Mesothelial Cell Adhesion Research Articles

Composite Polycaprolactone/Gelatin Nanofiber Membrane Scaffolds for Mesothelial Cell Culture and Delivery in Mesothelium Repair.

To repair damaged mesothelium tissue, which lines internal organs and cavities, a tissue engineering approach with mesothelial cells seeded to a functional nanostructured scaffold is a promising approach. Therefore, this study explored the uses of electrospun nanofiber membrane scaffolds (NMSs) as scaffolds for mesothelial cell culture and transplantation. We fabricated a composite NMS through electrospinning by blending polycaprolactone (PCL) with gelatin. The addition of gelatin enhanced the membrane's hydrophilicity while maintaining its mechanical strength and promoted cell attachment. The in vitro study demonstrated enhanced adhesion of mesothelial cells to the scaffold with improved morphology and increased phenotypic expression of key marker proteins calretinin and E-cadherin in PCL/gelatin compared to pure PCL NMSs. In vivo studies in rats revealed that only cell-seeded PCL/gelatin NMS constructs fostered mesothelial healing. Implantation of these constructs leads to the regeneration of new mesothelium tissue. The neo-mesothelium is similar to native mesothelium from hematoxylin and eosin (H&E) and immunohistochemical staining. Taken together, the PCL/gelatin NMSs can be a promising scaffold for mesothelial cell attachment, proliferation, and differentiation, and the cell/scaffold construct can be used in therapeutic applications to reconstruct a mesothelium layer.

Matriptase drives dissemination of ovarian cancer spheroids by a PAR-2/PI3K/Akt/MMP9 signaling axis.

The transmembrane serine protease matriptase is a key regulator of both barrier-disruptive and protective epithelial cell-cell interactions. Elevated matriptase is a consistent feature of epithelial ovarian cancers (OvCa), where multicellular spheroids shed from the primary tumor into the peritoneal cavity are critical drivers of metastasis. Dynamic cell-to-cell adhesive contacts are required for spheroid formation and maintenance. Here, we show that overactive matriptase, reflected in an increased ratio of matriptase to its inhibitor hepatocyte growth factor activator inhibitor 1 (HAI-1), disrupts cell-cell contacts to produce loose prometastatic spheroids that display increased mesothelial cell adhesion and submesothelial invasion. We show that these activities are dependent on the matriptase activation of a protease-activated receptor-2 (PAR-2) signaling pathway involving PI3K/Akt and MMP9-induced disruption of cell-cell adhesion by the release of the soluble E-cadherin ectodomain. These data reveal a novel pathological connection between matriptase activation of PAR-2 and disruption of cell-cell adhesion, and support the clinical investigation of this signaling axis as a therapeutic strategy for aggressive metastatic OvCa.

TMIGD1 Inhibited Abdominal Adhesion Formation by Alleviating Oxidative Stress in the Mitochondria of Peritoneal Mesothelial Cells.

Background Postoperative abdominal adhesion remains one of the frequent complications after abdominal surgery and lacks effective intervention. Peritoneal mesothelial cell injury and healing play crucial roles in the process of adhesion formation, and identifying this mechanism might provide new insight into possible new therapeutic strategies for this disease. Transmembrane and immunoglobulin domain-containing 1 (TMIGD1) has been proven to protect renal epithelial cells from injury induced by oxidative stress and has also been identified as a novel adhesion molecule. Here, we investigated the role of TMIGD1 and its possible mechanism in adhesion formation. Materials and Methods Immunohistochemistry (IHC), qPCR, and immunofluorescence (IHF) were used to detect the expression of TMIGD1. The grade and tenacity score of adhesion were used to evaluate the adhesion formation conditions. A TMIGD1-overexpressing HMrSV5 cell line was established. MTT assay, Western blotting, Annexin V apoptosis analysis, and CK19 staining were used to measure mesothelial cell viability, apoptosis, and completeness. ROS and MDA detection were used to measure mesothelial cell oxidative stress levels. JC-1 staining, IHF, and transmission electron microscopy were performed to assess mitochondrial function. Scratch-wound and adhesion assays were used to evaluate the adhesion ability of mesothelial cells. Results First, we showed that TMIGD1 was decreased in mouse abdominal adhesion tissue and peritoneal mesothelial cells. Second, TMIGD1 overexpression inhibited adhesion formation. Third, TMIGD1 overexpression protected mesothelial cells from hydrogen peroxide- (H2O2-) induced oxidative stress injury. Fourth, TMIGD1 overexpression alleviated oxidative stress by protecting the mitochondrial function of mesothelial cells. In addition, TMIGD1 overexpression enhanced mesothelial cell adhesion. Conclusion Our findings suggest that TMIGD1 protects mesothelial cells from oxidative stress injury by protecting their mitochondrial function, which is decreased in regular abdominal adhesion tissue. In addition, TMIGD1 enhances peritoneal mesothelial cell adhesion to promote healing.

