Washington ? A dab of sugar may double the shelf life of blood platelets, a lifesaving clotting component that is in chronic short supply because of spoilage.

Harvard University researchers report this week in the journal Science that laboratory tests show that putting a small amount of galactose, a type of sugar, into isolated platelets allows the blood components to be refrigerated and usefully preserved for at least 12 days.

That more than doubles the shelf life of the current routine, which is to store the platelets at room temperature for only five days. Because of spoilage, more than 25 percent of all platelets must be discarded. Extending the shelf life of platelets would significantly improve supply, experts say.

Platelets play a central role in forming blood clots, an essential action to prevent uncontrolled bleeding in the body. Platelets are made in the bone marrow and typically live 10 to 12 days in the bloodstream, so the body has to constantly make more platelets to replace those that die.

Many cancer and leukemia patients are unable to naturally replace their platelets. Aggressive chemotherapy used to treat many cancers can cause the bone marrow to shut down, leaving these patients, at least temporarily, without natural platelet replacement.

As a result, about 2 million patients a year require platelet transfusions to avoid possibly lethal, uncontrolled bleeding. To get enough platelets for a single treatment, blood centers have to process four to six pints of blood.