Citation Details

Journal Article

IVIS, Xen29, Xen 29, Staphylococcus aureus Xen29, Animals; Disease Models, Animal; Female; Mice; Mice, Inbred C57BL; Pneumonectomy/*adverse effects; Postoperative Complications/*surgery; Stem Cell Transplantation/*methods; Thoracic Cavity/*surgery; Thoracoplasty/*methods; Tissue Engineering/*methods

BACKGROUND: Transfer of viable tissue flaps and thoracoplasty are effective against pleural space complications after pneumonectomy but highly disfiguring. The aim of this study was to explore the possibility of engineered tissue to treat space complications after pneumonectomy. METHODS: A left pneumonectomy was performed in mice, and the cavity immediately filled with the cellularized collagen matrices. First, bone marrow derived-mesenchymal stroma cells with luciferase expression were used as donor cells to evaluate cell viability and angiogenesis using bioluminescence imaging. Second, using bone marrow cells from GFP mice, histologic evaluation, immunohistochemistry for von Willebrand Factor, and flow cytometric analysis was performed compared with acellular matrix implants. The effect on bacterial clearance was examined using an empyema model with Staphylococcus aureus expressing luciferase. RESULTS: Embedded cells proliferated within the denatured collagen matrices ex vivo. In vivo, bioluminescent imaging activity could be detected till day 8, and the slope (suggesting rate of perfusion with luciferin) increased with time up to day 6 but decreased after day 7. Although GFP-positive donor cells decreased with time, total cellularity increased. Furthermore, vessels stained by von Willebrand factor were significantly increased. Both cellularized and acellularized matrices showed bacterial clearance in vivo. CONCLUSIONS: Cells within collagen matrices survive in the thoracic cavity at early time points. Cellularized matrices quickly lead to neovascularization and recipient cell infiltration. Both cellularized and acellularized matrices show bacterial clearance in vivo. This study indicates the potential feasibility of a novel tissue engineering approach to problems of the postpneumonectomy space.

Journal Article

aneurysm; imaging; vasculature; in vivo imaging; FMT; MMPSense

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Journal Article

Xen36, Xen 36, Staphylococcus aureus Xen36, IVIS, Adsorption/drug effects; Anti-Bacterial Agents/chemistry/*pharmacology; Biological Markers/metabolism; *Bone Transplantation; Cell Differentiation/drug effects; Cell Shape/drug effects; Cells, Cultured; Colony Count, Microbial; Drug Stability; Fetus/cytology; Fluorescence; Gene Expression Profiling; Humans; Microbial Sensitivity Tests; Osteoblasts/cytology/drug effects/metabolism; Phenotype; Time Factors; Transplantation, Homologous; Vancomycin/chemistry/*pharmacology

Bacterial contamination of bone allograft is a significant complication of orthopedic surgery. To address this issue, we have engineered a method for covalently modifying bone allograft tissue with the antibiotic vancomycin. The goal of this investigation was to compare the biocidal properties of this new allograft material with those of vancomycin physisorbed onto graft material. The duration of antibiotic release from the vancomycin-modified allograft matrix was determined, and no elution was observed. In contrast, the adsorbed antibiotic showed a peak elution at 24h that then decreased over several days. We next used an Staphylococcus aureus disk diffusion assay to measure the activity of the eluted vancomycin. Again we found that no active antibiotic was eluted from the covalently modified allograft. Similarly, when the vancomycin-modified allograft morsel was used in the assay, no measurable elution was observed; amounts of antibiotic released from the adsorbed samples inhibited S. aureus growth for 4-7 days. Probably the most telling property of the allograft was that after 2 weeks, the tethered allograft was able to resist bacterial colonization. Unlike the elution system in which vancomycin was depleted over the course of days-weeks, the antibiotic on the allograft was stably bound even after 300 days, while its biocidal activity remained undiminished for 60 days. This finding was in stark contrast to the antibiotic impregnated allograft, which was readily colonized by bacteria. Finally we chose to evaluate three indicators of cell function: expression of a key transcription factor, expression of selected transcripts, and assessment of cell morphology. Since the tethered antibiotic appeared to have little or no effect on any of these activities, it was concluded that the stable, tethered antibiotic prevented bacterial infection while not modifying bone cell function.

