify the genes which might be responsible for the cell phenotypic change using genechips. Cultured rat AFs were treated with TGF-beta1 (10 ng/ml) for 0 min, 5 min, 15 min, 2 h, 12 h and 24 h, respectively. Then the cells were gathered to prepare total RNA. We examined TGF-beta1-induced gene expression profiling using Affymetrix oligonucleotide microarrays and analyzed data by GCOS1.2 software. Moreover, expressional similarity was measured by hierarchical clustering. Some of genechip results were confirmed by real-time quantitative RT-PCR. Microarray analysis identified 2121 genes with a 2-fold change or above after TGF-beta1 stimulation. 1318 genes showed a greater than 2-fold increase and 761 genes were reduced 2 folds or more at mRNA levels, whereas a small portion of the total regulated genes (42 genes) displayed dynamically up- and down-regulated pattern. Genes were further segregated for early (peak at 5 min, 15 min and/or 2 h), late (peak at 12 h and/or 24 h), and sustained (2-fold change or above at five time points) temporal response groups according to the time of their peak expression level. Among 1318 up-regulated genes, 333 genes (25.3%) responded rapidly to TGF-beta1 and 159 genes (12.1%) responded in a sustained manner. Most genes (826, 62.6%) were regulated at 12 h or later. For the 761 down-regulated genes, numbers of early and late responsive genes were 335 (44%) and 267 (36.1%), respectively. There were also 159 genes, 19.9% of total down-regulated genes, decreased at five time points treated by TGF-beta1. The results suggested that the gene expressions of secreted phosphoprotein 1 (APP1) and Rho-associated coiled-coil forming kinase 2 (ROCK2) had the same trends as alpha-smooth muscle-actin, a marker of MF differentiation. In addition, the gene expression of potassium voltage-gated channel, Shal-related family and member 2 (KCND2) was up-regulated. Furthermore, it was found that endothelin 1 (EDN1), some complement components, NADPH oxidase 4 (NOX4) and NAD(P)H dehydrogenase, quinone 1 (NQO1) might be involved in MF differentiation. Using microarrary technique, we confirmed some genes that have been identified by other techniques were implicated in MF differentiation and observed new genes involved in this process. Our results suggest that gene expression profiling study is helpful in identifying genes and pathways potentially involved in cell differentiation.
Adventitia ; cytology ; Animals ; Aorta, Thoracic ; cytology ; Cell Transdifferentiation ; genetics ; Cells, Cultured ; Female ; Fibroblasts ; cytology ; Gene Expression Profiling ; Gene Expression Regulation ; Male ; Myofibroblasts ; cytology ; Rats ; Rats, Sprague-Dawley

Endothelial injury, smooth muscle cells (SMCs) proliferation and migration are the same common pathophysiological processes of many cardiovascular diseases, such as atherosclerosis, hypertension, diabetes and restenosis. It is important to determine the functional interactions between endothelial cells (ECs) and SMCs under pathologic conditions. This work was to study the effects of ECs growth states on the proliferation and migration of vascular SMCs in cell coculture system. (3)H-TdR incorporation and flow cytometry were used to determine the effects of ECs growth states on the proliferation of SMCs. The number of migrating SMCs was counted. RT-PCR was used to analyze the expression of alpha-SM-actin mRNA. The results showed that (3)H-TdR incorporation decreased significantly from 14,900+/-1035 cpm/well in the control group to 8,575+/-749 cpm/well in the confluent ECs group (n=6, P<0.01), and increased to 27,268+/-2310 cpm/well in the proliferative ECs group ( n=6, P<0.01). The transition of SMCs from G(0)/G(1) phase to G(2)/M and S phases was blocked in the confluent ECs group but promoted in the proliferative ECs group. Compared with the control group, the number of migrating cells was about 4 times higher in the proliferative ECs group (n=6, P<0.01), while it in the confluent ECs group was only the half of the number of the control(n=6, P<0.05). The expression of alpha-SM-actin mRNA was increased significantly in the confluent ECs group(2.3+/-0.11 vs 1.4+/-0.12, P<0.05), but decreased significantly in the proliferative ECs group(0.92+/-0.08 vs 1.4+/-0.12, P<0.05). The results suggest that the biologic features of SMCs are influenced by ECs growth states. The proliferative ECs promote SMCs proliferation, migration and downregulate alpha-SM-actin mRNA expression significantly.
Actins ; metabolism ; Aorta ; cytology ; Cell Differentiation ; Cell Division ; Cell Movement ; Cells, Cultured ; Coculture Techniques ; Endothelium, Vascular ; cytology ; Epithelial Cells ; cytology ; Muscle, Smooth, Vascular ; cytology

The non-random distribution of atherosclerosis was related to local hemodynamic environment. The stabilization of endothelium was important in this process. We studied the effect of magnitude of shear stress on proliferation of endothelial cells. It was shown the proliferation of endothelial cells was inhibited by shear stress, and was related to the magnitude of shear stress. A parallel plate sudden-expansion flow chamber was constructed, and the effect of flow pattern was also studied. It was shown the inhibition effect produced by shear stress was decreased in this chamber.
Animals ; Aorta ; cytology ; Cattle ; Cell Division ; physiology ; Cells, Cultured ; Endothelium, Vascular ; cytology ; physiology ; Models, Cardiovascular ; Stress, Mechanical