Chapter 5.5: Temperature Stability of Poly-[hemoglobinsuperoxide dismutase-catalase-carbonic anhydrase] in the Form of a Solution or in the Lyophilized Form During Storage at –80°C, 4°C, 25°C and 37°C or Pasteurization at 70°C
The text and figures of this paper were reproduced from (Guo et al., 2015) with copyright permission.
Polyhemoglobin-superoxide dismutase-catalase-carbonic anhydrase (poly-[Hb-SOD-CAT-CA]) contains all three major functions of red blood cells (RBCs) at an enhanced level. It transports oxygen, removes oxygen radicals and transports carbon dioxide. Our previous studies in a 90-minute 30 mm Hg MAP-sustained hemorrhagic shock rat model showed that it was more effective than blood in the lowering of elevated intracellular PCO2, recovery of ST-elevation and histology of the heart and intestine. This paper analyzes the storage and temperature stability. The allowable storage time for RBCs is about 1 day at room temperature and 42 days at 4°C. Also, RBCs cannot be pasteurized to remove infective agents like HIV and Ebola. PolyHb can be heat sterilized and can be stored for a year even at room temperature. However, poly-[Hb-SOD-CAT-CA] contains both Hb and enzymes, and enzymes are particularly sensitive to storage and heat. We thus carried out studies to analyze its storage stability at different temperatures and heat pasteurization stability. The results of the storage stability show that lyophillization extends the storage time to a year at 4°C and 40 days at room temperature (compared to 42 days and 1 day, respectively, for RBCs). After the freeze-dry process, the enzyme activities of poly-[SFHb-SOD-CAT-CA] was 100 ± 2% for CA, 100 ± 2% for SOD, and 93 ± 3.5% for CAT. After heat pasteurization at 70°C for 2 hours, lyophilized poly-[Hb-SOD-CAT-CA] retained good enzyme activities of CA (97 ± 4%), SOD (100 ± 2.5%) and CAT (63.8 ± 4%). More CAT can be added during the crosslinking process to maintain the same enzyme ratio after heat pasteurization. Heat pasteurization is possible only for the lyophilized form of poly-[Hb-SOD-CAT-CA] and not for the solution. It can be easily reconstituted by dissolving it in suitable solutions that continue to have good storage stability (though less than that for the lyophilized form). According to the P50 value, poly-[SFHb-SOD-CAT-CA] retains its oxygen-carrying ability before and after long-term storage.
