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Post-arthroplasty infections are a devastating problem in orthopaedic surgery. While acute infections can be treated with a single stage washout and liner exchange, chronic infections lead to multiple reoperations, prolonged antibiotic courses, extended disability, and worse clinical outcomes. Unlike previous mouse models that studied an acute infection, this work aimed to develop a model of a chronic post-arthroplasty infection. To achieve this, a stainless steel implant in the knee joints of mice was inoculated with a bioluminescent Staphylococcus aureus strain (1 x 10(2) -1 x 10(4) colony forming units, CFUs) and in vivo imaging was used to monitor the bacterial burden for 42 days. Four different S. aureus strains were compared in which the bioluminescent construct was integrated in an antibiotic selection plasmid (ALC2906), the bacterial chromosome (Xen29 and Xen40), or a stable plasmid (Xen36). ALC2906 had increased bioluminescent signals through day 10, after which the signals became undetectable. In contrast, Xen29, Xen40, and Xen36 had increased bioluminescent signals through 42 days with the highest signals observed with Xen36. ALC2906, Xen29, and Xen40 induced significantly more inflammation than Xen36 as measured by in vivo enhanced green fluorescence protein (EGFP)-neutrophil flourescence of LysEGFP mice. All four strains induced comparable biofilm formation as determined by variable-pressure scanning electron microscopy. Using a titanium implant, Xen36 had higher in vivo bioluminescence signals than Xen40 but had similar biofilm formation and adherent bacteria. In conclusion, Xen29, Xen40, and especially Xen36, which had stable bioluminescent constructs, are feasible for long-term in vivo monitoring of bacterial burden and biofilm formation to study chronic post-arthroplasty infections and potential antimicrobial interventions. (c) 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Journal Article

A549-luc-C8, A549-luc, IVIS, Bioware, Calcium/chemistry; Cell Line; Cell-Penetrating Peptides/administration & dosage/*chemistry; Drug Carriers/administration & dosage/adverse effects/*chemistry; *Gene Silencing; Genetic Therapy/*methods; Humans; Luciferases; Nanoparticles/administration & dosage/chemistry; RNA, Small Interfering/*administration & dosage/chemistry; Tissue Distribution

The development of short-interfering RNA (siRNA) offers new strategies for manipulating specific genes responsible for pathological disorders. Myriad cationic polymer and lipid formulations have been explored, but an effective, non-toxic carrier remains a major barrier to clinical translation. Among the emerging candidates for siRNA carriers are cell penetrating peptides (CPPs), which can traverse the plasma membrane and facilitate the intracellular delivery of siRNA. Previously, a highly efficient and non-cytotoxic means of gene delivery was designed by complexing plasmid DNA with CPPs, then condensing with calcium. Here, the CPP TAT and a longer, 'double' TAT (dTAT) were investigated as potential carriers for siRNA. Various N/P ratios and calcium concentrations were used to optimize siRNA complexes in vitro. Upon addition of calcium, 'loose' siRNA/CPP complexes were condensed into small nanoparticles. Knockdown of luciferase expression in the human epithelial lung cell line A549-luc-C8 was high (up to 93%) with no evidence of cytotoxicity. Selected formulations of the dTAT complexes were dosed intravenously up to 1000 mg/kg with minimal toxicity. Biodistribution studies revealed high levels of gene knockdown in the lung and muscle tissue suggesting these simple vectors may offer a translatable approach to siRNA delivery.

Journal Article

IntegriSense, Angiogenesis Inhibitors/therapeutic use; Animals; Diagnostic Imaging/*methods; Fluorescence; Humans; Luminescence/diagnostic use; Magnetic Resonance Angiography/methods; Magnetic Resonance Imaging/methods; Microscopy/methods; Neoplasms/*blood supply/therapy; *Neovascularization, Pathologic/pathology/ultrasonography; Positron-Emission Tomography/methods; Tomography/methods; Tomography, Emission-Computed, Single-Photon/methods; Tomography, X-Ray Computed/methods; X-Ray Microtomography/methods

