We describe the isolation and the ultrastructural characteristics of adult bovine articular chondrocytes in vitro . Slices of bovine articular cartilage undergo sequential digestions with pronase and collagenase in order to release cells . Chondrocytes are plated at high density (1 x 105 cells/cm 2 ) in culture dishes or roller bottles with Ham's F-12 medium, supplemented with 10% fetal bovine serum . Before culture, chondrocytes are freed of surrounding territorial matrix . Within the first few days of culture they re-establish a territorial matrix . As time progresses, chondrocytes synthesize both territorial and extraterritorial matrices . The matrices are rich in collagen fibrils and ruthenium red-positive proteoglycans . These features are most apparent in mass roller cultures in which aggregates of cells and matrix appear as long streaks and nodules . This morphology reveals an organization of chondrocytes and their matrices that is similar to that of the parent articular cartilage in vivo .

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Background: CCN-proteins are known to be involved in development, homeostasis and repair of mesenchymal tissues. Since these processes implicate recruitment of cells with the potential to be committed to various phenotypes, we studied the effect of CYR61/CCN1 and WISP3/CCN6 on migration of human bone marrow derived mesenchymal stroma cells (MSCs) in comparison to in vitro osteogenic differentiated MSCs using a modified Boyden chamber assay.

Transforming growth factor-beta 1 (TGF-β₁) is a key regulator of immune tolerance. TGF-β₁ controls T lymphocte activation and is involved in the immunosuppressive function and generation of regulatory T lymphocytes. Connective tissue growth factor (CTGF) has an essential role in the formation of connective tissue and blood vessels. CTGF expression is induced by TGF-β₁ in several cell types and CTGF mediates several of the downstream actions of TGF-β₁. Since little is known about the potential synergy between CTGF and TGF-β₁ in T lymphocyte biology, the purpose of the present study was to determine whether CTGF can modulate TGF-β₁-mediated effects on human CD4+ T lymphocytes. Human recombinant CTGF was expressed in HEK293 cells. rCTGF was biologically active demonstrated by induction of proliferation in the endothelial cell line EA hy 926. rCTGF alone did not potentiate or diminish anti-CD3-induced CD4+ T lymphocyte proliferation and did not activate the Smad signaling pathway in CD4+ T lymphocytes. Furthermore, rCTGF did not attenuate TGF-β₁-mediated inhibition of CD4+ T lymphocyte proliferation and TGF-β₁-induced Smad signaling in CD4+ T lymphocytes. These results indicate that rCTGF had no detectable effects of its own on human CD4+ T lymphocytes and did not potentiate the effects of low amounts of TGF-β₁ on human CD4+ T lymphocytes. Overall, these data support the hypothesis that CTGF does not act on CD4+ T lymphocytes.