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At least 73 records · Page 4Linked to original sources
PubMed1986

Specific bioactivities of monocyte-derived interleukin 1 alpha and interleukin 1 beta are similar to each other on cultured murine thymocytes and on cultured human connective tissue cells.

In this report we compare the bioactivities of pure, human monocyte-derived interleukin 1 (IL-1) alpha and beta in the standard murine thymocyte proliferation assay, a human dermal fibroblast proliferation assay, and in an assay measuring stimulation of prostaglandin E2 (PGE2) release from human rheumatoid synoviocytes. In each case the different species of IL-1 produced saturable stimulation and gave similar dose response curves. Half-maximal stimulation was observed at average IL-1 concentrations of 29 pM in the thymocyte assay, 2 pM in the dermal fibroblast proliferation assay, and 5 pM in the synovial cell assay. Our results show that native, monocyte-derived IL-1 alpha and IL-1 beta are both potent stimulators of connective tissue cells and that the specific bioactivities of these molecules are similar to each other in tests on human connective tissue cells, as well as on murine lymphoid cells.

Adult↗
PubMed1978

Heavy meromyosin labeling of intermediate filaments in cultured connective tissue cells.

Mild treatment with trypsin causes a radical change in the heavy meromyosin (HMM) binding properties of intermediate filaments in glycerinated, myosin-extracted cultured chick embryo connective tissue cells. In non-trypsin-treated cells, HMM labeling of filaments was often indistinct and variable in its distribution. By contrast, in cells treated with trypsin (under conditions which allowed most intermediate filaments to survive), virtually all filaments, including those of intermediate size, decorated with HMM to give distinct arrowhead patterns. We suggest that most intermediate filaments in such cells contain a core of F-actin masked by trypsin-labile accessory proteins.

Actins↗
PubMed2002

Expression of smooth muscle actin in connective tissue cells participating in fracture healing in a murine model.

The role of alpha-smooth muscle actin (SMA)-expressing fibroblasts in the contraction of skin wounds has been known for three decades. Recent studies have demonstrated that osteoblasts can also express the gene for this contractile muscle actin isoform and can contract a collagen-glycosaminoglycan analog of extracellular matrix in vitro. These findings provided rationale for the hypothesis that SMA-expressing cells contribute to fracture healing by drawing the bone ends together. To begin to test this hypothesis, immunohistochemistry was employed to evaluate the distribution of connective tissue cells expressing SMA in a mouse model of successful fracture healing. The results demonstrated that the majority of the cells comprising the mesenchymal tissue interposed between the fracture ends contained SMA after 7 and 21 days, supporting the working hypothesis. Most of the osteoblasts lining the surfaces of newly forming bone and the chondrocytes comprising the cartilaginous callus also expressed this contractile actin isoform. The maximal SMA expression extended from 7 to 21 days postfracture. The finding of high levels of SMA expression in connective tissue cells participating in fracture healing suggests that SMA-enabled contraction may be playing a role in the healing process. These results warrant further study of the specific SMA-dependent cell behavior.

Actins↗
PubMed1991

Plasticity of integrin expression by nerve-derived connective tissue cells. Human Schwann cells, perineurial cells, and fibroblasts express markedly different patterns of beta 1 integrins during nerve development, neoplasia, and in vitro.

Strikingly selective expression patterns of beta 1, alpha 2, alpha 3, and alpha 5 integrin subunits were revealed in endoneurium, perineurium, and epineurium of fetal and adult human peripheral nerve by immunostaining with specific antibodies. The alpha 2 subunit was expressed only on Schwann cells both in fetal and adult nerve, whereas the alpha 3 epitopes were expressed exclusively in the adult tissue and were primarily present on perineurial cells. The alpha 5 epitopes were expressed only on the innermost cell layer of perineurium of fetal and adult nerve. The tumor cells within schwannomas and cutaneous neurofibromas expressed both alpha 2 and alpha 3 subunits, indicating that Schwann cells have the potential to express also the alpha 3 subunit in vivo. Cell cultures established from human fetal nerve and neurofibromas revealed expression of the alpha 2 and alpha 5 epitopes on Schwann cells, perineurial cells, and fibroblasts, whereas only Schwann cells contained the alpha 3 epitopes which were occasionally concentrated on the adjacent Schwann cells at cell-cell contacts. Our findings emphasize that nerve connective tissue cells change their profiles for expression of extracellular matrix receptors under conditions which have different regulatory control signals exerted by, for example, axons, humoral factors, or the extracellular matrix of the peripheral nerve. This plasticity may play an important role during nerve development and in neoplastic processes affecting the connective tissue compartments of peripheral nerve.

