Supervised Machine Learning Algorithm Reveals Human Lung EVLP Perfusate Cell Populations are Associated with Donor Mode of Death and Post-Transplant Primary Graft Dysfunction.

Lung transplantation (LT) is limited by the lack of suitable donor lungs, and early-post LT survival is hampered by primary graft dysfunction (PGD). Both neurological determination of death (NDD) and donation after circulatory death (DCD) are associated with donor lung injuries, and ex vivo lung perfusion (EVLP) can be used to assess donor lung suitability. The relationship of donor leukocytes within the EVLP perfusate to donor mode of death and PGD is not well studied. Using CITRUS, an algorithm designed to identify stratifying biological signatures, we hypothesized that there would be differences in perfusate leukocyte composition based on donor mode of death and recipient PGD status. Clinical EVLP cases from donor lungs of NDD (n = 20) and DCD (n = 20) origin were retrospectively selected. In a separate cohort, clinical EVLP cases were selected and grouped based on recipient PaO2/FiO2 (P/F) ratio at 72h post-LT into two groups: PGD3 (n = 33) and PGD0/1 (n = 25). Cryopreserved perfusate cells, from 1h and 4h of perfusion, were subjected to flow cytometry and then underwent CITRUS analysis, comparing NDD to DCD and PGD0/1 to PGD3 to identify significantly stratifying cell populations (p < 0.01). When comparing perfusate cells between NDD and DCD, NK cells and macrophages were observed to be higher in NDD whereas memory T cells were enriched in DCD (Fig A). In the comparison of PGD0/1 and PGD3, neutrophils (Nφ) were found to be significantly higher in the PGD3 whereas NK cells were significantly higher in the PGD0/1 group (Fig B). We have shown that certain perfusate cell populations are enriched based on donor mode of death, possibly due to distinct donor lung injury. The association of Nφ with PGD3 suggests a potential biomarker and therapeutic target. This work illustrates the value of cellular analysis of acellular EVLP perfusate, as all cells in the perfusate emanate from the donor lung and reflect its status. [ABSTRACT FROM AUTHOR]