Dataset Information

Endothelial Glycocalyx Shedding Occurs during Ex Vivo Lung Perfusion: A Pilot Study.

ABSTRACT:

Background

Damage to the endothelium has been established as a key pathological process in lung transplantation and ex vivo lung perfusion (EVLP), a new technology that provides a platform for the assessment of injured donor lungs. Damage to the lung endothelial glycocalyx, a structure that lines the endothelium and is integral to vascular barrier function, has been associated with lung dysfunction. We hypothesised that endothelial glycocalyx shedding occurs during EVLP and aimed to establish a porcine model to investigate the mechanism underlying glycocalyx breakdown during EVLP.

Methods

Concentrations of endothelial glycocalyx breakdown products, syndecan-1, hyaluronan, heparan sulphate, and CD44, were measured using the ELISA and matrix metalloproteinase (MMP) activity by zymography in the perfusate of both human (n?=?9) and porcine (n?=?4) lungs undergoing EVLP. Porcine lungs underwent prolonged EVLP (up to 12?hours) with perfusion and ventilation parameters recorded hourly.

Results

During human EVLP, endothelial glycocalyx breakdown products in the perfusate increased over time. Increasing MMP-2 activity over time was positively correlated with levels of syndecan-1 (r?=?0.886; p=0.03) and hyaluronan (r?=?0.943; p=0.02). In the porcine EVLP model, hyaluronan was the only glycocalyx product detectable during EVLP (1?hr: 19 (13-84) vs 12?hr: 143 (109-264)?ng/ml; p=0.13). Porcine hyaluronan was associated with MMP-9 activity (r?=?0.83; p=0.02) and also with dynamic compliance (r?=?0.57; p=0.03).

Conclusion

Endothelial glycocalyx products accumulate during both porcine and human EVLP, and this accumulation parallels an accumulation of matrix-degrading enzyme activity. Preliminary evidence in our porcine EVLP model suggests that shedding may be related to organ function, thus warranting additional study.

SUBMITTER: Sladden TM

PROVIDER: S-EPMC6732651 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Publications

Endothelial Glycocalyx Shedding Occurs during Ex Vivo Lung Perfusion: A Pilot Study.

Sladden Timothy M TM Yerkovich Stephanie S Wall Douglas D Tan Maxine M Hunt William W Hill Jonathan J Smith Ian I Smith Ian I Hopkins Peter P Chambers Daniel C DC

Journal of transplantation 20190825

<h4>Background</h4>Damage to the endothelium has been established as a key pathological process in lung transplantation and ex vivo lung perfusion (EVLP), a new technology that provides a platform for the assessment of injured donor lungs. Damage to the lung endothelial glycocalyx, a structure that lines the endothelium and is integral to vascular barrier function, has been associated with lung dysfunction. We hypothesised that endothelial glycocalyx shedding occurs during EVLP and aimed to esta ...[more]

PMID: 31534794

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Project description:OBJECTIVE:Critical organ shortages have resulted in ex vivo lung perfusion gaining clinical acceptance for lung evaluation and rehabilitation to expand the use of donation after circulatory death organs for lung transplantation. We hypothesized that an innovative use of airway pressure release ventilation during ex vivo lung perfusion improves lung function after transplantation. METHODS:Two groups (n = 4 animals/group) of porcine donation after circulatory death donor lungs were procured after hypoxic cardiac arrest and a 2-hour period of warm ischemia, followed by a 4-hour period of ex vivo lung perfusion rehabilitation with standard conventional volume-based ventilation or pressure-based airway pressure release ventilation. Left lungs were subsequently transplanted into recipient animals and reperfused for 4 hours. Blood gases for partial pressure of oxygen/inspired oxygen fraction ratios, airway pressures for calculation of compliance, and percent wet weight gain during ex vivo lung perfusion and reperfusion were measured. RESULTS:Airway pressure release ventilation during ex vivo lung perfusion significantly improved left lung oxygenation at 2 hours (561.5 ± 83.9 mm Hg vs 341.1 ± 136.1 mm Hg) and 4 hours (569.1 ± 18.3 mm Hg vs 463.5 ± 78.4 mm Hg). Likewise, compliance was significantly higher at 2 hours (26.0 ± 5.2 mL/cm H2O vs 15.0 ± 4.6 mL/cm H2O) and 4 hours (30.6 ± 1.3 mL/cm H2O vs 17.7 ± 5.9 mL/cm H2O) after transplantation. Finally, airway pressure release ventilation significantly reduced lung edema development on ex vivo lung perfusion on the basis of percentage of weight gain (36.9% ± 14.6% vs 73.9% ± 4.9%). There was no difference in additional edema accumulation 4 hours after reperfusion. CONCLUSIONS:Pressure-directed airway pressure release ventilation strategy during ex vivo lung perfusion improves the rehabilitation of severely injured donation after circulatory death lungs. After transplant, these lungs demonstrate superior lung-specific oxygenation and dynamic compliance compared with lungs ventilated with standard conventional ventilation. This strategy, if implemented into clinical ex vivo lung perfusion protocols, could advance the field of donation after circulatory death lung rehabilitation to expand the lung donor pool.

