Marcelo Cypel

Normothermic Ex Vivo Lung Perfusion in Clinical Lung Transplantation

BACKGROUND More than 80% of donor lungs are potentially injured and therefore not considered suitable for transplantation. With the use of normothermic ex vivo lung perfusion (EVLP), the retrieved donor lung can be perfused in an ex vivo circuit, providing an opportunity to reassess its function before transplantation. In this study, we examined the feasibility of transplanting high-risk donor lungs that have undergone EVLP. METHODS In this prospective, nonrandomized clinical trial, we subjected lungs considered to be high risk for transplantation to 4 hours of EVLP. High-risk donor lungs were defined by specific criteria, including pulmonary edema and a ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen (PO(2):FIO(2)) less than 300 mm Hg. Lungs with acceptable function were subsequently transplanted. Lungs that were transplanted without EVLP during the same period were used as controls. The primary end point was primary graft dysfunction 72 hours after transplantation. Secondary end points were 30-day mortality, bronchial complications, duration of mechanical ventilation, and length of stay in the intensive care unit and hospital. RESULTS During the study period, 136 lungs were transplanted. Lungs from 23 donors met the inclusion criteria for EVLP; in 20 of these lungs, physiological function remained stable during EVLP and the median PO(2):FIO(2) ratio increased from 335 mm Hg in the donor lung to 414 and 443 mm Hg at 1 hour and 4 hours of perfusion, respectively (P<0.001). These 20 lungs were transplanted; the other 116 lungs constituted the control group. The incidence of primary graft dysfunction 72 hours after transplantation was 15% in the EVLP group and 30% in the control group (P=0.11). No significant differences were observed for any secondary end points, and no severe adverse events were directly attributable to EVLP. CONCLUSIONS Transplantation of high-risk donor lungs that were physiologically stable during 4 hours of ex vivo perfusion led to results similar to those obtained with conventionally selected lungs. (Funded by Vitrolife; ClinicalTrials.gov number, NCT01190059.).

Technique for Prolonged Normothermic Ex Vivo Lung Perfusion

BACKGROUND The inhibition of cellular metabolism induced by hypothermia obviates the possibility of substantial reparative processes occurring during organ preservation. The aim of this study was to develop a technique of extended (12-hour) ex vivo lung perfusion (EVLP) at normothermia for assessment and protective maintenance of the donor lung. METHODS Six double-lung blocks from 35-kg pigs and 5 single human lungs were subjected to 12 hours of normothermic EVLP using acellular Steen Solution. In the animal studies, the left lung was transplanted into recipients at the end of EVLP and reperfused for 4 hours to evaluate the impact of prolonged EVLP on post-transplant lung function. A protective mode of mechanical ventilation with controlled perfusion flows and pressures in the pulmonary vasculature were employed during EVLP. Lung oxygenation capacity (DeltaPo(2)), pulmonary vascular resistance and airway pressures were evaluated in the system. Red blood cells were added to the perfusate to a hematocrit of 20% at the end of human lung EVLP to study lung functional assessment with and without cells. RESULTS Lung function was stable during 12 hours of EVLP. This stability during prolonged normothermic EVLP translated into excellent post-transplant lung function (Pao(2)/Fio(2): 527 +/- 22 mm Hg), low edema formation (wet/dry ratio: 5.24 +/- 0.38) and preserved lung histology after transplantation. The acellular perfusion assessment of lung function accurately correlated with post-transplant graft function. CONCLUSIONS Twelve hours of EVLP at physiologic temperatures using an acellular perfusate is achievable and maintains the donor lungs without inflicting significant added injury. This system can be used to assess, maintain and treat injured donor lungs.

