Storage of Platelets in Additive Solutions: Effects of Phosphate

Abstract

Background and Objectives: In a previous study, low adenine nucleotide levels and a reduced rate of glycolysis were found in platelet concentrates (PCs) prepared by apheresis and stored in a platelet additive solution (PAS). Our objective was to investigate whether the use of PAS with or without phosphate can influence platelet metabolism in a similar way. Materials and Methods: The in vitro effects of storage in either plasma or a PAS (T-Sol or PAS-III, both containing citrate, acetate and sodium chloride, PAS-III containing also phosphate) of buffy-coat-de rived pooled platelet concentrates (BC PCs) and apheresis platelets were investigated. The use of PAS implies inclusion of some plasma (20 or 35%). Paired studies over 7 days included investigation of cell counts, pH, PO2, PCO2, bicarbonate, glucose, lactate, adenine nucleotides, and extracellular adenylate kinase activity as a marker for disintegration of platelets. The expected concentration of phosphate in T-Sol is 0.6–1.8 mmol/I (with CPD plasma) and 0.2–0.6 mmol/l (with ACD plasma), and in PAS-III, 15–25 mmol/I (calculated values). Results: BC-PCs were compared during storage in 35% CPD plasma and 65% PAS (T-Sol or PAS-III) (experiment 1), or alternatively 20% CPD plasma and 80% PAS (T-Sol or PAS-III) (experiment 3). In both studies, PAS-III shows similar and significantly higher rates of glycolysis in terms of consumption of glucose (0.06 vs. 0.04 mmol/day/1011 platelets) and production of lactate (0.11 vs. 0.07 mmol/day/1011 platelets) compared with T Sol. Levels of pH and adenine nucleotides were similar when 35% plasma was used. With only 20% plasma, significantly higher levels of adenine nucleotides were found with PAS-III compared to T-Sol. The storage of apheresis platelets in 35% ACD plasma and 65% PAS (either, T-Sol or PAS-III (experiment 5) gave significantly higher values for PAS-III compared to T-Sol with regard to consumption of glucose (0.08 vs. 0.06 mmol/day/1011 platelets), production of lactate (0.14 vs. 0.11 mmol/day/1011 platelets) and adenine nucleotide levels. Conclusion: With respect to apheresis PCs stored in media containing ACD plasma, our results suggest that the differences found are related to the concentration of phosphate. The results for BC-PCs stored in media containing CPD plasma suggest that PAS-III is preferable to T-Sol as the PAS at plasma concentrations below 35%. The mechanism behind the phenomena observed with BC-PCs is not known.