Polymerized pyridoxylated hemoglobin: a red cell substitute with normal oxygen capacity

Area of Science:

• Biochemistry
• Biomedical Engineering
• Hematology

Background:

• Stroma-free hemoglobin (SFH) solutions are potential blood substitutes.
• Pyridoxylated hemoglobin (SFH-P) has been investigated for oxygen (O2) carrying capacity.
• Polymerization of SFH-P aims to improve its properties as a blood substitute.

Purpose of the Study:

• To compare the in vivo O2-carrying capacity and intravascular persistence of polymerized SFH-P versus SFH-P.
• To evaluate the impact of poly SFH-P on colloid osmotic pressure (COP) and P50 in vivo.
• To assess the potential of poly SFH-P as a blood substitute approximating whole blood.

Main Methods:

• Partial exchange transfusion (900 ml) with poly SFH-P or SFH-P in adult baboons (n=4 per group).
• Measurement of O2-carrying capacity, intravascular persistence, COP, P50, and methemoglobin conversion rate.
• Analysis of plasma protein concentration changes.

Main Results:

• Poly SFH-P demonstrated a 77% greater O2-carrying capacity than SFH-P (8.0 vs 4.5 vol%).
• Poly SFH-P provided significant O2-carrying capacity for up to 48 hours, while SFH-P was depleted within 24 hours.
• Normal COP was maintained with poly SFH-P despite increased plasma protein concentration.

Conclusions:

• Polymerized pyridoxylated hemoglobin (poly SFH-P) is a promising blood substitute with enhanced O2-carrying capacity and prolonged persistence.
• Poly SFH-P maintains normal colloid osmotic pressure, a critical factor for blood substitutes.
• Poly SFH-P approximates the O2-carrying capacity of whole blood and can be infused without altering plasma COP.