Pleural Effusion IL-33/sST2 Levels and Effects of Low and High IL-33/sST2 Levels on Human Mesothelial Cell Adhesion and Migration.

Interleukin 33 (IL-33) is an alarmin with multiple roles in immunity and cell homeostasis, highly expressed in barrier sites, acting via the suppression of tumorigenicity 2 receptor (ST2). Production of IL-33 and soluble ST2 (sST2), a decoy receptor for IL-33, has been implicated in several pulmonary diseases, but both have been scarcely investigated in pleural diseases. The aim of this study was to determine the levels of IL-33 and sST2 in transudative (TrPEs), malignant (MPEs), and parapneumonic (PPEs) pleural effusions (PEs) and investigate the effect of PE fluids from each group with low and high IL-33/sST2 levels on MeT-5A cell adhesion and migration. IL-33 and sST2 pleural fluid levels were similar among TrPEs, MPEs, and PPEs. However, a significant correlation was found between IL-33 and LDH and in sST2 levels with lymphocyte counts in TrPEs. Additionally, in MPEs the levels of IL-33 correlated with the levels of sST2 and with the red blood cell counts. Furthermore, incubation of MeT-5A cells with MPEs and PPEs bearing low or high levels of IL-33/sST2 yielded significant differential effects on MeT-5A cell adhesion and migration. In MPEs, high IL-33/sST2 levels led to increased adhesion and migration of MeT-5A cells, while in PPEs the effect was the opposite, while no effect in both cell phenotypes was determined for TrPEs. These results reveal a clinical context dependent effect of the IL-33/sST2 axis in PEs.

A fibrin-coated pericardial extracellular matrix prevented heart adhesion in a rat model.

As most surgical treatments pose a risk of tissue adhesion, methods to prevent adhesion are needed across various surgical fields. In this study, we investigated the use of a decellularized pericardium with fibrin glue to prevent rat heart adhesion. Porcine pericardia were decellularized by a high-hydrostatic pressure method. Cells adhered to the resulting pericardial extracellular matrix (ECM) during an in vitro cell-seeding test, but fibrin-coated pericardial ECM showed reduced cell adhesion. In a rat surgical model of heart adhesion, the fibrin-coated pericardial ECM did not adhere to the heart and mesothelial cell adhesion was observed on the ECM surface. Notably, the anti-adhesion effect of fibrin-coated pericardial ECM was observed 4 weeks after surgery. These results support the utility of fibrin-coated pericardial ECM as an adhesion prevention material for cardiovascular surgery. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1088-1094, 2019.

Heterogeneous Cadherin Expression and Multicellular Aggregate Dynamics in Ovarian Cancer Dissemination

Epithelial ovarian carcinoma spreads via shedding of cells and multicellular aggregates (MCAs) from the primary tumor into peritoneal cavity, with subsequent intraperitoneal tumor cell:mesothelial cell adhesion as a key early event in metastatic seeding. Evaluation of human tumor extracts and tissues confirms that well-differentiated ovarian tumors express abundant E-cadherin (Ecad), whereas advanced lesions exhibit upregulated N-cadherin (Ncad). Two expression patterns are observed: “mixed cadherin,” in which distinct cells within the same tumor express either E- or Ncad, and “hybrid cadherin,” wherein single tumor cell(s) simultaneously expresses both cadherins. We demonstrate striking cadherin-dependent differences in cell-cell interactions, MCA formation, and aggregate ultrastructure. Mesenchymal-type Ncad+ cells formed stable, highly cohesive solid spheroids, whereas Ecad+ epithelial-type cells generated loosely adhesive cell clusters covered by uniform microvilli. Generation of “mixed cadherin” MCAs using fluorescently tagged cell populations revealed preferential sorting into cadherin-dependent clusters, whereas mixing of cell lines with common cadherin profiles generated homogeneous aggregates. Recapitulation of the “hybrid cadherin” Ecad+/Ncad+ phenotype, via insertion of the CDH2 gene into Ecad+ cells, resulted in the ability to form heterogeneous clusters with Ncad+ cells, significantly enhanced adhesion to organotypic mesomimetic cultures and peritoneal explants, and increased both migration and matrix invasion. Alternatively, insertion of CDH1 gene into Ncad+ cells greatly reduced cell-to-collagen, cell-to-mesothelium, and cell-to-peritoneum adhesion. Acquisition of the hybrid cadherin phenotype resulted in altered MCA surface morphology with increased surface projections and increased cell proliferation. Overall, these findings support the hypothesis that MCA cadherin composition impacts intraperitoneal cell and MCA dynamics and thereby affects ultimate metastatic success.