Functional Repair of Human Donor Lungs by IL-10 Gene Therapy

Treatment of damaged donor lungs with the cytokine interleukin-10 improves their function, allowing previously unacceptable organs to be used for transplantation. Living Well After Lung Replacement Bumper stickers that counsel motorists to “just breathe” abound—easier said than done when it comes to patients with serious lung disorders. Lung transplantations are on the rise, from 203 in 1990 to more than 1200 in 2008 in the United States. Earlier this year, transplant surgeons at Johns Hopkins presented evidence that more is better—hospitals that perform 20 or more lung transplants per year have the best patient survival rates. However, successful surgeries require healthy donor lungs, a resource that remains in short supply. Now, Keshavjee and colleagues describe a gene therapy treatment protocol to repair lungs after removal from the donor and before transplantation into patients. Candidates for lung transplantation are patients suffering from end-stage lung diseases, such as emphysema, cystic fibrosis, pulmonary fibrosis, and pulmonary arterial hypertension. Organ donors are people who have undergone brain death, a process that is as violent as it sounds: Brain death is accompanied by the spewing of inflammation-inducing molecules called cytokines that damage more than 80% of donated lungs. These injured organs are highly inflamed, and their alveoli—the gas exchange machinery in lungs—are disrupted and only mildly functional. To avoid primary graft dysfunction—lung damage that occurs within the 72 hours after transplantation—transplant surgeons usually reject such injured organs. A method is needed to heal these fixer-upper organs so that they can be used to give patients a new lease on life. Using IL-10, an anti-inflammatory cytokine, Keshavjee’s team devised a treatment to quell inflammation in the injured donor lungs and refurbish the alveoli. Although the standard technique for the handling of organs is to keep them on ice in a sealed bag, this IL-10 gene therapy approach must be performed at body temperature so that the lung’s cellular machinery can express the gene efficiently. The researchers then carried out prolonged ex vivo lung perfusion (EVLP) and kept the lungs breathing outside the body in conditions that mimic physiological ones. Pig lungs that were subjected to IL-10 gene therapy and EVLP for 12 hours displayed reduced inflammation and enhanced function when transplanted into donor pigs, relative to control organs. The same treatment was applied to human lungs deemed unsuitable for transplantation, and these organs, relative to controls, displayed the presence of anti-inflammatory cytokines, repair of alveoli, and improved function, determined by measuring gas exchange and pulmonary vascular resistance. This procedure can yield a larger number of usable lungs and thus more successful transplantations so that patients can “just breathe.” More than 80% of potential donor lungs are injured during brain death of the donor and from complications experienced in the intensive care unit, and therefore cannot be used for transplantation. These lungs show inflammation and disruption of the alveolar-capillary barrier, leading to poor gas exchange. Although the number of patients in need of lung transplantation is increasing, the number of donors is static. We investigated the potential to use gene therapy with an adenoviral vector encoding human interleukin-10 (AdhIL-10) to repair injured donor lungs ex vivo before transplantation. IL-10 is an anti-inflammatory cytokine that mainly exerts its suppressive functions by the inactivation of antigen-presenting cells with consequent inhibition of proinflammatory cytokine secretion. In pigs, AdhIL-10–treated lungs exhibited attenuated inflammation and improved function after transplantation. Lungs from 10 human multiorgan donors that had suffered brain death were determined to be clinically unsuitable for transplantation. They were then maintained for 12 hours at body temperature in an ex vivo lung perfusion system with or without intra-airway delivery of AdhIL-10 gene therapy. AdhIL-10–treated lungs showed significant improvement in function (arterial oxygen pressure and pulmonary vascular resistance) when compared to controls, a favorable shift from proinflammatory to anti-inflammatory cytokine expression, and recovery of alveolar–blood barrier integrity. Thus, treatment of injured human donor lungs with the cytokine IL-10 can improve lung function, potentially rendering injured lungs suitable for transplantation into patients.

Normothermic Ex Vivo Perfusion Prevents Lung Injury Compared to Extended Cold Preservation for Transplantation

Treatment of injured donor lungs ex vivo to accelerate organ recovery and ameliorate reperfusion injury could have a major impact in lung transplantation. We have recently demonstrated a feasible technique for prolonged (12 h) normothermic ex vivo lung perfusion (EVLP). This study was performed to examine the impact of prolonged EVLP on ischemic injury. Pig donor lungs were cold preserved in Perfadex® for 12 h and subsequently divided into two groups: cold static preservation (CSP) or EVLP at 37°C with Steen™ solution for a further 12 h (total 24 h preservation). Lungs were then transplanted and reperfused for 4 h. EVLP preservation resulted in significantly better lung oxygenation (PaO2 531 ± 43 vs. 244 ± 49 mmHg, p < 0.01) and lower edema formation rates after transplantation. Alveolar epithelial cell tight junction integrity, evaluated by zona occludens‐1 protein staining, was disrupted in the cell membranes after prolonged CSP but not after EVLP. The maintenance of integrity of barrier function during EVLP translates into significant attenuation of reperfusion injury and improved graft performance after transplantation. Integrity of functional metabolic pathways during normothermic perfusion was confirmed by effective gene transfer and GFP protein synthesis by lung alveolar cells. In conclusion, EVLP prevents ongoing injury associated with prolonged ischemia and accelerates lung recovery.

