Divalent magnesium restores cytoskeletal storage lesions in cold-stored platelet concentrates

Abstract

\n Cold storage of platelet concentrates (PC) has become attractive due to the reduced risk of bacterial proliferation, but in vivo circulation time of cold-stored platelets is reduced. Ca2+ release from storage organelles and higher activity of Ca2+ pumps at temperatures\u2009<\u200915°C triggers cytoskeleton changes. This is suppressed by Mg2+ addition, avoiding a shift in Ca2+ hemostasis and cytoskeletal alterations. We report on the impact of 2–10 mM Mg2+ addition on cytoskeleton alterations of platelets from PC stored at room temperature (RT) or 4°C in additive solution (PAS), 30% plasma. Deformation of platelets was assessed by real-time deformability cytometry (RT-DC), a method for biomechanical cell characterization. Deformation was strongly affected by storage at 4°C and preserved by Mg2+ addition\u2009≥\u20094 mM Mg2+ (mean\u2009±\u2009SD of median deformation 4°C vs. 4°C\u2009+\u200910mM Mg2+ 0.073\u2009±\u20090.021 vs. 0.118\u2009±\u20090.023, p\u2009<\u20090.01; n\u2009=\u20096, day 7). These results were confirmed by immunofluorescence microscopy, showing that Mg2+ ≥ 4mM prevents 4°C storage induced cytoskeletal structure lesion. Standard in vitro platelet function tests showed minor differences between RT and cold-stored platelets. Hypotonic shock response was reduced in cold-stored platelets (45.65\u2009±\u200911.59% vs. RT stored platelets 56.38\u2009±\u200929.36; p\u2009=\u20090.042) but normal at 4°C\u2009+\u200910 mM Mg2+ (55.22\u2009±\u200911.16%, all n\u2009=\u20096, day 1). CD62P expression and platelet aggregation response were similar between RT and 4°C stored platelets, with minor changes in the presence of higher Mg2+ concentrations. In conclusion, increasing Mg2+ up to 10 mM in PAS counteracts 4°C storage lesions in platelets, maintains platelet cytoskeletal integrity and biomechanical properties comparable to RT stored platelets.