Metabolic and functional changes in apheresis platelets during cold and room temperature storage: A pilot in vitro study

Background: Platelet concentrates are conventionally stored at room temperature (20–24°C), which preserves platelet viability but is associated with progressive metabolic deterioration and increased risk of bacterial contamination. Cold storage (4°C) has re-emerged as a potential alternative strategy; however, its impact on platelet metabolism, activation, and hemostatic function during extended storage remains incompletely characterized. Aim: To evaluate metabolic and functional changes in apheresis platelet concentrates during storage under cold and room temperature conditions. Methods: Apheresis platelet concentrates obtained from two healthy donors were stored in platelet additive solution with or without pathogen inactivation. Platelets were stored at 20–24°C (up to 7 days) or 4°C (up to 21 days). Metabolic parameters (pH, glucose, lactate), activation markers (CD62P, Annexin V), and hemostatic function (thromboelastography) were assessed at predefined time points. Because this was an exploratory pilot study with two independent donors, the analysis was primarily descriptive and no inferential statistical comparisons were performed. Results: Cold storage was associated with slower glucose consumption and lower lactate accumulation during the early storage period, accompanied by a progressive decline in pH during prolonged storage. Cold-stored platelets showed increased CD62P expression and phosphatidylserine exposure, as reflected by Annexin V binding, particularly during prolonged storage. Thromboelastographic analysis showed relative preservation of clot strength during the first 7 days of cold storage, with mean maximum amplitude values remaining approximately 72–79 mm during this period. Conclusion: Cold storage was associated with distinct metabolic and functional changes, including slower early glucose consumption, lower lactate accumulation, increased platelet activation and phosphatidylserine exposure, and relative preservation of clot strength during the first 7 days. Given the exploratory design and limited sample size, these findings should be considered preliminary and require confirmation in larger experimental and clinical studies.