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Blood vessel formation is an important initial step for bone formation during development as well as during remodelling and repair in the adult skeleton. This results in a heavily vascularized tissue where endothelial cells and skeletal cells are constantly in crosstalk to facilitate homeostasis, a process that is mediated by numerous environmental signals, including mechanical loading. Breakdown in this communication can lead to disease and/or poor fracture repair. Therefore, this study aimed to determine the role of mature bone cells in regulating angiogenesis, how this is influenced by a dynamic mechanical environment, and understand the mechanism by which this could occur. Herein, we demonstrate that both osteoblasts and osteocytes coordinate endothelial cell proliferation, migration, and blood vessel formation via a mechanically dependent paracrine mechanism. Moreover, we identified that this process is mediated via the secretion of extracellular vesicles (EVs), as isolated EVs from mechanically stimulated bone cells elicited the same response as seen with the full secretome, while the EV-depleted secretome did not elicit any effect. Despite mechanically activated bone cell-derived EVs (MA-EVs) driving a similar response to VEGF treatment, MA-EVs contain minimal quantities of this angiogenic factor. Lastly, a miRNA screen identified mechanoresponsive miRNAs packaged within MA-EVs which are linked with angiogenesis. Taken together, this study has highlighted an important mechanism in osteogenic-angiogenic coupling in bone and has identified the mechanically activated bone cell-derived EVs as a therapeutic to promote angiogenesis and potentially bone repair. [ABSTRACT FROM AUTHOR]

Background: The transfusion of peripheral blood stem cell (PBSC) concentrates is sometimes associated with febrile transfusion reactions. PBSC concentrates contain large numbers of white blood cells, and during storage the levels of soluble cytokines that could cause transfusion reactions may increase.Study Design and Methods: Aliquots of granulocyte-colony-stimulating factor (CSF)-mobilized PBSC concentrates from nine healthy subjects were stored in bags at 2 to 8°C for 48 hours. The levels of 19 growth factors and biologic response modifiers were measured in the plasma of PBSC concentrates at 0, 24, and 48 hours of storage using a nested enzyme-linked immunosorbent assay. The same 19 factor levels were also measured in blood plasma from six healthy subjects.Results: There were no significant differences in the PBSC and plasma levels of soluble interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α, which can cause febrile reactions. The levels of TGF-β1, matrix metalloproteinase-8, CCL5/(reduced on activation normal T expressed and secreted), and platelet (PLT)-derived growth factor-AB were significantly greater in PBSCs than in plasma and the level of CCL2/MCP-1 was significantly less in PBSCs. Duration of PBSC storage had no effect on the levels of these five factors. There was a trend for reduced levels of IL-1β, IL-2, IL-7, IL-8, IL-12p70, IL-15, interferon-γ, CD40L, and granulocyte-macrophage-CSF and increased levels of TNF-α and IL-10 levels in PBSC concentrates, but the differences were not significant.Conclusions: There was no increase in stored PBSC concentrates of cytokines that have been associated with febrile transfusion reactions; however, the levels of other factors that were likely released by PLTs and granulocytes during the collection process were elevated. [ABSTRACT FROM AUTHOR]

Prolonged seizures (status epilepticus) are associated with brain region-specific regulation of apoptosis-associated signaling pathways. Bcl-2 homology domain 3-only (BH3) members of the Bcl-2 gene family are of interest as possible initiators of mitochondrial dysfunction and release of apoptogenic molecules after seizures. Previously, we showed that expression of the BH3-only protein, Bcl-2 interacting mediator of cell death (Bim), increased in the rat hippocampus but not in the neocortex after focal-onset status epilepticus. In this study, we examined Bim expression in mice and compared seizure damage between wild-type and Bim-deficient animals. Status epilepticus induced by intra-amygdala kainic acid (KA) caused extensive neuronal death within the ipsilateral hippocampal CA3 region. Hippocampal activation of factors associated with transcriptional and posttranslational activation of Bim, such as CHOP and c-Jun NH(2)-terminal kinases, was significant within 1 h. Upregulation of bim mRNA was evident after 2 h and Bim protein increased between 4 and 24 h. Hippocampal CA3 neurodegeneration was reduced in Bim-deficient mice compared with wild-type animals after seizures in vivo, and short interfering RNA molecules targeting bim reduced cell death after KA treatment of hippocampal organotypic cultures. In contrast, neocortical Bim expression declined after status epilepticus, and neocortex damage in Bim-deficient mice was comparable with that in wild-type animals. These results show region-specific differential contributions of Bim to seizure-induced neuronal death. [ABSTRACT FROM AUTHOR]