Imaging Platelet Processes and Function—Current and Emerging Approaches for Imaging in vitro and in vivo

Abstract

Platelets are small anucleate cells that are essential for many biological processes including hemostasis, thrombosis, inflammation, innate immunity, tumor metastasis, and wound healing. Platelets circulate in the blood and in order to perform all of their biological roles, platelets must be able to arrest their movement at an appropriate site and time. Our knowledge of how platelets achieve this has expanded as our ability to visualize and quantify discreet platelet events has improved. Platelets are exquisitely sensitive to changes in blood flow parameters and so the visualization of rapid intricate platelet processes under conditions found in flowing blood provides a substantial challenge to the platelet imaging field. The platelet's size (∼2 µm), rapid activation (milliseconds), and unsuitability for genetic manipulation, means that appropriate imaging tools are limited. However, with the application of modern imaging systems to study platelet function, our understanding of molecular events mediating platelet adhesion from a single-cell perspective, to platelet recruitment and activation, leading to thrombus (clot) formation has expanded dramatically. This review will discuss current platelet imaging techniques in vitro and in vivo, describing how the advancements in imaging have helped answer/expand on platelet biology with a particular focus on hemostasis. We will focus on platelet aggregation and thrombus formation, and how platelet imaging has enhanced our understanding of key events, highlighting the knowledge gained through the application of imaging modalities to experimental models in vitro and in vivo. Furthermore, we will review the limitations of current imaging techniques, and questions in thrombosis research that remain to be addressed. Finally, we will speculate how the same imaging advancements might be applied to the imaging of other vascular cell biological functions and visualization of dynamic cell-cell interactions.

Thrombocytopathies: Not Just Aggregation Defects—The Clinical Relevance of Procoagulant Platelets

“…Intravital microscopy permits the study of physiological haemostasis and the appreciation the heterogeneous structure of a growing thrombus [ 243 , 244 ]. More and more publications are present in the literature assessing the heterogeneous platelet activation status with a particular focus on the role of procoagulant platelets [ 134 , 245 , 246 ].…”

Hematological Alterations Induced by Zinc Oxide Nanoparticles and Preventive Role of Moringa Oleifera: In vivo

“…Platelets come after RBCs as the second most cell population found in the blood. The drop in platelet count resulting from either reduced platelet production or high platelet destruction is termed as thrombocytopenia 32 . The platelets are produced from megakaryocytes and play essential roles in haemostasis 33 .…”

Control of data variations in intravital microscopy thrombosis models

“…It will continue to evolve and provide vital information in scientific discoveries as well as drug development. 25,29,30…”

“…Notably and importantly, despite the existing data variations, the intravital microscopy system has provided us a very powerful tool to study the real‐time molecular and cellular events in vivo for hemostasis and thrombosis. It will continue to evolve and provide vital information in scientific discoveries as well as drug development 25,29,30 …”