Circulating endothelial cell
Circulating endothelial cells (CECs) are endothelial cells that have been shed from the lining of the vascular wall into the blood stream. Endothelial cells normally line blood vessels to maintain vascular integrity and permeability, but when these cells enter into the circulation, this could be a reflection of vascular dysfunction and damage.
Source: Wikipedia — Circulating endothelial cell (CC BY-SA 4.0)