Purpose: Lung transplantation (LTx) for patients with pulmonary arterial hypertension (PAH) reportedly has high postoperative mortality and requires vigilant peri-operative management. Extracorporeal membrane oxygenation (ECMO) is a powerful tool to support patients' hemodynamics during and after LTx. However, the optimal ECMO strategy remains to be an issue of debate. Here, we report our unique strategy for patients with PAH utilizing postoperative central veno-arterial (VA) ECMO combined with delayed chest closure.

Purpose: Congenital portosystemic shunts (CPSS) are rare vascular malformations which cause partial or complete shunting of portal blood into the systemic circulation. Pulmonary arterial hypertension (PAH) is one of its major complications, and therapeutic outcomes for children have been reported. However, clinical courses of CPSS-related PAH in adolescent and adult cases are not well known.

Purpose Intraoperative extracorporeal circulation for lung transplant is a major cause of bleeding. The approach of point of care (POC) with thromboelastography (TEG®) during surgery may reduce the amount of hemorrhage, even under an extracorporeal device, which might lead to a shorter hemostatic time. This study aimed to investigate whether TEG provides these benefits for lung transplantation with veno-arterial extracorporeal membrane oxygenation (VA-ECMO). Methods We retrospectively identified 78 lung transplantation recipients at our institution between January 2018 and July 2021. Patients aged ≥15 years who underwent lung transplantations under VA-ECMO were eligible. The implementation of POC by TEG began in March 2020. Before the introduction of TEG, conventional management by the activated clotting time had been conducted. In coagulation management by TEG, our transplant team, which comprised a medical engineer and anesthesiologist, decided whether to provide transfusions on the basis of TEG results. The Student t-test and Mann-Whitney U test were performed to compare surgical factors before and after the introduction of TEG. P values <0.05 indicated a significant difference using a two-tailed test. Results Thirty-six patients for whom intraoperative VA-ECMO was applied for the first time were enrolled. They were categorized according to the method of coagulation management (n=17 with conventional care and n=19 with POC by TEG). There was no significant difference in the procedure type between two groups (bilateral vs. single, p=1.000 and living vs. cadaveric, p=0.410). The total operative time was significantly shorter with POC by TEG than with conventional care (mean: 557 vs. 721 min, p=0.010). Additionally, POC by TEG resulted in a significantly shorter operative time after ECMO withdrawal than that with conventional care (mean: 108 vs. 157 min, p=0.005). Total blood loss was significantly lower in POC by TEG (median: 1740 vs. 2990 ml with conventional care, p=0.044). However, there was no decrease in the consumption of fresh frozen plasma (p=0.762), platelet concentrate (p=0.270), or red blood cells (p=0.363) with POC by TEG. Conclusion During lung transplantation under VA-ECMO, POC by TEG has the benefits of decreasing blood loss and the hemostatic time.

Mouse single lung transplantation is one of the most technically challenging animal models. It remains a powerful model to study underlying mechanisms of LTx biology. However, the significant learning curve and surgeon-dependent variability in histopathological findings need to be taken into account when designing experimental protocols.

Tumor spread through air spaces (STAS) is reportedly a poor prognostic factor in non-small cell lung cancer. However, little is known about the molecular background and tumor microenvironment associated with STAS. This study assessed the relationship between STAS and tumor microenvironment in lung squamous cell carcinoma using next generation sequencing data. RNA-sequencing and whole-exome sequencing were performed in 20 surgically resected lung squamous cell carcinoma cases. Pathological specimens were reviewed to determine the existence of STAS. Somatic mutations, gene expression and gene set enrichment were analyzed and compared between STAS positive and negative tumors. Among 20 patients, nine were pathological stage I, six stage II and five stage III. In all, eight tumors were positive for STAS and 12 were negative. While STAS was not associated with tumor size, all N2 tumors were positive for STAS. Tumor mutational burden was not associated with STAS. Hierarchical clustering using the single sample Gene Set Enrichment Analysis score of 4872 immunologic signature gene sets revealed two clusters (Figure 1). Cluster 1 revealed lower expression of immune-related genes, forming a cluster of non-inflamed (cold) tumors. The cluster of non-inflamed tumors showed a tendency to higher STAS positivity (Cluster 1, 67%; Cluster 2, 18%; p=0.065). Next, we performed Gene Set Enrichment Analysis between STAS positive and negative tumors. Using 50 Hallmark gene sets in the Molecular Signatures Database, gene sets of allograft rejection, IL2-STAT5 signaling, inflammatory response and complement were found to have a significantly lower expression in STAS positive tumors (q <0.05). We further investigated the expression of each immune-related gene and compared them between STAS positive and negative tumors, which showed that PD-L1 gene expression was significantly lower in STAS positive tumors (p=0.023). STAS positivity was associated with the non-inflamed tumor-immune microenvironment in lung squamous cell carcinoma. Our findings might partly explain the aggressive behavior of STAS positive tumors. Since the efficacy of immunotherapy might differ between STAS positive and negative tumors, further investigation of immunological and molecular aspects of STAS positive tumors is needed.

