Cold-stored platelet units often form clumps during storage that make them unusable, and a recently published study shows this could be tied to the platelet donor rather than how the units are shipped or handled.
The research, published in Vox Sanguinis, examined 79 platelet units collected for a cardiac surgery trial and stored cold for up to 14 days. More than half, precisely 57%, developed visible clumps, known as aggregates, that would normally lead the units to be discarded. These clumps were associated with differences in age, sex and blood type.
Most platelets are stored at room temperature, where bacteria can grow and units last only a few days before they must be discarded. Keeping platelets cold slows spoilage, allowing them to be stored longer, therefore reducing waste and easing ongoing shortages.
Platelet transfusions are part of care for many patients, including newborns with fetal and neonatal alloimmune thrombocytopenia (FNAITFetal and neonatal alloimmune thrombocytopenia A rare condition in which a mother’s immune system attacks fetal platelets, leading to dangerously low platelet levels before and/or after birth.), a condition in which a baby can be born with a dangerously low platelet countPlatelet count A measure of how many platelets are in the blood. FNAIT is characterized by severely reduced counts in a fetus or newborn.. Understanding what makes cold-stored platelets usable for longer periods, therefore, has broad relevance for the blood supply.
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The researchers found that the time units spent in shipping or in the hospital laboratory did not differ between those that clumped and those that did not, suggesting the problem starts with the donor.
Platelets from female donors and from donors with type A blood were more likely to clump, while platelets from male donors, donors with type O blood, and donors aged 60 and older were less likely to do so.
Researchers also evaluated 2 blood proteins that play a role in aggregate formation. Units that clumped had higher levels of von Willebrand factor, a protein that helps platelets stick together, and lower levels of thrombomodulin, a protein that helps keep clotting in check.
However, when the team directly altered von Willebrand factor levels in laboratory and animal experiments, it did not reliably trigger or prevent clumping, implicating that several factors act together.
The results raise the possibility that donor characteristics could one day help blood centers predict which units are most likely to stay usable. Still, the authors noted clear limits: the donor group was small and uneven, mostly male, type A and Rh-positive, which makes the subgroup patterns less certain, and every unit traveled the same long shipping route.
They called for “larger and more balanced cohorts” to confirm the effects tied to donor sex, age and blood type.
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