Calcium chelation: a novel approach to reduce cryopreservation-induced damage to frozen platelets.

BACKGROUND: Cryopreserved platelets are phenotypically and functionally different to conventionally stored platelets. Calcium may be released from internal stores during the freeze-thaw process, initiating signaling events which lead to these alterations. It was hypothesized that the addition of a calcium chelator prior to cryopreservation may mitigate some of these changes. METHODS: Buffy coat-derived platelets that had been pooled and split were tested fresh and following cryopreservation (n = 8 per group). Platelets were cryopreserved using 5%-6% dimethylsulfoxide (DMSO) or were supplemented with increasing concentrations of the internal calcium chelator, BAPTA-AM (100 µM, 200 µM, or 400 µM), prior to storage at -80°C. RESULTS: Supplementation of platelets with BAPTA-AM prior to freezing improved platelet recovery in a dose response manner (400 µM: 84 ± 2%) compared to standard DMSO cryopreserved platelets (70 ± 4%). There was a loss of GPIbα, GPVI, and GPIIb/IIIa receptors on platelets following cryopreservation, which was rescued when platelets were supplemented with BAPTA-AM (400 µM: p < 0.0001 for all). Platelet activation markers, such as phosphatidylserine and P-selectin, were externalized on platelets following cryopreservation. However, the addition of BAPTA-AM significantly reduced the increase of these activation markers on cryopreserved platelets (400 µM: p < 0.0001 for both). Both cryopreserved platelet groups exhibited similar functionality as assessed by thromboelastography, forming clots at a faster rate than fresh platelets. CONCLUSIONS: This study demonstrates that calcium plays a crucial role in mediating cryopreservation-induced damage to frozen platelets. The addition of the calcium chelator, BAPTA-AM, prior to cryopreservation reduces this damage.

Postdonation iron replacement for maintaining iron stores in female whole blood donors in routine donor practice: results of two feasibility studies in Australia.

BACKGROUND: Iron deficiency represents a risk to donor health and the blood supply. Efficacy trials indicate that postdonation iron replacement improves iron stores but they do not account for complexities of implementation in the routine collection context. We therefore conducted two prospective feasibility studies in Australian donor centers. STUDY DESIGN AND METHODS: In both studies we recruited female donors between 18 and 45 years who had made at least one donation in the previous 12 months. In READ (replacement advice), female donors were given a recommendation to self-procure postdonation iron. In DIRECT (donor iron replacement), donors were provided with a course of iron supplements. Donors could return to donate at their discretion and were surveyed after the recruitment visit and again toward the end of the 13-month follow-up. Donor uptake, adverse effects, effectiveness in maintaining iron stores, and workflow impact were assessed. RESULTS: We recruited 1404 (70.9% of invited) donors to READ and 768 (53.2% of invited) to DIRECT. READ and DIRECT extended predonation interviews by 1 and 5 minutes, respectively. Among participants, 44 and 88% took iron in READ and DIRECT, respectively. Adverse effects were common but usually mild. READ failed to maintain iron stores in the population, but was effective in donors who consumed more than 75% of the recommended dose. DIRECT was effective in preventing declines in ferritin concentration. CONCLUSION: Trade-offs between cost, complexity, uptake, and effectiveness must be considered in the implementation of postdonation iron supplementation.