Hemostatic function of apheresis platelets stored at 4°C and 22°C

Abstract

Introduction: Platelet refrigeration decreases the risk of bacterial contamination and may preserve function better than standard-of-care room temperature (RT) storage. Benefits could include lower transfusion-related complications, decreased costs, improved hemostasis in acutely bleeding patients, and extended shelf life. In this study, we compared the effects of 22°C and 4°C storage on the functional and activation status of apheresis platelets.

Methods: Apheresis platelets (n = 5 per group) were stored for 5 days at 22°C with agitation (RT) versus at 4°C with agitation (4°C + AG) and without (4°C). Measurements included platelet counts, mean platelet volume, blood gas analytes, aggregation response, thromboelastography, thromboxane B2 and soluble CD40 ligand release, activation markers, and microparticle formation.

Results: Sample pH levels were within acceptable limits for storage products (pH 6.2-7.4). Platelet glucose metabolism (P < 0.05), aggregation response (adenosine diphosphate: RT 0; 4°C + AG 5.0 ± 0.8; 4°C 5.6 ± 0.9; P < 0.05), and clot strength (maximum amplitude: RT 58 ± 2; 4°C + AG 63 ± 2; 4°C 67 ± 2; P < 0.05) were better preserved at 4°C compared with RT storage. Refrigerated samples were more activated compared with RT (P < 0.05), although thromboxane B2 (P < 0.05) and soluble CD40 ligand release (P < 0.05) were higher at RT. Agitation did not improve the quality of 4°C-stored samples.

Conclusions: Apheresis platelets stored at 4°C maintain more viable metabolic characteristics, are hemostatically more effective, and release fewer proinflammatory mediators than apheresis platelets stored at RT over 5 days. Given the superior bacteriologic safety of refrigerated products, these data suggest that cold-stored platelets may improve outcomes for acutely bleeding patients.

Conflict of interest statement

Conflict of interest The authors declare that they have no conflicts of interest relevant to this manuscript.

Figures

Figure 1

Aggregation of platelets without (A, B, C) and with RBCs (D, E, F) when stimulated with (A, D) ADP, (B, E) Collagen, and (C, F) TRAP. Bar graphs D, E, and F are comparisons between Baseline versus Day 5 RT and 4C AP. Treatment conditions are represented as follows: RT = ; 4C = ; 4C+AG = . Area under the curve (AUC) are represented as mean ± SEM. Differences compared to baseline (*), compared to RT (†), and between samples without RBCs versus with (δ) are shown if results from both the one-way ANOVA for repeated measures and the post hoc Bonferroni test comparisons are significant (P < 0.05). (Note: - RBC AUC values are higher in graphs D-F compared to A-C because aggregation was measured over 12 minutes instead of 6.)

Figure 2

Measurement of clot properties by thromboelastography. (A) R time; (B) K time; (C) α angle; (D) Maximum amplitude. Treatment conditions are represented as follows: RT = ; 4C = ; 4C+AG = . Data are represented as mean ± SEM. Differences from Baseline (*) and between treatment groups (†) are shown if results from both the one-way ANOVA for repeated measures and the post-hoc Bonferroni test comparisons are significant (P<0.05).

Figure 3

Estimation of surface receptor levels by flow cytometry. (A) P-Selectin; (B) lactadherin binding (PS exposure); (C) CD40L expression; (D) Microparticle release; and (E) GP Ibα. Treatment conditions are represented as follows: RT = ; 4C = ; 4C+AG = . The expression levels are represented as mean±SEM. Differences from Baseline (*) and between treatment groups (†) are shown if results from both the one-way ANOVA for repeated measures and the post-hoc Bonferroni test comparisons are significant (P<0.05).

Figure 4

ELISA quantification of soluble factors released by platelets. (A) TxB2, and (B) sCD40L. Treatment conditions are represented as follows: RT = ; 4C = ; 4C+AG = . The concentrations are represented as mean ± SEM. Differences from Baseline (*) and between treatment groups (†) are shown if results from both the one-way ANOVA for repeated measures and the post-hoc Bonferroni test comparisons are significant (P<0.05).