Statin Islands and PPAR Ligands in Platelets

Abstract

Platelets are formed from megakaryocytes, where they are released into the blood stream via proplatelet extensions into the blood vessel lumen.1 Being the most numerous “white blood cell” and despite lacking a nucleus, they are highly complex cells containing a surface connected canalicular and tubular system, mitochondria, granules, and bioactive mediators. Platelets are well-known for their seminal role in hemostasis and thrombosis.2 Aside from these physiological functions, new roles for platelets are being identified in unwanted thrombosis that occurs in diabetes and cancer. See accompanying article on page 706 Platelets have been thought of as a kind of “cellular island” owing to their traditional role as mere hemostatic plugs. However, recent studies show that platelets are much more than simple cellular elements involved in sealing wounds. They are now recognized as highly interactive cells that influence both bone marrow–derived and nonbone marrow–derived cells.2 They accomplish this by their ability to release and synthesize a host of mediators that influence other cell types. For example, platelets produce a variety of important cytokines such as TGFβ and lipid mediators such as prostaglandins that stimulate many types of cells. Platelets also express and release CD40 ligand (CD154), which can quickly activate CD40-bearing cells such as …