Lyophilized annelid mega-hemoglobin retains its' quaternary structure and oxygen equilibrium properties after room temperature storage for over 6 months

The long-term storage stability and portability of hemoglobin (Hb)-based oxygen carriers are important design criteria in the development of these therapeutics. Lyophilization or storing proteins in a freeze-dried form is known to increase storage lifetime and reduce overall weight. In this study, we lyophilized the extracellular mega-hemoglobin of the annelid Lumbricus terrestris and tested the storage stability at different temperatures and oxygenation conditions. Storage in refrigerated conditions for over 6 months in the presence of N-2 reduced oxidation by 50% while storage at room temperature in the presence of N-2 reduced oxidation by 60%, all while maintaining the structural stability of the mega-hemoglobin. We also demonstrated a reliable strategy to freeze dry Hbs in the presence of a minimally non-reducing disaccharide sugar that could be easily re-solubilized in deionized water. Overall, this study made significant advances towards long term storage stability of oxygen therapeutics for direct applications in transfusion medicine.

Automated summary

This study investigates the long-term storage stability of extracellular mega-hemoglobin from the annelid Lumbricus terrestris and proposes a reliable freeze-drying strategy for re-solubilization. The findings suggest that lyophilization and storage in specific conditions can significantly enhance storage lifetime of hemoglobin-based oxygen carriers.