Description:
Blood platelets are increasingly recognized as playing versatile roles in hemostasis and thrombosis, innate immunity, and tumor growth regulation. This scientific session will highlight state-of-the-art methodologies that have emerged in recent years to investigate the cell biology of platelets and megakaryocytes, their precursors. The first two presentations will focus on innovative imaging technologies to observe bone marrow megakaryocytes and blood platelets through electron tomography and dynamic live imaging, respectively. The third presentation will focus on novel next generation sequencing methodologies used to determine genetic and genomic factors contributing to individual platelet parameter variability. 

Dr. Anita Eckly will present 3D imaging of megakaryocytes with electron tomography and large volume Focused Ion Beam-Scanning Electron Microscopy (FIB-SEM), Focused ion beam (FIB) SEM providing insight into the substructure of MKs in their native environment at ultrastructural resolution. She will list their advantages and limitations, the resolution that can be achieved, the technical difficulties, and applications in megakaryocyte biology. For example, she will highlight how these approaches can help to further the understanding of megakaryocyte crossing through bone marrow sinusoids and their functional interactions with neutrophils. To conclude, Dr. Eckly will discuss some future perspectives with respect to recent cryo-EM techniques developments and correlative live-imaging. 

Dr. Florian Gaertner will discuss live-cell imaging techniques that allow tracking and morphological analysis of individual platelets in thrombosis and inflammation.  The breakdown of vascular barriers in inflammatory diseases is a major complication, and platelets play a crucial role in safeguarding inflamed blood vessels. Dr Gaertner will discuss live cell imaging techniques that allow tracking and morphological analysis of individual platelets in thrombosis and inflammation in vitro and in vivo. Using these techniques, his group has shown that platelets form lamellipodia in vivo to spread on the inflamed vasculature, enabling haptotactic migration along adhesive gradients. Disruption of haptotaxis impairs platelet repositioning, compromising vessel sealing and causing microbleeds. Platelets also migrate to capture bacteria during infection, preventing them from spreading throughout the body. 

 

Dr. Andrew Johnson will review how advances in sequencing technologies scaled to populations and clinical samples are changing our understanding of platelet biology including the discovery of new gene loci and the ability to provide diagnoses for rare platelet, thrombotic and bleeding disorders (BTPD). This includes application of gene-mapping and sequencing strategies to find determinants of variation in platelet count and platelet function. It also extends to the development of targeted sequencing panels with high levels of evidence and application of exome and genome sequencing in affected individuals and families. Furthermore, the role of platelet transcriptome (RNA) sequencing will be described for understanding platelet function, genetic cases and in prediction of disease outcomes (e.g., tumor-educated platelets). Finally, the results of a global survey of BTPD practitioners will be summarized identifying prevalent approaches to application of sequencing and functional testing, along with potential gaps in practice. The audience members will learn more about the application of Genetics to BTPD in current practice (for example ISTH Gold Variants, ClinGen), complemented with specific functional testing, as well as emerging areas of other OMICs (for example platelet RNA-seq and proteomes) for diagnosis and characterization of clinical cases.