The DumontUCLA Transplant Center, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA

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Dual Endothelin Receptor Blockade with Tezosentan
Ameliorates Ischemia/ Reperfusion Injury in Rat
Models of Cold Ischemia Followed by Perfusion or
Transplantation
Fady Kaldas, Xiu-da Shen, Bibo Ke, Dean Anselmo,
Charles Lassman, Ronald W Busuttil, Jerzy W
Kupiec-Weglinski, and Douglas G Farmer.
The Dumont-UCLA Transplant Center, David Geffen
School of Medicine at UCLA, Los Angeles, CA, USA
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Background
Ischemia/ reperfusion (I/R) injury remains an
important clinical problem in liver
transplantation - impacts short and long term
graft function - increases immunogenicity of
allografts Pirenne et al, 1997Reduction of I/R
injury will allow use of marginal allografts as a
means to expand the donor pool, Urena et al, 1999
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Tezosentan
Tezosentan is a novel compound that competitively
antagonizes specific binding of ET-1 and ET-3 on
tissues carrying ETa and ETb receptors
  Tezosentan has never been investigated in
models of liver I/R injury but has demonstrated
efficacy in renal I/R injury Wilhelm et al, 2001
C27H25N9Na2O6S
Actelion Pharmacuticals No Financial subsidy
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Hypothesis
Pretreatment with Tezosentan will reduce hepatic
injury after ischemia/ reperfusion through
prevention of microvascular disturbances and
hypoxia
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ISOLATED RAT LIVER PERFUSION APPARATUS (IRLPA)
Temp 37C
RESERVOIR
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sGOT

500
Control
400
Tezosentan

300
IU/L

200
100
0
P lt 0.05
30
60
90
120
TIME (min)
7
Portal Blood Flow
Oxygen Extraction Ratio
1.4
Control
1

Control

Tezosentan
1.2
Tezosentan



0.8

1
0.8
0.6
ml/min/gm tissue
0.6
0.4
0.4
0.2
0.2
0
0
30
60
90
120
30
60
90
120
P lt 0.05
TIME (min)
TIME (min)
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OLT Model
Sprague Dawley Donor
Treatment groups 1) No Treatment 2) Tezosentan
(15mg/Kg I.V.)
Prior to PV Anastamosis
Non-Arterialized OLT
24 hr storage in UW
Sprague Dawley Recipient
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sGOT-OLT

10000
Control
Tezosentan
8000
IU/L
6000

4000
2000
0
6h
24h
P lt 0.05
Time
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Histopathology-OLT
24h Tezosentan
24h Control
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RT-PCR-OLT
IL-1b
MIP-2
3
3
2
2
IL-1b/b-actin
MIP-2/b-actin


1
1
0
0
Control
Tezo
Control
Tezo
P lt 0.05
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MPO Activity-OLT
6
5
4
3
U/gm

2
1
0
Control
Tezo
P lt 0.05
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Survival Post OLT
plt0.05
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Summary

• Tezosentan treatment significantly reduced I/R
  injury in ex-vivo perfused or transplanted livers
  after 24 h cold preservation by reducing serum
  transaminases, improving tissue histology and
  animal survival.
• This outcome was associated with decreased
  expression of pro-inflammatory and chemotactic
  signals, and neutrophil infiltration.

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Conclusion
These data underscore the effect of Endothelin
antagonism using tezosentan on attenuating the
Ag-independent immune inflammatory process that
occurs in response to the primary vascular and
parenchymal insult following I/R.