Lung-Mimetic Hydrofoam Sealant to Treat Pulmonary Air Leak.

Pulmonary air leak is the most common complication of lung surgery, contributing to post-operative morbidity in up to 60% of patients; yet, there is no reliable treatment. Available surgical sealants do not match the demanding deformation mechanics of lung tissue; and therefore, fail to seal air leak. To address this therapeutic gap, a sealant with structural and mechanical similarity to subpleural lung is designed, developed, and systematically evaluated. This "lung-mimetic" sealant is a hydrofoam material that has alveolar-like porous ultrastructure, lung-like viscoelastic properties (adhesive, compressive, tensile), and lung extracellular matrix-derived signals (matrikines) to support tissue repair. In biocompatibility testing, the lung-mimetic sealant shows minimal cytotoxicity and immunogenicity in vitro. Human primary monocytes exposed to sealant matrikines in vitro upregulate key genes (MARCO, PDGFB, VEGF) known to correlate with pleural wound healing and tissue repair in vivo. In rat and swine models of pulmonary air leak, this lung-mimetic sealant rapidly seals air leak and restores baseline lung mechanics. Altogether, these data indicate that the lung-mimetic sealant can effectively seal pulmonary air leak and promote a favorable cellular response in vitro.

Recovery of extracorporeal lungs using cross-circulation with injured recipient swine.

OBJECTIVE: Lung transplantation remains limited by the shortage of healthy organs. Cross-circulation with a healthy swine recipient provides a durable physiologic environment to recover injured donor lungs. In a clinical application, a recipient awaiting lung transplantation could be placed on cross-circulation to recover damaged donor lungs, enabling eventual transplantation. Our objective was to assess the ability of recipient swine with respiratory compromise to tolerate cross-circulation and support recovery of donor lungs subjected to extended cold ischemia. METHODS: Swine donor lungs (n = 6) were stored at 4 °C for 24 hours while recipient swine (n = 6) underwent gastric aspiration injury before cross-circulation. Longitudinal multiscale analyses (blood gas, bronchoscopy, radiography, histopathology, cytokine quantification) were performed to evaluate recipient swine and extracorporeal lungs on cross-circulation. RESULTS: Recipient swine lung injury resulted in sustained, impaired oxygenation (arterial oxygen tension/inspired oxygen fraction ratio 205 ± 39 mm Hg vs 454 ± 111 mm Hg at baseline). Radiographic, bronchoscopic, and histologic assessments demonstrated bilateral infiltrates, airway cytokine elevation, and significantly worsened lung injury scores. Recipient swine provided sufficient metabolic support for extracorporeal lungs to demonstrate robust functional improvement (0 hours, arterial oxygen tension/inspired oxygen fraction ratio 138 ± 28.2 mm Hg; 24 hours, 539 ± 156 mm Hg). Multiscale analyses demonstrated improved gross appearance, aeration, and cellular regeneration in extracorporeal lungs by 24 hours. CONCLUSIONS: We demonstrate that acutely injured recipient swine tolerate cross-circulation and enable recovery of donor lungs subjected to extended cold storage. This proof-of-concept study supports feasibility of cross-circulation for recipients with isolated lung disease who are candidates for this clinical application.

Future trends in incidence and long-term survival of metastatic cancer in the United States.

