Tracheal Tissue Engineering: Principles and State of the Art.

Patients affected by long-segment tracheal defects or stenoses represent an unsolved surgical issue, since they cannot be treated with the conventional surgery of tracheal resection and consequent anastomosis. Hence, different strategies for tracheal replacement have been proposed (synthetic materials, aortic allografts, transplantation, autologous tissue composites, and tissue engineering), each with advantages and drawbacks. Tracheal tissue engineering, on the other hand, aims at recreating a fully functional tracheal substitute, without the need for the patient to receive lifelong immunosuppression or endotracheal stents. Tissue engineering approaches involve the use of a scaffold, stem cells, and humoral signals. This paper reviews the main aspects of tracheal TE, starting from the choice of the scaffold to the type of stem cells that can be used to seed the scaffold, the methods for their culture and expansion, the issue of graft revascularization at the moment of in vivo implantation, and experimental models of tracheal research. Moreover, a critical insight on the state of the art of tracheal tissue engineering is also presented.

Human tracheal transplantation: A systematic review of case reports.

BACKGROUND: Patients with long-segment airway stenosis not amenable to conventional surgery may benefit from tracheal transplantation. However, this procedure has been only anecdotally reported, and its indications, techniques, and outcomes have not been extensively reviewed. METHODS: We conducted a systematic Literature search to identify all original articles reporting attempts at tracheal transplantation in humans. RESULTS: Of 699 articles found by the initial search, 11 were included in the systematic review, describing 14 cases of tracheal transplantation. Patients underwent transplantation for benign stenosis in nine cases, and for malignancies in five cases. In 12 cases blood supply to the trachea was provided by wrapping the graft in a vascularized recipient's tissue, while in 2 cases the trachea was directly transplanted as a vascularized composite allograft. The transplantation procedure was aborted before orthotopic transplantation in two patients. Among the remaining 12 patients, there was 1 operative mortality, while 4 patients experienced complications. Immunosuppressants drugs were administered to the majority of patients postoperatively, and only one group of authors attempted their withdrawal, in five patients. At the end of follow-up, all 11 patients surviving the operation were alive, but 2 had a recurrent tracheal stenosis requiring an airway appliance for breathing. CONCLUSION: Human tracheal transplantation is still at an embryonic phase. Studies available in the Literature report different surgical techniques, and information on long-term outcomes is still limited. Future research is needed in order to understand the clinical value of this procedure.

Surgery for tracheal and laryngotracheal stenosis: a historical case series.

OBJECTIVES: Benign (laryngo-)tracheal stenosis is a relatively rare pathology and its surgical treatment is performed only at few specialized centres. This study aims to investigate outcomes after (laryngo-)tracheal resection-anastomosis, to explore potential risk factors for postoperative complications and to assess whether, over a 33-year period, there were major changes in surgical indications, techniques or outcomes. METHODS: Retrospective, single-centre review of all consecutive patients who underwent tracheal or laryngo-tracheal resection/anastomosis for benign pathologies from 1990 to 2023. RESULTS: Overall, 211 patients underwent tracheal (149 patients, 70.6%) and laryngo-tracheal (62 patients, 29.4%) resection-anastomosis. Of these, 195 patients (93.8%) were affected by iatrogenic stenosis, while 13 (6.2%) suffered from idiopathic stenosis. The median length of stenosis was 25 mm (interquartile range 1-3, 20-30). The overall morbidity rate was 27.5%, while major morbidity occurred in 10.5% of cases. One patient (0.5%) died in the postoperative period. Glottic oedema (17 patients, 8.1%), granulations (12 patients, 5.7%) and restenosis (10 patients, 4.7%) were the main complications. The only independent risk factor for postoperative complications was the length of the resected airway (P = 0.019). In the latest half of the study period, an older median age was observed, and no patient with idiopathic tracheal stenosis underwent surgery. Postoperative outcomes were comparable between surgical eras. CONCLUSIONS: Surgical treatment of (laryngo-)tracheal stenosis is challenging and should be performed by specialized centres. In our experience, morbidity and mortality rates were satisfactory, and in most cases, patients could breathe without tracheostomy. The length of the stenosis was the most significant risk factor for postoperative complications.

An alternative surgical access for posterior tracheal defects or fistulae situated between the cervical and thoracic region.

