IRI causes perioperative morbidity and mortality after lung transplantation. Understanding molecular pathways associated with IRI would reduce morbidity and facilitate use of lungs from non-heart beating donors to address the shortage of transplantable lungs. Our goal was to elucidate gene expression patterns of IRI in human lungs following transplantation.
Eight patients receiving bilateral sequential lung transplants without cardiopulmonary bypass had biopsies taken from their donor lungs prior to reperfusion and prior to chest closure from each lung. Pre-reperfusion biopsies, mean cold ischemic time 3 hours 56 min ± 72 min (SD), were compared to short and long reperfusion time samples with mean reperfusion times of 24 min ± 7 min and 3 hours 10 min ± 20 min respectively. RNA was extracted and analyzed with Affymetrix® U133A and B chips and Genespring® software. Changes in selected genes were confirmed with quantitative RT-PCR and MAP kinase activation was studied by western blot.
Using a cross gene error model (p value cutoff: 0.05) and applying Benjamini and Hochberg FDR multiple testing correction, we found over 700 genes and ESTs changed among 24 chips. Cluster analysis of the 425 changed genes on the U133A chip showed strong correlation between pre, short and long reperfusion time samples (n=8 each), with only one of the pre-reperfusion samples mixed into the short reperfusion group. Evidence of altered gene expression was present in pre vs. short reperfusion groups but more differences occurred between the pre vs. long reperfusion samples. RT-PCR confirmed microarray results in all samples tested thus far. Several genes regulated by MAP kinases were identified. Activation of ERK 1 and 2, p38, and JNK MAP kinases following reperfusion was demonstrated by western blot.
Microarrays provides valuable and novel insight into human lung IRI consequent to lung transplantation.
Better understanding of IRI could improve transplantation outcomes and increase the number of transplantable lungs.
E. Olson, None.