Development of chronic lung allograft dysfunction involves various alloimmune-independent insults including those mediated by toll-like receptor (TLR) signaling. We hypothesized that TLR signaling promotes allograft airway fibrosis.

Obliterative bronchiolitis (OB) is a major cause of morbidity and mortality after lung transplantation (LTx). Club cells are bronchiolar epithelial progenitor cells that produce club cell secretory protein (CCSP), which has anti-inflammatory functions. We previously showed that depleting grafts of club cells using naphthalene (NA) results in OB in both syngeneic and allogeneic murine LTx. We aimed to determine whether post-transplant treatment with CCSP decreases acute rejection or OB in club cell-depleted grafts.

Development of chronic lung allograft dysfunction involves various alloimmune-independent insults including those mediated by Toll-like receptor (TLR) signaling, which is known to activate alloimmune responses. We hypothesized that TLR signaling may also contribute to the activation of fibroblasts and promoting allograft airway fibrosis. Mouse orthotopic tracheal transplants were conducted between major histocompatibility complex (MHC)-mismatched Balb/c donor and wild-type C3H or C3H-derived TLR4 mutant recipients (nonfunctional TLR4). Immunohistochemistry on day 21 showed significantly smaller alpha-smooth muscle actin (α-SMA)-positive areas in TLR4 mutant recipients than wild-type recipients (P = .01). No difference was found for CD3+ T-cell infiltration. Proliferation of alloreactive T cells derived from the recipient spleen showed no difference between TLR4 mutant and wild-type recipients in a mixed lymphocyte reaction. The effect of TLR4 signaling was examined in primary pulmonary fibroblast cultures both with lipopolysaccharide (LPS) and transforming growth factor (TGF)-β1. Stimulation with LPS significantly increased expression of α-SMA mRNA in wild-type fibroblasts cultured with TGF-β1 compared with the control without LPS (P = .001). Taken together, these findings suggest disruption of TLR signaling leads to reduced activation of fibroblasts without affecting T-cell infiltration and proliferation in this model. TLR4-mediated activation of fibroblasts may be a potentially important mechanism of allograft remodeling.

Chronic lung allograft dysfunction is the major complication after lung transplantation (LTx) that results from a complex interplay of inflammatory and alloimmune factors, culminating in parenchymal and/or airway fibrosis with obliterative bronchiolitis (OB). The lung allograft is constantly exposed to noxious stimuli from the external environment via the airways. We hypothesized that repeated administration of lipopolysaccharide (LPS) would augment alloimmunity and trigger chronic rejection and fibrosis in a mouse minor alloantigen-mismatched orthotopic lung transplant model (C57BL/10 [B10] → C57BL/6 [B6]).

Obliterative bronchiolitis (OB) is a primary contributor to the poor long-term survival of lung transplant recipients. OB manifests as fibroproliferative obliteration of the lumen of small airways, suggesting that inadequate epithelial repair may contribute to the pathobiology. Club cells are bronchiolar epithelial progenitor cells and are central to small airway repair processes. We hypothesized that insufficiency in the epithelial repair by club cells results in OB. We performed murine lung transplantations with club cell-depleted grafts using the club cell-specific naphthalene (NA) injury and assessed the prevalence of OB.

