One-year experience with ex vivo lung perfusion: Preliminary results from a single center

Composition of ex vivo perfusion solutions and kinetics define differential cytokine/chemokine secretion in a porcine cardiac arrest model of lung preservation

Background

Ex vivo lung perfusion (EVLP) uses continuous normothermic perfusion to reduce ischemic damage and to improve post-transplant outcomes, specifically for marginal donor lungs after the donation after circulatory death. Despite major efforts, the optimal perfusion protocol and the composition of the perfusate in clinical lung transplantation have not been identified. Our study aims to compare the concentration levels of cytokine/chemokine in different perfusion solutions during EVLP, after 1 and 9 h of cold static preservation (CSP) in a porcine cardiac arrest model, and to correlate inflammatory parameters to oxygenation capacities.

Methods

Following cardiac arrest, the lungs were harvested and were categorized into two groups: immediate (I-EVLP) and delayed EVLP (D-EVLP), after 1 and 9 h of CSP, respectively. The D-EVLP lungs were perfused with either Steen or modified Custodiol-N solution containing only dextran (CD) or dextran and albumin (CDA). The cytokine/chemokine levels were analyzed at baseline (0 h) and after 1 and 4 h of EVLP using Luminex-based multiplex assays.

Results

Within 4 h of EVLP, the concentration levels of TNF-α, IL-6, CXCL8, IFN-γ, IL-1α, and IL-1β increased significantly (P < 0.05) in all experimental groups. The CD solution contained lower concentration levels of TNF-α, IL-6, CXCL8, IFN-γ, IL-2, IL-12, IL-10, IL-4, IL-1RA, and IL-18 (P < 0.05) compared with those of the Steen solution. The concentration levels of all experimental groups have correlated negatively with the oxygenation capacity values (P < 0.05). Protein concentration levels did not reach statistical significance for I-EVLP vs. D-EVLP and CD vs. CDA solutions.

Conclusion

In a porcine cardiac arrest model, a longer period of CSP prior to EVLP did not result in an enhanced protein secretion into perfusates. The CD solution reduced the cytokine/chemokine secretion most probably by iron chelators and/or by the protecting effects of dextran. Supplementing with albumin did not further reduce the cytokine/chemokine secretion into perfusates. These findings may help in optimizing the preservation procedure of the lungs, thereby increasing the donor pool of organs.

The role of ex-situ perfusion for thoracic organs

PURPOSE OF REVIEW

Ex-situ machine perfusion for both heart (HTx) and lung transplantation (LuTx) reduces ischemia-reperfusion injury (IRI), allows for greater flexibility in geographical donor management, continuous monitoring, organ assessment for extended evaluation, and potential reconditioning of marginal organs. In this review, we will delineate the impact of machine perfusion, characterize novel opportunities, and outline potential challenges lying ahead to improve further implementation.

RECENT FINDINGS

Due to the success of several randomized controlled trials (RCT), comparing cold storage to machine perfusion in HTx and LuTx, implementation and innovation continues. Indeed, it represents a promising interface for organ-specific therapies targeting IRI, allo-immune responses, and graft reconditioning. These mostly experimental efforts range from genetic approaches and nanotechnology to cellular therapies, involving mesenchymal stem cell application. Despite tremendous potential, prior to clinical transition, more data is needed.

SUMMARY

Collectively, machine perfusion constitutes the vanguard in thoracic organ transplantation research with extensive potential for expanding the donor pool, enhancing transplant outcomes as well as developing novel therapy approaches.

Taking a Deep Breath: an Examination of Current Controversies in Surgical Procedures in Lung Transplantation

Purpose of Review

This article reviews controversial questions within the field of lung transplantation, with a focus on data generated within the last 3 years. We aim to summarize differing opinions on a selection of topics, including bridge-to-transplantation, intraoperative machine circulatory support, bronchial anastomosis, size mismatch, delayed chest closure, and ex vivo lung perfusion.

Recent Findings

With the growing rate of lung transplantations worldwide and increasing numbers of patients placed on waiting lists, the importance of determining best practices has only increased in recent years. Factors which promote successful outcomes have been identified across all the topics, with certain approaches promoted, such as ambulation in bridge-to-transplant and widespread intraoperative ECMO as machine support.

