Donor leukocyte trafficking during human ex vivo lung perfusion.

BACKGROUND: Ex vivo lung perfusion (EVLP) is used to assess and preserve lungs prior to transplantation. However, its inherent immunomodulatory effects are not completely understood. We examine perfusate and tissue compartments to determine the change in immune cell composition in human lungs maintained on EVLP. METHODS: Six human lungs unsuitable for transplantation underwent EVLP. Tissue and perfusate samples were obtained during cold storage and at 1-, 3- and 6-h during perfusion. Flow cytometry, immunohistochemistry, and bead-based immunoassays were used to measure leukocyte composition and cytokines. Mean values between baseline and time points were compared by Student's t test. RESULTS: During the 1st hour of perfusion, perfusate neutrophils increased (+22.2 ± 13.5%, p < 0.05), monocytes decreased (-77.5 ± 8.6%, p < 0.01) and NK cells decreased (-61.5 ± 22.6%, p < 0.01) compared to cold storage. In contrast, tissue neutrophils decreased (-22.1 ± 12.2%, p < 0.05) with no change in monocytes and NK cells. By 6 h, perfusate neutrophils, NK cells, and tissue neutrophils were similar to baseline. Perfusate monocytes remained decreased, while tissue monocytes remained unchanged. There was no significant change in B cells or T cell subsets. Pro-inflammatory cytokines (IL-1b, G-CSF, IFN-gamma, CXCL2, CXCL1 granzyme A, and granzyme B) and lymphocyte activating cytokines (IL-2, IL-4, IL-6, IL-8) increased during perfusion. CONCLUSIONS: Early mobilization of innate immune cells occurs in both perfusate and tissue compartments during EVLP, with neutrophils and NK cells returning to baseline and monocytes remaining depleted after 6 h. The immunomodulatory effect of EVLP may provide a therapeutic window to decrease the immunogenicity of lungs prior to transplantation.

Ventricular Fibrillatory Arrest: A Safe Option in Robotic Totally Endoscopic Intracardiac Surgery.

BACKGROUND: Moderate hypothermic ventricular fibrillatory arrest during heart surgery is an alternative to cardioplegic arrest in selected patients. We reviewed our experience using a ventricular fibrillatory arrest technique in robotic totally endoscopic intracardiac surgery. METHODS: From February 2014 through July 2022, 128 patients who underwent robotic totally endoscopic intracardiac surgical procedures performed using moderate hypothermic ventricular fibrillatory arrest were reviewed. Patients were chosen based on the risk of aortic manipulation, complexity of the procedure, grade of aortic valve insufficiency and comorbidities, including history of prior cardiac surgery and peripheral vascular disease. RESULTS: Patients were a mean age of 65 ± 14 years, and the mean The Society of Thoracic Surgeons score was 2.7 ± 2.9. Fourteen patients (11%) had a history of previous cardiac surgery. The intracardiac procedures were mitral valve surgery in 84 patients (66%), isolated cryomaze procedure in 27 (21%), and other in 17 (13%). The mean ventricular fibrillatory arrest time was 79 ± 26 minutes, and the mean cardiopulmonary bypass time was 174 ± 49 minutes. There was no conversion to sternotomy. Seven patients (5.5%) required inotropic support, and 2 patients (1.6%) needed an intra-aortic balloon pump. There was no incidence of postoperative stroke or clinical myocardial infarction. The mean hospital and intensive care unit lengths of stay were 3.1 ± 1.7 and 1.4 ± 0.7 days, respectively. One death (0.78%) occurred due to respiratory failure. CONCLUSIONS: Moderate hypothermic ventricular fibrillatory arrest in robotic intracardiac surgery may be a safe and effective alternative in selected patients.

The Effect of Normothermic Machine Perfusion on the Immune Profile of Donor Liver.

Background: Normothermic machine perfusion (NMP) allows viability assessment and potential resuscitation of donor livers prior to transplantation. The immunological effect of NMP on liver allografts is undetermined, with potential implications on allograft function, rejection outcomes and overall survival. In this study we define the changes in immune profile of human livers during NMP. Methods: Six human livers were placed on a NMP device. Tissue and perfusate samples were obtained during cold storage prior to perfusion and at 1, 3, and 6 hours of perfusion. Flow cytometry, immunohistochemistry, and bead-based immunoassays were used to measure leukocyte composition and cytokines in the perfusate and within the liver tissue. Mean values between baseline and time points were compared by Student's t-test. Results: Within circulating perfusate, significantly increased frequencies of CD4 T cells, B cells and eosinophils were detectable by 1 hour of NMP and continued to increase at 6 hours of perfusion. On the other hand, NK cell frequency significantly decreased by 1 hour of NMP and remained decreased for the duration of perfusion. Within the liver tissue there was significantly increased B cell frequency but decreased neutrophils detectable at 6 hours of NMP. A transient decrease in intermediate monocyte frequency was detectable in liver tissue during the middle of the perfusion run. Overall, no significant differences were detectable in tissue resident T regulatory cells during NMP. Significantly increased levels of pro-inflammatory and anti-inflammatory cytokines were seen following initiation of NMP that continued to rise throughout duration of perfusion. Conclusions: Time-dependent dynamic changes are seen in individual leukocyte cell-types within both perfusate and tissue compartments of donor livers during NMP. This suggests a potential role of NMP in altering the immunogenicity of donor livers prior to transplant. These data also provide insights for future work to recondition the intrinsic immune profile of donor livers during NMP prior to transplantation.