Posterior tracheal lesion defects between the cervical and the thoracic region represent a surgical challenge. Cervicotomy or median sternotomy might not allow a satisfactory exposure of the defect, and a history of prior neck surgeries could further complicate the procedure. We propose a high posterior right thoracotomic approach, by which the entire posterior aspect of the trachea is visible, up to the cervical region. We describe our experience with this approach, which is best suited for cases where a non-circumferential repair of the trachea is attempted.

Three-Dimensional Imaging-Guided Lung Anatomic Segmentectomy: A Single-Center Preliminary Experiment.

Background and objectives: VATS segmentectomy has been proven to be effective in the treatment of stage I NSCLC, but its technical complexity remains one of the most challenging aspects for thoracic surgeons. Furthermore, 3D-CT reconstruction images can help in planning and performing surgical procedures. In this paper, we present our personal experience of 11 VATS anatomical resections performed after accurate pre-operative planning with 3D reconstructions. Materials and methods: A 3D virtual model of the lungs, airways, and vasculature was obtained, starting from a 1.25 mm 3-phase contrast CT scan, and the original images were used for the semi-automatic segmentation of the lung parenchyma, airways, and tumor. Results: Six males and five females were included in this study. The median diameter of the pulmonary lesion at the pre-operative chest CT scan was 20 mm. The surgical indication was confirmed in seven patients: in three cases, a lobectomy, instead of a segmentectomy, was needed due to intraoperative findings of nodal metastasis. Meanwhile, only in one case, we performed a lobectomy because of inadequate surgical resection margins. Skin-to-skin operative average time was 142 (IQR 1-3 105-182.5) min. The median post-operative stay was 6 (IQR 1-3 3.5-7) days. The mean value of the closest surgical margin was 13.7 mm. Conclusion: Image-guided reconstructions are a useful tool for surgeons to perform complex resections in order to spare healthy parenchyma and to ensure disease-free margins. Nevertheless, human skill and surgeon experience still remain fundamental for the final decisions regarding the proper resection to perform.

Impact of a standardized protocol for chest tube management after VATS pulmonary resections on post-operative outcomes and complications.

Chest tube management represents a major issue after lung surgery as no protocol is widely accepted and tube management is generally based on local or personal habits. Aim of this study is to evaluate the impact of a standardized protocol for chest tube management after pulmonary resections on the post-operative outcomes. We performed a single center retrospective analysis of all adult patients undergoing thoracoscopic pulmonary resection from January 2020 to December 2021. Starting from January 2021 a standardized protocol of chest tube management was applied after all procedures. Patients were divided into two groups according to the chest tube management strategy. he two groups had similar pre-operative characteristics and the extent of lung resection was comparable. Intervention group had significantly shorter time to chest tube removal (median 1 vs 3 days, p < 0.001) and post-operative length of stay (median 3 vs 4 days, p < 0.001). Despite earlier chest tube removal, there was not an increased incidence of post-removal complications. On multivariable analysis, the new chest drain management strategy was an independent predictor of earlier chest tube removal. A standardized protocol of chest tube management allows for an earlier chest tube removal and a shorter hospital stay, without an increase in post-operative complications.

Microscopical Variables and Tumor Inflammatory Microenvironment Do Not Modify Survival or Recurrence in Stage I-IIA Lung Adenocarcinomas.

Microscopical predictors and Tumor Immune Microenvironment (TIME) have been studied less in early-stage NSCLC due to the curative intent of resection and the satisfactory survival rate achievable. Despite this, the emerging literature enforces the role of the immune system and microscopical predictors as prognostic variables in NSCLC and in adenocarcinomas (ADCs) as well. Here, we investigated whether cancer-related microscopical variables and TIME influence survival and recurrence in I-IIA ADCs. We retrospectively collected I-IIA ADCs treated (lobectomy or segmentectomy) at the University Hospital (Padova) between 2016 and 2022. We assigned to pathological variables a cumulative pathological score (PS) resulting as the sum of them. TIME was investigated as tumor-infiltrating lymphocytes (TILs < 11% or ≥11%) and PD-L1 considering its expression (<1% or ≥1%). Then, we compared survival and recurrence according to PS, histology, TILs and PD-L1. A total of 358 I-IIA ADCs met the inclusion criteria. The median PS grew from IA1 to IIA, indicating an increasing microscopical cancer activity. Except for the T-SUVmax, any pathological predictor seemed to be different between PD-L1 < 1% and ≥1%. Histology, PS, TILs and PD-L1 were unable to indicate a survival difference according to the Log-rank test (p = 0.37, p = 0.25, p = 0.41 and p = 0.23). Even the recurrence was non-significant (p = 0.90, p = 0.62, p = 0.97, p = 0.74). According to our findings, resection remains the best upfront treatment in I-IIA ADCs. Microscopical cancer activity grows from IA1 to IIA tumors, but it does not affect outcomes. These outcomes are also unmodified by TIME. Probably, microscopical cancer development and immune reaction against cancer are overwhelmed by an adequate R0-N0 resection.

