Introduction Mechanisms of cold injury Impact of cold ischemia Impact of warm ischemia Prevention

Impact of Warm and Cold ischemia time on RenalTransplant Allografts

Ivaylo Mitsiev, MD - Transplant Fellow

SUNY Downstate Medical Center

September 30, 2008

Introduction Mechanisms of cold injury Impact of cold ischemia Impact of warm ischemia Prevention

Definitions: Cold Ischemia Time (CIT)

Time of cold storage with or without perfusion with a

storage solution.

The CIT is significant in transplants from diseased donors.Rewarm time refers to the time between removal the kidney fromthe cold storage and beginning the reperfusion after completion ofthe arterial anastomosis.

Introduction Mechanisms of cold injury Impact of cold ischemia Impact of warm ischemia Prevention

Definitions: Warm Ischemia Time (WIT)

The period between the circulatory arrest and beginning of

the cold storage.

With the current procurement techniques the warm ischemia timeis in SDC cases essentially zero.The WIT is significant in DCD cases.Up to 20 minutes of warm ischemia are well tolerated by thekidney. The rates of delayed function and nonfunction increasemarkedly thereafter.

Introduction Mechanisms of cold injury Impact of cold ischemia Impact of warm ischemia Prevention

History of cold storage

1849: first recorded attempt at perfusion of an isolated organ(Loebel)

1937: creation of a perfusion apparatus by Lindbergh andCarrel

1953: successfully transplantations of limbs and kidneyspreserved at 4◦C (Lapchinsky)

1969: developing of the Euro-Collins cold storage solution(Collins et al.)

1987: development of the UW solution (Belzer et al.)

Source: International Society for Organ Preservation (http://www.i-s-o-p.net/historyset.htm)

Introduction Mechanisms of cold injury Impact of cold ischemia Impact of warm ischemia Prevention

Why cold ischemia time?

The degradative reactions are slowed with hypothermia eventhough not halted. Preserving an organ at 4◦C slows themetabolism by a factor of 11-12.

During the procurement the organs are flushed with a coldpreservation solution. Rapid cooling to 4◦C remain the mainstrategy to minimize ischemic injury and increase viability.

Introduction Mechanisms of cold injury Impact of cold ischemia Impact of warm ischemia Prevention

Components of cold ischemic transplant injury

Complex mechanisms of injury:

Coupled effect of ischemia and hypothermia during coldstorage,

Coupled effect of reperfusion and rewarming aftertransplantation.

Introduction Mechanisms of cold injury Impact of cold ischemia Impact of warm ischemia Prevention

The cold ischemic injury is related to

Aerobic metabolism: intracellular acidosis due to theaccumulation of lactic acid generated from the anaerobicmetabolism of glucose,

Perturbations in osmoregulation,

interstitial expansion and edema due to reduction in interstitialoncotic pressure,capillary compression, tissue injury, and poor organ functionafter transplantation,cell swelling due to reduced Na-K-ATPase activity and ATPlevels (intracellular accumulation of sodium and water).

Source: Weinberg JM. The cell biology of ischemic renal injury. Kidney Int 39: 476-500, 1991

Introduction Mechanisms of cold injury Impact of cold ischemia Impact of warm ischemia Prevention

What happens in the cells under cold ischemia?

Source: Salahudeen, A. K. Am J Physiol Renal Physiol 287: F181-F187 2004

Introduction Mechanisms of cold injury Impact of cold ischemia Impact of warm ischemia Prevention

Newly discussed effects of cold ischemia

Apoptosis: during reperfusion a significant proportion ofsublethally injured cells undergo apoptosis,

Rise in free cytosolic calcium: activation of calpain(Ca-dependant protease), degradation of the cytoskeletalprotein spectrin,

Free radicals: most probably produced by mitochondria,

Free iron release: catalyzation of reactions, wihch lead togeneration of toxic hydroxyl radicals,

cold-induced F2-Isoprostanes: vasoconstrictiveprostaglandins formed during free radical-catalyzed lipidperoxidation.

Introduction Mechanisms of cold injury Impact of cold ischemia Impact of warm ischemia Prevention

Data analysis: Delayed Graft Function (DGF)

Ojo et al. analyzed 44,703 patients prospectively compiled bythe U.S. Renal Data System in the period 1985-1992.

