Imaging platelet biogenesis in vivo

Schulze, Harald; Stegner, David

doi:10.1002/rth2.12112

Cited by 18 publications

(12 citation statements)

References 58 publications

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“…The recent development of new bone cutting and staining methods [25], the availability of more subtype-specific antibodies, together with novel microscopic approaches that allow the acquisition of overview images of whole bones by maintaining high resolution images for detail analyses, has enabled the in-depth analysis of MK matrix interactions in situ. These advancements now allow to deduce an organ-wide information on biological processes [26].…”

Section: Discussionmentioning

confidence: 99%

Impact of Itga2-Gp6-double collagen receptor deficient mice for bone marrow megakaryocytes and platelets

et al. 2019

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The two main collagen receptors on platelets, GPVI and integrin α2β1, play an important role for the recognition of exposed collagen at sites of vessel injury, which leads to platelet activation and subsequently stable thrombus formation. Both receptors are already expressed on megakaryocytes, the platelet forming cells within the bone marrow. Megakaryocytes are in permanent contact with collagen filaments in the marrow cavity and at the basal lamina of sinusoids without obvious preactivation. The role of both collagen receptors for megakaryocyte maturation and thrombopoiesis is still poorly understood. To investigate the function of both collagen receptors, we generated mice that are double deficient for Gp6 and Itga2 . Flow cytometric analyses revealed that the deficiency of both receptors had no impact on platelet number and led to the expected lack in GPVI responsiveness. Integrin activation and degranulation ability was comparable to wildtype mice. By immunofluorescence microscopy, we could demonstrate that both wildtype and double-deficient megakaryocytes were overall normally distributed within the bone marrow. We found megakaryocyte count and size to be normal, the localization within the bone marrow, the degree of maturation, as well as their association to sinusoids were also unaltered. However, the contact of megakaryocytes to collagen type I filaments was decreased at sinusoids compared to wildtype mice, while the interaction to type IV collagen was unaffected. Our results imply that GPVI and α2β1 have no influence on the localization of megakaryocytes within the bone marrow, their association to the sinusoids or their maturation. The decreased contact of megakaryocytes to collagen type I might at least partially explain the unaltered platelet phenotype in these mice, since proplatelet formation is mediated by these receptors and their interaction to collagen. It is rather likely that other compensatory signaling pathways and receptors play a role that needs to be elucidated.

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Section: Discussionmentioning

confidence: 99%

Impact of Itga2-Gp6-double collagen receptor deficient mice for bone marrow megakaryocytes and platelets

et al. 2019

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“…Of note, platelet spreading assays, which are not affected by low platelet count, can help define bleeding phenotypes in patient samples that are negative for an aggregation defect (85). The combination of biological optical microimaging with genomic information has opened up new avenues to test and evaluate these rare conditions that are not limited by low platelet counts but are still constrained by the limits of optical diffraction (86,87).…”

Section: Micro-imaging Platelets In a Dishmentioning

confidence: 99%

“…Studies using transgenic mice expressing LifeAct-GFP have also revealed details of platelet actin cytoskeletal structure and nodules (65, 163). When pairing these fluorescent transgenic mice with an intravital microscope, it becomes possible to delve deep underneath dense tissue and potentially observe megakaryopoiesis and changes in ploidy and proplatelet formation and release into the blood stream (87,164). Fluorescently-labeled platelets have enabled studies of platelet migration and platelet interactions with other blood cells, in a number of physiology scenarios, including inflammation (139), infection (165), and cancer (166).…”

Section: Hemostasis and Thrombus Formation In Its Natural Microenviromentioning

confidence: 99%

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

et al. 2020

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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.

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“…Thus, at present, it is completely unknown if platelets can escape from the ridge area in the same manner as RBCs. Since it is extremely difficult to image platelets under visible or near-infrared light without labeling, fluorescence imaging has typically been employed for this purpose [34][35][36]. However, the rate of blood flow inside the hydrodynamic bearing of a rotary blood pump is very high, so it will be necessary to development a process allowing the high-speed fluorescent imaging of platelets.…”

Section: Limitations and Future Workmentioning

confidence: 99%

Plasma skimming efficiency of human blood in the spiral groove bearing of a centrifugal blood pump

et al. 2020

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This work investigates the plasma skimming effect in a spiral groove bearing within a hydrodynamically levitated centrifugal blood pump when working with human blood having a hematocrit value from 0 to 40%. The present study assessed the evaluation based on a method that clarified the limitations associated with such assessments. Human blood was circulated in a closed-loop circuit via a pump operating at 4000 rpm at a flow rate of 5 L/min. Red blood cells flowing through a ridge area of the bearing were directly observed using a high-speed microscope. The hematocrit value in the ridge area was calculated using the mean corpuscular volume, the bearing gap, the cross-sectional area of a red blood cell, and the occupancy of red blood cells. The latter value was obtained from photographic images by dividing the number of pixels showing red blood cells in the evaluation area by the total number of pixels in this area. The plasma skimming efficiency was calculated as the extent to which the hematocrit of the working blood was reduced in the ridge area. For the hematocrit in the circuit from 0 to 40%, the plasma skimming efficiency was approximately 90%, meaning that the hematocrit in the ridge area became 10% as compared to that in the circuit. For a hematocrit of 20% and over, red blood cells almost completely occupied the ridge. Thus, a valid assessment of plasma skimming was only possible when the hematocrit was less than 20%.

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Imaging platelet biogenesis in vivo

Cited by 18 publications

References 58 publications

Impact of Itga2-Gp6-double collagen receptor deficient mice for bone marrow megakaryocytes and platelets

Impact of Itga2-Gp6-double collagen receptor deficient mice for bone marrow megakaryocytes and platelets

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

Plasma skimming efficiency of human blood in the spiral groove bearing of a centrifugal blood pump

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