Project description:ImportanceThe mortality rate for individuals on the wait list for lung transplant is 15% to 25%, and still only 20% of lungs from multiorgan donors are used for lung transplant. The lung donor pool may be increased by assessing and reconditioning high-risk extended criteria donor lungs with ex vivo lung perfusion (EVLP), with similar short-term outcomes.ObjectiveTo assess the long-term outcomes of transplant recipients of donor lungs treated with EVLP.Design, setting, and participantsThis retrospective cohort single-center study was conducted from August 1, 2008, to February 28, 2017, among 706 recipients of donor lungs not undergoing EVLP and 230 recipients of donor lungs undergoing EVLP.ExposureDonor lungs undergoing EVLP.Main outcomes and measuresThe incidence of chronic lung allograft dysfunction and allograft survival during the 10-year EVLP era were the primary outcome measures. Secondary outcomes included donor characteristics, maximum predicted percentage of forced expiratory volume in 1 second, acute cellular rejection, and de novo donor-specific antibody development.ResultsThis study included 706 patients (311 women and 395 men; median age, 50 years [interquartile range, 34-61 years]) in the non-EVLP group and 230 patients (85 women and 145 men; median age, 46 years [interquartile range, 32-55 years]) in the EVLP group. The EVLP group donors had a significantly lower mean (SD) Pao2:fraction of inspired oxygen ratio than the non-EVLP group donors (348 [108] vs 422 [88] mm Hg; P < .001), higher prevalence of abnormal chest radiography results (135 of 230 [58.7%] vs 349 of 706 [49.4%]; P = .02), and higher proportion of smoking history (125 of 204 [61.3%] vs 322 of 650 [49.5%]; P = .007). More recipients in the EVLP group received single-lung transplants (62 of 230 [27.0%] vs 100 of 706 [14.2%]; P < .001). There was no significant difference in time to chronic lung allograft dysfunction between the EVLP and non-EVLP group (70% vs 72% at 3 years; 56% vs 56% at 5 years; and 53% vs 36% at 9 years; log-rank P = .68) or allograft survival between the EVLP and non-EVLP groups (73% vs 72% at 3 years; 62% vs 58% at 5 years; and 50% vs 44% at 9 years; log-rank P = .97) between the 2 groups. All secondary outcomes were similar between the 2 groups.Conclusions and relevanceSince 2008, 230 of 936 lung transplants (24.6%) in the Toronto Lung Transplant Program were performed after EVLP assessment and treatment. Use of EVLP-treated lungs led to an increase in the number of patients undergoing transplantation, with comparable long-term outcomes.