Chronic lung allograft dysfunction (CLAD) is the primary contributor to the poor long-term survival of lung transplant recipients. Pathologically, CLAD manifests as obliterative bronchiolitis (OB) and/or parenchymal fibrosis. OB is characterized by fibrotic obliteration of small airways. This fibrosis includes inappropriate extracellular matrix component deposition by myofibroblasts, suggesting myofibroblasts are key players in this pathophysiology. Determining the origin of myofibroblasts in transplanted organs will be a key step towards understanding post-transplant fibrosis pathogenesis. Whether these fibroblasts originate from the organ donor or recipient remains controversial. The purpose of this study was to determine the donor versus recipient origin of myofibroblasts in post-transplant lung fibrosis. We studied fibrosis in the minor-mismatched mouse orthotopic single lung transplant model. Transgenic C57BL/6(B6)-background mice that ubiquitously express green fluorescent protein (GFP) (B6-GFP) were used as donors or recipients in combination with C57BL/10(B10) mice. On post-op day 28, we evaluated the origin of myofibroblasts in OB by immunofluorescent staining for the myofibroblast marker (α-SMA) and GFP in four groups: 1) B10 to B6-GFP, 2) B6-GFP to B10, 3) B6 to B6-GFP, and 4) B6-GFP to B6 (n=5 in each group). One case in each minor-mismatched group showed OB. In the grafts transplanted from B10 to B6-GFP, α-SMA-positive cells were GFP-negative (Figure 1A). Conversely, most of α-SMA-positive cells were GFP-positive in the transplanted graft from B6-Tg to B10 (Figure 1B). The incidence of OB in this minor-mismatched strain combination was lower than the previously reported rates. Our study suggests that the myofibroblasts found in the obliterative fibrosis in the mouse lung transplant model originate from the donor. This mechanistic insight will be important in the future development of strategies to prevent and treat CLAD-associated fibrosis.

Objectives: Favourable short- and long-term outcomes for patients who underwent lung lobectomy for early stage non-small-cell lung cancer (NSCLC) by video-assisted thoracoscopic surgery (VATS) have been mainly reported in retrospective settings. However, using the current T descriptor, which reflects whole tumour size but does not reflect solid tumour size, the interpretation of those results may be biased. In this study, we conducted a propensity score matching analysis to compare short- and long-term outcomes of patients who underwent VATS or open lobectomy. Methods: We retrospectively reviewed patients who underwent lung lobectomy for cT1-2N0M0 NSCLC from 2001 to 2010. We only collected data from patients whose preoperative high-resolution computed tomography results were available. The outcomes of patients who underwent VATS lobectomy were compared to those who underwent open lobectomy before and after performing propensity score matching, which evaluated preoperative variables, including solid tumour size and tumour-disappearance ratio. Results: There were 101 VATS patients and 184 open lobectomy patients. Before propensity score matching, the VATS group had a higher mean age (P < 0.0001), smaller solid tumour size (P = 0.0042), similar whole tumour size (P = 0.2082), larger tumour-disappearance ratio (P = 0.0007), shorter operation time (P = 0.0002), less blood loss (P < 0.0001), shorter chest tube duration (P = 0.0002), shorter hospital stay (P < 0.0001), and better disease-free, disease-specific, and overall survival rates (P-values: 0.0049, 0.0154, 0.032, respectively). After propensity score matching, all differences, except operation time, blood loss, chest tube duration, and hospital stay, were no longer significant. Conclusions: VATS lobectomy is less invasive than open lobectomy, but in terms of survival outcomes, the oncological benefit of VATS may be overestimated under the current TNM classification system. Disclosure: No significant relationships.

