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A Microfluidic Flow Chamber Model for Platelet Transfusion and Hemostasis Measures Platelet Deposition and Fibrin Formation in Real-time
Published on: February 14, 2017
Platelet-induced expression of tissue factor procoagulant activity in freshly isolated human mononuclear cells:
S R Meisel1, M Shechter, X-P Xu
1Department of Medicine, Division of Cardiology, Atherosclerosis Research Center, Cedar-Sinai Burns & Allen Research Institute, Israel. meisel@netvision.net.il
Abstract:
Monocytes express tissue factor (TF) as a result of cytokine stimulation or endothelial adherence. We evaluated monocyte-platelet interaction in vitro as another trigger for monocyte TF enhancement in human mononuclear cells isolated by density gradient centrifugation from peripheral blood. Cell TF procoagulant activity (TF-PCA) was quantitated by a one-stage recalcification clotting time assay. Platelets were counted and identified by whole blood flow cytometry as CD61 positive particles, activated platelets were characterized by P-Selectin (CD62) expression, and monocytes by surface CD14 expression. A significant correlation between normalized TF-PCA of isolated mononuclear cells and platelet count was shown (r = 0.43, P < 0.001). Percentage of activated platelets in baseline samples was 4.2 +/- 3.5 while adenosine diphosphate (ADP) increased platelet positivity to 34 +/- 17% (P < 0.001). After isolation, 52 +/- 12% of platelets within suspensions were activated (P < 0.0001). Percentage of CD62-positive monocytes (CD14+ particles) increased from baseline 5% to 13 +/- 6% in ADP-stimulated samples to 53 +/- 17% after isolation (P < 0.001). These findings suggest that density gradient centrifugation activates platelets and that an adhesive interaction between monocytes and platelets may promote TF-PCA expression in isolated mononuclear suspensions. Enhanced monocyte TF expression as a result of an activated platelet-monocyte interaction seems to be an important laboratory effect requiring consideration when utilizing this technique in an experimental setup.
Insights
Monocyte tissue factor expression is enhanced by platelet interaction. Density gradient centrifugation activates platelets, potentially influencing monocyte tissue factor procoagulant activity in isolated cell studies.
Area of Science:
- Hematology
- Immunology
- Cell Biology
Background:
- Monocytes express tissue factor (TF) upon cytokine stimulation or endothelial adherence.
- Monocyte-platelet interactions are increasingly recognized as significant in hemostasis and inflammation.
Purpose of the Study:
- To investigate monocyte-platelet interaction in vitro as a trigger for monocyte TF enhancement.
- To evaluate the impact of density gradient centrifugation on monocyte and platelet activation.
Main Methods:
- Human mononuclear cells were isolated using density gradient centrifugation.
- Cellular tissue factor procoagulant activity (TF-PCA) was measured using a one-stage recalcification clotting time assay.
- Flow cytometry (CD61, CD62, CD14) was used to quantify platelets, activated platelets, and monocytes.
Main Results:
- A significant positive correlation was observed between normalized TF-PCA and platelet count in isolated mononuclear cells (r = 0.43, P < 0.001).
- Density gradient centrifugation led to significant platelet activation (52% vs. baseline 4.2%) and monocyte activation (53% CD62+ monocytes vs. baseline 5%).
- Platelet activation, particularly with adenosine diphosphate (ADP), significantly increased monocyte TF-PCA.
Conclusions:
- Density gradient centrifugation activates platelets, which in turn can promote TF-PCA expression in monocytes.
- The adhesive interaction between activated platelets and monocytes is a critical factor influencing TF-PCA in isolated cell suspensions.
- Researchers should consider the impact of platelet activation during isolation techniques when studying monocyte TF expression.
