Identifying human pulmonary artery endothelial cells (HPAECs) by flow cytometry.

(A) Commercially purchased HPAECs were analyzed by flow cytometry using anti-CD31 and anti-CD144 Abs #12 and #13. Compared with HPASMCs and HLFs, high expression of CD31 and CD144 was observed only in HPAECs. These results served as a positive control for further experiments aiming to confirm that cells isolated from rat lungs ex vivo were, in fact, endothelial. (B) Commercially purchased HPAECs were used to test the generalizability of these results. Alternative anti-CD31 and anti-CD144 antibodies did not reliably identify endothelial cell surface markers, supporting our earlier findings indicating variability in reactivity (i.e., quality) of tested antibodies across experimental methods, including flow cytometry. Representative plots and histograms shown. Means ± standard error, % CD31 or CD144 positive, N = 4-5/condition. Ab, antibody; Iso, Isotype control.