Vox Sanguinis International Forum on platelet cryopreservation: Summary (original) (raw)

The demand for platelets continues to rise, outstripping supply worldwide. In higher-income countries, cancer patients remain platelet transfusion dependent for extended periods, which leads to sporadic and chronic regional shortages that are secondary to uncontrolled fluctuations in supply. In less-developed countries, the supply to demand ratio is critical for obstetric haemorrhage, trauma and medical patients. All countries, however, share the difficulty in providing platelets to rural areas or in support of troops in remote military theatres. Alternatives to conventional 5-to 7-day room temperature-stored platelets are needed. Cryopreservation of platelets is likely the best alternative to balance the supply and demand for platelets in cities and less accessible areas. Cryopreserved platelet units (CPP) can be shipped on dry ice and stored for 2 years or more in mechanical freezers or using liquid nitrogen [1]. This controlled supply may be used as a backup to liquid units in well-stocked hospitals, or as the sole source of platelets in remote or underserved settings. Cryopreserved units can be stockpiled for natural disasters, or special HLA-or HPA-selected units may be stored for patients who are refractory to platelet transfusions due to antibodies. In addition, cryopreservation reduces the risk of septic transfusion reactions, as bacteria will not proliferate under these conditions. Cryopreservation of platelets has been available since the 1970s, when Valeri published his original method for storing platelets in 6% dimethyl sulphoxide (DMSO) at-80°C [2]. Subsequent work led to an improved 'no-wash' method, which removed the DMSO prior to freezing, thus allowing for easier post-thaw utilization [1]. While other methods for cryopreservation have been published [3, 4], most data on CPPs in vitro characteristics, storage duration, autologous survival/recovery, clinical safety and efficacy have been developed using the 'no-wash' approach. Extensive in vitro characterization has been performed using CPP resuspended in plasma, saline or platelet additive solutions. These studies have shown that post-thaw platelets, when compared to liquid platelets, are partially activated, contain a distinct microparticle population and