Cell Culture Grade. Passage 1 cells are shipped in proliferating culture with a confluence of >90%. ENDO-Growth medium containing 5% serum and growth supplement is recommended for culture. Cells have an average population doubling level of >20 when cultured. When you receive the cells, leave the flask in 37°C CO2 incubator for 1 hour. Then replace the transport medium with fresh ENDO-Growth medium. Let the cells grow for 24 hour before subculture. Source: Human Umbilical Vein Endothelial Cells (HUVECs), isolated from a normal human umbilical vein. Cell Number: >90% confluent in T25 flask Cell Characterization: Cytoplasmic VWF/Factor VIII: >95% positive by immunofluorescence Cytoplasmic uptake of Di-I-Ac-LDL: >95% positive by immunofluorescence Cytoplasmic PECAM1: >95% positive by immunofluorescence HUVECs are negative for HIV-1, HBV, HCV, and mycoplasma. Important Note: Cells are provided either in a T-25 flask or as a 1ml frozen vial. Store 1ml vials at -70°C. Store T-25 flasks at 37°C in 5% CO2.