BACKGROUND: Previous studies have demonstrated epidemiological trends in individual metastatic cancer subtypes; however, research forecasting long-term incidence trends and projected survivorship of metastatic cancers is lacking. We assess the burden of metastatic cancer to 2040 by (1) characterizing past, current, and forecasted incidence trends, and (2) estimating odds of long-term (5-year) survivorship. METHODS: This retrospective, serial cross-sectional, population-based study used registry data from the Surveillance, Epidemiology, and End Results (SEER 9) database. Average annual percentage change (AAPC) was calculated to describe cancer incidence trends from 1988 to 2018. Autoregressive integrating moving average (ARIMA) models were used to forecast the distribution of primary metastatic cancer and metastatic cancer to specific sites from 2019 to 2040 and JoinPoint models were fitted to estimate mean projected annual percentage change (APC). RESULTS: The average annual percent change (AAPC) in incidence of metastatic cancer decreased by 0.80 per 100,000 individuals (1988-2018) and we forecast an APC decrease by 0.70 per 100,000 individuals (2018-2040). Analyses predict a decrease in metastases to liver (APC = -3.40, 95% CI [-3.50, -3.30]), lung (APC (2019-2030) = -1.90, 95% CI [-2.90, -1.00]); (2030-2040) = -3.70, 95% CI [-4.60, -2.80]), bone (APC = -4.00, 95% CI [-4.30, -3.70]), and brain (APC = -2.30, 95% CI [-2.60, -2.00]). By 2040, patients with metastatic cancer are predicted to have 46.7% greater odds of long-term survivorship, driven by increasing plurality of patients with more indolent forms of metastatic disease. CONCLUSIONS: By 2040, the distribution of metastatic cancer patients is predicted to shift in predominance from invariably fatal to indolent cancers subtypes. Continued research on metastatic cancers is important to guide health policy and clinical intervention efforts, and direct allocations of healthcare resources.

Cancer that has spread beyond the area where it originated and into different organs is called metastatic cancer. This study analyzed trends in metastatic cancer incidence, the proportion of those with metastatic cancer surviving 5 years after diagnosis and the locations in the body each cancer had spread to. The incidence of metastatic cancer decreased between 1988 and 2018 and is expected to continue to decrease until 2040. Some of the most common locations cancer spreads to is the lung, liver, brain, and bone. Metastatic cancer incidence to these areas is predicted to decrease. Also, the likelihood of surviving for more than 5 years after diagnosis with metastatic cancer is predicted to increase by 2040. This research should facilitate optimal planning of future healthcare resources and policy.

Emerging Imaging Modalities for Functional Assessment of Donor Lungs Ex Vivo.

The severe shortage of functional donor lungs that can be offered to recipients has been a major challenge in lung transplantation. Innovative ex vivo lung perfusion (EVLP) and tissue engineering methodologies are now being developed to repair damaged donor lungs that are deemed unsuitable for transplantation. To assess the efficacy of donor lung reconditioning methods intended to rehabilitate rejected donor lungs, monitoring of lung function with improved spatiotemporal resolution is needed. Recent developments in live imaging are enabling non-destructive, direct, and longitudinal modalities for assessing local tissue and whole lung functions. In this review, we describe how emerging live imaging modalities can be coupled with lung tissue engineering approaches to promote functional recovery of ex vivo donor lungs.

Opto-electromechanical quantification of epithelial barrier function in injured and healthy airway tissues.

The airway epithelium lining the luminal surface of the respiratory tract creates a protective barrier that ensures maintenance of tissue homeostasis and prevention of respiratory diseases. The airway epithelium, unfortunately, is frequently injured by inhaled toxic materials, trauma, or medical procedures. Substantial or repeated airway epithelial injury can lead to dysregulated intrinsic repair pathways and aberrant tissue remodeling that can lead to dysfunctional airway epithelium. While disruption in the epithelial integrity is directly linked to degraded epithelial barrier function, the correlation between the structure and function of the airway epithelium remains elusive. In this study, we quantified the impact of acutely induced airway epithelium injury on disruption of the epithelial barrier functions. By monitoring alternation of the flow motions and tissue bioimpedance at local injury site, degradation of the epithelial functions, including mucociliary clearance and tight/adherens junction formation, were accurately determined with a high spatiotemporal resolution. Computational models that can simulate and predict the disruption of the mucociliary flow and airway tissue bioimpedance have been generated to assist interpretation of the experimental results. Collectively, findings of this study advance our knowledge of the structure-function relationships of the airway epithelium that can promote development of efficient and accurate diagnosis of airway tissue injury.

A clinically relevant model of acute respiratory distress syndrome in human-size swine.

