New α-Granule Biology Reveals How Platelets May Regulate Angiogenesis

Abstract SCI-35

In addition to their “classic” role in hemostasis, platelets are now known to be major contributors in wound healing, tumor growth, and angiogenesis. Stored within the α-granules is an array of angiogenic regulatory proteins, which are deposited by the secretion reaction of surface-activated platelets into the local environment of a tumor or wound. Despite the recognized importance of platelets in regulating new blood vessel growth, our understanding of how platelets modulate the angiogenic response remains unclear. Here, we consider how new α-granule biology may provide insights into how platelets regulate angiogenesis. First, we will present data on a new form of α-granule movement. We will show that actin filament assembly can power the propulsion of α-granule movement, and this may be a novel mechanism underlying the secretion reaction. Second, we show that one mechanism by which anticoagulants may impact malignancy is by disrupting the tumor cells' ability to hijack the angiogenic potential of platelets. Third, we will review the molecular basis of transport and delivery of α-granules to assembling platelets. Finally, we will discuss the concept of using “designer platelets” as a drug delivery system for targeted agents.