Warming blood products for transfusion to neonates: In vitro assessments. Blood products may be transfused into neonates at temperatures at or below room temperature. The benefits and risks of warming blood to 37°C are not defined in this population. The investigators used an in vitro model of neonatal transfusions, with a syringe pump, blood tubing, and 24-gauge catheter and compared current practice (cold products) vs an inline blood warmer. Transfusions were performed rapidly (30 minutes) and slower (120 minutes) to model emergent vs routine situations. They tested red blood cells, fresh-frozen plasma, apheresis platelets (PLTs), and cold-stored low-titer group O whole blood and detected no warmer-induced damage. At least in simulations, an inline blood warmer can deliver blood products at near-physiologic temperatures with no detected damage. In vivo testing of warmed NICU transfusions is now indicated.
A murine neonatal model of necrotizing enterocolitis caused by anemia and red blood cell transfusions. Necrotizing enterocolitis (NEC) is an idiopathic, inflammatory bowel necrosis of premature infants. Clinical studies have linked NEC with antecedent red blood cell (RBC) transfusions, but the underlying mechanisms are unclear. The authors developed a neonatal murine model to investigate this association. C57BL/6 mouse pups rendered anemic by timed phlebotomy and then given RBC transfusions, developed NEC-like intestinal injury with prominent necrosis, inflammation, and submucosal edema in the ileocecal region and colon within 12-24 h. The anemic intestine was infiltrated by inflammatory macrophages, which are activated in situ by RBC transfusions via a Toll-like receptor (TLR)-4-mediated mechanism and cause bowel injury. Intestinal injury worsened with increasing severity and the duration of anemia prior to transfusion, indicating a need for the re-evaluation of current transfusion guidelines for premature infants.
Role of macrophages in fetal development and perinatal disorders. This article reviews the role of fetal and neonatal macrophages in immune surveillance, innate immunity, homeostasis, tissue remodeling, angiogenesis, and repair of damaged tissues. The authors also discuss the possibility of therapeutic manipulation of the relative abundance and activation status of macrophages in various diseases.
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