Reducing Ischemia–Reperfusion Injury in Clinical Lung Transplantation

Xenogeneic and Allogeneic Mesenchymal Stem Cells Effectively Protect the Lung Against Ischemia-reperfusion Injury Through Downregulating the Inflammatory, Oxidative Stress, and Autophagic Signaling Pathways in Rat

This study tested the hypothesis that both allogenic adipose-derived mesenchymal stem cells (ADMSCs) and human inducible pluripotent stem cell-derived MSCs (iPS-MSCs) offered a comparable effect for protecting the lung against ischemia-reperfusion (IR) injury in rodent through downregulating the inflammatory, oxidative stress, and autophagic signaling pathways. Adult male Sprague–Dawley rats (n = 32) were categorized into group 1 (sham-operated control), group 2 (IRI), group 3 [IRI + ADMSCs (1.0 × 10⁶ cells)/tail-vein administration at 0.5/18/36 h after IR], and group 4 [IRI + iPS-MSCs (1.0 × 10⁶ cells)/tail-vein administration at 0.5/18/36 h after IR], and lungs were harvested at 72 h after IR procedure. In vitro study demonstrated that protein expressions of three signaling pathways in inflammation (TLR4/MyD88/TAK1/IKK/I-κB/NF-κB/Cox-2/TNF-α/IL-1ß), mitochondrial damage/cell apoptosis (cytochrome C/cyclophilin D/DRP1/ASK1/APAF-1/mitochondrial-Bax/caspase3/8/9), and autophagy/cell death (ULK1/beclin-1/Atg5,7,12, ratio of LCB3-II/LC3B-I, p-AKT/m-TOR) were significantly higher in lung epithelial cells + 6h hypoxia as compared with the control, and those were significantly reversed by iPS-MSC treatment (all P < 0.001). Flow cytometric analysis revealed that percentages of the inflammatory cells in bronchioalveolar lavage fluid and circulation, and immune cells in circulation/spleen as well as circulatory early and late apoptotic cells were highest in group 2, lowest in group 1, and significantly higher in group 3 than in group 4 (all P < 0.0001). Microscopy showed the lung injury score and numbers of inflammatory cells and Western blot analysis showed the signaling pathways of inflammation, mitochondrial damage/cell apoptosis, autophagy, and oxidative stress exhibited an identical pattern of flow cytometric results among the four groups (all P < 0.0001). Both xenogeneic and allogenic MSCs protected the lung against IRI via suppressing the inflammatory, oxidative stress, and autophagic signaling.

Inhaled Pulmonary Vasodilators and Thoracic Organ Transplantation: Does Evidence Support Its Use and Cost Benefit?

In heart transplantation, pulmonary hypertension and increased pulmonary vascular resistance followed by donor right ventricular dysfunction remain a major cause of perioperative morbidity and mortality. In lung transplantation, primary graft dysfunction remains a major obstacle because it can cause bronchiolitis obliterans and mortality. Pulmonary vasodilators have been used as an adjunct therapy for heart or lung transplantation, mainly to treat pulmonary hypertension, right ventricular failure, and associated refractory hypoxemia. Among pulmonary vasodilators, inhaled nitric oxide is unique in that it is selective in pulmonary circulation and causes fewer systemic complications such as hypotension, flushing, or coagulopathy. Nitric oxide is expected to prevent or attenuate primary graft dysfunction by decreasing ischemia-reperfusion injury in lung transplantation. However, when considering the long-term benefit of these medications, little evidence supports their use in heart or lung transplantation. Current guidelines endorse inhaled vasodilators for managing immediate postoperative right ventricular failure in lung or heart transplantation, but no guidance is offered regarding agent selection, dosing, or administration. This review presents the current evidence of inhaled nitric oxide in lung or heart transplantation as well as comparisons with other pulmonary vasodilators including cost differences in consideration of economic pressures to contain rising pharmacy costs.

Preactivated and Disaggregated Shape-Changed Platelets Protected Against Acute Respiratory Distress Syndrome Complicated by Sepsis Through Inflammation Suppression

BACKGROUND

This study tested the hypothesis that preactivated and disaggregated shape-changed platelet (PreD-SCP) therapy attenuates lung injury from acute respiratory distress syndrome (ARDS) induced by 100% oxygen inhalation and complicated by sepsis through peritoneal administration of 1.5 mg/kg lipopolysaccharide (LPS).

