At day 12 after differentiation, adherent cells were harvested using TrypleE and made into a single-cell suspension in EGM-2 medium. Cells were counted and aliquots of the cell suspension were prepared for antibody staining.
FcR blocking reagent (Miltenyi Biotech) was added to prevent the non-specific binding of antibodies. Anti-human CD31 (
CD31-FITC, clone WM59 from BD Pharmingen), CD144 (CD144-PE, clone 16B1 from eBioscience) and NRP-1 (NRP-1-APC, clone AD5-176 from Miltenyi Biotech) antibodies were used at concentrations that were titrated before use (
Supplementary Table 2).
Propidium iodide (PI, Sigma) was added to the cell suspension for dead cell staining. Flow cytometric detection of the cell surface antigens and cells sorting were performed on an LSR II and
FACSAria (Becton Dickinson), respectively. Compensation was set by single-positive controls using cord blood–derived ECFCs. A gating of targeted cell population was determined based on fluorescent minus one (FMO) controls for each fluorescent color.
Prasain N., Lee M.R., Vemula S., Meador J.L., Yoshimoto M., Ferkowicz M.J., Fett A., Gupta M., Rapp B.M., Saadatzadeh M.R., Ginsberg M., Elemento O., Lee Y., Voytik-Harbin S.L., Chung H.M., Hong K.S., Reid E., O'Neill C.L., Medina R.J., Stitt A.W., Murphy M.P., Rafii S., Broxmeyer H.E, & Yoder M.C. (2014). Differentiation of human pluripotent stem cells to cells similar to cord-blood endothelial colony–forming cells. Nature biotechnology, 32(11), 1151-1157.