Project description:Ischemia reperfusion (IR) injury is a key complication following lung transplantation, and it remains to be fully resolved. Ex vivo lung perfusion (EVLP) has shown its significance as a platform to assess and repair marginal donor lungs prior to transplants with good clinical outcomes. Recently, it has been shown that Glutamax supplementation to Steen solution can improve basic cellular function as well as porcine EVLP duration with stable lung quality. To better understand the molecular mechanisms of IR injury, acellular EVLP, and Glutamax supplementation during EVLP, transcriptomic changes in cell culture models simulating IR and EVLP have been investigated. Briefly, human pulmonary microvascular endothelial cells (HPMEC) and human lung epithelial cells (BEAS-2B) were cultured in DMEM+10%FBS, then were perfused with Perfadex at 4°C for 18H to simulate cold ischemic time (CIT). Subsequently, the cells were perfused in either DMEM+10%FBS (IR model) or in Steen solution or Steen with 4mM Glutamax (EVLP models) for 4H. RNA samples were collected for CIT, IR, and two EVLP conditions, and sequencing data were analyzed for differentially expressed genes and pathways. HPMEC and BEAS-2B cells showed significant changes in gene expressions for IR and EVLP models. In pathway analyses, IR models of both cell types had up-regulated pro-inflammatory responses and down-regulated cell metabolism, and there was up-regulation of epithelial process and/or vascular activation. Steen alone EVLP models exhibited down-regulation of cell metabolism, with an absence of inflammatory and vascular or epithelial signals, while Steen with Glutamax exhibited similar down-regulation of cell metabolism as well as down-regulated inflammatory and vascular process. The commonly used EVLP perfusate, acellular Steen solution, can silence the activation of pro-inflammatory signaling in HPMEC and BEAS-2B cell culture models. This finding may yield insights into how acellular EVLP has been successful in safe preservation of the donor lungs during organ evaluation and repair prior to lung transplantation.

Project description:BackgroundThe endothelial glycocalyx (EG) on the luminal surface of endothelial cells contributes to the permeability barrier of vessels and prevents activation of the coagulation cascade. Endothelial glycocalyx damage, which occurs in the shock state, results in endotheliopathy. Interleukin (IL)-22 is a cytokine with both proinflammatory and anti-inflammatory properties, and how IL-22 affects the EG has not been studied. We hypothesized that IL-22:Fc, a recombinant fusion protein with human IL-22 and the Fc portion of human immunoglobulin G1 (which extends the protein half-life), would not affect EG shedding in endothelium after injury.MethodsHuman umbilical vein endothelial cells (HUVECs) were exposed to 1 μg/mL lipopolysaccharide (LPS). Lipopolysaccharide-injured cells (n = 284) were compared with HUVECs with LPS injury plus 0.375 μg/mL of IL-22:Fc treatment (n = 293) for 12 hours. These two cohorts were compared with control HUVECs (n = 286) and HUVECs exposed to IL-22:Fc alone (n = 269). Cells were fixed and stained with fluorescein isothiocyanate-labeled wheat germ agglutinin to quantify EG. Total RNA was collected, and select messenger RNAs were quantified by real time - quantitative polymerase chain reaction (RT-qPCR) using SYBR green fluorescence.ResultsExposure of HUVECs to LPS resulted in degradation of the EG compared with control (5.86 vs. 6.09 arbitrary unit [AU], p = 0.01). Interleukin-22:Fc alone also resulted in degradation of EG (5.08 vs. 6.09 AU, p = 0.01). Treatment with IL-22:Fc after LPS injury resulted in less degradation of EG compared with LPS injury alone (5.86 vs. 5.08 AU, p = 0.002). Expression of the IL-22Ra1 receptor was not different for IL-22:Fc treated compared with LPS injury only (0.69 vs. 0.86 relative expression, p = 0.10). Treatment with IL-22:Fc after LPS injury resulted in less matrix metalloproteinase 2 (0.79 vs. 1.70 relative expression, p = 0.005) and matrix metalloproteinase 14 (0.94 vs. 2.04 relative expression, p = 0.02).ConclusionsInterleukin-22:Fc alone induces EG degradation. However, IL-22:Fc treatment after LPS injury appears to mitigate EG degradation. This protective effect appears to be mediated via reduced expression of metalloproteinases.

Dataset Information

Endothelial Glycocalyx Shedding Occurs during Ex Vivo Lung Perfusion: A Pilot Study.

Background

Methods

Results

Conclusion

Publications

Endothelial Glycocalyx Shedding Occurs during Ex Vivo Lung Perfusion: A Pilot Study.

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