Journal Article

Angiopoietin-2; Animals; Bioware; Breast Neoplasms; Capillary Permeability; Female; Gene Expression; Humans; Lung; Lung Neoplasms; Matrix Metalloproteinase 10; Matrix Metalloproteinase 3; MDA-MB-231-D3H1 cells; Melanoma, Experimental; Mice; Mice, Inbred C57BL; Mice, Nude; RNA Interference; Up-Regulation

Before metastasis, certain organs have already been influenced by primary tumors. However, the exact alterations and regulatory mechanisms of the premetastatic organs remain poorly understood. Here, we report that, in the premetastatic stage, angiopoietin 2 (Angpt2), matrix metalloproteinase (MMP) 3, and MMP10 are up-regulated in the lung by primary B16/F10 tumor, which leads to the increased permeability of pulmonary vasculatures and extravasation of circulating tumor cells. Subsequent studies show that Angpt2, MMP3, and MMP10 have a synergistic effect on disrupting vascular integrity in both in vitro and in vivo models. Lentivirus-based in vivo RNA interference of Angpt2, MMP3, and MMP10 attenuates the pulmonary vascular permeability and suppresses the infiltration of myeloid cells in the premetastatic lung. Moreover, knocking down these factors significantly inhibits the spontaneous lung metastasis in the model by orthotopic implantation of MDA-MB-231-Luc-D3H1 cells in nude mice. Further investigations reveal that the malignancy of tumor cells is positively correlated with their capabilities to induce the expression of Angpt2, MMP3, and MMP10. Luciferase reporter assay and chromatin immunoprecipitation assay also suggest that transforming growth factor-beta1 and tumor necrosis factor-alpha signaling are involved in the regulation of these premetastatic factors. Our study shows that pulmonary vascular destabilization in the premetastatic phase promotes the extravasation of tumor cells and facilitates lung metastasis, which may provide potential targets for clinical prevention of metastasis.

Journal Article

IVIS, Xen29, Xen 29, Staphylococcus aureus Xen29, Animals; *Biofilms; Catheter-Related Infections/immunology/metabolism/microbiology; Cytokines/immunology/metabolism; Green Fluorescent Proteins/genetics/metabolism; Host-Pathogen Interactions/immunology; Immune Evasion/immunology; Inflammation/*immunology/metabolism; Macrophages/*immunology/metabolism; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Microscopy, Confocal; Microscopy, Electron, Scanning; Models, Immunological; Phagocytosis/*immunology; Staphylococcal Infections/*immunology/metabolism/microbiology; Staphylococcus aureus/*immunology/physiology/ultrastructure; Toll-Like Receptor 2/genetics/immunology; Toll-Like Receptor 9/genetics/immunology

Biofilms are complex communities of bacteria encased in a matrix composed primarily of polysaccharides, extracellular DNA, and protein. Staphylococcus aureus can form biofilm infections, which are often debilitating due to their chronicity and recalcitrance to antibiotic therapy. Currently, the immune mechanisms elicited during biofilm growth and their impact on bacterial clearance remain to be defined. We used a mouse model of catheter-associated biofilm infection to assess the functional importance of TLR2 and TLR9 in the host immune response during biofilm formation, because ligands for both receptors are present within the biofilm. Interestingly, neither TLR2 nor TLR9 impacted bacterial density or inflammatory mediator secretion during biofilm growth in vivo, suggesting that S. aureus biofilms circumvent these traditional bacterial recognition pathways. Several potential mechanisms were identified to account for biofilm evasion of innate immunity, including significant reductions in IL-1beta, TNF-alpha, CXCL2, and CCL2 expression during biofilm infection compared with the wound healing response elicited by sterile catheters, limited macrophage invasion into biofilms in vivo, and a skewing of the immune response away from a microbicidal phenotype as evidenced by decreases in inducible NO synthase expression concomitant with robust arginase-1 induction. Coculture studies of macrophages with S. aureus biofilms in vitro revealed that macrophages successful at biofilm invasion displayed limited phagocytosis and gene expression patterns reminiscent of alternatively activated M2 macrophages. Collectively, these findings demonstrate that S. aureus biofilms are capable of attenuating traditional host proinflammatory responses, which may explain why biofilm infections persist in an immunocompetent host.