The paper by Takaguchi et al. reports the effects of hemoglobin vesicles (HbVs) developed as oxygen-carrying blood substitutes in controlling E. coli growth. The study was carried out in rats, using a double-hit model of hemorrhagic shock and sepsis that replicates clinical sepsis in patients after trauma. The basic result is that 10% of RBC-resuscitated rats survived 168 h after the induction of caecum ligation and puncture, while 40% of the HbV-resuscitated animals survived. It was also shown that the plasma of rats resuscitated with HbVs suppressed E. coli growth. The mechanisms proposed for these effects are activation of the complement system and the potential formation of reactive oxygen species, at levels that control bacterial development but do not cause endothelial damage. Removal of gram-negative bacteria, especially E. coli, at an early phase of resuscitation from hemorrhagic shock is a critical issue, since 10% of transfused patients with massive hemorrhage are reported to develop nosocomial infections. Therefore, the results reported increase our confidence in the deployment of HbVs as blood substitutes.

– Marcos Intaglietta