Summary

While great strides have been made in the operative procedures involved in lung transplantation, there are still key questions to be answered. The consensus which can be reached will be instrumental in further improving outcomes in recipients.

Reversible occlusion of the pulmonary vasculature by transarterial embolisation with degradable starch microspheres: preclinical assessment in a human isolated lung perfusion model

BACKGROUND

Transpulmonary embolisation (TPE) using degradable starch microspheres (DSM) is a potential approach to treat pulmonary metastases. However, there is a paucity of detailed information on perfusion dynamics. The aim of this study was to establish a human ex vivo isolated lung perfusion (ILP) model to observe and evaluate the effects of DSM-TPE in a near-physiologic setting.

METHODS

ILP was carried out on six surgically resected lung lobes. At baseline, computed tomography (CT), including CT perfusion imaging (CTPI), and histopathological sampling were performed (t30). DSM-TPE was initiated and increased stepwise (t45, t60, t75, and t90) to be followed by CT imaging, histopathological sampling, and pulmonary arterial pressure (PAP). After the last assessment (t90), alpha-amylase was injected into the pulmonary artery to allow for DSM hydrolysation and two additional assessments (t105; t120). Histopathological specimens were evaluated using a semiquantitative ordinal score. CTPI was used for time to peak (TTP) analysis.

RESULTS

After DSM administration, PAP and TTP increased significantly: PAP slope 95% confidence interval (CI) 0.104-0.483, p = 0.004; TTP t30 versus t45, p = 0.046. After the addition of alpha-amylase, functional parameters reverted to values comparable to baseline. In histopathological samples, embolisation grades increased significantly until t90 (slope 95% CI 0.027-0.066, p < 0.001) and decreased after addition of alpha-amylase (slope 95% CI -0.060-0.012, p = 0.165), CONCLUSIONS: The ILP model demonstrated successfully both the physiologic effect of DSM-TPE on human lungs and its reversibility with alpha-amylase. Thus, it can be used as a near-physiologic preclinical tool to simulate and assess later clinical approaches.

The potential of ex vivo lung perfusion on improving organ quality and ameliorating ischemia reperfusion injury

Allogeneic lung transplantation (LuTx) is considered the treatment of choice for a broad range of advanced, progressive lung diseases resistant to conventional treatment regimens. Ischemia reperfusion injury (IRI) occurring upon reperfusion of the explanted, ischemic lung during implantation remains a crucial mediator of primary graft dysfunction (PGD) and early allo-immune responses. Ex vivo lung perfusion (EVLP) displays an advanced technique aiming at improving lung procurement and preservation. Indeed, previous clinical trials have demonstrated a reduced incidence of PGD following LuTx utilizing EVLP, while long-term outcomes are yet to be evaluated. Mechanistically, EVLP may alleviate donor lung inflammation through reconditioning the injured lung and diminishing IRI through storing the explanted lung in a non-ischemic, perfused, and ventilated status. In this work, we review potential mechanisms of EVLP that may attenuate IRI and improve organ quality. Moreover, we dissect experimental treatment approaches during EVLP that may further attenuate inflammatory events deriving from tissue ischemia, shear forces or allograft rejection associated with LuTx.

Common Criteria for Ex Vivo Lung Perfusion Have No Significant Impact on Posttransplant Outcomes

BACKGROUND

Although it is intense in health care resources, by facilitating assessment and reconditioning, ex vivo lung perfusion (EVLP) has the potential to expand the donor pool and improve lung transplant outcomes. However, inclusion criteria used in EVLP trials have not been validated.

METHODS

This retrospective study from 2014 to 2018 reviewed our local state-based donation organization donor records as well as subsequent recipient outcomes to explore the relation between EVLP indications used in clinical trials and recipient outcomes. The primary outcome was primary graft dysfunction grade 3 at 24 hours, with 30-day mortality and posttransplant survival time as secondary outcomes, compared with univariate and multivariate analysis.

RESULTS

From 705 lung donor referrals, 304 lung transplantations were performed (use rate of 42%); 212 of recipients (70%) met at least 1 of the commonly cited EVLP initiation criteria. There was no significant difference in primary graft dysfunction grade 3 or 30-day mortality between recipients with or without an EVLP indication (10.2% versus 7.8%, P = .51; and 2.4% versus 0%, P = .14, respectively). Multivariate analyses showed no significant relationship between commonly cited EVLP criteria and primary graft dysfunction grade 3 or survival time. Recipient outcomes were significantly associated with recipient diagnosis.

