Severe BPD infants displayed lower levels of EPCs compared to mild BPD infants on day 7, which was statistically significant for KDR+CD133+ cells (0.002[0.001–0.002]% vs. 0.007[0.005–0.022]%; P<0.01) and CD34+KDR+CD133+ cells (0.002[0.001–0.002]% vs. 0.007[0.005–0.020] %; P<0.01) (Fig. 1). Here, CD34 is linked to bronchopulmonary dysplasia.