Abstract NTOC-113: TGF–β SIGNALING INHIBITION AS A POTENTIAL APPROACH TO TARGET SUBOPTIMALLY DEBULKED OVARIAN TUMORS

Abstract The current standard of care for all patients with high-grade, advanced-stage serous ovarian cancer is surgery followed by adjuvant chemotherapy. Resection of all visible residual disease to less than 1 cm is associated with a favorable prognosis, but this optimal debulking can only be achieved in ~70% of patients. Patients with suboptimal cytoreduction are presumed to have lower response rates to subsequent chemotherapy and are known to have a poor prognosis. Recently, we performed a meta-analysis of 1,525 publicly available expression profiling assays and identified a 200-gene expression signature of primary ovarian tumors to predict the outcome of debulking surgery. The signature was validated using two independent sets of tumors. This debulking signature consists of transcripts positively regulated by TGF-β, indicating that hyperactivation of TGF-β signaling may be responsible of the aggressive biological and clinical behavior of suboptimally debulked tumors. In this study, we evaluated the potential anti-tumor effect of TGF-β signaling blockade in ovarian cancer cells in vitro and in vivo. Integrated TGF-β signaling was observed in 8 of 10 ovarian cancer cell lines tested by a SMAD-binding element based luciferase assay. The potential anti-tumor effect of a small molecular TGFBR1 kinase inhibitor LY2157299 was further investigated in SKOV3 cell line, which presents both endogenous and inducible TGF-β signaling and is highly disseminative when inoculated into immunodeficient mice. Although imposing minimal effect on in vitro cellular proliferation, LY2157299 significantly inhibited tumor-dissemination related biological processes in SKOV3 cells including migration, invasion and mesothelial cell adhesion. In an interperitoneal SKOV3 xenograft model, administration of LY2157299 significantly increased cisplatin related cytotoxicity and tumor burden reduction. Taken together, our study has provided evidence for the potential clinical use of LY2157299 to improve the treatment and survival of women with suboptimal surgery. Citation Format: Wei Wei and Michael J. Birrer. TGF–β SIGNALING INHIBITION AS A POTENTIAL APPROACH TO TARGET SUBOPTIMALLY DEBULKED OVARIAN TUMORS [abstract]. In: Proceedings of the 11th Biennial Ovarian Cancer Research Symposium; Sep 12-13, 2016; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(11 Suppl):Abstract nr NTOC-113.

Abstract 5401: TGF-β signaling inhibition as a potential approach to target suboptimally debulked ovarian tumors