Experience with the first 50 ex vivo lung perfusions in clinical transplantation.

OBJECTIVE Normothermic ex vivo lung perfusion is a novel method to evaluate and improve the function of injured donor lungs. We reviewed our experience with 50 consecutive transplants after ex vivo lung perfusion. METHODS A retrospective study using prospectively collected data was performed. High-risk brain death donor lungs (defined as Pao(2)/Fio(2) <300 mm Hg or lungs with radiographic or clinical findings of pulmonary edema) and lungs from cardiac death donors were subjected to 4 to 6 hours of ex vivo lung perfusion. Lungs that achieved stable airway and vascular pressures and Pao(2)/Fio(2) greater than 400 mm Hg during ex vivo lung perfusion were transplanted. The primary end point was the incidence of primary graft dysfunction grade 3 at 72 hours after transplantation. End points were compared with lung transplants not treated with ex vivo lung perfusion (controls). RESULTS A total of 317 lung transplants were performed during the study period (39 months). Fifty-eight ex vivo lung perfusion procedures were performed, resulting in 50 transplants (86% use). Of these, 22 were from cardiac death donors and 28 were from brain death donors. The mean donor Pao(2)/Fio(2) was 334 mm Hg in the ex vivo lung perfusion group and 452 mm Hg in the control group (P = .0001). The incidence of primary graft dysfunction grade 3 at 72 hours was 2% in the ex vivo lung perfusion group and 8.5% in the control group (P = .14). One patient (2%) in the ex vivo lung perfusion group and 7 patients (2.7%) in the control group required extracorporeal lung support for primary graft dysfunction (P = 1.00). The median time to extubation, intensive care unit stay, and hospital length of stay were 2, 4, and 20 days, respectively, in the ex vivo lung perfusion group and 2, 4, and 23 days, respectively, in the control group (P > .05). Thirty-day mortality (4% in the ex vivo lung perfusion group and 3.5% in the control group, P = 1.00) and 1-year survival (87% in the ex vivo lung perfusion group and 86% in the control group, P = 1.00) were similar in both groups. CONCLUSIONS Transplantation of high-risk donor lungs after 4 to 6 hours of ex vivo lung perfusion is safe, and outcomes are similar to those of conventional transplants. Ex vivo lung perfusion improved our center use of donor lungs, accounting for 20% of our current lung transplant activity.

Bridge to Thoracic Organ Transplantation in Patients with Pulmonary Arterial Hypertension Using a Pumpless Lung Assist Device

We describe a novel technique of pumpless extracorporeal life support in four patients with cardiogenic shock due to end‐stage pulmonary hypertension (PH) including patients with veno‐occlusive disease (PVOD) using a pumpless lung assist device (LAD). The device was connected via the pulmonary arterial main trunk and the left atrium, thereby creating a septostomy‐like shunt with the unique addition of gas exchange abilities in parallel to the lung. Using this approach, all four patients were successfully bridged to bilateral lung transplantation and combined heart–lung transplantation, respectively. Although all patients presented in cardiogenic shock, hemodynamic unloading of the right ventricle using the low‐resistance LAD stabilized the hemodynamic situation immediately so that no pump support was subsequently required.

Impact of extracorporeal life support on outcome in patients with idiopathic pulmonary arterial hypertension awaiting lung transplantation

BACKGROUND Our management of patients with idiopathic pulmonary arterial hypertension (iPAH) awaiting lung transplantation changed in 2006 with the introduction of extracorporeal life support (ECLS) as an option to bridge these patients to transplantation (BTT). METHODS To study the effect of this change on waiting list mortality and post-transplant outcome, 21 consecutive iPAH patients listed for lung transplantation between January 2006 and September 2010 (second cohort) were compared with 23 consecutive iPAH patients listed between January 1997 and December 2005 (first cohort). RESULTS Between the first and second cohort, the number of patients admitted to the hospital as BTT increased from 4% (1 of 23) to 48% (10 of 21; p = 0.0009). Six patients were BTT with ECLS in the second cohort, including 4 with the Novalung device (Novalung GmbH, Hechingen, Germany) connected as a pumpless oxygenating right-to-left shunt between the pulmonary artery and left atrium. While on the waiting list, 5 patients (22%) died in the first cohort and none in the second cohort (p = 0.03). Time on the waiting list decreased from 118 ± 85 to 53 ± 40 days between the first and second cohort (p = 0.004). After lung transplantation, the 30-day mortality was 16.7% in the first cohort and 9.5% in the second cohort (p = 0.5). The postoperative intensive care unit stay increased from 17 ± 13 to 36 ± 30 days between the first and second cohort (p = 0.02). The long-term outcome after lung transplantation remained similar between both cohorts. CONCLUSIONS Aggressive management with ECLS of iPAH patients awaiting lung transplantation could have a major impact to reduce the waiting list mortality. This may, however, be associated with longer intensive care unit stay after transplant.