Antibodies, Monoclonal↗
PubMed1977

The effect of bone matrix on young connective tissue cells in culture.

Human and rat decalcified bone matrix preparations were shown to be active in inducing cartilage formation by subcutaneous implantation in the rat. When young rat fibroblastic cells were grown in cultures, which also contained bone matrix preprations in particulate form, the fibroblastic cells underwent a uniform and consistent morphological alteration. These altered cells showed higher rates of synthesis of hyaluronic acid and chondroitin sulfate than the controls and exhibited very active amino-sugar-nucleotide metabolism. It is suggested that this approach to the culture of connective tissue cells will allow a more precise definition of the early steps of connective tissue differentiation.

Animals↗
PubMed1993

Expression of laminin isoforms by peripheral nerve-derived connective tissue cells in culture. Comparison with epitope distribution in normal human nerve and neural tumors in vivo.

BACKGROUND: Laminins are a family of multifunctional glycoproteins that play a role in various aspects of cell biology. Three different isoforms of laminin have been described, and each comprises a molecule consisting of three subunit polypeptides, the A, B1, B2, M or S chain. EXPERIMENTAL DESIGN: The expression pattern of laminin isoforms was studied by indirect immunofluorescence staining of human peripheral nerve in situ or cell cultures derived from such nerve by using monoclonal antibodies recognizing the subunit epitopes. RESULTS: Selective expression of the subunit polypeptides of laminin isoforms in endoneurium and perineurium was demonstrated. Specifically, an intense immunoreaction for A, B2 and S chain epitopes could be detected in perineurium, whereas endoneurium revealed the presence of B1, B2, M and S chains. Examination of the laminin isoform expression in perineurial cells, Schwann cells, and fibroblasts in cultures derived from normal human nerve indicated, however, that these cells under in vitro conditions were capable of expressing all five laminin chains. Cutaneous neurofibromas, tumors characterized by the presence of mixed cell populations consisting of Schwann cells, perineurial cells, and fibroblasts, demonstrated the expression of B1, B2 and M chain epitopes, whereas only a weak immunostaining could be detected with antibodies recognizing the A and S chains. Similar observations were made on schwannomas, a Schwann cell tumor. CONCLUSIONS: Collectively, the observations of this study attest to the plasticity of neural-derived connective tissue cells with respect to laminin isoform expression. Such plasticity may relate to the cell-cell and cell-matrix interactions during development of peripheral nerves and the potential for neural regeneration.

Adult↗
PubMed1964

REDIFFERENTIATION OF CONNECTIVE TISSUE CELLS IN SERIAL CULTURE.

When cell cultures are initiated from aortic connective tissue of rats and maintained as monolayers on glass, the differentiated property of collagen production disappears. However, these same cells, when placed in diffusion chambers in the peritoneal cavities of other rats, produce collagen, as indicated both morphologically and by the accumulation of hydroxy-proline within the chambers.

Aorta↗
PubMed1986

Nonrandom distribution of coated pits and vesicles in the connective tissue cells of the trabecular meshwork of rabbit.

Coated pits (CPs) and coated vesicles (CVs) are distributed nonrandomly along the surface of the connective tissue cells of the rabbit trabecular meshwork. Morphometric and statistical analyses of the distances between consecutive structures reveal a tendency to cluster, which is apparently higher among CVs than among CPs. The spatial relationship between CVs and CPs is also demonstrated by the analysis of their association (presence/absence) in each cell. The data suggest the hypothesis that each cluster is formed by structures in the same stage of maturation. In addition to the recent demonstration of the clustering of CPs in transformed cells in vitro (Pfeiffer et al. 1980), our findings indicate that: (a) clustering is characteristic of both CVs and CPs; (b) it also occurs in normal tissue cells; (c) it represents a further peculiarity, which confirms the specific nature of receptor-mediated endocytosis; (d) it reflects, at a higher level, the clustering of the receptor molecules, which are responsible for the high selectivity of the endocytic process.