METHODS

Adult male Sprague-Dawley rats, weighing 325 to 350 g, were randomized into group 1 (normal controls [NC]), group 2 (NC + PreD-SCP [3.0 × 10, intravenous administration]), group 3 (ARDS-LPS), and group 4 (ARDS-LPS + PreD-SCP), and sacrificed by 72 h after ARDS induction.

RESULTS

The lung injury score was significantly higher in group 3 than that in other groups, and significantly higher in group 4 than that in groups 1 and 2, whereas the numbers of alveolar sacs and oxygen saturation (%) showed a reversed pattern compared with that of lung injury score among the four groups (all P < 0.0001) without significant difference between groups 1 and 2. The expressions of proinflammatory cells (CD11+, CD14+, CD68+) and proteins (tumor necrosis factor [TNF]-α, nuclear factor [NF]-κB, interleukin [IL]-1ββ, matrix metalloproteinase [MMP]-9, inducible nitric oxide synthase, intercellular adhesion molecule-1) exhibited a pattern identical to the lung injury score. Circulating levels of white blood cell, IL-6, TNF-α, myeloperoxidase and CCL5, and pulmonary protein expressions of oxidative stress (NOX-1/NOX-2, oxidized protein), apoptotic (Bax, cleaved caspase 3/poly (ADP-ribose) polymerase), fibrotic (Smad3, transforming growth factor [TGF]-β), and DNA damage (γ-H2AX) biomarkers showed an identical pattern, whereas protein expressions of antifibrotic (Smad1/5, bone morphogenetic protein [BMP]-2) and anti-inflammatory (Bcl-2) biomarkers demonstrated an opposite pattern compared with the proinflammatory indices among the four groups (all P < 0.001).

CONCLUSIONS

PreD-SCP therapy effectively improved lung injury in ARDS complicated by sepsis.

Ischemia preconditioning protects rat submandibular glands from ischemia/reperfusion injuries

To investigate the effects of ischemia/reperfusion on rat submandibular glands without denervation and the possible protective effects of ischemia preconditioning on the glands that experienced ischemia/reperfusion, in-situ ischemia/reperfusion and ischemia preconditioning experimental models of submandibular glands of healthy male Wistar rats were conducted. For ischemia/reperfusion groups, the glands were subjected to 90 min of ischemia without denervation, followed by 1, 12, 24, or 72 h of reperfusion. Ischemia preconditioning was achieved by 3 min of ischemia following 3 min of reperfusion, performed three times before ischemia/reperfusion. Salivary secretion, histological changes, alterations of tight junctions, myeloperoxidase activity, cellular apoptosis, and reactive oxygen species levels were detected. In ischemia/reperfusion glands, rising acute-inflammation responses, reduced tight-junction width, and increased myeloperoxidase activity, reactive oxygen species levels, and apoptotic cell numbers were observed, along with secretory dysfunction, especially at 1 and 12 h post-reperfusion, which seemed to gradually return to normal by 72 h post-reperfusion. In contrast, ischemia preconditioning showed the potential to ameliorate the injury-stress responses caused by ischemia/reperfusion. Our study revealed that ischemia/reperfusion could cause a series of injury-stress responses and ultimately lead to hyposecretion, independently of the parasympathetic nerve supply, which might play an important role in the early-phase dysfunction of the transplanted glands. Ischemia preconditioning could protect the involved glands and improve ischemia/reperfusion-induced hyposecretion.

A Case of Fatal Acute Lung Injury after Balloon Valvuloplasty of Pulmonary Stenosis: Case Report and Review of Literature

A newly described immediate complication after percutaneous pulmonary valvuloplasty isacute lung injury. Here we report a case of fatal acute lung injury after pulmonary valvuloplasty.The patient was a 26-year-old woman, referred to a general hospital with the diagnosis of livercirrhosis. In her work-ups severe pulmonary stenosis was detected and so a decision was madeto relieve the valve stenosis. Despite the procedural success, the patient developed severe dyspneaand desaturation a few hours later and died within 3 days due to shock state. Although thedefinition, incidence or severity of acute lung injury after pulmonary balloon valvuloplasty is notyet clear, this is as far as we know the first mortality reported in literature. This presentation inour patient should prompt clinicians to consider a more aggressive approach at the first sight ofthis previously considered innocent complication.

