The expression levels of platelet adhesive receptors in PRP derived platelet concentrates during storage

Major platelet adhesive receptors that contribute significantly to thrombus formation include platelet receptor glycoprotein Ibα (GPIbα) of the GPIb-IX-V complex and platelet glycoprotein VI (GPVI). GPIbα plays a crucial role in platelet tethering to sub-endothelial matrix, which initiates thrombus formation at arterial shear rates, whereas GPVI is critically involved in platelets firm adhesion to the site of injury regardless of shear condition. During storage, platelets experience some changes that deleteriously affect the expression levels of platelet receptors, which in turn can alter platelet functional behaviors. Considering the important roles of GPIbα and GPVI in platelet adhesion, it seems that any dramatic changes in the expression levels of these receptors can influence adhesive function of transfused platelets. Thereby examining GPIbα and GPVI expression during the storage of platelet concentrates may provide some useful information about the functional quality of these products after transfusion.
In our experimental study, 5 PRP-platelet concentrates were randomly obtained from Iranian Blood Transfusion Organization (IBTO). All the platelet products met the standard quality assessment based on AABB (American Association of Blood Banks) guidelines. Washed platelets were subjected to flowcytometry analysis for the evaluation of GPIbα and GPVI receptor expression in day 1, 3 and 5 after storage. Data were presented as mean fluorescence intensity (MFI) and analyzed by Kruskal-Wallis test with Dunn’s multiple comparison test.
The GPIbα expression on first day (MFI=86±5.9) was reduced three days after storage (MFI= 69±6.9). The expression levels continued to reduce until day 5 in which GPIbα expression was markedly decreased to (MFI= 61±7.7) (P= 0.0094). GPVI expression on the days 1, 3 and 5 after storage were 20.6±3.3, 24±2.5 and 14±4.9, respectively. The results showed a significant decrease of expression on day 5, compared to that in day 3 after storage (P= 0.0213).
Our study showed significant decreases in the expression of platelet receptors GPIbα and GPVI after 5 days storage, suggesting a major defect in adhesive function of platelets during this term.