CONCLUSIONS

At least 1 commonly cited criterion for EVLP initiation was present in 70% of the transplanted donors, and yet it did not predict clinical results; acceptable outcomes were seen in both subgroups. To discover the true utility of EVLP beyond good clinical management and focus EVLP on otherwise unacceptable lungs, a reconsideration of EVLP inclusion criteria is required.

Impact of normothermic ex vivo lung perfusion on early post-transplantation cytomegalovirus infection

Background

The low acceptance rates in lung transplantation underline the importance to use every potential transplantable organ. With the use of normothermic ex vivo lung perfusion (EVLP) there is a potential to use more donor lungs for transplantation. Aim of this study was to evaluate if EVLP has an effect on cytomegalovirus (CMV) infection after lung transplantation.

Methods

Between May 2016 and October 2018, 57 lung transplants were performed. Out of these 21 extended criteria lungs were evaluated by EVLP and 16 transplanted. In a retrospective study, results of EVLP treated lungs were compared with lungs after cold storage preservation (CSP). Donor/recipient CMV IgG status and seroconversion rate was examined.

Results

Donors were CMV IgG+ in EVLP 69% and CSP 61% (n.s.). Best pO₂ on procurement at FiO₂ 1.0 was in EVLP 278±76 versus CSP 413±96 mmHg (P≤0.05). Recipients were CMV IgG+ in EVLP 38% and CSP 63% (P<0.07). CMV seroconversion: EVLP 12%, CSP 20% (P<0.05), in the CSP group in 5% recipients with more than 1,000 copies/mL were diagnosed by PCR and treated for CMV infection. Procalcitonin (PCT) levels from day 1 to day 5 were significantly lower for CSP group (P<0.05). 30-day mortality was 12% for EVLP recipients.

Conclusions

Normothermic EVLP did not influence CMV infection rate, however early PCT levels were higher in EVLP group. Short-term results were comparable to standard lung transplantation.

Early pulmonary function and mid-term outcome in lung transplantation after ex-vivo lung perfusion - a single-center, retrospective, observational, cohort study

Outcomes after transplantation of lungs (LuTX) treated with ex-vivo lung perfusion (EVLP) are debated. In a single-center 8 years of retrospective analysis, we compared: donors' and recipients' characteristics, gas exchange and lung mechanics at ICU admission, 3, 6, and 12 months, and patients' survival of LuTX from standard donors compared with EVLP-treated grafts. A total of 193 LuTX were performed. Thirty-one LuTX, out of 50 EVLP procedures, were carried out: 7 from nonheart beating and 24 from extended criteria brain-dead donors. Recipients' characteristics were similar. At ICU admission, compared with standard donors, EVLP patients had worse PaO₂ /FiO₂ [276 (206; 374) vs. 204 (133; 245) mmHg, P < 0.05], more frequent extracorporeal support (18% vs. 32%, P = 0.053) and longer mechanical ventilation duration [28 days of ventilator-free days: 27 (24; 28) vs. 26 (19; 27), P < 0.05]. ICU length of stay [4 (2; 9) vs. 6 (3; 12) days, P = 0.208], 28-day survival (99% vs. 97%, P = 0.735), and 1-year respiratory function were similar between groups. Log-rank analysis (median follow-up 2.5 years) demonstrated similar patients' survival (P = 0.439) and time free of chronic lung allograft disease (P = 0.484). The EVLP program increased by 16% the number of LuTX. Compared to standard donors, EVLP patients had worse respiratory function immediately after LuTX but similar early and mid-term outcomes.

[Current developments in lung transplantation]

BACKGROUND

Lung transplantation is the established treatment of benign end-stage pulmonary diseases after failure of alternative surgical and medical treatment options. The aim of this paper is to provide an overview of current developments in selected fields of lung transplantation.

METHODS

A selective literature search was conducted.

RESULTS

Lung transplantation in Germany is currently limited by a donor organ shortage. Measures to increase organ donation rates and to optimize the use of available donor organs are required. Ex-vivo lung perfusion, currently mainly used to re-evaluate marginal donor organs, has the potential to increase the available donor pool and to serve as a platform for additional therapies.