Initial experience with lung donation after cardiocirculatory death in Canada.

BACKGROUND Organ donation after cardiac death (DCD) has the potential to alleviate some of the shortage of suitable lungs for transplantation. Only limited data describe outcomes after DCD lung transplantation. This study describes the early and intermediate outcomes after DCD lung transplantation in Canada. METHODS Data were collected from donors and recipients involved in DCD lung transplantations between June 2006 and December 2008. Described are the lung DCD protocol, donor characteristics, and the occurrence of post-transplant events including primary graft dysfunction (PGD), bronchial complications, acute rejection (AR), bronchiolitis obliterans syndrome (BOS), and survival. RESULTS Successful multiorgan controlled DCD increased from 4 donors in 2006 to 26 in 2008. Utilization rates of lungs among DCD donors were 0% in 2006, 11% in 2007, and 27% in 2008. The lung transplant team evaluated 13 DCD donors on site, and lungs from 9 donors were ultimately used for 10 recipients. The 30-day mortality was 0%. Severe PGD requiring extracorporeal membrane oxygenation occurred in 1 patient. Median intensive care unit stay was 3.5 days (range, 2-21 days). Hospital stay was 25 days (range, 9-47 days). AR occurred in 2 patients. No early BOS has developed. Nine (90%) patients are alive at a median of 270 days (range, 47-798 days) with good performance status and lung function. One patient died of sepsis 17 months after transplantation. CONCLUSION DCD has steadily increased in Canada since 2006. The use of controlled DCD lungs for transplantation is associated with very acceptable early and intermediate clinical outcomes.

Extracorporeal life support for adults with severe acute respiratory failure.

Extracorporeal life support (ECLS) is an artificial means of maintaining adequate oxygenation and carbon dioxide elimination to enable injured lungs to recover from underlying disease. Technological advances have made ECLS devices smaller, less invasive, and easier to use. ECLS might, therefore, represent an important step towards improved management and outcomes of patients with acute respiratory distress syndrome. Nevertheless, rigorous evidence of the ability of ECLS to improve short-term and long-term outcomes is needed before it can be widely implemented. Moreover, how to select patients and the timing and indications for ECLS in severe acute respiratory distress syndrome remain unclear. We describe the physiological principles, the putative risks and benefits, and the clinical evidence supporting the use of ECLS in patients with acute respiratory distress syndrome. Additionally, we discuss controversies and future directions, such as novel technologies and indications, mechanical ventilation of the native lung during ECLS, and ethics considerations.

Physiologic assessment of the ex vivo donor lung for transplantation

BACKGROUND The evaluation of donor lungs by normothermic ex vivo acellular perfusion has improved the safety of organ utilization. However, this strategy requires a critical re-evaluation of the parameters used to assess lungs during ex vivo perfusion compared with those traditionally used to evaluate the donor lung in vivo. Using a porcine model, we studied the physiology of acellular lung perfusion with the aim of improving the accuracy of clinical ex vivo evaluation. METHODS Porcine lungs after 10 hours of brain death and 24 hours of cold ischemia and uninjured control lungs were perfused for 12 hours and then transplanted. PaO2, compliance, airway pressure and pulmonary vascular resistance were measured. Ventilation with 100% nitrogen and addition of red blood cells to the perfusate were used to clarify the physiologic disparities between in vivo blood perfusion and ex vivo acellular perfusion. RESULTS During 12 hours of ex vivo perfusion, injured lungs developed edema with decreased compliance and increased airway pressure, but ex vivo PO2 remained stable. After transplantation, injured lungs demonstrated high vascular resistance and poor PaO2. A reduced effect of shunt on ex vivo lung perfusion PO2 was found to be attributable to the linearization of the relationship between oxygen content and PO2, which occurs with acellular perfusate. CONCLUSIONS Ex vivo PO2 may not be the first indication of lung injury and, taken alone, may be misleading in assessing the ex vivo lung. Thus, evaluation of other physiologic parameters takes on greater importance.