Platelet storage media.

Platelet additive solutions (PASs) can be used as a substitute for plasma for the storage of platelet concentrates (PCs) in order to recover plasma for other purposes, to avoid transfusion of large volumes of plasma to patients, to improve storage conditions, and to make possible photochemical treatment for viral inactivation of PCs. The effects on platelet metabolism associated with different factors and compounds in PAS are only partly known. Available studies suggest that: (1) The presence of glucose in the platelet storage medium during the entire storage period is necessary for platelet metabolism. (2) Acetate is used as a substrate for platelet metabolism reducing production of lactate by platelets. By formation of bicarbonate, it maintains stable pH levels during storage. (3) The fall in pH can be rapid in PAS-containing media, due to the very limited buffering capacity of PAS compared with that of plasma. (4) Platelets stored in PAS at a citrate concentration of 8 mmol/l produce only half the quantity of lactate as that of platelets at 14-26 mmol/l of citrate. (5) Free fatty acids from plasma can be used as substrate for platelet metabolism and are supposed to be made available by the hydrolysis of plasma triglycerides. (6) For apheresis PCs with ACD anticoagulant, the presence of phosphate in PAS seems to be a critical factor to avoid low adenine nucleotide levels during storage. The results of available studies suggest that PAS for storing platelets has a great potential for wide use in transfusion medicine. A number of interesting questions regarding the effects of different compounds in PAS are still to be answered. It is expected that answers to these questions will be provided over the next few years.