In vitro interaction between cultured cells and human blood platelets

Area of Science:

• Hematology
• Cell Biology
• Biochemistry

Background:

• Investigating the interaction between cultured human cells and blood platelets is crucial for understanding hemostasis and thrombosis.
• Previous studies suggest cell-derived factors can influence platelet function.

Purpose of the Study:

• To determine the effects of washed human cultured cells (tumor cells and Chang liver cells) on human blood platelets.
• To elucidate the mechanisms underlying cell-induced platelet aggregation.

Main Methods:

• Studied platelet aggregation in heparinized plasma induced by suspensions of cultured tumor cells and Chang liver cells.
• Performed ultrastructural examination of platelet aggregates.
• Analyzed washing fluids for the presence of adenosine diphosphate (ADP) and assessed the role of ADP using apyrase.

Main Results:

• Tumor cell suspensions induced significant platelet aggregation, characterized by tightly packed central aggregates with intact alpha-granules and peripheral aggregates showing organelle loss and fibrin strands.
• Washing fluids from tumor cells also induced aggregation, which was reversible by apyrase, indicating ADP mediation.
• Two of three Chang liver cell lines induced aggregation, correlating with detectable ADP in their washing fluids.

Conclusions:

• Cell-induced platelet aggregation is primarily mediated by adenosine diphosphate (ADP).
• A potential additional role for coagulation activity in platelet aggregation induced by certain cultured cells cannot be excluded.
• Variability exists among different cell lines (e.g., Chang liver cells) in their capacity to induce platelet aggregation.