Exposure of human megakaryocytes to high shear rates accelerates platelet production
Autor: | Claude Capron, Claire Dunois-Lardé, Dominique Baruch, Elisabeth Cramer-Bordé, Serge Fichelson, Thomas M. Bauer |
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Rok vydání: | 2009 |
Předmět: |
Blood Platelets
P-selectin Immunology Biochemistry Models Biological Thrombopoiesis Thrombin Von Willebrand factor Megakaryocyte Microtubule Tubulin von Willebrand Factor medicine Humans Platelet Cytoskeleton Cells Cultured Microscopy Confocal Microscopy Video biology Chemistry Cell Membrane Cell Biology Hematology Flow Cytometry Cell biology Perfusion Microscopy Electron medicine.anatomical_structure biology.protein Stress Mechanical Megakaryocytes medicine.drug |
Zdroj: | Blood. 114(9) |
ISSN: | 1528-0020 |
Popis: | Platelets originate from megakaryocytes (MKs) by cytoplasmic elongation into proplatelets. Direct platelet release is not seen in bone marrow hematopoietic islands. It was suggested that proplatelet fragmentation into platelets can occur intravascularly, yet evidence of its dependence on hydrodynamic forces is missing. Therefore, we investigated whether platelet production from MKs could be up-regulated by circulatory forces. Human mature MKs were perfused at a high shear rate on von Willebrand factor. Cells were observed in real time by videomicroscopy, and by confocal and electron microscopy after fixation. Dramatic cellular modifications followed exposure to high shear rates: 30% to 45% adherent MKs were converted into proplatelets and released platelets within 20 minutes, contrary to static conditions that required several hours, often without platelet release. Tubulin was present in elongated proplatelets and platelets, thus ruling out membrane tethers. By using inhibitors, we demonstrated the fundamental roles of microtubule assembly and MK receptor GPIb. Secretory granules were present along the proplatelet shafts and in shed platelets, as shown by P-selectin labeling. Platelets generated in vitro were functional since they responded to thrombin by P-selectin expression and cytoskeletal reorganization. In conclusion, MK exposure to high shear rates promotes platelet production via GPIb, depending on microtubule assembly and elongation. |
Databáze: | OpenAIRE |
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