Caspase 3 inhibition improves survival and reduces early graft injury after ischemia and reperfusion in rat liver transplantation.
BACKGROUND
Apoptosis plays a crucial role after ischemia-reperfusion in organ transplantation. It is executed by caspases and influenced by the rheostat of pro- and anti-apoptotic proteins of the bcl-2 family. This study investigated the effect of specific inhibition of caspases 3 and 7 on graft function, survival, and hepatic bcl-2 levels after liver transplantation.


METHODS
Lewis rats underwent syngeneic orthotopic liver transplantation after 16 hr of cold graft storage (in University of Wisconsin solution). Livers of donor animals treated with D(OMe)E(OMe)VD(OMe)-fluoromethylketone (specific inhibitor of apoptosis executor caspases 3 and 7), and appropriate control groups, were investigated. Early graft injury was quantified by measurement of bile flow and determination of microvascular graft injury by using in vivo fluorescence microscopy. Apoptosis and its regulation were examined by terminal deoxynucleotide transferase-mediated dUTP nick-end labeling staining and Western blot analysis of cell death effectors, respectively.


RESULTS
After specific in vivo caspase inhibition, Western blot analysis revealed inhibition of caspase-induced cleavage of poly-ADP-ribose-polymerase. Inhibition of caspases 3 and 7 resulted in a significantly decreased number of apoptotic endothelial cells and improved microvascular perfusion. A cell protective effect was also suggested by an increase of bcl-2 levels at 7 days. Most important, specific caspase blockade resulted in improved rat survival after liver transplantation.


CONCLUSIONS
Specific inhibition of apoptosis executor caspases effectively reduces graft ischemia-reperfusion injury and improves survival in liver transplantation. Better tissue preservation after caspase inhibition correlates with reduced apoptosis execution, improved microvascular perfusion, and bcl-2 up-regulation. Therefore, specific caspase inhibition represents a promising regimen for clinical use in liver transplantation.
Mueller
Thomas H J
TH
Department of Surgery, University of Regensburg, 93053 Regensburg, Germany.
Kienle
Klaus
K
Beham
Alexander
A
Geissler
Edward K
EK
Jauch
Karl W
KW
Rentsch
Markus
M
D000818:Animals; D017209:Apoptosis; D053148:Caspase 3; D061945:Caspase Inhibitors; D008099:Liver / Q000098:blood supply; D016031:Liver Transplantation / Q000401:mortality; D008297:Male; D008833:Microcirculation / Q000473:pathology; D009842:Oligopeptides / Q000494:pharmacology; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis; D051381:Rats; D011917:Rats, Inbred Lew; D015427:Reperfusion Injury / Q000517:prevention & control*
D061945:Caspase Inhibitors; D009842:Oligopeptides; D019253:Proto-Oncogene Proteins c-bcl-2; C110772:benzoylcarbonyl-aspartyl-glutamyl-valyl-aspartyl-fluoromethyl ketone; D011065:Poly(ADP-ribose) Polymerases; C505410:Casp3 protein, rat; D053148:Caspase 3