Combination therapy with human umbilical cord mesenchymal stem cells and angiotensin-converting enzyme 2 is superior for the treatment of acute lung ischemia-reperfusion injury in rats

Acute lung ischemia-reperfusion injury (ALIRI) is a serious disease that seriously affects human's life. In this study, we aimed to explore a more effective treatment method by combining human umbilical cord mesenchymal stem cells (HUMSCs) and angiotensin-converting enzyme 2 (ACE2) for ALIRI. Fifty rats were firstly divided into five groups, namely sham surgery group (sham) and four model groups (model, ACE2, HUMSCs and HUMSCs + ACE2) that were reperfused with 0.1 ml physiological saline (PS), 0.1 ml PS containing 1 × 10(6) lentiviral-ACE2/HUMSCs/ACE2 + UMSCs, respectively. Quantitative reverse transcription-PCR (qRT-PCR) and western blot assays were then conducted to detect the messenger RNA (mRNA) and protein levels of inflammatory cytokines [intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), tumour necrosis factor α (TNF-α), nuclear factor κB (NF-κB), platelet-derived growth factor (PDGF) and angiotensin II (Ang II)], antioxidant proteins [NAD(P)H quinone oxidoreductase 1 (NQO1), heme oxygenase 1 (HO-1)], DNA damage and apoptotic indicators [BCL2-associated X (Bax), cleaved caspase-3 (C-Csp 3), cleaved-poly(ADP-ribose) polymerase (C-PARP), Y-H2AX], anti-apoptotic indicator (Bcl-2) and smooth muscle cell proliferation indicator [connexin 43 (Cx43)]. According to the qRT-PCR and western results, the mRNA and protein expression levels of ICAM-1, VCAM-1, TNF-α, NF-κB, PDGF, Bax, C-Csp 3, C-PARP and Y-H2AX were significantly higher in model group than those in sham group and they were significantly reduced by HUMSCs or ACE2 treatment (P < 0.05). On the contrary, Bcl-2 showed an opposite expression trend with the previous proteins. The mRNA and protein levels of NQO1 and HO-1 were sequentially increased in sham, model, ACE2, HUMSCs and HUMSCs + ACE2 groups. Besides, HUMSCs combined with ACE2 exhibited a better inhibition effect on ALIRI than HUMSCs or ACE2 alone (P < 0.05). In summary, HUMSCs combined with ACE2 was demonstrated to have the best therapeutic effect on ALIRI through anti-inflammation, oxidative stress and anti-apoptotic processes.

Infusion of mesenchymal stem cells protects lung transplants from cold ischemia-reperfusion injury in mice

BACKGROUND

Cold ischemia-reperfusion injury (IRI) is a major cause of graft failure in lung transplantation. Despite therapeutic benefits of mesenchymal stem cells (MSCs) in attenuating acute lung injury, their protection of lung transplants from cold IRI remains elusive. The present study was to test the efficacy of MSCs in the prevention of cold IRI using a novel murine model of orthotopic lung transplantation.

METHODS

Donor lungs from C57BL/6 mice were exposed to 6 h of cold ischemia before transplanted to syngeneic recipients. MSCs were isolated from the bone marrows of C57BL/6 mice for recipient treatment. Gas exchange was determined by the measurement of blood oxygenation, and lung injury and inflammation were assessed by histological analyses.

RESULTS

Intravenously delivered MSC migration/trafficking to the lung grafts occurred within 4-hours post-transplantation. As compared to untreated controls, the graft arterial blood oxygenation (PaO2/FiO2) capacity was significantly improved in MSC-treated recipients as early as 4 h post-reperfusion and such improvement continued over time. By 72 h, oxygenation reached normal level that was not seen in controls. MSCs treatment conferred significant protection of the grafts from cold IRI and cell apoptosis, which is correlated with less cellular infiltration, a decrease in proinflammatory cytokines (TNF-α, IL-6) and toll-like receptor 4, and an increase in anti-inflammatory TSG-6 generation.

CONCLUSIONS

MSCs provide significant protection against cold IRI in lung transplants, and thus may be a promising strategy to improve outcomes after lung transplantation.

