Each vial contains 300,000 Normal Human Umbilical Vein Endothelial Cells (HUVEC), pooled from multiple donors. Prior to cryopreservation, the parental HUVEC are lentivirally infected to stably express Incucyte® Cytolight Green Lentivirus driven off of a CMV promoter. This results in a >90% transduction efficiency of the HUVEC population as measured by flow cytometry analysis. Upon thawing, the Cytolight Green HUVECs are guaranteed to be ≥ 70% viable. Normal human cells have a limited life span in vitro. When cultured according to protocol, these Cytolight Green HUVEC can achieve several population doublings.