PB0893 - Storage of apheresis platelets in lipaemic plasma affects aspects of platelet function and surface receptor expression

Background: Lipaemia in blood donations is typically caused by consuming a high fat meal prior to donating, metabolic disorders, or medication. The visual appearance of lipaemic platelet concentrates often raises questions concerning safety and quality, hence they are often discarded.

Aims: As there is little data regarding the quality of platelets stored in lipaemic plasma, this was investigated.

Methods: Double apheresis platelet components were pooled, centrifuged and resuspended in 70% SSP+/30% plasma, either control (non-lipaemic) and moderately lipaemic plasma (n=5), or non-lipaemic and severely lipaemic plasma (n=6). Plasma was graded for extent of lipaemia based on opacity. Platelet concentrates were stored for 7 days at 20-24°C with agitation. Platelet metabolism, mitochondrial membrane polarisation (TMRE), activation and function were measured. Data were analysed using a two-way repeated measures ANOVA.

Results: Storage of platelets in moderately and severely lipaemic plasma had no effect on platelet concentration, mean platelet volume, pH, glucose consumption or lactate production. Mitochondrial membrane depolarisation was significantly higher in platelets stored in moderately (p=0.001) and severely lipaemic plasma (p=0.037). Storage in lipaemic plasma had no effect on phosphatidylserine exposure, cell surface CD62P and soluble CD62P release. However, CD62P expression following TRAP-6 was blunted in platelets stored in moderately and severely lipaemic plasma (p=0.009 and p=0.002) respectively. Storage in moderately and severely lipaemic plasma reduced surface GPIbα (p=0.015 and p=0.008), GPVI (p=0.027 and p=0.008) and CD61 (p=0.007). Most viscoelastic parameters (thromboelastography) were not significantly different. Release of PF4 was increased (p=0.0058) in platelets stored in severely lipaemic plasma (p=0.007).

Conclusion(s): Storage of platelets in lipaemic plasma does not affect platelet metabolism, but differentially affects platelet receptor expression and their ability to respond to platelet agonists. These changes may be reduce their efficacy upon transfusion, warranting further investigation.