Abstract The current standard of care for all patients with high-grade, advanced-stage serous ovarian cancer is surgery followed by adjuvant chemotherapy. Resection of all visible residual disease to less than 1 cm is associated with a favorable prognosis, but this optimal debulking can only be achieved in ∼70% of patients. Patients with suboptimal cytoreduction are presumed to have lower response rates to subsequent chemotherapy and are known to have a poor prognosis. Recently, we performed a meta-analysis of 1,525 publicly available expression profiling assays and identified a 200-gene expression signature of primary ovarian tumors to predict the outcome of debulking surgery. The signature was validated using two independent sets of tumors. This debulking signature consists of transcripts positively regulated by TGF-β, indicating that hyperactivation of TGF-β signaling may be responsible of the aggressive biological and clinical behavior of suboptimally debulked tumors. In this study, we evaluated the potential anti-tumor effect of TGF-β signaling blockade in ovarian cancer cells in vitro and in vivo. Integrated TGF-β signaling was observed in 8 of 10 ovarian cancer cell lines tested by a SMAD-binding element based luciferase assay. The potential anti-tumor effect of a small molecular TGFBR1 kinase inhibitor LY2157299 was further investigated in SKOV3 cell line, which presents both endogenous and inducible TGF-β signaling and is highly disseminative when inoculated into immunodeficient mice. Although imposing minimum effect on in vitro cellular proliferation, LY2157299 significantly inhibited tumor-dissemination related biological processes in SKOV3 cells including migration, invasion and mesothelial cell adhesion. In an interperitoneal SKOV3 xenograft model, administration of LY2157299 significantly increased cisplatin related cytotoxicity and tumor burden reduction. Taken together, our study has provided evidence for the potential clinical use of LY2157299 to improve the treatment and survival of women with suboptimal surgery. Citation Format: Wei Wei, Michael J. Birrer. TGF-β signaling inhibition as a potential approach to target suboptimally debulked ovarian tumors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5401. doi:10.1158/1538-7445.AM2015-5401

Abstract LB-84: Mutant p53 enhances the metastatic potential of ovarian cancer cells

Abstract Missense-mutations of TP53 resulting in accumulation of mutant proteins are very frequent in human cancer including ovarian cancer. Aggressive ovarian cancer is characterized by a peritoneal metastasis which involves the adhesion, migration, and invasion of tumor cells to the peritoneal cavity. In the present study, we investigated the effect of p53 GOF mutation (p53R248) on the metastatic potential of human ovarian cancer cells. We found that forced overexpression of p53R248 significantly increased adhesion to mesothelial cell Met5A, migration, and invasion in p53-null SKOV-3 cells. Conversely, knockdown of mutant p53 using siRNA significantly compromised p53R248-induced cell adhesion, migration, and invasion. Microarray analysis revealed that several metastasis-related genes including integrins and S1PR1(Sphingosine-1-phosphate receptor 1), and certain signaling pathway including PI3K/AKT were markedly up-regulated in p53R248 transfectant SKOV-3R248 cells. Inhibition of PI3K/Akt signaling using specific inhibitor significantly attenuated p53R248-mediated mesothelial cell adhesion, migration, and invasion. These finding show for the first time that mutant p53R248 may exert gain-of-function activity to regulate metastasis-related gene expression and the PI3K/Akt singling pathway in ovarian cancer. Citation Format: Ji-Hye Ahn, Jong-Gyu Lee, Jung-Hye Choi. Mutant p53 enhances the metastatic potential of ovarian cancer cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-84. doi:10.1158/1538-7445.AM2014-LB-84

Effect of chemokine stromal cell derived factor-1 and its receptor CXCR4 on the peritoneal carcinometastasis of gastric cancer

