Both acute delivery of and storage with magnesium sulfate promote cold-stored platelet aggregation and coagulation function

BACKGROUND: The platelet storage lesion causes loss of function and viability over time. A new paradigm for platelet storage is desired to enable safer, more effective transfusions while reducing waste. We hypothesized that repletion of Mg²⁺, which is chelated by citrate anticoagulant, could reduce platelet storage lesion severity when given in conjunction with storage at a refrigerated temperature. METHODS: Apheresis platelet units were collected from healthy donors and stored at 22-C or 4-C. On Days 0, 2, 4, and 8, samples were collected for analyses of receptor-mediated aggregation, coagulation, adhesion to collagen under flow, and viability. In the first series, samples were given an acute dose ofMgSO₄ before testing; in the second series, storage bagswere supplemented with 0-, 3-, or 6-mMMgSO4. RESULTS: Acutely delivered MgSO₄ induced a more rapid coagulation time in apheresis platelets, further enhanced by storage at 4-C. Platelet adhesion to a collagen surfacewhile exposed to arterial shear rates (920 sj1) was enhanced by MgSO₄ supplementationVacute MgSO₄ had a large effect on adhesion of fresh platelets, which diminished more rapidly in 22-C samples, while storage with MgSO₄ showed significant benefits even out to Day 4 at both temperatures. Although 4-C storage improves the longevity of platelet aggregation responses to agonists, MgSO4 supplementation did not change those responses. CONCLUSION: Acute MgSO₄ reduces clot time likely through the transient increase of free Ca²⁺. Limited differences between platelet function in acute delivery of and storagewith MgSO₄ diminish the possibility thatMg-inducedmetabolic inhibition of platelets synergizeswith 4-C storage. Regardless,magnesium supplementation to platelets is an exciting possibility in transfusion because the adhesion response of 22-C-stored platelets onDay 4 is significantly enhancedwhen storedwith 6-mMMgSO₄.