N. Aboelnazar

A Leukocyte Filter Does Not Provide Further Benefit During Ex Vivo Lung Perfusion

Normothermic ex vivo lung perfusion (EVLP) allows for assessment and reconditioning of donor lungs. Although a leukocyte filter (LF) is routinely incorporated into the EVLP circuit; its efficacy remains to be determined. Twelve pig lungs were perfused and ventilated ex vivo in a normothermic state for 12 hours. Lungs (n = 3) were allocated to four groups according to perfusate composition and the presence or absence of a LF in the circuit (acellular ± LF, cellular ± LF). Acceptable physiologic lung parameters were achieved during EVLP; however, increased amounts of pro-inflammatory cytokines (TNF-&agr; and IL-6) and leukocytes in the perfusate were observed despite the presence or absence of a LF. Analysis of cells washed off the LF demonstrates that it trapped leukocytes although being ineffective throughout perfusion as it became saturated over 12 hours of EVLP. We conclude that there is no objective evidence to support the routine incorporation of a LF during EVLP as it does not provide further benefit and its removal does not appear to cause harm. The lack of hypothesized benefit to a LF may be because of the saturation of the LF with donor leukocytes, leading to similar amounts of circulating leukocytes still present in the perfusate with and without a LF.

Common Hospital Ingredient Perfusate Equivalent to Standard Krebs–Henseleit Buffer with Serum Albumin Derived Perfusate in Negative Pressure Ventilation Ex Vivo Lung Perfusion

Introduction Normothermic ex-vivo lung perfusion (EVLP) using negative pressure ventilation (NPV) and red blood cell-based perfusate solutions have been shown to decrease edema formation and pro-inflammatory cytokine production compared to positive pressure ventilation (PPV). We sought to develop a common hospital ingredient derived perfusate (CHIP) with equivalent functional and inflammatory characteristics to the standard Krebs–Henseleit buffer with 8% serum albumin derived perfusate (KHB-Alb) in order to improve access and reduce costs of ex vivo organ perfusion. Methods Porcine lungs were perfused using NPV-EVLP for 12 hours in a normothermic state, and were allocated to two groups: KHB-Alb (n=8) vs CHIP (n=4). Physiologic parameters, cytokine profiles, and edema formation were compared between treatment groups. Results Perfused lungs in both groups demonstrated equivalent oxygenation (partial pressure of arterial oxygen/ fraction of inspired oxygen ratio >350 mmHg) and physiologic parameters. There was equivalent generation of tumor necrosis factor-&agr;, irrespective of perfusate solution used, when comparing CHIP vs KHB-Alb. Pig lungs developed equivalent edema formation between groups (CHIP: 15.7 ± 5.8%, STEEN 19.5 ± 4.4%, p>0.05). Conclusion A perfusate derived of common hospital ingredients provides equivalent results to standard Krebs–Henseleit buffer with 8% serum albumin based perfusate in NPV-EVLP. Canadian Institutes for Health Research - Canadian National Transplant Research Program (CIHR-CNTRP). University Hospital Foundation (UHF). Mazankowski Alberta Heart Institute - University Hospital Foundation Gerald Averback Award in Cardiovascular Gene Therapy / Genomics and Vascular Biology.

A Decrease in Hypoxic Pulmonary Vasoconstriction Correlates With Increased Inflammation During Extended Normothermic Ex Vivo Lung Perfusion: HYPOXIC PULMONARY VASOCONSTRICTION DURING EX VIVO LUNG PERFUSION

Normothermic ex vivo lung perfusion (EVLP) is an evolving technology to evaluate function of donor lungs to determine suitability for transplantation. We hypothesize that hypoxic pulmonary vasoconstriction (HPV) during EVLP will provide a more sensitive parameter of lung function to determine donor lung quality for lung transplantation. Eight porcine lungs were procured, and subsequently underwent EVLP with autologous blood and STEEN solution for 10 h. Standard physiologic parameters including dynamic compliance, peak airway pressure, and pulmonary vascular resistance (PVR) remained stable (P = 0.055), mean oxygenation (PO2 /FiO2 ) was 400 ± 18 mm Hg on average throughout perfusion. Response to hypoxia resulted in a robust increase in PVR (ΔPVR) up to 4 h of perfusion, however the HPV response then blunted beyond T6 (P < 0.01). The decrease in HPV response inversely correlated to cytokine concentrations of Interleukin-6 and tumor necrosis factor-α (P < 0.01). Despite acceptable lung oxygenation and standard physiologic parameters during 10 h of EVLP, there is a subclinical deterioration of lung function. HPV challenges can be performed during EVLP as a simple and more sensitive index of pulmonary vascular reactivity.

Ex vivo perfusion induces a time- and perfusate-dependent molecular repair response in explanted porcine lungs

Ex vivo lung perfusion (EVLP) shows promise in ameliorating pretransplant acute lung injury (ALI) and expanding the donor organ pool, but the mechanisms of ex vivo repair remain poorly understood. We aimed to assess the utility of gene expression for characterizing ALI during EVLP. One hundred sixty-nine porcine lung samples were collected in vivo (n = 25), after 0 (n = 11) and 12 (n = 11) hours of cold static preservation (CSP), and after 0 (n = 57), 6 (n = 8), and 12 (n = 57) hours of EVLP, utilizing various ventilation and perfusate strategies. The expression of 53 previously described ALI-related genes was measured and correlated with function and histology. Twenty-eight genes were significantly upregulated and 6 genes downregulated after 12 hours of EVLP. Aggregate gene sets demonstrated differential expression with EVLP (P < .001) but not CSP. Upregulated 28-gene set expression peaked after 6 hours of EVLP, whereas downregulated 6-gene set expression continued to decline after 12 hours. Cellular perfusates demonstrated a greater reduction in downregulated 6-gene set expression vs acellular perfusate (P < .038). Gene set expression correlated with relevant functional and histologic parameters, including P/F ratio (P < .001) and interstitial inflammation (P < .005). Further studies with posttransplant results are warranted to evaluate the clinical significance of this novel molecular approach for assessing organ quality during EVLP.

Ex-Vivo Lung Perfusion: From Bench to Bedside

Lung transplantation is an established treatment option for eligible patients with endstage lung disease. Nonetheless, there exists an imbalance between donor lungs considered suitable for transplantation and the ever-growing number of patients dying on the waiting list. This chapter reflects the potential alternative, normothermic exvivo lung perfusion (EVLP), which has emerged to address this issue and how it can expand the currently limited donor pool. Normothermic ex-vivo lung perfusion (EVLP), as a novel preservation technique, is capable of assessing, evaluating, and improving lung function prior to lung transplantation. Here, we (1) contrast the various available commercial EVLP available and used around the world; (2) outline the University of Alberta novel EVLP circuit; (3) discuss the limitations present between clinical and laboratory applications; and (4) present what we are currently working on at the laboratory to further improve the assessment techniques used on EVLP.