CONCLUSIONS

Refinements in organ allocation, perioperative management, immunosuppression, and in the understanding of acute cellular and humoral rejection as well as chronic lung allograft dysfunction contributed to improvements in long-term outcome after lung transplantation.

Ex-Vivo Normothermic Limb Perfusion With a Hemoglobin-Based Oxygen Carrier Perfusate

INTRODUCTION

Ex-vivo normothermic limb perfusion (EVNLP) has been proven to preserve limb viability better than standard cold storage. Perfusates containing packed red blood cells (pRBC) improve outcomes when compared to acellular perfusates. Limitations of pRBC-based perfusion include limited availability, need for cross match, mechanical hemolysis, and activation of pro-inflammatory proteins. Hemoglobin-based oxygen carrier (HBOC)-201 (Hemopure) is a solution of polymerized bovine hemoglobin, characterized by low immunogenicity, no risk of hemolytic reaction, and enhanced convective and diffusive oxygen delivery. This is a preliminary study on the feasibility of EVNLP using HBOC-201 as an oxygen carrier.

MATERIALS AND METHODS

Three porcine forelimb perfusions were performed using an established EVNLP model and an HBOC-201-based perfusate. The perfusion circuit included a roller pump, oxygenator, heat exchanger, and reservoir. Electrolytes, limb temperature, weight, compartment pressure, nerve conduction, and perfusion indicated by indocyanine green angiography and infra-red thermography were monitored. Histological evaluation was performed with hematoxylin and eosin and electron microscopy.

RESULTS

Three limbs were perfused for 21.3 ± 2.1 hours. Muscle contractility was preserved for 10.6 ± 2.4 hours. Better preservation of the mitochondrial ultrastructure was evident at 12 hours in contrast to crystallization and destruction features in the cold-storage controls.

CONCLUSIONS

An HBOC-201-EVNLP produced outcomes similar to RBC-EVNLP with preservation of muscle contractility and mitochondrial structure.

Ex-vivo lung perfusion versus standard protocol lung transplantation-mid-term survival and meta-analysis

Background

While extended criteria lung donation has helped expand the lung donor pool, utilization of lungs from donors of at least one other solid organ is still limited to around 15-30%. Ex-vivo lung perfusion (EVLP) offers the ability to expand the number of useable lung grafts through assessment and reconditioning of explanted lungs, particularly those not initially meeting criteria for transplantation. This meta-analysis aimed to examine the mid- to long-term survival and other short-term outcomes of patients transplanted with EVLP-treated lungs versus standard/cold-storage protocol lungs.

Methods

Literature search of ten medical databases was conducted for original studies involving "ex-vivo lung perfusion" and "EVLP". Included articles were assessed by two independent researchers, survival data from Kaplan-Meier curves digitized, and individual patient data imputed to conduct aggregated survival analysis. Meta-analyses of suitably reported outcomes were conducted using a random-effects model.

Results

Thirteen studies met inclusion criteria, with a total of 407 EVLP lung transplants and 1,765 as per standard/cold storage protocol. One study was a randomized controlled trial while the remainder were single-institution cohort series of varying design. The majority of donor lungs were from brain death donors, with EVLP lungs having significantly worse PaO₂/FiO₂ ratio and significantly greater rate of abnormal chest X-ray. Aggregated survival analysis of all included studies revealed no significant survival difference for EVLP or standard protocol lungs (hazard ratio 1.00; 95% confidence interval: 0.79-1.27, P=0.981). Survival at 12, 24, and 36 months for the EVLP cohort was 84%, 79%, and 74%, respectively. Survival at 12, 24, and 36 months for the standard protocol cohort was 85%, 79%, and 73%, respectively. Meta-analysis did not find a significant difference in risk of 30-day mortality or primary graft dysfunction grade 3 at 72 hours between cohorts.

Conclusions

There was no significant difference in mid- to long-term survival of EVLP lung transplant patients when compared to standard protocol donor lungs. The incidence of 30-day mortality and primary graft dysfunction grade 3 at 72 hours did not differ significantly between groups. EVLP offers the potential to increase lung donor utilization while providing similar short-term outcomes and mid- to long-term survival.

