Method of lyophilizing platelets by incubation with high carbohydrate concentrations and supercooling prior to freezing

A process and medium are disclosed for the lyophilization of platelets. During lyophilization, carbohydrate-load platelets are supercooled while suspended in a buffer solution including a biocompatible polymer that serves to preserve the structure of the platelets. The supercooled platelets are then frozen at a temperature below the glass transition temperature of the suspension. A vacuum is placed on the frozen suspension to remove most of the water therefrom. Then, the temperature of the platelets is increased to the supercooled temperature while the vacuum is maintained. After being sealed under vacuum, the lyophilized platelets may be reconstituted to form viable, transfusable platelets. The reconstituted platelets have a high aggregation index, retain normal agglutination and degranulation capability, and are able to participate in clot formation.