Microstructure of calcium phosphate ceramics has been shown to influence long-term in vitro cellular events like proliferation and differentiation, and to favor bone integration in vivo. As long-term cellular events are known to be dependent of early cell adhesion events, we decided to study the in vitro influence of the microstructure of a microporous hydroxyapatite (mHA) and a nonmicroporous hydroxyapatite (pHA) ceramic on serum protein adsorption and SaOs-2 human bone cells attachment after 30 min, 1, 4, and 24 h and cell growth after 96 h. Plastic coverslips were used as controls. Hydroxyapatite composition of mHA and pHA was confirmed by X-ray diffraction and Fourier transform infra-red spectroscopy. The surface energies of ceramics were calculated from contact-angle measurements in di-iodomethane, water or complete culture medium. The total surface energy was 44.8 mJ/m(2) for pHA and 48.7 mJ/m(2) for plastic. The contact-angle measurement was impossible on mHA likely because they displayed 12% of open microporosity, pHA ceramic exhibiting only closed pores (2.5%). Moreover, the roughness amplitude was largely higher on mHA (Sa = 4.35 microm) than on pHA (Sa = 0.065 microm) and plastic (Sa = 0.042 microm). Three different techniques were used to evaluate protein adsorption on the ceramics. SDS-PAGE of desorbed proteins demonstrated that more proteins desorbed from mHA (66.02 microg/m(2)) than from pHA (17.2 microg/m(2)) or plastic (0.08 microg/m(2)). A new method was used to evaluate in situ the quantity of adsorbed total proteins: the temperature-programmed desorption (TPD) analysis coupled with mass spectrometry. The TPD analysis confirmed that 10-fold more proteins adsorbed on mHA compared with those on pHA. A direct immunolabeling on ceramics revealed than more fibronectin and serum albumin adsorbed on microporous ceramic than on dense ceramic. The morphology of SaOs-2 cells was the same on all the substrates after 30 min. At later time points, cell morphology on mHA was radically different than on other surfaces, with the particularity of the cytoplasmic edge that appeared undistinguishable from the surface. Only the extremity of the cells and lamellipodia were visible. Cells seemed like "adsorbed" by the mHA surface, whereas on plastic and pHA surfaces the cells displayed classical aspects of polygonal spreading. The cells displayed on mHA the highest initial attachment potential after 30 min, 1, 4, 24 h but the lower proliferation potential after four days. This study confirms that a microporous ceramic surface can modulate the adsorption of proteins and further the adhesion and proliferation of human bone cells.

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At least one-third of patients with epithelial ovarian cancer (OC) present ascites at diagnosis and almost all have ascites at recurrence. The presence of ascites, which acts as a dynamic reservoir of active molecules and cellular components, correlates with the OC peritoneal metastasis and is associated with poor prognosis. Since epithelial-mesenchymal transition (EMT) is involved in different phases of OC progression, we have investigated the effect of the unique ascitic tumor microenvironment on the EMT status and the behavior of OC cells. The exposure of three OC cell lines to ascites leads to changes in cellular morphologies. Within ascites, OC cells harboring an initial intermediate epithelial phenotype are characterized by marked dislocation of epithelial markers (E-cadherin, ZO-1 staining) while OC cells initially harboring an intermediate mesenchymal phenotype strengthen their mesenchymal markers (N-cadherin, vimentin). Ascites differentially triggers a dissemination phenotype related to the initial cell features by either allowing the proliferation and the formation of spheroids and the extension of colonies for cells that present an initial epithelial intermediate phenotype, or favoring the migration of cells with a mesenchymal intermediate phenotype. In an ascitic microenvironment, a redeployment of αv integrins into cells was observed and the ascites-induced accentuation of the two different invasive phenotypes (i.e. spheroids formation or migration) was shown to involve αv integrins. Thus, ascites induces a shift toward an unstable intermediate state of the epithelial-mesenchymal spectrum and confers a more aggressive cell behavior that takes on a different pathway based on the initial epithelial-mesenchymal cell features.

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The expansion of solid tumours is critically dependent on vascular networks resulting from angiogenesis that provide nutrients to support tumour growth. 1 In this tumoural angiogenic context, the provisionally endothelium extracellular matrix (ECM) of new capillary provide a permissive microenvironment enabling tumour cell anchorage and subsequent invasion. 1 In order for a tumour to grow and metastasise, neoplastic and endothelial cells must remodel ECM, migrate and invade into the surrounding tissues. 2 Thus, concerted and controlled expression of cell adhesion molecules and proteolytic enzymes seems to be required to promote tumour migration especially into endothelial environment.Cell adhesion to ECM is mainly mediated by integrins, a transmembrane receptors family, composed of 18 ␣ and 8 ␤ chains that combine to give 24 heterodimeric glycoproteins with distinct cellular and adhesive specificities. 2 Among them, ␣v integrins are receptors for a wide variety of ECM proteins including fibronectin (Fn) and vitronectin (Vn) and appear to be pivotal in tumour behaviour. Indeed, ␣v␤3 is strongly involved in tumour growth and invasion such as melanoma and breast cancer, 3,4 while engagement of this adhesive receptor during melanoma transendothelial migration has been recently reported. 5 Integrins are also involved in regulating activities of matrix metalloproteinases (MMPs), a family of zinc and calcium dependent enzymes. 2,6 MMPs mediate invasive properties of most malignant cells and promote angiogenesis through their ability to degrade basement membranes and to remodel ECM architecture. 6 -8 In particular, increasing expression of MMP2 by cancer cells is generally correlated with a poor prognosis. 7,8 Recent reports also showed that angiogenesis and corresponding tumour growth are reduced in MMP2 knock-out mice suggesting that MMP2 is a key player in neoangiogenesis. 7 MMP2 is secreted as an inactive zymogen that can be activated by MT1-MMP, a membrane bound MMPs, reported to be over expressed in several malignant tumour tissues. [7][8][9] Recent studies demonstrated that MMP2 activating complex also includes ␣v␤3 integrin. 9 Thus, MMP2-MT1MMP and ␣v␤3 integrin are functionally linked to activate MMP2, thereby localising its proteolytic activity to the invasive front of tumour cells 10 and to promote cancer cell locomotion. 9 Ovarian carcinoma, which arise from the malignant transformation of ovarian surface epithelium cells, 11 are associated with a poor prognosis and are diagnosed at advanced stages. Ovarian carcinoma are highly vascularised 12 and their expansion seems to be dependent upon their vascularisation. Some studies suggested that tumour angiogenesis is a prognostic factor in ovarian carcinoma, 12,13 while reports described the presence of ovarian metastasis localised in extraperitoneal sites like bone marrow and brain. 14,15 Taken together these data suggest the existence of a haematogenous way of dissemination for ovarian carcinoma. Nevertheless, cellular processes that lead to ovarian cancer cel...

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