Endothelial biomedicine: its status as an interdisciplinary field, its progress as a basic science, and its translational bench-to-bedside gap.

The endothelium, a layer of endothelial cells lining the luminal surface of all blood vessels, functions as a highly metabolically active organ spatially distributed throughout the body. Despite enormous advances in our understanding of endothelial cell biology, little awareness of this organ reaches clinical practice. The present study aims to document the extent and scope of the bench-to-bedside gap in endothelial biomedicine, and to offer hypotheses to explain the gaping chasm. A PubMed search using keywords "endothelial cells" and "endothelium" yielded over 90,000 publications, increasing exponentially over the past decade. A Scirus search without date restriction returned journal results for the endothelium not greatly fewer than for the epithelium. A survey of representative vascular biology meetings revealed a high percentage of talks related to the endothelium. The number of grants awarded by the National Institutes of Health for studies in endothelial cell biology continues to steadily increase. At the bedside, however, few clinicians give consideration to the health of the endothelium. A survey of the major medical textbooks revealed a paucity of index entries for "endothelial cells" or "endothelium." The endothelium does not offer itself for inspection, palpation, percussion, and/or auscultation. No convenient blood tests measure endothelial function. The authors propose to explain the bench-to-bedside gap in endothelial biomedicine as a function of (1) historical constraints, (2) the unseen and diffuse nature of the cell layer, (3) the complexity of the system, and (4) its adaptability. Until the bench-to-bedside gap closes, the enormous potential of the endothelium as a diagnostic, preventive, and therapeutic target will remain largely untapped.