To investigate the effect of chemokine stromal cell-derived factor-1 (SDF-1) and its receptor CXCR4 on the peritoneal carcinometastasis of gastric cancer. Human gastric cancer cells of the lie NUGC4 and mesothelial cells of the line HMrSV were cultured. RT-PCR was used to detect the expression of CXCR4 and SDF-1 mRNA in the NUGC4 and HMrSV cells. The proliferation of NUGC4 cells was detected by MTT method. In mesothelial cell adhesion teat NUGC4 cells were cultured with confluent HMrSV mesothelial cells in 24-well plate and then divided into 3 groups: chemokine group, added with SDF-1, antibody blocking group, in which the NUGC4 cells were pre-incubated with CXCR4 monoclonal antibody for 2 h and then SDF-1 was added, and control group added with only culture fluid. Microscopy was used to calculate the number of gastric cancer cells adhered with mesothelial cells. In the mesothelial cell migration test HMrSV cells were put in the upper chamber of a Transwell chamber so as to cover the infiltration membrane. This Transwell chamber was put into a culture plate, NUGC4 cells, divided into 3 groups as mentioned above were put into the upper chamber, 24 h later HE staining and microscopy were performed to calculate the number of the NUGC4 cells that penetrated the membrane. BALB/c nu/nu female nude mice underwent intraperitoneal injection of NUGC4 cells, and then with PBS or AMD3100, small molecular specific antagonist, one day after the cancer cell injection once a day for 2 weeks. Then the mice were killed to observe the intraperitoneal tumorigenesis. CXCR4 mRNA was highly expressed in the NUGC4 cells but only very weekly expressed in the HMrSV cells. SDF-1 mRNA expression was seen in the HMrSV cells but in the NUGC4 cells. Anti-CXCR4 monoclonal antibody (McAb) inhibited the proliferation of NUGC4 cells significantly (P < 0.05). In mesothelial cell adhesion test, the number of the NUGC4 cells adhered with HMrSV cells after SDF-1 stimulation was 84.4 +/- 21.2, significantly higher than that of the control group (43.6 +/- 12.4, P < 0.05). The number of migrating NUGC4 cells in the chemokine group was 170.8 +/- 24.2, significantly higher than hat of the control group (102.8 +/- 18.2, P < 0.05); and the number of migrating NUGC4 cells in the antibody blocking group was 114.7 +/- 20.3, significantly lower than that of the chemokine group (P < 0.05). The survival time of the mice injected with both NUGC4 cells and AMD3100 was (43.8 +/- 2.8) days, significantly longer than that of the control group [(28.2 +/- 2.5) days, P < 0.01]. The tumor number of the AMD3100 group was (64.6 +/- 8.2), significantly lower than that of the control group [(103 +/- 12.4), P < 0.01]. SDF-1 and its receptor CXCR4 play an important role in the development of peritoneal carcinometastasis from gastric cancer. Interfering with the SDF-1/CXCR4 biological axis may become a potential strategy in the prevention and treatment of peritoneal carcinometastasis from gastric cancer.

The TGF- -induced gene product, ig-h3: its biological implications in peritoneal dialysis

TGF-beta is involved in peritoneal changes during long-term peritoneal dialysis (PD). TGF-beta induces betaig-h3 in several cell lines, and betaig-h3 may be a marker for biologically active TGF-beta. However, no study has reported induction of betaig-h3 in human peritoneal mesothelial cells (HPMCs) or its involvement in PD-related peritoneal membrane changes. We used cultured HPMCs to investigate the biological roles of betaig-h3 during mesothelial cell injury and repair, employing the adhesion, spreading, scratching and cell migration assays. Changes in betaig-h3 expression after high glucose exposure in vivo were also evaluated using an animal chronic PD model. In vitro, TGF-beta1 induced betaig-h3 in cultured HPMCs, and betaig-h3-mediated mesothelial cell adhesion occurred via alphavbeta3 integrin. betaig-h3 enhanced mesothelial cell adhesion and migration and, in part, wound healing during mesothelial cell injury. The animal study demonstrated that compared to the control group, betaig-h3 concentrations in the dialysate effluent increased in the dialysis group with alterations in peritoneal structure and function during PD, and betaig-h3 positively correlated with peritoneal solute transport. Immunohistochemical and immunoblotting results showed that betaig-h3 localizes in the mesothelium and submesothelial matrix of the parietal peritoneum, and in the vascular endothelium of omentum. betaig-h3 protein expression was higher in the dialysis group. In vitro, betaig-h3 induced by TGF-beta1 in HPMCs improved adhesion and migration of HPMCs during wound healing. In the chronic infusion model of PD, betaig-h3 played a role in the functional deterioration of the peritoneal membrane, which is associated with fibrosis.

Pathogenesis of endometriosis — Current research

Proliferative, secretory and menstrual endometrial cells of both the stroma and epithelium adhere to intact peritoneal mesothelium and mesothelial monolayers. Endometrial attachment to the mesothelium appears to occur rapidly (within 1 h) and transmesothelial invasion occurs between 1 and 18–24 h. These results demonstrate that the mesothelium is not a ‘no-stick˚s surface and indicates that molecules present at the surface of the mesothelium are involved in the pathogenesis of the early endometriotic lesion. The inhibition of endometrial cell adherence to peritoneal mesothelium by hyaluronidase indicates that CD44-hyaluronan binding is at least one of the mechanisms involved in the pathogenesis of endometriosis. We believe that investigation of mesothelial cell adhesion molecules is central to understanding the pathogenesis of endometriosis.

