Freeze-drying of human platelets: Influence of intracellular trehalose and extracellular protectants

Freeze-drying is an ideal alternative for long-term preservation of platelets in blood banks. Intracellular trehalose is believed to be an effective lyoprotectant for preserving cells during freeze-drying. In this study, 13 mM intracellular trehalose was loaded into human platelets through fluid-phase endocytosis pathway. Bovine serum albumin and trehalose were used as extracellular protectants. The effects of intracellular trehalose and extracellular protectants on freeze-dried platelets were studied respectively. The results showed 13 mM intracellular trehalose was beneficial to freeze-dried human platelets, but only slightly enhanced the protection afforded by extracellular protectants. Loaded with 13 mM intracellular trehalose, platelets were freeze-dried in a formulation of 1% bovine serum albumin and 1% trehalose, 40 days later, the survival rate of rehydrated platelets was about 85%, the morphology of rehydrated platelets was intact and the aggregation percentage with thrombin (1 U/ml) was 97.3%.