Platelet-endothelial cell interactions in vitro following freeze-thaw injury or detergent treatment

Summary

Platelet interactions with cultured bovine endothelial cells were studied following freeze-thaw damage or detergent tratment. Platelets from whole blood, platelet-rich plasma, or gel-filtered plasma did not interact directly with freeze-thaw-damaged endothelial cells. Freezing and thawing did result in the exposure of an extracellular matrix located beneath the cells, which proved very thrombogenic. Platelets from all sources attached to both microfilament and amorphous components of the extracellular matrix, although only platelets from whole blood demonstrated aggregation and extensive pseudopodia formation. Treatment of cells with Triton-X detergent resulted in exposure of an intracellular cytoskeleton. Most platelets attached to the cytoskeleton were located near the cell border and had one or more pseudopodia either in contact with extracellular or intracellular material. Adhesion of platelets to the extra-cellular matrix may represent platelet-collagen or plateletfibronectin interactions since both are produced by an incorporated into the extracellular matrix. Platelet interaction with endothelial cytoskeletons may represent contact of pseudopodia with the now exposed matrix located beneath the cells. The possibility that platelets also adhered to intra-cellular components could not be eliminated. These findings are in agreement with data from a freeze-thaw injury model of perfused aorta. In addition, they tend to indicate that physical insult is not sufficient to induce platelet interaction with the endothelial surface, but that chemical modification enhances platelet deposition.