Short-term culture of peritoneum explants confirms attachment of endometrium to intact peritoneal mesothelium

Objective: To evaluate the initial adhesion of endometrium to the peritoneum. Design: Descriptive study using light and confocal laser-scanning microscopy, immunohistochemistry, and transmission electron microscopy. Setting: University-based laboratory. Patient(s): Women without endometriosis undergoing surgery for benign conditions. Intervention(s): None. Main Outcome Measure(s): Explants of peritoneum ( n = 20), prepared from four patients, were cultured for 1 hour with mechanically dispersed proliferative or secretory endometrium. Peritoneum was cultured with endometrium from the same patient. Specimens were fixed and serially sectioned for hematoxylin and eosin stain, immunohistochemistry using an anti-cytokeratin monoclonal antibody, and transmission electron microscopy. Result(s): In 17 of 20 explants, endometrium was adherent to intact mesothelium. There was no evidence of transmesothelial invasion at any sites of attachment. Although in most cases endometrium was adherent to mesothelium via endometrial stroma, there were many sites of endometrial epithelium–mesothelium attachment. Confocal laser scanning microscopy demonstrated an intact monolayer of cytokeratin-positive cells below the sites of endometrial implantation. Transmission electron microscopy demonstrated intact, viable, mesothelial cells below sites of attachment. Conclusion(s): This study demonstrates that endometrium rapidly adheres to intact peritoneal mesothelium. In addition, this study demonstrates that endometrial epithelial cells, as well as stroma, can attach to mesothelium. Further studies are needed that characterize the mechanism of endometrial–mesothelial cell adhesion.

HB-EGF is produced in the peritoneal cavity and enhances mesothelial cell adhesion and migration

The mesothelial cell monolayer lining the peritoneal membrane needs constant repair in response to peritonitis and to the toxicity of peritoneal dialysate. In many continuous ambulatory peritoneal dialysis (CAPD) patients, the repair process progressively fails, and membrane dysfunction and fibrosis occur. Heparin-binding epidermal growth factor-like growth factor (HB-EGF) has an important role in wound repair and is also fibrogenic, and thus may be involved in these processes in the peritoneal cavity. The presence of HB-EGF, its receptors, and its associated proteins was determined in peritoneal membrane biopsies, cultured human peritoneal mesothelial cells (HPMCs), and peritoneal macrophages from CAPD patients by reverse transcription-polymerase chain reaction, flow cytometry, and immunofluorescence immunocytochemistry with confocal microscopy. HB-EGF effects on HPMC adhesion were measured by a static adhesion assay, on integrin expression by flow cytometry, and on migration by wound healing and chemotaxis assays. HB-EGF, its receptors HER-1 and HER-4, and the associated proteins CD9, CD44, and integrin alpha(3)beta(1) were expressed by HPMCs and peritoneal macrophages. HB-EGF colocalized with HER-1 and HER-4 in HPMCs and induced their adhesion to collagen type I, expression of beta 1 integrins, and migration. HB-EGF is produced by cells in the peritoneal cavity of CAPD patients and has functional effects on HPMCs that would facilitate repair of the mesothelial layer.

Ultrastructural study of the sinus venosus in embryos of the dogfish ( Scyliorhinus canicula )

An ultrastructural study of the development of the sinus venosus has been carried out on seven embryos of the dogfish (Scyliorhinus canicula L.) between 10.5 and 69 mm of total length (TL). The sinus venosus appears at the end of the looping process of the cardiac tube, namely in the 10.5 mm embryo, when the heart reaches its adult tetracameral S-form. The endocardium of the smallest embryo is constituted of a single layer of cubic cells. In larger embryo, these cells progressively acquire a squamous appearance as well as electron-dense cytoplasmic inclusions. The subendocardium is progressively populated by ganglion cells, Schwann cells and bundles of amyelinic fibers that can first be recognised in the embryo of 34 mm TL. Some subendocardial mesenchymal cells located in earlier embryos close to the entrance of the ducts of Cuvier might be their ectomesenchymal progenitors. The myocardium is initially constituted of a single layer of cubic cells. In the embryos of 19, 27 and 34 mm TL, the myocardium becomes multilayered, and the myocardiocytes develop myofibrils randomly arranged throughout the sarcoplasm. In later embryos, the myocardiocytes are innervated and arranged in oval bundles surrounded by a basal lamina. The epicardium covers the sinus venosus by the retrograde migration of the epithelium already established around the atrioventricular groove and, in a lesser degree, by the adhesion of mesothelial cells that are floating free in the pericardial cavity. This process has finished in the embryo of 34 mm TL. The differentiation of the sinus venosus (including the endocardial and myocardial differentiation as well as the epicardial covering) progresses in an anteroventral-posterodorsal direction.

