Platelets induce sinusoidal endothelial cell apoptosis upon reperfusion of the cold ischemic rat liver.
OBJECTIVE
Sinusoidal endothelial cell (SEC) apoptosis is a central feature of reperfusion injury in liver transplantation. Platelet sequestration occurs after transplantation with possible deleterious effects. We tested the hypothesis that platelets mediate SEC apoptosis.


METHODS
Livers were perfused after 24 hours of cold preservation in University of Wisconsin solution in an isolated perfused rat liver model. The perfusate contained isolated syngeneic red blood cells and purified platelets. Effects of inhibiting platelet adhesion on SEC apoptosis was tested using sialyl Lewis-X oligosaccharide (sLe(x)), a natural ligand of selectin adhesion molecules. Reperfusion injury was assessed by established markers of injury. Apoptosis was determined by TUNEL and electron microscopy.


RESULTS
A third of the circulating platelets was rapidly sequestered in the liver after reperfusion. This was associated with increased graft injury. Single platelets were adherent to sinusoidal lining without morphological or dynamic evidence of impairment of microcirculation. TUNEL staining revealed a 6-fold increase in the number of apoptotic SECs at 1 hour of reperfusion. No hepatocyte death or evidence of necrosis was detected up to 3 hours of reperfusion. Addition of sLe(x) inhibited adhesion and significantly reduced SEC apoptosis.


CONCLUSIONS
Platelets cause SEC apoptosis upon reperfusion of liver grafts. Prevention of adhesion is protective.
Sindram
D
D
Hepatobiliary and Liver Transplant Laboratory, Duke University Medical Center, Durham, North Carolina 27710, USA.
Porte
R J
RJ
Hoffman
M R
MR
Bentley
R C
RC
Clavien
P A
PA
D000818:Animals; D017209:Apoptosis; D001667:Binding, Competitive; D001792:Blood Platelets / Q000502:physiology*; D004727:Endothelium / Q000166:cytology; D007983:Lewis Blood Group Antigens / Q000378:metabolism; D008099:Liver / Q000098:blood supply*; D009844:Oligosaccharides / Q000378:metabolism; D010477:Perfusion; D010973:Platelet Adhesiveness; D051381:Rats; D017208:Rats, Wistar; D015427:Reperfusion Injury / Q000473:pathology*; D019087:Selectins / Q000378:metabolism; D000080506:Sialyl Lewis X Antigen
D007983:Lewis Blood Group Antigens; D009844:Oligosaccharides; D019087:Selectins; D000080506:Sialyl Lewis X Antigen