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Background. Platelet adhesion to hepatic sinusoidal endothelial cells (SEC) is a major mechanism of cold preservation injury. This study was performed to determine whether cold preservation leads to adhesion between SEC and platelets in the absence of other cell types, whether adherent platelets become activated upon adhesion, and whether there is increased expression of the platelet receptor von Willebrand factor (vWF) on cold preserved SEC. Because we previously showed that cold causes actin disassembly and matrix metalloprotease (MMP) secretion by SEC, we also questioned whether these events are related to increased adhesion of platelets to SEC after preservation. Methods. Isolated SEC were cold preserved for 8 hr and rewarmed briefly. Biotinylated platelets were added to the plates and adhesion was assessed. Activation of platelets was determined by staining with antibody to P-selectin. Expression of vWF was assessed with a specific antibody. Results. Cold preservation induced increased adhesion of platelets to SEC in the absence of other cell types. Adherent platelets were activated. Preservation increased the expression of vWF on SEC. Pretreatment with phalloidin or treatment with MMP inhibitors partly prevented platelet adhesion and activation, as well as vWF expression. Treatment of SEC at 37°C with recombinant human MMPs for 24 hr also rendered the SEC more adherent for unactivated platelets. Conclusion. Cold preservation of SEC results in increased expression of the platelet receptor vWF, increased platelet adhesion, and platelet activation. This is at least partly mediated by actin disassembly and MMP secretion. |
