Surface morphology of human platelets during in vitro aggregation.

Area of Science:

• Hematology
• Cell Biology
• Biophysics

Background:

• Platelet aggregation is crucial for hemostasis and thrombosis.
• Understanding platelet shape changes during activation is essential for interpreting aggregometry data.
• Scanning electron microscopy (SEM) offers high-resolution visualization of cellular morphology.

Purpose of the Study:

• To investigate the dynamic surface morphological alterations of human platelets during in vitro aggregation.
• To correlate observed SEM changes with the light transmission patterns in aggregometer tracings.
• To identify limitations of aggregometry in reflecting all platelet morphological changes.

Main Methods:

• Human platelet-rich plasma was incubated at 37°C to ensure discoid morphology.
• Platelet aggregation was induced using collagen or adenosine diphosphate (ADP).
• Surface morphology was examined using scanning electron microscopy (SEM) at various stages of aggregation.

Main Results:

• Platelets initially formed slender pseudopods, transitioning to bulbous protrusions upon activation.
• Decreased light transmission (%T) correlated with enlarged bulbous protrusions and spherical platelet shape.
• Platelet aggregation induced by collagen or ADP involved two distinct pseudopod formations.
• Aggregate dissociation did not always restore the discoid platelet shape, with pseudopods persisting.

Conclusions:

• The aggregometer tracing closely reflects specific surface morphological changes in platelets.
• SEM reveals dynamic morphological transformations not fully captured by aggregometry.
• Distinct pseudopod generations occur during platelet aggregation.
• Platelet shape changes can persist even after aggregate dissociation.