Laser-assisted lung metastasectomy: a systematic review.

Laser-assisted resection (LAR) of pulmonary metastases offers several potential advantages compared to conventional surgical techniques. However, the technical details, indications and outcomes of LAR have not been extensively reviewed. We conducted a systematic literature search to identify all original articles reporting on LAR of pulmonary metastases. All relevant outcomes, including morbidity rate, R0 rate, pulmonary function tests, overall- (OS) and relapse-free survival (RFS) rates were collected. Additionally, a comparison between outcomes obtained by laser-assisted and conventional resection techniques was provided. Of 2629 articles found by the initial search, 12 were selected for the systematic review. Following LAR, the R0 rate ranged between 72 and 100% and the morbidity rate ranged from 0 to 27.5%. The postoperative decline in forced expiratory volume in 1 s varied between 3.4 and 11%. Median OS and RFS were 42-77.6 months and 9-34.1 months, respectively. Compared with patients treated by other resection techniques, patients treated by LAR frequently had a higher number of metastases and a higher rate of bilateral disease. Despite this, no significant differences were observed in R0 rate, morbidity rate, and median OS rate, while only 1 study found a lower RFS rate in the LAR cohort. Although selection bias limits the comparability of outcomes, the findings of this review suggest that LAR is a valid alternative to conventional procedures of lung metastasectomy. The main difficulties of this technique consist in the adoption of a video-assisted thoracoscopic approach, and in the pathologic assessment of resection margins.

Preclinical and clinical orthotopic transplantation of decellularized/engineered tracheal scaffolds: A systematic literature review.

Severe tracheal injuries that cannot be managed by mobilization and end-to-end anastomosis represent an unmet clinical need and an urgent challenge to face in surgical practice; within this scenario, decellularized scaffolds (eventually bioengineered) are currently a tempting option among tissue engineered substitutes. The success of a decellularized trachea is expression of a balanced approach in cells removal while preserving the extracellular matrix (ECM) architecture/mechanical properties. Revising the literature, many Authors report about different methods for acellular tracheal ECMs development; however, only few of them verified the devices effectiveness by an orthotopic implant in animal models of disease. To support translational medicine in this field, here we provide a systematic review on studies recurring to decellularized/bioengineered tracheas implantation. After describing the specific methodological aspects, orthotopic implant results are verified. Furtherly, the only three clinical cases of compassionate use of tissue engineered tracheas are reported with a focus on outcomes.

Precision Surgery in NSCLC.

Non-small cell lung cancer (NSCLC) is still one of the leading causes of death worldwide. This is mostly because the majority of lung cancers are discovered in advanced stages. In the era of conventional chemotherapy, the prognosis of advanced NSCLC was grim. Important results have been reported in thoracic oncology since the discovery of new molecular alterations and of the role of the immune system. The advent of new therapies has radically changed the approach to lung cancer for a subset of patients with advanced NSCLC, and the concept of incurable disease is still changing. In this setting, surgery seems to have developed a role of rescue therapy for some patients. In precision surgery, the decision to perform surgical procedures is tailored to the individual patient; taking into consideration not only clinical stage, but also clinical and molecular features. Multimodality treatments incorporating surgery, immune checkpoint inhibitors, or targeted agents are feasible in high volume centers with good results in terms of pathologic response and patient morbidity. Thanks to a better understanding of tumor biology, precision thoracic surgery will facilitate optimal and individualized patient selection and treatment, with the goal of improving the outcomes of patients affected by NSCLC.