The Conversional Efficacy of Ex Vivo Lung Perfusion and Clinical Outcomes in Patients Undergoing Transplantation of Donor Lungs by Ex Vivo Lung Perfusion: A Meta-Analysis

Background

Ex vivo lung perfusion (EVLP) is a relatively new technique that can be used to assess and repair the donor lungs, increasing the utilization of high-risk lungs. However, its effect on outcomes of lung transplantation patients is uncertainty. This meta-analysis is conducted to assess the impact of EVLP on donor lungs and outcomes of recipients compared with the standard lung transplantation.

Material/Methods

We systematically searched for studies comparatively analyzing the efficacy of EVLP and standard cold storage in lung transplantation. The hazard ratio (HR), relative risk (RR), and weighted mean difference (WMD) were used as the effect size (ES) to evaluate the survival outcomes, categorical variables, and continuous variables respectively.

Results

A total of 20 published articles (including 2574 donors and 2567 recipients) were eligible. The chest x-ray manifestations and PaO₂/FiO₂ 100% were more deficient in the EVLP group than the standard group. EVLP improved the function of high-risk donor lungs with the conversion rate ranging from 34% to 100%. The EVLP group had a lower incidence of primary graft dysfunction 3, but longer intensive care unit stay. Other clinical outcomes between the 2 groups were similar.

Conclusions

The pooled results indicated that EVLP could be used to assess and improve high-risk donor lungs and had non-inferior postoperative outcomes compared with the standard cold storage. EVLP not only increased the utilization of marginal donors, but also could extend preservation time and reduce the total ischemia time of donors.

Implementation of an experimental isolated lung perfusion model on surgically resected human lobes

Isolated lung perfusion (ILP) is an ideal model to study treatment effects on a variety of pathologies. As published research mostly relies on rejected donor lungs or animal organs, this study investigates the use of surgically resected human lobes as an alternative and novel model for personalized experimental research. Ten surgically resected lobes were perfused in acellular and normothermic condition. The indication for surgery was lung cancer. Perfusion and ventilation were adapted to the size of the lobes and both functional and metabolic parameters were assessed during ILP. Patients (age 67.5 y (59–81)|♀n = 3|♂n = 7) underwent anatomic pulmonary lobectomy. Ischemic time between arterial ligation and ILP was 226 minutes (161–525). Median duration of ILP was 135 (87–366) minutes. Gas exchange and mechanical respiratory parameters remained steady during ILP (pulmonary venous pO₂ 196(151–219) mmHg | peak AWP: 14.5(11–22) cmH₂O). Metabolism stayed constant during ILP (Glucose consumption: 1.86 mg/min/L_TLC (95%CI: −2.09 to −1.63) | lactate production: 0.005 mmol/min/ L_TLC (95%CI: 0.004 to 0.007)). ILP of surgically resected human lobes is a feasible and promising method. By maintaining a near physiological setting, this model may pave the way for future experimental lung research including cancer research, transplantation, physiology, pharmacology and mechanical ventilation.

Noteworthy Literature Published in 2018 for Thoracic Organ Transplantation

Publications of note from 2018 are reviewed for the cardiothoracic transplant anesthesiologist. Strategies to expand the availability of donor organs were highlighted, including improved donor management, accumulating experience with increased-risk donors, ex vivo perfusion techniques, and donation after cardiac death. A number of reports examined posttransplant outcomes, including outcomes other than mortality, with new data-driven risk models. Use of extracorporeal support in cardiothoracic transplantation was a prominent theme. Major changes in adult heart allocation criteria were implemented, aiming to improve objectivity and transparency in the listing process. Frailty and prehabilitation emerged as targets of comprehensive perioperative risk mitigation programs.

Ex vivo lung perfusion prior to transplantation: an overview of current clinical practice worldwide

Lung transplantation is a lifesaving treatment in numerous forms of end-stage lung disease but organ shortage remains nowadays his biggest issue. Ex vivo lung perfusion (EVLP) has recently emerged as a solution to this problem and begins to be accepted is clinical practice. In this review, we will focus on his experience worldwide. We would like to describe the technique and the criteria used to select the donors and the transplantable lungs. We will also browse the acceptance rate described in literature as well as numerous other aspects of this new tool.