Polyhemoglobin-fibrinogen: A novel oxygen carrier with platelet-like properties in a hemodiluted setting

Polyhemoglobin ( polyHb) is currently being assessed in phase III trials under various formulations. At present, none contain clotting factors or platelet substitutes to aid in hemostasis. We have prepared a novel blood substitute that is an oxygen carrier with platelet-like activity. This is formed by crosslinking fibrinogen to hemoglobin to form polyhemoglobin-fibrinogen (polyHb-Fg). This was studied and compared to polyHb for its effect on coagulation both in vitro and in vivo. In the in vitro experiments, PolyHb-Fg showed similar clotting times as whole blood, whereas polyHb showed significantly higher clotting times. This result was confirmed in in vivo experiments using an exchange transfusion rat-model. Using PolyHb, exchange transfusion of 80% or more increased the normal clotting time (1-2 mins) to > 10 mins. Partial clots formed with PolyHb did not adhere to the tubing wall. With PolyHb-Fg, a normal clotting time is maintained, even with 98% exchange transfusion.