Abstract Title: DIFFERENTIALLY EXPRESSED GENES IN DECEASED KIDNEYS UNDERGOING PUMP PERFUSION PRESERVATION

Valeria Mas, PhD1-2, Catherine Dumur, PhD2, Robert Fisher, MD1, Kenneth Yanek, MD1, Eric Gibney, MD1, Anne King, MD1, Adrian Cotterell, MD1, Marc Posner, MD1 and Daniel Maluf, MD1. 1Surgery, Hume-Lee Transplant Center, VCUHS, Richmond, VA, United States and 2Pathology, VCUHS, Richmond, VA, United States.

Body: Background. Ischemia/reperfusion-associated injury depends primarily on the conditions of donor organ preservation. For establishing the molecular mechanisms of preservation-induced injury we studied molecular profiles in kidney (Kd) biopsies from deceased donor kidneys (DDK) undergoing pump perfusion preservation (PPP) and cold storage preservation (CSP).

Methods. Gene expression profiling was performed in Kd tissues from 27 DDK using microarray. The robust-multiarray average method was used to estimate probe set (Pset) expression summaries. The significance analysis of microarrays method was used to identify Pset differentially expressed while controlling for the false discovery rate (FDR). Microarray results were confirmed using qRT-real time PCR. DDK were classified by with the donor age (>55 vs. 55 yo). Donor and recipient demographic information was collected. Delayed graft function (DGF, defined as requirement of dialysis during the first week post-transplantation) was evaluated.

Results. Nine DDK had PPP (CIT=995323 min) and 18 DDK had CSP (CIT=1,084352 min). Recipient demographics included 52% AA, mean age: 43.2 +/-15.2 yo. Donors included 63% Caucasian, mean age: 39.1+/-16.0 yo. DGF rate was 35.3% (11% PPP vs. 44.4% CSP). >50yo DDK distribution was 44.4% PPP vs. 27.7% CSP. DGF distribution for >55yo DDK between groups was 0% PPP vs. 60% CSP. 349 Psets were found (=0.01) differentially expressed between both groups. Gene ontology terms classified these genes as related to transport, cell growth, cytoskeleton organization and biosynthesis. Anti-apoptotic genes were over expressed in the DDK in PPP (TRA-1, TNFRSF10D) and inductors of apoptosis were down regulated (CASP9, BAX). Genes involved in oxygen transport and delivery (NGB, AGPTL4, TBXA2R) and with calcium and potassium ion binding were over expressed (TNNC1, CDH22, KCND3) in PPP-DDK. Genes related to proteolysis (CTSK, MSTP9) were down regulated. 121 Psets were differentially expressed between >55 vs. 55 yo DDKs. Apoptotic (FAF1, CASP6, GADD456), complement (C4BP6), regulation of glycolysis, and matrix deposition related genes were over expressed in >55yo DDKs.

Conclusions. Important sets of differentially expressed genes were identified between DDK-PPP and CSP groups. PPP-DDKs were related to expression of genes involved in apoptosis regulation and oxygen transport.