Endothelial Cells Grown on Filter Membranes

Abstract

The endothelium is a single layer of epithelioid cells which lines the blood vessels. Because of this unique geography, the endothelium is potentially important in the control of many of the events of vascular biology. The endothelium could be important in determining the flux of molecules into and out of the vascular space. The endothelium could also control the movement of cells from the blood to the tissues and potentially the flow of tissue lymphocytes back into the circulation. Because of its unique location and own active metabolism the endothelium could also act as a sensor of intravascular events and at the same time an initiator of messages to parts of the vessel wall outside the vessel lumen. All of these potential roles have stimulated investigators for many years. However, the geography of the endothelium has also made it very difficult to precisely investigate these potential functions and ascribe them solely to the endothelium. Other components of the vessel wall may contribute to limiting the flux of molecules from the blood to the tissues, and it is very difficult to sample the contents of the immediate extravascular space. Other components of the vessel wall may also restrict the movement of cells from the blood to the tissues and vice versa. Similarly, the endothelium is not the only cell type in the vessel wall capable of secreting important messenger molecules. Even when these messenger molecules are identified in cultures of endothelium, the potential precision of the message that might reside in the polarity of release of the molecules remains difficult to determine.

Supported in part by grants from the National Institutes of Health, HL 33540, HL 36605, and HL14230