Development of zero-link polymers of hemoglobin, which do not extravasate and do not induce pressure increases upon infusion

Abstract

Intramolecular crosslink of hemoglobin tetramers solved the problem of urine elimination and short intravascular retention time of cell free hemoglobin infusion. It also produced a family of crosslinked hemoglobins with P50 between 18 and 30 mmHg. However, it did not solve the problem of MAP increases in infused animals. It was proven that extravasation of hemoglobin into interstitial fluid was responsible for MAP increases. Extravasation and the MAP increase was avoided using a hemoglobin polymer with average size near 25 MDa. In spite of a very high oxygen affinity, this polymer delivered oxygen to tissues, producing either vasodilation or vasoconstriction according to oxygen needs. It was also proven that cell free hemoglobins are more efficient than red cells in delivering oxygen to tissues.

Figure 1

Transient of the pressure response after infusion in the cat of sebacoyl crosslinked HbA.

Figure 2

Transients of hilar lymph concentration in rats 30% exchange-transfused with unmodified hemoglobin (UMB), DECA, and marked albumin. (Adapted from Matheson et al., 2000).

Figure 3

Exchange transfusion of ZL-HbBv produced no change in mean arterial pressure (±SD) over a 4-h observation period in anesthetized cats (A) or over a 48-h observation period in unanesthetized cats (B). (Adapted from Matheson et al., 2002).

Figure 4

(A). Percent change (±SE) in pial arteriolar diameter measured through a closed cranial window in anesthetized cats after a 40% exchange-transfusion with 5% albumin or 6% ZL-HbBv. The constriction observed with ZL-HbBv at reduced hematocrit and blood viscosity was reversed to dilation in a group in which plasma viscosity was simultaneously increased by co-infusion of 20% polyvinylpyrrolidone (PVP). *P < .05 from time control group. (B). The constrictor response to ZL-HbBv exchange-transfusion in anesthetized rats was blocked by superfusing the cranial window with the cytochrome P450 w-hydroxylase inhibitor N-methylsulfonyl-12,12-dibromododec-11-enamide (DDMS; 50 μM). This indicates that the vasoconstriction in panel A was not NO dependent. (Adapted from Rebel et al., 2003).

Figure 5

Transport of glucose and amino acids through a rabbit jejunal membrane voltage clamped in a Ussing chamber. The Ringer’s perfusate was equilibrated with 30% O₂, 5% CO₂ and contained either 3 g=dl DECA or an equivalent suspension of bovine red cells. After 4 h of perfusion, red cells failed to support transport. (Adapted from Bucci et al., 2003).