Development and In Vitro/In Vivo Comparative Characterization of Cryopreserved and Decellularized Tracheal Grafts.

Tracheal reconstruction represents a challenge when primary anastomosis is not feasible. Within this scenario, the study aim was to develop a new pig-derived decellularized trachea (DecellT) to be compared with the cryopreserved counterpart (CryoT) for a close predictive analysis. Tracheal segments underwent decellularization by a physical + enzymatic + chemical method (12 cycles); in parallel, cryopreserved samples were also prepared. Once decellularized (histology/DNA quantification), the two groups were characterized for Alpha-Gal epitopes/structural proteins (immunohistochemistry/histology/biochemical assays/second harmonic generation microscopy)/ultrastructure (Scanning Electron Microscopy (SEM))/mechanical behaviour. Cytotoxicity absence was assessed in vitro (extract-test assay/direct seeding, HM1SV40 cell line) while biocompatibility was verified in BALB/c mice, followed by histological/immunohistochemical analyses and SEM (14 days). Decellularization effectively removed Alpha-Gal epitopes; cartilage histoarchitecture was retained in both groups, showing chondrocytes only in the CryoT. Cryopreservation maintained few respiratory epithelium sparse cilia, not detectable in DecellT. Focusing on ECM, preserved structural/ultrastructural organization and collagen content were observed in the cartilage of both; conversely, the GAGs were significantly reduced in DecellT, as confirmed by mechanical study results. No cytotoxicity was highlighted by CryoT/DecellT in vitro, as they were also corroborated by a biocompatibility assay. Despite some limitations (cells presence/GAGs reduction), CryoT/DecellT are both appealing options, which warrant further investigation in comparative in vivo studies.

A prognostic score from a multicentric retrospective analysis of patients affected by sarcoma with metachronous lung metastases undergoing metastasectomy.

BACKGROUND: Despite the lack of evidence-based on prospective randomized studies, surgery has become the cornerstone of the treatment in patients with pulmonary oligometastatic sarcomas. Our study aimed to construct a composite prognostic score for metachronous oligometastatic sarcoma patients. METHODS: A retrospective analysis was performed on data patients who underwent radical surgery for metachronous metastases in six research institutes from January 2010 to December 2018. The log-hazard ratio (HR) obtained from the Cox model was used to derive weighting factors for a continuous prognostic index designed to identify differential outcome risks. RESULTS: A total of 251 patients were enrolled in the study. In the multivariate analysis, a longer disease-free interval (DFI) and a lower neutrophil-to-lymphocytes ratio (NLR) were predictive of a better overall survival (OS) and disease-free survival (DFS). A prognostic score was developed based on DFI and NLR data, identifying 2 risk class groups for DFS (3-years DFS 20.2% for the high-risk group [HRG]and 46.4% for the low-risk group [LRG] [<0.0001]) and 3 risk groups for OS (3 years OS 53.9% for the HRG vs. 76.9% for the intermediate-risk group and 100% of the LRG (p < 0.0001)). CONCLUSION: The proposed prognostic score effectively predicts outcomes for patients with lung metachronous oligo-metastases from the surgically treated sarcoma.

Postoperative hypoxaemic acute respiratory failure after neoadjuvant treatment for lung cancer: radiologic findings and risk factors.

OBJECTIVES: To investigate the rate of hypoxaemic acute respiratory failure (hARF) on patients undergoing surgery for non-small-cell lung cancer (NSCLC) after neoadjuvant chemotherapy, to describe clinical and radiological findings and to explore potential risk factors for this complication. METHODS: Retrospective review of medical records of all patients who underwent surgery for NSCLC after neoadjuvant chemotherapy at a single centre between 2014 and 2021. Computed tomography scans of patients who developed hARF were reviewed by an experienced radiologist to provide a quantitative assessment of radiologic alterations. RESULTS: The final cohort consisted of 211 patients. Major morbidity was 13.3% (28/211) and hARF was the most common major complication (n = 11, 5.2%). Postoperative mortality was 1.9% (4/211) and occurred only in patients who experienced hARF. Most patients who experienced hARF underwent major procedures, including pneumonectomy (n = 3), lobectomy with chest wall resection (n = 3), bronchial or vascular reconstructions (n = 3) and extended or bilateral resections (n = 2). Analysis of computed tomography findings revealed that crazy paving and ground glass were the most common alterations and were more represented in the non-operated lung. Male gender, current smoking status, pathologic stage III-IV and operative time resulted significant risk factors for hARF at univariable analysis (P < 0.05). CONCLUSIONS: hARF is the main cause of major morbidity and mortality after neoadjuvant therapy and surgery for NSCLC and occurs more frequently after complex and lengthier surgical procedures. Overall, our findings suggest that operative time may represent the most important risk factor for hARF.

