Freeze-Drying Blood Platelets for Long-Term Storage

A new method of freeze-drying may allow the long-term storage of blood platelets. Currently, platelets must be stored at room temperature because they activate and clot in the cold.

Scientists from the University of California, Davis (USA), reported in the January 2002 issue of the Journal of Cellular Physiology that chilling causes changes in the outer surface of the platelets' membrane. When the temperature drops, some of the molecules in the membrane, such as cholesterol and sphingomyelin, clump into distinct islands in the membrane called lipid rafts. This phenomenon prevents the long-term storage of platelets under refrigeration. Some proteins attached to the surface, including some that carry signals from the cell surface to the inside, are also collected into these rafts.

The same research team has been exploring ways to store platelets without causing them to activate. They have developed a new process allowing platelets to be freeze-dried and stored for at least a year at room temperature before being reconstituted with water. This information was released March 15, 2002, on the UC Davis website. The researchers were able to cause platelets to take up the sugar trehalose. Trehalose replaces water in the shell around proteins and other large molecules in the cell and seems to protect the structure of these proteins as water is removed by freeze-drying.

The dried platelets may be stored without refrigeration and can be reconstituted after at least a year. The method is currently in clinical trials for use with human and animal blood.




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Univ. of California, Davis