Effects of Prolonged Cold Ischemia On Intragraft Gene Expression Profiles.

Abstract

Background: Deceased-donor (DD) kidneys are at higher risk for ischemia/reperfusion injury leading to increased inflammatory mediators and innate immune response. We aimed to investigate the effects of prolonged cold ischemia on intragraft molecular gene expression profiles of DD kidneys comparing to living-donors (LD) before and after transplantation using microarrays. Methods: There were 20 pre-implantation kidney biopsy samples (10 LD and 10 DD). The cold ischemia time (CIT) was < 24 hours in 7 and > 24 hours in 3 DD kidneys. There were 15 post-transplant biopsy samples from DD (8 had CIT < 24 h and 7 had > 24 h) with the diagnosis of acute tubular necrosis (ATN) which were compared to 9 normal transplant biopsies. The gene expression profiles were studied by Affymetrix HuGene 1.0 ST expression arrays. Results: There were 336 differentially expressed genes when pre-implantation DD biopsies were compared to LD biopsies (Both False discovery rate p<0.05 and fold change >2). Pathogenesis based transcripts (PBT) showed increased transcripts associated with injury and response (IRIT), Cytotoxic T-cell (CAT), Natural-Killer cell (NKAT), Constitutive Macrophage (CMAT), and Gamma Interferon (GRIT) in DD samples compared to pre-implantation LD biopsies. There was no difference in T-regulatory cell (TREG), B-cell (BAT), and Endothelial cell (ENDAT) associated gene transcripts between 2 groups. However, there was no statistically significant difference in expression of any PBTs studied when biopsies with CIT > 24 hours compared to biopsies with CIT < 24 hours. There was also no difference in expression of any PBTs studied in post-transplant DD biopsies with the diagnosis of ATN compared to normal transplant biopsies (Table, P-value for significance <0.05). Conclusions: Pre-implantation DD biopsies showed increased expression of gene transcripts associated with inflammatory mediators (IRIT and GRIT) and innate immune response involving NKAT and CAT compared to LD kidneys. However, increased CIT does not change the intragraft gene expression profiles before and after transplantation.Table: No Caption available.