Tracheal resection and anastomosis for squamous cell carcinoma.

Tracheal malignant tumors are uncommon lesions. The rarity of this condition may generate uncertainties in the diagnosis and treatment. For this reason especially, the surgical treatment should be performed only in centers with a high expertise in tracheal surgery. If the involved tracheal tract is less than 4-5 cm and the tumor is localized, the treatment of choice is based on a segmental tracheal resection with an end-to-end anastomosis. In this video tutorial, we describe how we perform tracheal resection with an end-to-end anastomosis in a patient with a squamous cell carcinoma.

Surgical management of post-transplant bronchial stenoses: a single-center experience.

PURPOSE: Bronchial stenoses are challenging complications after lung transplantation and are associated with high rates of morbidity and mortality. We report a series of patients who underwent bronchoplasty or sleeve resection for bronchial stenoses that did not resolve with endoscopic treatment after lung transplantation. METHODS: Between 1995 and 2020, 497 patients underwent lung transplantation at our Institution. 35 patients (7.0%) experienced bronchial stenoses with a median time from transplantation of 3 months. Endoscopic management was effective in 28 cases (5.6%) while 1 patient required re-transplantation. Six patients (1.2%) underwent bronchoplasty or sleeve resection. RESULTS: The procedures of the six patients who underwent bronchoplasty or sleeve resection were as follows: lower sleeve bilobectomy (n = 3), wedge bronchoplasty of the bronchus intermedius (n = 1), isolated sleeve resection of the bronchus intermedius (n = 1), and isolated sleeve resection of the bronchus intermedius (n = 1), associated with a middle lobectomy. All patients were discharged after a median time of 11 days. At a median of 12 months from surgery, two patients remain alive with a preserved pulmonary function. Four patients died after a median time of 56 months from bronchoplasty of causes that were not related to surgery. CONCLUSIONS: Bronchial reconstructions are challenging procedures that can be performed in highly specialized centers. Despite this, they can be considered a good strategy to obtain a definitive resolution of stenosis after lung transplantation.

Adult Benign, Non-Iatrogenic Bronchoesophageal Fistulae: Systematic Review and Descriptive Analysis of Individual Patient Data.

BACKGROUND: Adult, benign, non-iatrogenic bronchoesophageal fistula (BEF) is a rare condition, which is occasionally described in single case reports. Therefore, little is known about its possible causes, presentation and management. METHODS: A systematic search of the literature in MEDLINE, PubMed Central and EMBASE databases between 1990 and 2020 was carried out to identify all cases of BEF. The initial database search identified 19,452 articles, of which 183 (251 individual patient cases) were included in the final analysis. RESULTS: Main causes of BEF were congenital malformations (97/251, 38.7%) and infections (82/251, 32.7%), while 33/251 (13.1%) fistulae were regarded as idiopathic and 39/251 (15.5%) attributed to other causes. Esophagograpy was the most sensitive method of diagnosis (97.4%) compared with esophagoscopy (78.9%), computed tomography (49.6%) and bronchoscopy (46.0%). Definitive treatment was surgical for 176 patients (70%), endoscopic for 25 (10%) and medical for 37 (14.7%). Compared with congenital BEFs, infective BEFs had shorter median symptom duration and were distributed more proximally over the bronchial tree. Definitive treatment was almost only surgical for congenital BEFs, while infective BEFs were treated also endoscopically (12%) and by medical therapy (38%). Morbidity, treatment failure and recurrence rates were higher for infective BEFs. CONCLUSIONS: BEFs are rare. Symptoms are non-specific and a high index of suspicion is necessary for diagnosis. Patients with infective BEF tend to have a more severe clinical picture than those with congenital BEF. Surgery is the main treatment for patients affected by congenital BEF, while infective BEFs may heal conservatively.

