Freeze-drying of human red blood cells: Influence of carbohydrates and their concentrations

Lyophilization (freeze-drying) is one potential approach for long-term preservation of biological materials such as human platelets and erythrocytes (red blood cells; RBCs). It has advantages in comparison with conventional cryopreservation, including the elimination of the need for storage at low temperatures (low cost), and reduced weight (easy for storing and shipping). However, recovery of RBC viability and function after lyophilization has been generally low, as detailed in previous reports and patents. Many factors may influence the recovery of cell viability during the freeze-drying process. Such factors include the lyoprotectants (sugars, polymers), the operating condition during the drying process (primary and secondary drying), and the rehydration process. In this study, the influence of the sugars (as lyoprotectants) on the RBC recovery after lyophilization has been investigated. Cell integrity, hematocrit (HCT), and hemoglobin content were used to evaluate the recovery rate after lyophilization and rehydration. It was revealed that glucose is the most effective sugar amongst those tested, and the concentration of glucose was very sensitive and critical to the survival of red blood cells during lyophilization.