Blood-Derived Extracellular RNA and Platelet Pathobiology: Adding Pieces to a Complex Circulating Puzzle

The interaction between blood cells and disease has continued to grow both more complex and increasingly intriguing. Once thought to be static populations, circulating blood cells are now known to interact and communicate in ways far beyond the singular processes historically attributed to each population. A primary example is the platelet, an anucleate cell with a traditional role in hemostasis and thrombosis. The platelets’ defined biological roles have expanded exponentially over the last decade to include immunity, inflammation, and mediation of oncogenesis.1 Platelets, although anucleate, contain a wealth of transcriptomic information. When viewed from the perspective of a large population analysis, platelets demonstrate wide diversity, important patterns, including association with obesity and diabetes mellitus, and distinct expression profiles as compared with white cells.2 Platelets’ ability to participate in diverse systemic responses has been elucidated by our growing understanding of their contents and the revelation of their capacity to share these contents. Platelets are now known to horizontally transfer RNA, traffic pathogens, and regulate physiological and pathophysiological processes far beyond hemostasis.3,4 Article, see p 420 As part of our expanded understanding of platelet transfer processes, we have begun to appreciate the ability of the platelet to transfer transcripts, including mRNA and microRNA (miRNA), to recipient cells with functional implications (Figure).4,5 The observation that platelets possess the capacity to transfer cytosolic RNA suggests a new function for platelets in the regulation of vascular homeostasis.4 The processes involved …