Prognostic Factors Affecting Survival after Pulmonary Resection of Metastatic Renal Cell Carcinoma: A Multicenter Experience.

In this paper we aimed to address the role of pulmonary metastasectomy (PM) in patients affected by Lung Metastases (LM) from Renal Cell Carcinoma (RCC) and to analyse prognostic factors affecting overall survival (OS), disease-free interval (DFI) between primary RCC and first LM, and disease-free survival (DFS) after PM and before lung recurrence. Medical records of 210 patients who underwent PM from RCC in 4 Italian Thoracic Centres, from January 2000 to September 2019, were collected and analysed. All patients underwent RCC resection before lung surgery. The main RCC histology was clear cells (188, 89.5%). The 5- and 10-year OS from the first lung operation were 60% and 34%, respectively. LM synchronous with RCC (p = 0.01) and (Karnofsky Performance Status Scale) KPSS < 80% (p < 0.001) negatively influenced OS. Five- and 10-year DFI were 54% and 28%, respectively. The main factors negatively influencing DFI were: male gender (p = 0.039), KPSS < 80% (p = 0.009) and lactate dehydrogenase > 1.5 times 140 U/L (p = 0.001). Five- and 10-year disease-free survival were 54% and 28%, respectively; multiple LM (p = 0.036), KPSS < 80% (p = 0.001) and histology of RCC other than clear cells negatively influenced disease-free survival. Conclusions: patients with KPSS > 80%, single metachronous LM with a long DFI from RCC diagnosis, and clear cell histology, benefit from pulmonary metastasectomy.

Vascular Involvement in Thymic Epithelial Tumors: Surgical and Oncological Outcomes.

BACKGROUND: The involvement of mediastinal great vessels is common in advanced stage thymic tumors, which makes their surgical resection challenging. Moreover, the impact of vascular involvement on the oncological prognosis is still unclear. The aim of this study is to investigate the surgical and oncological outcomes and the impact of vascular involvement in a population of patients operated for advanced stage thymic tumors. METHODS: A retrospective analysis on four hundred and sixty-five patients undergoing resection for advanced stage (Masaoka III-IV) thymic tumors in a single high-volume center was performed. One hundred forty-four patients met the inclusion criteria and were eligible for the study. Patients were divided in two groups according to the presence or absence of vascular involvement. RESULTS: the two groups did not differ for the baseline characteristics and showed comparable surgical outcomes. Vascular involvement was not associated with worse overall survival but with an increased recurrence rate (p = 0.03). Multivariable analysis demonstrated a higher risk of recurrence in patients without R0 resection (HR 0.11, 0.02-0.54, p = 0.006) and with thymic carcinoma (HR 2.27, 1.22-4.24, p = 0.01). CONCLUSIONS: resection of thymic tumors with vascular involvement can be performed with optimal surgical results in a high volume center. From the oncological point of view, the involvement of the great vessels seems to be associated with a higher recurrence rate without affecting long-term survival.

Short- and Long-Term Impact of Smoking Donors in Lung Transplantation: Clinical and Pathological Analysis.

BACKGROUND: The use of smoking donors (SD) is one strategy to increase the organ pool for lung transplantation (LT), but the benefit-to-risk ratio has not been demonstrated. This study aimed to evaluate the impact of SD history on recipient outcomes and graft alterations. METHODS: LTs in 293 patients were retrospectively reviewed and divided into non-SD (n = 225, group I), SD < 20 pack-years (n = 45, group II), and SD ≥ 20 pack-years (n = 23, group III) groups. Moreover, several lung donor biopsies before implantation (equally divided between groups) were evaluated, focusing on smoking-related lesions. Correlations were analyzed between all pathological data and smoking exposure, along with other clinical parameters. RESULTS: Among the three groups, donor and recipient characteristics were comparable, except for higher Oto scores and age in group III. Group III showed a longer intensive care unit (ICU) and hospital stay compared with the other two groups. This finding was confirmed when SD history was considered as a continuous variable. However, survival and other mid- and long-term major outcomes were not affected by smoking history. Finally, morphological lesions did not differ between the three groups. CONCLUSIONS: In our study, SDs were associated with a longer post-operative course, without affecting graft aspects or mid- and long-term outcomes. A definition of pack-years cut-off for organ refusal should be balanced with the other extended criteria donor factors.