In line with these preclinical findings, angiogenic factors such as VEGF and its associated receptor FMS-like tyrosine kinase (FLT-1) (encoding VEGFR1), as well as the angiopoetin-1 receptor (also called TIE-2) have been reported to be crucial players both during normal pulmonary vascular formation and in human preterm infants suffering from BPD [4,26,27,28,29,30,31]. Here, FLT1 is linked to bronchopulmonary dysplasia.