THE REHYDRATION INJURY STUDY OF FREEZE-DRIED RED BLOOD CELLS DURING REHYDRATION

摘要

The injuries caused during rehydration, including membranes phase transition and volume response, are very important factors that lead to low recovery rate of freeze-dried red blood cells after rehydration. During rehydration, the membranes of lyophilized red blood cells maybe suffer phase transition because membranes with different water contents have different phase transition temperatures. At the same time, the osmolality of the environmental solution and the volumes of the cells change greatly. If the rehydration temperature and procedures are not optimum, the injuries caused by the leakage of intracellular substances and extreme volume response of the cells will occur. In order to explore the phase transition of the membranes of lyophilized red blood cells, the ghosts of red blood cells were prepared and freeze dried. Their phase transition temperatures were measured to be about 10°C and 32-34°C, with Differential Scanning Calorimeter (DSC). The membrane's phase transitions of freeze dried red blood cells before, during and after rehydration were analyzed. In order to avoid the injury caused by the phase transitions of the membranes, the rehydration temperature should be above 34°C. In experiments, the red blood cells were freeze-dried and rehydrated at different temperatures. The rehydration temperature resulting in highest cell recovery rate was 37°C, which was consisted with the injury analysis of phase transitions. On the other hand, in order to explore the volume response injury mechanism, an alternative method to study the volume response of lyophilized cells was provided. Under the Environmental Scanning Electrical Microscopy (ESEM), the changes of the cell sizes during rehydration could be obtained. The rehydration velocity could be controlled by changing the relative humidity in ESEM. The results imply that, at the beginning stage of rehydration the thickness and diameter of cells increase firstly, and then decrease. The respond magnitude and capacity of the thickness are greater than those of diameter. The hemolysis will occur when the volume excursion becomes serious. According to the results of the experiments, it is very important to control the rehydration conditions to avoid the hemolysis caused by membrane phase transitions and extreme volume response of the lyophilized red blood cells. This work implies the injury mechanism of rehydration of freeze-dried red blood cells caused by phase transitions and cell volume response. It's also helpful for the freeze-drying preservation of other cells.