Pleural mesothelioma mimics the integrin profile of activated, sessile rather than detached mesothelial cells.

Mesothelial cells (MC) form a polarized monolayer lining serosal cavities. During serositis, the MC lining undergoes hyperplasia, and MC are shed into effusions. During these processes, contact with basement membrane and, ultimately, neighboring cells is at least temporarily lost, suggesting regulated alterations in cell/matrix and cell/cell adhesion. Such interactions are primarily mediated by integrins. Malignant mesothelioma has a growth pattern characterized by lateral, limited invasive but contiguous spread. During serositis, activated MC, both sessile and detached, expressed an extended spectrum of beta1, beta3 and beta4 integrins compared with resting MC, as shown by immunohistology. Malignant mesothelioma had an integrin repertoire and a subcellular distribution resembling that of activated sessile rather than floating MC. In vitro, MC exposed a more comprehensive pattern of integrins than that of the newly established mesothelioma cell lines ME-HD-1 and ME-HD-2, as shown by flow cytometry. MC consistently adhered better than mesothelioma cells to laminin, tenascin, fibronectin and collagen type IV. Adhesion of MC and mesothelioma cells to these matrix proteins was, at least in part, mediated via beta1 integrins. The different integrin profiles and adhesion properties of cultured MC and mesothelioma cells may reflect a limited functional differentiation of the latter.

Pleural mesothelioma mimics the integrin profile of activated, sessile rather than detached mesothelial cells

Mesothelial cells (MC) form a polarized monolayer lining serosal cavities. During serositis, the MC lining undergoes hyperplasia, and MC are shed into effusions. During these processes, contact with basement membrane and, ultimately, neighboring cells is at least temporarily lost, suggesting regulated alterations in cell/matrix and cell/cell adhesion. Such interactions are primarily mediated by integrins. Malignant mesothelioma has a growth pattern characterized by lateral, limited invasive but contiguous spread. During serositis, activated MC, both sessile and detached, expressed an extended spectrum of β1, β3 and β4 integrins compared with resting MC, as shown by immunohistology. Malignant mesothelioma had an integrin repertoire and a subcellular distribution resembling that of activated sessile rather than floating MC. In vitro, MC exposed a more comprehensive pattern of integrins than that of the newly established mesothelioma cell lines ME-HD-1 and ME-HD-2, as shown by flow cytometry. MC consistently adhered better than mesothelioma cells to laminin, tenascin, fibronectin and collagen type IV. Adhesion of MC and mesothelioma cells to these matrix proteins was, at least in part, mediated via β1 integrins. The different integrin profiles and adhesion properties of cultured MC and mesothelioma cells may reflect a limited functional differentiation of the latter. Int. J. Cancer 72:77–86, 1997. © 1997 Wiley-Liss Inc.

Extracellular matrix proteins modulate human peritoneal mesothelial cell behavior.

Human peritoneal mesothelial cells lie on a basement membrane-like material consisting of fibronectin (FN), type I collagen (CI), type III collagen (CIII) and laminin (LA). To understand how these extracellular matrix (ECM) proteins affect mesothelial cell behavior, we investigated their effect on the adhesion and proliferation of mesothelial cells. A modified methyltetrazolium dye method was used to assess cell number. The results showed that FN, CI, CIII and LA, all increased adhesion of mesothelial cells. The adhesive effect was blocked dose-dependently by a synthetic Arg-Gly-Asp-containing (RGD) peptide. When coated as a substratum (immobilized form), FN, CI, CIII and LA, all enhanced serum-stimulated and epidermal-growth-factor-stimulated cellular proliferation as compared with bovine-serum-albumin-blocked plastic surfaces. When added in a soluble form, all matrix proteins except FN inhibited serum-stimulated and epidermal-growth-factor-stimulated cellular proliferation at high concentrations (CI and CIII: 1-10 micrograms/ml, LA: 3-10 micrograms/ml). We conclude that peritoneal mesothelial cells possess an RGD-sensitive receptor and that the ECM can modulate adhesion and proliferation of peritoneal mesothelial cells. The growth-modulating effect depends on the form and concentration of the ECM proteins.