TissuePatch™ as a novel synthetic sealant for repair of superficial lung defect: in vitro tests results

Controversies surrounding the efficacy of surgical sealants against alveolar air leaks (AAL) in lung surgery abound in the literature. We sought to test the sealing efficacy of a novel synthetic sealant, TissuePatch? in an in vitro lung model. The lower lobe of freshly excised swine lung (n?=?10) was intubated and ventilated. A superficial parenchymal defect (40?×?25 mm) was created, followed by AAL assessment. After sealant application, AAL was assessed again until burst failure occurred. The length of defect was recorded to evaluate the elasticity of the sealant. Superficial parenchymal defects resulted in AAL increasing disproportionally with ascending maximal inspiratory pressure (Pmax). Multiple linear regression analysis revealed strong correlation between AAL and Pmax, compliance, resistance. After sealant application, AAL was sealed in all ten tests at an inspired tidal volume (TVi) of 400 ml, in nine tests at TVi?=?500 ml, in seven at TVi?=?600 ml and in five at TVi?=?700 ml. The mean burst pressure was 42?±?9 mBar. Adhesive and cohesive sealant failures were found in six and three tests respectively. The length of defect before sealant failure was 8.9?±?4.9% larger than that at TVi?=?400 ml, demonstrating an adequate elasticity of this sealant film. TissuePatch? may be a reliable sealant for alternative or adjunctive treatment for repair of superficial parenchymal defects in lung surgery. The clinical benefits of this sealant should be confirmed by prospective, randomised controlled clinical trials. Die Wirksamkeit von chirurgischen Klebstoffen zur Prävention von alveolo-pleuralem Luftleck (APL) ist trotz zunehmenden klinischen Anwendungen in Lungenchirurgie immer noch kontrovers diskutiert. Wir evaluierten die Abdichtungswirksamkeit von einem neuartigen synthetischen Kleber, TissuePatch? mittels eines in vitro Lungenmodels. Der Unterlappen von frisch entnommenen Schweinlungen (n?=?10) wurde intubiert und beatmet. Eine pleurale Läsion (40?×?25 mm) wurde erstellt und APL mit steigendem inspiratorischem Tidalvolumen (TVi) untersucht. Nach Applikation von TissuePatch? wurde APL auf die gleiche Weise gemessen bis zur Auftritt von Kleberbruch. Zur Untersuchung der Elastizität des Klebers wurde die Länge der pleuralen Läsion gemessen. Pleurale Läsion führte bei aufsteigendem maximalem inspiratorischem Druck (Pmax) zu überproportionalem Anstieg von APL. Multiple lineare Regressionsanalyse ergab eine starke Korrelation zwischen APL und Pmax, Lungencompliance sowie Widerstand. Nach der Applikation von Klebstoff wurde APL bei TVi?=?400 ml in allen zehn Testen versiegelt, bei TVi?=?500 ml in neun Testen, bei TVi?=?600 ml in sieben und bei TVi?=?700 ml in fünf Testen. Der mittlere Pmax, der zu Kleberbruch führte, betrug 42?±?9 mBar. Bei den Versuchen wurden adhäsiver und kohäsiver Kleberbruch in jeweils sechs und drei Testen gefunden. Die Länge der pleuralen Läsion vor dem Kleberbruch war 8,9?±?4,9% größer als die bei TVi?=?400 ml. Unsere Versuche zeigten eine zuverlässige Versiegelung von TissuePatch? unter mechanischer Ventilation. Die klinische Nützlichkeit vom Kleber als unterstützende Maßnahme zur Prävention von alveolo-pleuralem Luftleck in Lungenchirurgie sollte durch prospektive, randomisierte kontrollierte klinische Studien bestätigt werden.     

Immunogenicity of Intensively Decellularized Equine Carotid Arteries Is Conferred by the Extracellular Matrix Protein Collagen Type VI

The limited biocompatibility of decellularized scaffolds is an ongoing challenge in tissue engineering. Here, we demonstrate the residual immunogenicity of an extensively decellularized equine carotid artery (dEAC_intens) and identify the involved immunogenic components. EAC were submitted to an elaborated intensified decellularization protocol with SDS/sodium desoxycholate for 72 h using increased processing volumes (dEAC_intens), and compared to dEAC_ord prepared by an ordinary protocol (40 h, normal volumes). Matrix integrity was checked via correlative volumetric visualization which revealed only minor structural changes in the arterial wall. In dEAC_intens, a substantial depletion of cellular components was obvious for smooth muscle actin (100%), MHC I complexes (97.8%), alphaGal epitops (98.4% and 91.3%) and for DNA (final concentration of 0.34±0.16 ng/mg tissue). However, dEAC_intens still evoked antibody formation in mice after immunization with dEAC_intens extracts, although to a lower extent than dEAC_ord. Mouse plasma antibodies recognized a 140 kDa band which was revealed to contain collagen VI alpha1 and alpha2 chains via mass spectrometry of both 2D electrophoretically separated and immunoprecipitated proteins. Thus, even the complete removal of cellular proteins did not yield non-immunogenic dEAC as the extracellular matrix still conferred immunogenicity by collagen VI. However, as lower antibody levels were achieved by the intensified decellularization protocol, this seems to be a promising basis for further development.     

