Related Experiment Videos
Megakaryocyte interaction with subendothelial extracellular matrix is associated with adhesion, platelet-like shape
Abstract:
We have examined the morphological and secretory behavior of rat and guinea pig megakaryocytes exposed for up to 24 hours to extracellular matrix produced by cultured bovine endothelial cells. By phase-contrast microscopy of living cells and in more detail by scanning electron microscopy, the megakaryocytes showed a nonreversible adherence, an extensive formation of filopodia around the periphery like the rays of the sun, and a tendency toward flattening. These filopodia were generally linear with attenuated tips and were larger than, but resembled the filopodia of, rat or guinea pig platelets exposed to this extracellular matrix. In contrast, isolated megakaryocytes on glass or on uncoated plastic surfaces did not show these responses; adherence, in the face of gentle agitation before fixation, was minimal, with rare filopodia and no flattening. Megakaryocytes that interacted with the extracellular matrix produced significant amounts of thromboxane A2, but this did not occur on uncoated surfaces and could not be attributed to other contaminating cells in the megakaryocyte suspensions. The appearance in megakaryocytes of these typical platelet responses indicates that megakaryocytes acquire the functional capabilities of platelets by the synthesis and assembly of platelet substances and organelles. Thromboxane production by megakaryocytes stimulated by the extracellular matrix is a readily quantifiable measure of this capacity.
Insights
Megakaryocytes exposed to extracellular matrix exhibit platelet-like filopodia and flatten. This interaction stimulates thromboxane A2 production, indicating acquired platelet functions.
Area of Science:
- Cell Biology
- Hematology
- Biochemistry
Background:
- Megakaryocytes are precursors to platelets.
- Endothelial cell extracellular matrix plays a role in hemostasis.
- Platelet function involves specific morphological and secretory responses.
Purpose of the Study:
- To investigate the morphological and secretory behavior of megakaryocytes when exposed to endothelial cell extracellular matrix.
- To determine if megakaryocytes acquire platelet-like functional capabilities upon interaction with extracellular matrix.
- To assess thromboxane A2 production as a marker of megakaryocyte functional response.
Main Methods:
- Phase-contrast microscopy of live cells.
- Scanning electron microscopy for detailed morphological analysis.
- Measurement of thromboxane A2 production in megakaryocyte suspensions.
Main Results:
- Megakaryocytes showed irreversible adherence, extensive filopodia formation, and flattening when on extracellular matrix, resembling platelet behavior.
- These responses were absent on uncoated surfaces.
- Stimulation by extracellular matrix led to significant thromboxane A2 production by megakaryocytes.
Conclusions:
- Megakaryocytes acquire platelet-like functional capabilities, including filopodia formation and thromboxane A2 synthesis, upon interaction with endothelial extracellular matrix.
- Thromboxane A2 production serves as a quantifiable indicator of these acquired platelet functions in megakaryocytes.