Melatonin treatment improves adipose-derived mesenchymal stem cell therapy for acute lung ischemia-reperfusion injury

This study investigated whether melatonin-treated adipose-derived mesenchymal stem cells (ADMSC) offered superior protection against acute lung ischemia-reperfusion (IR) injury. Adult male Sprague-Dawley rats (n = 30) were randomized equally into five groups: sham controls, lung IR-saline, lung IR-melatonin, lung IR-melatonin-normal ADMSC, and lung IR-melatonin-apoptotic ADMSC. Arterial oxygen saturation was lowest in lung IR-saline; lower in lung IR-melatonin than sham controls, lung IR-melatonin-normal ADMSC, and lung IR-melatonin-apoptotic ADMSC; lower in lung IR-melatonin-normal ADMSC than sham controls and lung IR-melatonin-apoptotic ADMSC; lower in lung IR-melatonin-apoptotic ADMSC than sham controls (P < 0.0001 in each case). Right ventricular systolic blood pressure (RVSBP) showed a reversed pattern among all groups (all P < 0.0001). Changes in histological scoring of lung parenchymal damage and CD68+ cells showed a similar pattern compared with RVSBP in all groups (all P < 0.001). Changes in inflammatory protein expressions such as VCAM-1, ICAM-1, oxidative stress, TNF-α, NF-κB, PDGF, and angiotensin II receptor, and changes in apoptotic protein expressions of cleaved caspase 3 and PARP, and mitochondrial Bax, displayed identical patterns compared with RVSBP in all groups (all P < 0.001). Numbers of antioxidant (GR+, GPx+, NQO-1+) and endothelial cell biomarkers (CD31+ and vWF+) were lower in sham controls, lung IR-saline, and lung IR-melatonin than lung IR-melatonin-normal ADMSC and lung IR-melatonin-apoptotic ADMSC, and lower in lung IR-melatonin-normal ADMSC than lung IR-melatonin-apoptotic ADMSC (P < 0.001 in each case). In conclusion, when the animals were treated with melatonin, the apoptotic ADMSC were superior to normal ADMSC for protection of lung from acute IR injury.

Autologous transplantation of adipose-derived mesenchymal stem cells markedly reduced acute ischemia-reperfusion lung injury in a rodent model

Background

This study tested the hypothesis that autologous transplantation of adipose-derived mesenchymal stem cells (ADMSCs) can effectively attenuate acute pulmonary ischemia-reperfusion (IR) injury.

Methods

Adult male Sprague-Dawley (SD) rats (n = 24) were equally randomized into group 1 (sham control), group 2 (IR plus culture medium only), and group 3 (IR plus intravenous transplantation of 1.5 × 10⁶ autologous ADMSCs at 1h, 6h, and 24h following IR injury). The duration of ischemia was 30 minutes, followed by 72 hours of reperfusion prior to sacrificing the animals. Blood samples were collected and lungs were harvested for analysis.

Results

Blood gas analysis showed that oxygen saturation (%) was remarkably lower, whereas right ventricular systolic pressure was notably higher in group 2 than in group 3 (all p < 0.03). Histological scoring of lung parenchymal damage was notably higher in group 2 than in group 3 (all p < 0.001). Real time-PCR demonstrated remarkably higher expressions of oxidative stress, as well as inflammatory and apoptotic biomarkers in group 2 compared with group 3 (all p < 0.005). Western blot showed that vascular cell adhesion molecule (VCAM)-1, intercellular adhesion molecule (ICAM)-1, oxidative stress, tumor necrosis factor-α and nuclear factor-κB were remarkably higher, whereas NAD(P)H quinone oxidoreductase 1 and heme oxygenase-1 activities were lower in group 2 compared to those in group 3 (all p < 0.004). Immunofluorescent staining demonstrated notably higher number of CD68+ cells, but significantly fewer CD31+ and vWF+ cells in group 2 than in group 3.

Conclusion

ADMSC therapy minimized lung damage after IR injury in a rodent model through suppressing oxidative stress and inflammatory reaction.

A randomized, placebo-controlled trial of aprotinin to reduce primary graft dysfunction following lung transplantation

PURPOSE

Severe primary graft dysfunction (PGD) is the major early problem following lung transplantation. Aprotinin, a serine protease inhibitor, has many anti-inflammatory properties that might reduce or prevent lung injury. Our hypothesis was that the incidence of PGD could be reduced by a combination of donor lung perfusion and systemic administration of aprotinin to recipients.