The Cold Ischemia Time is the single most important riskfactor for DGF!

The DGF is an independent risk factor for long- andshort-term graft survival.

No confirmation of the hypothesis that the shipping ofzero-HLA-mismatched organs is responsible for prolonged CITMean overall CIT: 22.6 hr,CIT for zero-HLA-mismatched kidneys: 20.1 hr

Source: Ojo AO, Wolfe RA, Held PJ, Port FK, and Schmouder RL. Delayed graft function: risk factors and

implications for renal allograft survival. Transplantation 63: 968-974, 1997

Introduction Mechanisms of cold injury Impact of cold ischemia Impact of warm ischemia Prevention

Risk factors for DGF:Cold ischemia time is the single most important risk factor!

Source: A.O. Ojo, R.A. Wolfe and P.J. Held et al., Delayed graft function: risk factors and implications for renal

allograft survival, Transplantation 63 (1997), p. 968

Introduction Mechanisms of cold injury Impact of cold ischemia Impact of warm ischemia Prevention

DGF and acute rejection are predictive for long term graftsurvival

Source: A.O. Ojo, R.A. Wolfe and P.J. Held et al., Delayed graft function: risk factors and implications for renal

allograft survival, Transplantation 63 (1997), p. 968

Introduction Mechanisms of cold injury Impact of cold ischemia Impact of warm ischemia Prevention

Data analysis: Acute Rejection and DGF

Shoskes and Cecka analyzed 27,096 patients reported byUNOS in the period 1994-1997.

The DGF was confirmed to correlate with the CIT.

The prolonged CIT was shown to correlate also with higherrates of acute rejection.

CIT had a smaller influence on graft survival if consideredindependently of DGF or early acute rejection.

Source: D.A. Shoskes and J.M. Cecka, Deleterious effects of delayed graft function in cadaveric renal transplant

recipients independent of acute rejection, Transplantation 66 (1998), p. 1697

Introduction Mechanisms of cold injury Impact of cold ischemia Impact of warm ischemia Prevention

Rates of DGF and acute rejection correlate with aprolonged CIT

Source: D.A. Shoskes and J.M. Cecka, Deleterious effects of delayed graft function in cadaveric renal transplant

recipients independent of acute rejection, Transplantation 66 (1998), p. 1697

Introduction Mechanisms of cold injury Impact of cold ischemia Impact of warm ischemia Prevention

No independant influence of CIT on graft survival

Source: D.A. Shoskes and J.M. Cecka, Deleterious effects of delayed graft function in cadaveric renal transplant

recipients independent of acute rejection, Transplantation 66 (1998), p. 1697

Introduction Mechanisms of cold injury Impact of cold ischemia Impact of warm ischemia Prevention

Living donation eliminates the problem with the CIT andoutperforms the benefit of the HLA-match.

Source: Terasaki PI et al., High survival rates of kidney transplants from spousal and living unrelated donors, N

Engl J Med (1995), 333-336

Introduction Mechanisms of cold injury Impact of cold ischemia Impact of warm ischemia Prevention

Heart-beating vs. Non-heart-beating donor organs

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Introduction Mechanisms of cold injury Impact of cold ischemia Impact of warm ischemia Prevention

New potential strategies to prevent cold storage injury

apoptosis inhibiting concepts.

adding antioxidants (e.g. chelators like deferoxamine) to thestorage solution.

inducing HO-1 before cold storage: this stress protein is a32-kDa microsomal enzyme that stimulates the synthesis offerritin, degrades heme proteins, releases bilirubin, CO, andfree iron. The ferritin is most probably involved in themechanism leading to the protection of the cells against coldby HO-1.

Sources:Huang H, He Z, Roberts LJ, and Salahudeen AK. Deferoxamine reduces cold-ischemic renal injury in a syngeneickidney transplant model. Am J Transplant 3: 1531-1537, 2003.

Salahudeen AA, Jenkins JK, Huang H, Ndebele K, and Salahudeen AK. Overexpression of heme oxygenase protects

renal tubular cells against cold storage injury: studies using hemin induction and HO-1 gene transfer.

Transplantation 72: 1498-1504, 2001b.