title: In vitro model for the study of platelet-vessel wall interactions following a freeze- thaw injury.
abstract: Platelet-endothelial cell interactions are important for maintaining normal hemodynamics. The intact endothelial cell lining is considered nonthrombogenic, but following disruption of the lining, platelets bind to the subendothelium. There is also much conjecture concerning the affinity of platelets for damaged endothelial cells. A model is described for the study of platelet-aorta vessel wall interactions following freeze-thaw insult. Using this model, we found that control aortas (37 degrees C) perfused with platelet-rich plasma or gel-filtered platelets showed no generalized platelet-endothelial cell interactions, although some platelets did adhere to areas of exposed subendothelium. Following freeze-thaw insult (-15 degrees or -20 degrees C), the endothelial lining was grossly disrupted. The remaining endothelium was severely damaged, demonstrating holes and pits in the plasma membranes and separation of adjacent cell borders. Platelets readily adhered to the basal lamina but were rarely noted in sole contact with the damaged endothelium. Platelet binding did not result in morphologic changes, degranulation, or aggregation. Using transmission electron microscopy, we noted platelets in contact with amorphous material and microfibrils but not collagen fibers of the subendothelium. It is concluded that this model is suitable for the in vitro study of certain hemodynamic phenomena associated with blood vessel freeze-thaw injury. In addition, freeze-thaw damage in this in vitro model indicated that platelet-vessel wall interactions were limited to areas of exposed subendothelium.
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000166:cytology*; D001792:Blood Platelets / Q000502:physiology* / Q000648:ultrastructure; D002417:Cattle; D002450:Cell Communication; D004727:Endothelium / Q000502:physiology* / Q000648:ultrastructure; D005615:Freezing; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D010973:Platelet Adhesiveness