Despite over 30 years of intensive research for targeted therapies, treatment of acute respiratory distress syndrome (ARDS) remains supportive in nature. With mortality upwards of 30%, a high-fidelity pre-clinical model of ARDS, on which to test novel therapeutics, is urgently needed. We used the Yorkshire breed of swine to induce a reproducible model of ARDS in human-sized swine to allow the study of new therapeutics, from both mechanistic and clinical standpoints. For this, animals were anesthetized, intubated and mechanically ventilated, and pH-standardized gastric contents were delivered bronchoscopically, followed by intravenous infusion of Escherichia coli-derived lipopolysaccharide. Once the ratio of arterial oxygen partial pressure (PaO2) to fractional inspired oxygen (FIO2) had decreased to <150, the animals received standard ARDS treatment for up to 48 h. All swine developed moderate to severe ARDS. Chest radiographs taken at regular intervals showed significantly worse lung edema after induction of ARDS. Quantitative scoring of lung injury demonstrated time-dependent increases in interstitial and alveolar edema, neutrophil infiltration, and mild to moderate alveolar membrane thickening. This pre-clinical model of ARDS in human-sized swine recapitulates the clinical, radiographic and histopathologic manifestations of ARDS, providing a tool to study therapies for this highly morbid lung disease.

Pathological remodeling of distal lung matrix in end-stage cystic fibrosis patients.

BACKGROUND: Manifestations of cystic fibrosis, although well-characterized in the proximal airways, are understudied in the distal lung. Characterization of the cystic fibrosis lung 'matrisome' (matrix proteome) has not been previously described, and could help identify biomarkers and inform therapeutic strategies. METHODS: We performed liquid chromatography-mass spectrometry, gene ontology analysis, and multi-modal imaging, including histology, immunofluorescence, and electron microscopy for a comprehensive evaluation of distal human lung extracellular matrix (matrix) structure and composition in end-stage cystic fibrosis. RESULTS: Quantitative proteomic profiling identified sixty-eight (68) matrix constituents with significantly altered expression in end-stage cystic fibrosis. Over 90% of significantly different matrix peptides detected, including structural and basement membrane proteins, were expressed at lower levels in cystic fibrosis. However, the total abundance of matrix in cystic fibrosis lungs was not significantly different from control lungs, suggesting that cystic fibrosis leads to loss of diversity among lung matrix proteins rather than an absolute loss of matrix. Visualization of distal lung matrix via immunofluorescence and electron microscopy revealed pathological remodeling of distal lung tissue architecture and loss of alveolar basement membrane, consistent with significantly altered pathways identified by gene ontology analysis. CONCLUSIONS: Dysregulation of matrix organization and aberrant wound healing pathways are associated with loss of matrix protein diversity and obliteration of distal lung tissue structure in end-stage cystic fibrosis. While many therapeutics aim to functionally restore defective cystic fibrosis transmembrane conductance regulator (CFTR), drugs that target dysregulated matrix pathways may serve as adjunct interventions to support lung recovery.

Citrate-based materials fuel human stem cells by metabonegenic regulation.

A comprehensive understanding of the key microenvironmental signals regulating bone regeneration is pivotal for the effective design of bioinspired orthopedic materials. Here, we identified citrate as an osteopromotive factor and revealed its metabonegenic role in mediating citrate metabolism and its downstream effects on the osteogenic differentiation of human mesenchymal stem cells (hMSCs). Our studies show that extracellular citrate uptake through solute carrier family 13, member 5 (SLC13a5) supports osteogenic differentiation via regulation of energy-producing metabolic pathways, leading to elevated cell energy status that fuels the high metabolic demands of hMSC osteodifferentiation. We next identified citrate and phosphoserine (PSer) as a synergistic pair in polymeric design, exhibiting concerted action not only in metabonegenic potential for orthopedic regeneration but also in facile reactivity in a fluorescent system for materials tracking and imaging. We designed a citrate/phosphoserine-based photoluminescent biodegradable polymer (BPLP-PSer), which was fabricated into BPLP-PSer/hydroxyapatite composite microparticulate scaffolds that demonstrated significant improvements in bone regeneration and tissue response in rat femoral-condyle and cranial-defect models. We believe that the present study may inspire the development of new generations of biomimetic biomaterials that better recapitulate the metabolic microenvironments of stem cells to meet the dynamic needs of cellular growth, differentiation, and maturation for use in tissue engineering.