Endothelial cells provide the dynamic lining of blood vessels throughout the body and provide many tissue-specific functions, in addition to providing a nonthrombogenic surface for blood cells and conduit for oxygen and nutrient delivery. As might be expected, some endothelial cells are injured or become senescent and are sloughed into the bloodstream and most circulating endothelial cells display evidence of undergoing apoptosis or necrosis. Rare viable circulating endothelial cells that display properties consistent with those of a progenitor cell for the endothelial lineage. Mesenchymal stem/stromal cells (MSCs) are fibroblastoid cells capable of long-term expansion and skeletogenic differentiation. While MSCs are known to originate from neural crest and mesoderm, immediate mesodermal precursors that give rise to MSCs have not been characterized. The impact factor of journal provides quantitative assessment tool for grading, evaluating, sorting and comparing journals of similar kind. It reflects the average number of citations to recent articles published in science and social science journals in a particular year or period, and is frequently used as a proxy for the relative importance of a journal within its field. It is first devised by Eugene Garfield, the founder of the Institute for Scientific Information. The impact factor of a journal is evaluated by dividing the number of current year citations to the source items published in that journal during the previous two years.
Last date updated on July, 2014