Editorial

Platelets, the smallest blood cells, without nucleus, are present in peripheral blood with the mission of maintaining hemostasis [1]. When the quantity or quality of platelets is reduced or dysregulated by acquired or genetic causes, bleeding risk increases [2,3]. To overcome this situation, platelet transfusion is indicated [4]. This special issue of Platelets covers different topics related with platelet transfusion and platelet products.

Firstly, Smethurst & Cardigan [5] perform an excellent update on platelet transfusion, giving the readers an elegant vein-to-vein travel discussing not only wide variation in platelet donors, but also challenges with current platelet preparation methods, storage conditions, and platelet transfusion to different groups of recipients. Moreover, these authors wonder if several aspects considered today as a dogma need to be re-visited in view of new evidence. For example, liberal platelet transfusion strategy may not be justified due to safety concerns and assessment of current platelet transfusion endpoints should be changed according to platelet transfusion with therapeutic or prophylactic aim.

Ferrer-Marín & Sola-Visner [6] enlighten readers with the concept of “developmental haemostasis.” Platelets derived from cord blood and neonatal platelets in peripheral blood are less reactive to different platelet agonists when compared with adult platelets. However, these findings do not mean that there is a “neonatal thrombocytopathy.” Platelets readers will appreciate this update of the concept of whole hemostasis. Authors also focus on new data from three recent randomized controlled trials (RCT). The PlaNeT-2 study compared a liberal prophylactic platelet transfusion strategy (platelet count <50×10⁹/L) with a restrictive prophylactic platelet transfusion strategy (platelet count <25×10⁹/L). Remarkably, liberal transfusion was associated with higher incidence of death or major bleeding when compared with restrictive transfusion (26% versus 9%, 7% absolute-risk reduction). Overall, these RCTs strongly support data from observational studies regarding the more restrictive use of platelet transfusions in this population. Lastly, the authors provide clear and practical platelet transfusion guidelines for neonates.

Cid & Lozano [7] update the issue of pathogen inactivation of platelet products, which is a widely used strategy to prevent transfusion transmitted infection by platelet transfusion. Additional recognized benefits of this procedure include inactivation of residual leukocytes, to prevent transfusion-associated graft-versus-host disease, and prolongation of storage length from 5 to 7 days, with notable benefit in blood banking management of inventory and reduction of the number of outdates platelets. On the contrary, pathogen inactivation may have a deleterious effect on the clinical efficacy of platelets. Data from clinical studies assessing this point are discussed in this review.

Jimenez-Marco et al. have reviewed the topic of cold storage and cryopreservation of platelets [8]. These types of platelets have been available for decades, but their clinical use either abandoned or is very scarce. However, cold storage and cryopreservation of platelets has received renewed interest from both blood suppliers and transfusion practitioners. Indeed, storage of platelets at room temperature is associated with short product shelf life and significant risk of bacterial contamination, and cold storage and cryopreservation of platelets are attractive approaches to overcome these challenges. Moreover, refrigerated and frozen platelet products may provide more rapid and effective hemostatic responses in patients with active bleeding, and could therefore became the products of choice in the context of therapeutic platelet transfusion. These alternative platelet products may also offer logistic advantages for timely and urgent availability of platelets in remote areas and military operational fields. The last section in this review refers to novel strategies for combining cryopreservation, room and cold storage, and pathogen inactivation methods.

Luc et al. [9] introduce new approaches to succeed in dealing with current challenges in platelet transfusion practices, focusing in designing artificial platelets, either with adhesion or aggregation properties, or both. The summary presented by authors in a Table is very comprehensive and readers will find it a valulable reference.

To sum up, this Platelets Special Review Series provides an informative and comprehensive compendium of articles reviewing relevant aspects in platelet transfusion practice.

Disclosure Statement

No potential conflict of interest was reported by the author(s).