PurposeObliterative bronchiolitis (OB) is a limiting factor that affects long-term survival following lung transplantation. Fibroblasts and myofibroblasts are considered to be the key players in fibrosis in OB. The source of these fibroblasts is still in question. Two major possible sources of the fibroblasts are recipient bone marrow cells and transitioned epithelial cells through epithelial to mesenchymal transition. The aim of this study was to clarify whether the fibroblasts originate from donor or from recipient.Methods and MaterialsWe performed orthotopic tracheal transplantation with the combination of transgenic C57BL/6 mice ubiquitously expressing green fluorescent protein (GFP) (B6-Tg) and BALB/c mice, where syngeneic with BALB/c to BALB/c combination. After transplantation, ten allogeneic recipients (five each in BALB/c to B6-Tg; and B6-Tg to BALB/c groups) and three syngeneic recipients were sacrificed on day 28. Histologic evaluation was done by using hematoxylin-eosin (H&E) staining and immunofluorescence staining of the myofibroblast marker (α-SMA) and GFP.ResultsSubepithelial fibrosis was observed in rejected airway on H&E (Figure A, B, every scale bar means 100 μm). In grafts from BALB/c to B6-Tg (Figure A, C), α-SMA (red) positive subepithelial fibrotic areas were also GFP (green) positive. Conversely in grafts from B6-Tg to BALB/c (Figure B, D), α-SMA positive fibrotic areas were GFP negative.ConclusionsThe results showed that the fibroblasts in rejected airway originated from recipient, but the issue of exact source of fibroblasts (central stem cells vs local transitioned epithelial cells through epithelial to mesenchymal transition) still remained unclear. Obliterative bronchiolitis (OB) is a limiting factor that affects long-term survival following lung transplantation. Fibroblasts and myofibroblasts are considered to be the key players in fibrosis in OB. The source of these fibroblasts is still in question. Two major possible sources of the fibroblasts are recipient bone marrow cells and transitioned epithelial cells through epithelial to mesenchymal transition. The aim of this study was to clarify whether the fibroblasts originate from donor or from recipient. We performed orthotopic tracheal transplantation with the combination of transgenic C57BL/6 mice ubiquitously expressing green fluorescent protein (GFP) (B6-Tg) and BALB/c mice, where syngeneic with BALB/c to BALB/c combination. After transplantation, ten allogeneic recipients (five each in BALB/c to B6-Tg; and B6-Tg to BALB/c groups) and three syngeneic recipients were sacrificed on day 28. Histologic evaluation was done by using hematoxylin-eosin (H&E) staining and immunofluorescence staining of the myofibroblast marker (α-SMA) and GFP. Subepithelial fibrosis was observed in rejected airway on H&E (Figure A, B, every scale bar means 100 μm). In grafts from BALB/c to B6-Tg (Figure A, C), α-SMA (red) positive subepithelial fibrotic areas were also GFP (green) positive. Conversely in grafts from B6-Tg to BALB/c (Figure B, D), α-SMA positive fibrotic areas were GFP negative. The results showed that the fibroblasts in rejected airway originated from recipient, but the issue of exact source of fibroblasts (central stem cells vs local transitioned epithelial cells through epithelial to mesenchymal transition) still remained unclear.

Background. Aberrant epithelial repair is a crucial event in the airway remodeling that characterizes obliterative bronchiolitis (OB) in transplanted lungs. Recent data from experiments using epithelial cell lines and human airway tissues from lung transplant recipients suggest that epithelial to mesenchymal transition (EMT) plays an important role in OB. The aim of this study was to clarify whether EMT is involved in airway remodeling in an animal model.Methods. We performed orthotopic tracheal transplantation from BALB/c to C57BL/6 mice with from BALC/c to BALB/c mouse grafts as controls. Five allogeneic and 3 syngeneic recipients were humanely killed at predetermined postoperative days 2-12 as well as 14 and 21. Histology was evaluated using hematoxylin-eosin (H&E) staining. We studied the expression of specific markers, including E-cadherin, an epithelial marker; a-smooth muscle actin (SMA), and S100A4, mesenchymal markers, and zinc finger E-box-binding homeobox 1 (ZEB1), an EMT-related transcription factor.Results. Histologic assessment of serial H&E stains of allogeneic grafts showed remarkable pseudostratified respiratory epithelium with subepithelial inflammatory cell infiltration, as well as denuded and flattened epithelium and subepithelial fibrosis. The dynamic epithelial changes occurred earlier than the subepithelial fibrosis. Immunohistochemical evaluation indicated the emergence of alpha-SMA- positive epithelial cells that were most prominent on day 7. The expression of E-cadherin was attenuated in a-SMA positive epithelial cells. S100A4 was also expressed in epithelial cells. A few days before the intraepithelial expression of alpha-SMA, ZEB1 emerged in the nuclei of epithelial cells.Conclusions. We observed expression of an EMT-related transcription factor and mesenchymal markers along with the attenuation of epithelial marker expression in epithelial cells, several days before prominent subepithelial fibrosis formation, results that suggest epithelial cells to play an important fibrosis role in airway remodeling during epithelial to mesenchymal transition.

A case of undifferentiated pleomorphic sarcoma in the mediastinum is presented. A 74-year-old man with no complaint was referred to our department for treatment of mediastinal mass pointed out by chest X-ray. Chest computed tomography (CT) revealed 3 tumors located in the left mediastinum. The largest one was adjacent to the esophagus with 10 cm in diameter. The other one was located beneath the left inferior pulmonary vein, and the last adjacent to the pulmonary artery trunk. Complete extirpation of the tumors was unsuccessful because of the invasion to the pulmonary artery trunk. A diagnosis of undifferentiated pleomorphic sarcoma was made with negative immunohistochemical staining for markers except for vimentin. Tumor cells were found to be scattered in the partially resected thymus. We assume this is a rare presentation of mediastinal dissemination of the tumor.