Circulating endothelial progenitor cells in small-diameter artificial blood vessel.

In the tissue engineering research field, the presence of circulating endothelial progenitor cells (EPCs) in the peripheral blood of adults represents a promising cell source to grow autologous endothelium on blood-contacting devices. Materials functionalized with EPC-specific molecules are an intriguing strategy to induce the homing and differentiation of the trapped EPCs into endothelial cells to generate a non-thrombogenic surface. Although the EPCs have been identified in adult peripheral blood about 30 years ago, in the subsequent literatures, the term "EPCs" has encompassed different cell populations with a mixed ability to contribute to the formation of blood vessels. This confusion is due to limited functional characterization of "EPCs", an improper nomenclature, and the poorly standardized protocols. This review will screen the literature about "EPCs" to propose a specific nomenclature, phenotypic characterization, and, eventually, a protocol to perform reliable experiments.