Representative CEC enumeration by flow cytometry. Panels in the top row show the gate used to exclude platelets, dead cells, and debris, and the gate made to depict CD45-negative (ie, nonhematopoietic) cells. Panels in the middle row show the negative controls. Panels in the bottom row show the gate used to count CECs (left panel: CECs defined as CD45^–, CD31⁺, P1H12⁺, and CD133^–), the gate used to count CEPs (middle panel: CEPs defined as CD45^– and CD133⁺), and the gate used to investigate CEC viability by 7AAD (right panel indicates how 7AAD used as in Philpott et al12 discriminates between apoptotic and necrotic cells). Antibodies used were FITC-labeled anti-CD31, PE-labeled P1H12 (CD146),4,12 and APC-labeled anti-CD133.