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The role of endothelins (ET) in the biosynthesis of interleukin-6 (IL-6) with macrophage colony stimulating factor (M-CSF) during osteoblastic signal transduction events was analyzed in MC3T3-E1 cell lines. Enzyme-linked immunoabsorbent assay analysis of osteoblastic IL-6 and M-CSF synthesis in primary osteoblasts and MC3T3-E1 cell lines indicated the role of ET-1 in eliciting dose-dependent elevations of IL-6 levels in murine osteoblasts. Furthermore, the effects of ETs on IL-6 were mediated by ETA receptors.

Murine bone marrow cells were placed in co-culture with ST-2 stromal cells to examine how macrophage colony-stimulating factor (CSF-1) promotes the growth and differentiation of osteoclasts from precursor cells derived from bone marrow. The results show that CSF-1 was most effective in promoting differentiation into osteoclasts up to day six of co-culture, and its effect was significantly diminished beyond day nine of co-culture. These results indicate that CSF-1 promotes differentiation into osteoclasts before precursor cells are committed to any specific differentiation path.

ADAMTS13, the von Willebrand factor-cleaving protease, is constitutively produced by endothelial cells. The aim was to quantify ADAMTS13 production in proliferating and nonproliferating human umbilical vein endothelial cells (HUVECs) and to determine if such production was regulated. HUVECs were plated at 50,000 cells/cm2 or 10,000 cells/cm2, densities yielding confluence or subconfluence, respectively. Subconfluent HUVEC supernatants and cell lysates contained at least 2-fold more ADAMTS13 antigen than those of confluent HUVECs (p < 0.05). Immunohistochemistry supported this increase and indicated no dramatic shifts in subcellular localization of HUVEC ADAMTS13 by HUVEC proliferation. The activity of the ADAMTS13 produced by subconfluent HUVECs was increased about 2-fold also. HUVECs rapidly increased ADAMTS13 mRNA in response to subconfluent conditions. This change in regulation, in turn, leads to increased ADAMTS13 protein production and activity by these proliferating cells. Copyright © 2009 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

ADAMTS13, the von Willebrand factor-cleaving protease, is constitutively produced by endothelial cells. The aim was to quantify ADAMTS13 production in proliferating and nonproliferating human umbilical vein endothelial cells (HUVECs) and to determine if such production was regulated. HUVECs were plated at 50,000 cells/cm(2) or 10,000 cells/cm(2), densities yielding confluence or subconfluence, respectively. Subconfluent HUVEC supernatants and cell lysates contained at least 2-fold more ADAMTS13 antigen than those of confluent HUVECs (p < 0.05). Immunohistochemistry supported this increase and indicated no dramatic shifts in subcellular localization of HUVEC ADAMTS13 by HUVEC proliferation. The activity of the ADAMTS13 produced by subconfluent HUVECs was increased about 2-fold also. HUVECs rapidly increased ADAMTS13 mRNA in response to subconfluent conditions. This change in regulation, in turn, leads to increased ADAMTS13 protein production and activity by these proliferating cells., (Copyright 2009 S. Karger AG, Basel.)