Human platelets loaded with trehalose survive freeze-drying

Human blood platelets are stored in blood banks for 5 days, after which the y are discarded, by Federal regulation. This short lifetime has led to a ch ronic shortage of platelets, a problem that is particularly acute in immuno suppressed patients, such as those with AIDS. We report here that platelets can be preserved by freeze-drying them with trehalose, a sugar Found at hi gh concentrations in organisms that naturally survive drying. We suggest th at these findings will obviate the storage problem with platelets. Trehalos e is rapidly taken up by human platelets at 37 degreesC, with loading effic iencies of 50% or greater. Fluid-phase endocytosis plays an important role in this efficient uptake of trehalose, but other mechanisms may also be inv olved. Trehalose-loaded platelets were successfully freeze-dried, with exce llent recovery of intact platelets. Rehydration From the vapor phase led to a survival rate of 85%. The response of these platelets to the agonists th rombin (1 U/ml), collagen (2 mug/ml), ADP (20 muM), and ristocetin (1.6 ms/ ml) was almost identical to that of fresh, control platelets. Analysis by F ourier transform infrared spectroscopy demonstrated that the membrane and p rotein components of trehalose-loaded platelets after freeze-drying, prehyd ration, and rehydration were remarkably similar to those of fresh platelets . (C) 2001 Academic Press.