CD34 and acute respiratory distress syndrome: Compared to the ARDS group, inhaled NO induced a rapid elevation in the number of CD34+KDR+, KDR+CD133+ and CD34+KDR+CD133+ EPCs in blood (2163±454 vs. 1094±416, 1302±413 vs. 429±244, 1140±494 vs. 453±273 cells/ml, respectively, P<0.05), and a reduction in the percentage of KDR+CD133+ cells in bone marrow.