Methylprednisolone and Tacrolimus Prevent Hypothermia-Induced Endothelial Dysfunction

Received 5 December 2008; received in revised form 10 March 2009; accepted 7 April 2009. published online 15 May 2009.

Background

Hypothermia is used to preserve organs for transplantation and is the oldest method to protect organs during complex pediatric cardiac surgery. Loss of tissue function and tissue edema are common complications in children undergoing corrective cardiac surgery and heart transplantation. The present study was designed to examine the effects of methylprednisolone and tacrolimus on endothelial cell function and morphology after deep hypothermia and rewarming.

Methods

Human umbilical vein endothelial cells were pre-treated with methylprednisolone or tacrolimus, or both, incubated within a specially designed bioreactor or in monolayers, and then exposed to a dynamic cooling and rewarming protocol. Immunocytochemistry, time-lapse video microscopy, cell permeability and adherence assays, and Western blot analysis were performed.

Results

Confluent endothelial cells exposed to hypothermia displayed elongated cell shapes with intercellular gap formation, increased endothelial cell-layer permeability, and loss in adherence. Upon rewarming, however, endothelial cell integrity was restored. Opening and closing of intercellular gaps was dependent on extracellular signal-regulated kinase 1 and 2 (ERK 1/2) activation and connexin 43 expression. The combined treatment with methylprednisolone and tacrolimus inhibited these hypothermia-induced changes.

Conclusions

These results suggest that methylprednisolone and tacrolimus inhibit hypothermia-induced endothelial gap formation by phosphorylated ERK 1/2 inhibition and connexin 43 stabilization. Application of combined drugs that affect multiple targets may therefore be considered as a possible new therapeutic strategy to prevent endothelial dysfunction after hypothermia and rewarming.

a Department of Pediatric Cardiology, Charité-Universitätsmedizin Berlin, Berlin, Germany

b Department of General, Visceral and Transplantation Surgery, Charité-Universitätsmedizin Berlin, Berlin, Germany

c Department of Congenital Heart Disease/Pediatric Cardiology, Deutsches Herzzentrum Berlin, Berlin, Germany

Reprint requests: Katharina Rose Luise Schmitt, MD, Department of Congenital Heart Disease/Pediatric Cardiology, Deutsches Herzzentrum Berlin, Augustenburger Platz 1, 13353 Berlin, Germany. Telephone: 49-30-45-93-2800. Fax: 49-30-45-93-2900

The study was supported by Stiflung Deutsche Kinderherzzentren e.V. Bonn, Germany, Investitionsbank Berlin, Germany and the Fiebig Foundation.

⁎ These authors contributed equally to this work.

PII: S1053-2498(09)00225-3

doi:10.1016/j.healun.2009.04.003

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