METHODS AND MATERIALS

The study was randomized and placebo controlled. Donor lungs were perfused during procurement with 4 L Perfadex containing aprotinin (280 mg load + 70 mg/hL) or placebo. Aprotinin or placebo was also administered peri-operatively to the recipients. The study was powered to detect a 10% improvement in the primary endpoint of developing ISHLT grade III PGD anytime within 48 hr following the transplant procedure.

RESULTS

There were 48 patients randomized. Diagnosis and the use of bypass were different between groups. The study was stopped prematurely at the planned interim analysis point because of published concerns about renal toxicity of aprotinin. There was no difference in the occurrence of the primary endpoint between groups of patients. The median change from the baseline creatinine level at 24, 48, 72 hr; 7 and 30 d following the transplant was not associated with the administration of aprotinin.

CONCLUSIONS

There was no statistically significant difference in the incidence of the primary endpoint between groups in the study. Excess renal failure related to aprotinin administration in a patient population at high risk for the event was not observed.

Lung ischemia-reperfusion injury: a molecular and clinical view on a complex pathophysiological process

Lung ischemia-reperfusion injury remains one of the major complications after cardiac bypass surgery and lung transplantation. Due to its dual blood supply system and the availability of oxygen from alveolar ventilation, the pathogenetic mechanisms of ischemia-reperfusion injury in the lungs are more complicated than in other organs, where loss of blood flow automatically leads to hypoxia. In this review, an extensive overview is given of the molecular and cellular mechanisms that are involved in the pathogenesis of lung ischemia-reperfusion injury and the possible therapeutic strategies to reduce or prevent it. In addition, the roles of neutrophils, alveolar macrophages, cytokines, and chemokines, as well as the alterations in the cell-death related pathways, are described in detail.

Recipient treatment with L-arginine attenuates donor lung injury associated with hemorrhagic shock

BACKGROUND

Organ donors are frequently trauma victims, but the impact of donor hemorrhagic shock and resuscitation (HSR) on pulmonary graft function has not been assessed. L-arginine treatment during reperfusion increases the production of endothelial nitric oxide and thus ameliorates ischemia-reperfusion injury. Objective of the present porcine study was to investigate the effect of donor hemorrhage on pulmonary graft function and potential beneficial effects of L-arginine administration.

METHODS

In the control-group (n=6), lungs were harvested from donors without hypotensive periods. In the HSR-group (n=6) and HSR-Arg-group (n=6), donors were subjected to hemorrhagic shock (40% blood shed) and resuscitation before harvest. Left lungs were transplanted after hypothermic preservation of 18 hr, and graft function was observed for 6 hr after reperfusion. Recipients in the HSR-Arg-group received a bolus of L-arginine (50 mg/kg BW) intravenously 5 min before reperfusion followed by a continuous intravenous administration of L-arginine 200 mg/kg BW for 2 hr. Tissue specimens and bronchoalveolar lavage fluid were obtained at the end of the observation period.

RESULTS

Donor lung function did not differ between study groups. Compared with the control group, pulmonary graft gas exchange was significantly impaired in the HSR-group. Graft function in the HSR-Arg-group did not differ from control organs. Neutrophil fraction, protein content, and malondialdehyde levels in the bronchoalveolar lavage fluid in the HSR-group were higher compared with control and HSR-Arg-Group.

CONCLUSION

Although fulfilling ideal donor criteria, pulmonary graft function of lungs harvested from donors subjected to HSR is impaired, but improves significantly when l-arginine is administered during reperfusion.

Anesthetic Considerations for Lung Transplantation

Lung transplantation is the definitive treatment for end-stage lung disease. The number of lung transplantations performed is limited by the number of donors available and is far outnumbered by the potential recipients on the waiting list. Advances in surgical methods, organ preservation, and immunosuppression have decreased the morbidity and mortality associated with this procedure during the last few decades. Specific anesthetic concerns are associated with lung transplantation, including careful preoperative assessment of pulmonary and cardiac function, adequate venous access and monitors, and ventilation techniques, such as 1-lung ventilation and lung-protective strategies to decrease the risks of reperfusion injury, barotrauma, and re-expansion pulmonary edema. Intraoperative transesophageal echocardiography, cardiopulmonary bypass, and inhaled nitric oxide can also be important tools for the anesthesiologist to optimize patient care during this challenging procedure.