Umbilical or Adult Donor Red Blood Cells to Transfuse Extremely Low Gestational Age Neonates. A Randomized Trial to Assess the Effect on Retinopathy of Prematurity Severity.

Extremely low gestational age neonates (ELGAN, i.e., born before 28 gestation weeks) are among the most heavily transfused pediatric patients. In this clinical setting, repeated red blood cell (RBC) transfusions independently predict a poor outcome, with a higher risk for mortality and morbidity. Recent studies from our own and other groups highlighted a close association between low levels of fetal hemoglobin (HbF) and severity of retinopathy of prematurity (ROP) and bronchopulmonary dysplasia (BPD), two disabilities that frequently complicate preterm birth. This association is not surprising, considering that 1) preterm neonates have a highly immature antioxidant reserve and both ROP and BPD rely on the oxidative damage as underlying mechanism; 2) in comparison with HbA, HbF is endowed with higher oxygen affinity, greater redox potential, higher tetrameric stability, and higher ability to generate unbound nitric oxide, all functions potentially protective in presence of an oxidative challenge; 3) in normal prenatal life, developing organ and tissues are exposed exclusively to HbF until last weeks of gestation; 4) in preterm neonates, the switch of the synthesis from HbF to HbA occurs around their due date, i.e., several weeks after the premature birth; 5) when preterm neonates receive transfusions, their tissues are abruptly exposed to high levels of HbA. We have recently run a pilot trial demonstrating as a proof-of-concept that transfusing cord blood red blood cell concentrates (CB-RBC) effectively prevents or restrains the HbF loss consequent to adult donor standard transfusions (A-RBC). This study explores the hypothesis that transfusing CB-RBCs instead of A-RBC may lower the incidence of severe ROP in ELGANs needing transfusions.