Animals↗
PubMed1993

Plasminogen activators and plasminogen activator inhibitors in connective tissues and connective tissue cells: influence of the neuropeptide substance P on expression.

Tissue segments isolated from ligament, epiligament, and synovial tissues from mature female New Zealand White Rabbits were demonstrated to constitutively secrete a plasminogen activator. Several tissues were also observed to constitutively secrete a plasminogen activator inhibitor which was detected in the form of a PA-PAI complex. Heterogeneity was observed in PA and PAI activity between the different connective tissues. Heterogeneity also existed between and within the medial collateral (MCL), lateral collateral (LCL), and the anterior cruciate (ACL) ligaments. In addition to the differences in constitutive expression of PA and PAI activity, differences in the responsiveness to the neuropeptide substance P (10(-5)-10(-9) M) were also detected. This responsiveness to substance P was displayed by an increase in PA and PAI activity in the conditioned medium. The pattern of responsiveness reflected the degree of innervation of these tissues. That is, synovium and epiligament tissue were the most responsive tissues to substance P while the MCL, LCL and ACL were less responsive to the neuropeptide. Parallel results were obtained using cell culture with fibroblasts isolated from the above mentioned tissues. That is, the pattern of responsiveness was similar between cells and tissue segments. More specifically, cells isolated from both synovium and epiligament increased their both their PA (slightly) and PAI activity following exposure to substance P. This was demonstrated at both the protein and RNA level. Thus, cells within a tissue maintain their phenotype when removed from their three-dimensional matrix. These results are unique in demonstrating that normal ligament and synovial cells and tissue respond to substance P by altering the expression of PA and PAI activity. This investigation further supports the concept that innervation may be important in normal connective tissue function.

Animals↗
PubMed1986

Homogeneous interferon-beta-inducing 25K factor (IL-1 beta) has connective tissue cell stimulating activities.

The human interferon-beta-inducing 22K factor has been shown to have structural homologies with interleukin-1 beta (IL-1 beta) and some of the activities attributed to IL-1. We have shown that 22K factor, purified to homogeneity and endotoxin free, has connective tissue cell stimulating activities, indicating that these activities are due to a naturally occurring species of IL-1 beta and not contaminating factors. 22K factor stimulated the production of prostaglandin E, caseinase activity and plasminogen activator activity in human articular chondrocytes in culture. This cell system appears highly sensitive to 22K factor activity. 22K factor also stimulated the resorption of bovine nasal cartilage and neonatal mouse calvaria.

Animals↗
PubMed1989

Connective tissue cells in healing rat myocardium. A study of cell reactions in rhythmically contracting environment.

To better understand the tendency of myocardium to heal by scarring rather than regeneration, the authors examined the responses of connective tissue cells (CTCs) after three types of necrotizing injuries. Derived from myocardial interstitial cells, CTCs proliferated in both the connective tissue space and the compartment of necrotic myocytes. They assumed various cell forms: fibrocytelike CTCs throughout the sites of injury deposited extracellular scar tissue elements, established CTC-myocyte contacts, and helped anchor myocytes to scar tissue with myotendonlike specializations; CTCs with more complex forms established CTC-myocyte relationships, suggesting important roles in communication and tissue remodeling. CTCs within scar tissue differentiated into myofibrocytes, chondrocytes, and possibly smooth muscle cells. Most scar tissue elements were disposed in the long axis of myocytes. These alterations in form indicate that CTCs have various roles in myocardial repair and suggest that a number of the roles are modulated by contractile forces.

Animals↗
PubMed1997

[The collagen-binding membrane proteins of connective-tissue cells].

The pattern of cell membrane collagen-binding proteins was analysed by affinity chromatography with collagen types I, III and IV columns. We have found that connective tissue cells have three polypeptides which are able to recognize the types of collagen. These proteins have molecular weights 130, 190, and 250 kDa (reduced) according to SDS-PAGE. Proteins with M. W. 130 and 250 kDa show high affinity to collagen type III and IV, but not to collagen type I. Protein with M. W. 190 kDa binds collagen type I only. The distribution of these proteins between cells from various tissues strongly correlates with the set of collagen types interacting with cells in the intact tissue.

Animals↗