Abstract
Recent clinical evaluation of commercial glutaraldehyde-polymerized hemoglobins (PolyHbs) as transfusion solutions has demonstrated several adverse side effects. Chief among these is the hypertensive effect. Fortunately, previous studies have shown that the hypertensive effect can be attenuated by removing free hemoglobin (Hb) and low-molecular-weight (low-MW) PolyHbs from the PolyHb mixture. In this work, polymerized human Hb (PolyhHb) solutions were synthesized in two distinct quaternary states with high MW and subjected to extensive diafiltration to remove free Hb and low-MW PolyhHb components (<500 kDa). The resultant PolyhHb solutions possessed high MW, distinct quaternary state, distinct reactivities with O(2) and CO, similar NO deoxygenating rate constants, distinct autoxidation rate constants, high viscosity, and low colloid osmotic pressure. To preliminarily assess the ability of PolyhHb solutions to oxygenate surrounding tissues fed by a blood vessel, we evaluated the ability of PolyhHbs to transport O(2) to cultured hepatocytes in a mathematical model of a hollow fiber bioreactor. The structure of individual hollow fibers in the bioreactor is similar to that of a blood vessel and provides an easy way to assess the oxygenation potential of PolyhHbs without the need for expensive and time-consuming animal studies. It was observed that PolyhHbs with low O(2) affinities were more effective in oxygenating cultured hepatocytes inside the bioreactor than high O(2) affinity PolyhHbs. Taken together, our results show that it is possible to synthesize high-MW PolyhHbs with no free Hb and low-MW PolyhHb components that are capable of transporting O(2) to cultured cells/tissues.