Cell-cell and cell-matrix adhesion molecules in human heart and lung transplants

The interaction of immune cells with endothelial and target cells and extracellular matrix in human organ transplants is regulated by a number of receptor-ligand molecules. The molecules mediating intercellular adhesion and activation are classified as integrin, immunoglobulin and selectin families. In the present study the patterns of their cellular expression in human heart and lung transplants are described in normal state and during transplant rejection. The results reveal an organ specific regulation of the different adhesion molecules during transplant rejection. Specific differences were noted in the endothelial expression of vascular ligand molecules in the vascular segments of heart and lung transplants, especially in the lung capillaries. Cell type specific patterns of intercellular and cell-matrix adhesion molecules as their ligands were found in different states of graft rejection. Intravascular and interstitial differences in the expression patterns of leukocyte adhesion receptors support a concept of their stepwise function during graft infiltration. The implications for the organ specific appearance of inflammatory reactions in human heart and lung transplants as for immunosuppressive therapy are discussed.     

Cardiac Mass and Function Decrease in Bronchiolitis Obliterans Syndrome after Lung Transplantation: Relationship to Physical Activity?

Rationale

There is a need to expand knowledge on cardio-pulmonary pathophysiology of bronchiolitis obliterans syndrome (BOS) following lung transplantation (LTx).

Objectives

The purpose of this study was to assess MRI-derived biventricular cardiac mass and function parameters as well as flow hemodynamics in patients with and without BOS after LTx.

Methods

Using 1.5T cardiac MRI, measurements of myocardial structure and function as well as measurements of flow in the main pulmonary artery and ascending aorta were performed in 56 lung transplant patients. The patients were dichotomized into two gender matched groups of comparable age range: one with BOS (BOS stages 1–3) and one without BOS (BOS 0/0p).

Measurements and Main Results

Significantly lower biventricular cardiac mass, right and left ventricular end-diastolic volume, biventricular stroke volume, flow hemodynamics and significant higher heart rate but preserved cardiac output were observed in patients with BOS 1–3 compared to the BOS 0/0p group (p<0.05). In a stepwise logistic regression analysis global cardiac mass (p = 0.046) and days after LTx (p = 0.0001) remained independent parameters to predict BOS. In a second model an indicator for the physical fitness level - walking number of stairs - was added to the logistic regression model. In this second model, time after LTx (p = 0.005) and physical fitness (p = 0.01) remained independent predictors for BOS.

Conclusion

The observed changes in biventricular cardiac mass and function as well as changes in hemodynamic flow parameters in the pulmonary trunk and ascending aorta are likely attributed to the physical fitness level of patients after lung transplantation, which in turn is strongly related to lung function.     

Magnetic Resonance Imaging of Soft Tissue Infection with Iron Oxide Labeled Granulocytes in a Rat Model

Object

We sought to detect an acute soft tissue infection in rats by magnetic resonance imaging (MRI) using granulocytes, previously labeled with superparamagnetic particles of iron oxide (SPIO).

Materials and Methods

Parasternal infection was induced by subcutaneous inoculation of Staphylococcus aureus suspension in rats. Granulocytes isolated from isogenic donor rats were labeled with SPIO. Infected rats were imaged by MRI before, 6 and 12 hours after intravenous injection of SPIO-labeled or unlabeled granulocytes. MR findings were correlated with histological analysis by Prussian blue staining and with re-isolated SPIO-labeled granulocytes from the infectious area by magnetic cell separation.

Results

Susceptibility effects were present in infected sites on post-contrast T2*-weighted MR images in all animals of the experimental group. Regions of decreased signal intensity (SI) in MRI were detected at 6 hours after granulocyte administration and were more pronounced at 12 hours. SPIO-labeled granulocytes were identified by Prussian blue staining in the infected tissue and could be successfully re-isolated from the infected area by magnetic cell separation.

Conclusion

The application of SPIO-labeled granulocytes in MRI offers new perspectives in diagnostic specificity and sensitifity to detect early infectious processes.     

Angiotensin II induces MMP-2 in a p47phox-dependent manner

Activated matrix metalloproteinases (MMPs) in patients with acute coronary syndromes may contribute to plaque destabilization. Since reactive oxygen species (ROS) induce MMP-2 and angiotensin II (ANG II) enhances NADPH-oxidase-dependent ROS formation, we assessed whether ANG II induces MMP-2 in a NADPH-oxidase-dependent manner. MMP-2 mRNA expression and activity were analyzed in wildtype and p47phox-deficient (p47phox-/-) murine smooth muscle cells (SMC). To address a clinical implication, sections of human atherosclerotic arteries were stained for MMP-2, p47phox, ANG II, AT1-receptor, and alpha-smooth muscle cell actin (alpha-SMC actin). MMP-2 protein expression and activity from these arteries were compared to those without atherosclerosis. ANG II enhances mRNA synthesis and activity of MMP-2 in a p47phox-dependent manner. Immunohistochemical analyses revealed a co-localization of MMP-2 with p47phox, ANG II, AT1-receptor, and alpha-SMC actin. MMP-2 protein expression and gelatinolytic activity are increased in atherosclerotic arteries. Thus, activation of the renin-angiotensin system may contribute to plaque destabilization via ROS-dependent induction of MMP-2.