Reliability of Donor Lung Sampling in Lung Transplantation

Introduction: Ex vivo lung perfusion (EVLP) is a normothermic platform used to assess donor lungs. Many have studied biomarkers in lung injury, but it is unclear whether samples taken from one location are representative of the organ. Our objective was to investigate the uniformity of cytokine expression in tissue biopsies and in EVLP perfusates from various locations. Methods: In the tissue study, eight donor lungs were partitioned from apex to base. In each lung, three biopsies were taken from the third, sixth, and ninth slices, while two were taken from the lingula and an injury site. In the perfusate study, four samples were taken from four lobes in eight donors during EVLP. Expressions of IL-6, IL-8, IL-10, and IL-1β were measured using qPCR and ELISA. Results: In the tissue study, the mean intra-biopsy equal-variance F-value was 0.53. The median intra-biopsy coefficient of variation (CV) was 18%. In donors without gross focal injury, the mean comparisons of biopsies in each donor showed that the three consistent slices showed no differences and had a CV of 20%, which was similar to the intra-biopsy CV (p=0.80). Both the lingula and injury biopsies demonstrated larger differences from the rest. The median intra-lung CV of perfusates from different lobes was 4.9%. Conclusion: Intra-biopsy variances were consistent across biopsies. Lungs without gross focal injury demonstrated more consistent gene expression. The lingula is not a representative site due to high signal variability. The consistent measurements in EVLP perfusates provided a uniform picture of the inflammation.