HRC 101 Improves survival during hypoxia in sad mice

Abstract

INTRODUCTION: Red cell transfusion decreases morbidity in sickle cell disease (SCD), but is not without risk. Utilization of a hemoglobin-based oxygen carrier (HBOC) could offer the benefits of red cell transfusion while reducing transfusion-related complications. We studied the effect of a novel HBOC, HRC 101, on survival during acute hypoxia in a murine model of SCD, the transgenic mouse expressing hemoglobin SAD. METHODS: After approval from the Animal Care Committee, 66 pathogen-free wild-type (n = 30) and transgenic SAD mice (n = 36) aged 6 -13 weeks and weighing 17 -31g were assigned at random to receive 0.02 ml/g body weight HRC 101 or an equal volume of 5% albumin administered via a 26-G catheter over 2 min into a tail vein. Following fluid administration, the animals were placed in a custom built Plexiglas chamber and observed for 20 min while breathing room air. Anesthesia was induced with halothane in 30% oxygen using a calibrated vaporizer and a continuous fresh gas flow rate of 5 l/min. Lead II of the electrocardiogram was monitored using needle electrodes and data acquisition software (AcqKnowledge version 3, MP100 Work Station, Harvard Apparatus). During halothane anesthesia (0.5% inspired concentration) and spontaneous ventilation, either 30% or 6% oxygen was administered. Heart rate, inspired concentrations of oxygen and halothane, and rectal temperature were recorded every 5 min. Time to cessation of cardiac electrical activity was recorded. At the time of death (cessation of cardiac electrical activity) or at the end of 1 h, blood was sampled via cardiac puncture for determination of blood gases and lactate concentration. Kaplan-Meier analysis with the log-rank test was used to compare survival rates. Two-way repeated measures or one-way ANOVA and the Student-Newman-Keuls post hoc test were used for statistical comparisons as appropriate. P < 0.05 was considered significant. RESULTS: In control groups, all mice survived the 60-min study period, whether breathing 30% or 6% oxygen. In contrast, all SAD mice administered albumin and 6% oxygen died, with a median survival time of 9.0 min (interquartile range, 6.9 -11.6 min) (P < 0.0001). Administration of HRC 101 significantly increased median survival time in SAD mice breathing 6% oxygen (figure). Of twelve SAD mice administered HRC 101 and 6% oxygen, four survived the entire study period and eight died, with a median survival time of 48 min (19 -60 min) (P < 0.0001 vs. albumin).

Genetically altered mice, man and medicine

“…Differences in the main site of haematopoiesis (the spleen in the Berkeley mouse and the bone-marrow in SCA patients) might also contribute to species differences since splenic hypertrophy is apparent in 1-6 month old mice, whereas in humans, initial hypertrophy is followed by almost total loss of spleen function (Manci et al 2006). Despite these problems, studies in mouse SCA models have resulted in promising new therapies, including a new hemoglobin-based oxygen carrier (HBOC), HRC 101 (Hemosol in Shichor et al 2007). This is because the same organs are affected in mice and humans, albeit to different extents, and because the therapeutic efficacies of HBOCs are largely dependent on ADME and being able to reach the target site.…”