Significant advances have been made in understanding the role of tumor angiogenesis and its influence on tumor progression in cancer. Based on this knowledge, a series of inhibitors of angiogenesis have been developed and evaluated in preclinical and clinical trials. Since detailed information of tumor progression in response to therapy is important to assess the efficacy of anti-tumor treatment in vivo, noninvasive imaging techniques emerge more and more as important tools to monitor alterations in tumor growth and vessel recruitment, as well as metastatic spread over time. So far, remarkable efforts have been made to improve the technical capability of these imaging modalities based on better resolution, as well as to implement multimodal approaches combining molecular with anatomical information. Advanced imaging techniques not only allow the detection and monitoring of tumor development, but also facilitate a broad understanding of the cellular and molecular events that propagate tumor angiogenesis, as well as those occurring in response to therapy. This review provides an overview of different imaging techniques in preclinical settings of oncological research and discusses their potential impact on clinical translation. Imaging modalities will be presented that have been implemented to address key biological issues by exploring tumor angiogenic processes and evaluating antiangiogenic therapy.

Journal Article

MMPSense, IVIS, Animals; Cell Hypoxia; Cell Line, Tumor; Cell Movement; Enzyme Activation; Extracellular Signal-Regulated MAP Kinases/metabolism; Gene Knockdown Techniques; Glioblastoma/*enzymology/*pathology; Humans; JNK Mitogen-Activated Protein Kinases/metabolism; Matrix Metalloproteinase 9/metabolism; Mice; Mice, SCID; Molecular Imaging/*methods; NADPH Oxidase/*metabolism; NF-kappa B/metabolism; Neoplasm Invasiveness; Reactive Oxygen Species/metabolism; Tumor Microenvironment; Xenograft Model Antitumor Assays

PURPOSE: We determined the impact of the cycling hypoxia tumor microenvironment on tumor cell invasion and infiltration in U87 human glioblastoma cells and investigated the underlying mechanisms using molecular bio-techniques and imaging. PROCEDURES: The invasive phenotype of U87 cells and xenografts exposed to experimentally imposed cycling hypoxic stress in vitro and in vivo was determined by the matrigel invasion assay in vitro and dual optical reporter gene imaging in vivo. RNAi-knockdown technology was utilized to study the role of the NADPH oxidase subunit 4 (Nox4) on cycling hypoxia-mediated tumor invasion. RESULTS: Cycling hypoxic stress significantly promoted tumor invasion in vitro and in vivo. However, Nox4 knockdown inhibited this effect. Nox4-generated reactive oxygen species (ROS) are required for cycling hypoxia-induced invasive potential in U87 cells through the activation of NF-kappaB- and ERK-mediated stimulation of MMP-9. CONCLUSIONS: Cycling hypoxia-induced ROS via Nox4 should be considered for therapeutic targeting of tumor cell invasion and infiltration in glioblastoma.

Journal Article

IntegriSense, Animals; Carcinoma, Squamous Cell/*pathology/surgery; Fluorescent Dyes/*diagnostic use; Humans; Integrin alphaVbeta3/*metabolism; Mice; Mice, Inbred BALB C; Mouth Neoplasms/*pathology/surgery; Spectroscopy, Near-Infrared; *Surgery, Computer-Assisted

BACKGROUND AND OBJECTIVES: Near-infrared (NIR) fluorescence optical imaging is a promising technique to assess the tumor margins during cancer surgery. This technique requires targeting by specific fluorescence agents to differentiate tumor from normal surrounding tissue. We assessed the feasibility of cancer detection using NIR fluorescence agents that target either alphavbeta3 integrins or the enhanced permeability and retention (EPR) effect in an orthotopic mouse model of oral cancer. METHODS: Binding of the integrin-targeted agent to tumor cells was assessed in vitro. Oral cancer was induced in 6 BALB/c nu/nu mice by submucosal inoculation of human OSC19-luc cells into the tongue. Tumor growth was followed with bioluminescence imaging. A combination of agents targeting integrins or EPR effect was injected followed by fluorescence imaging in vivo and ex vivo after resection of the tongues. RESULTS: Oral cancer was clearly demarcated in vitro; in vivo; and on histological analysis with sufficient tumor-to-background ratios of the contrast agents. CONCLUSION: This study demonstrates the feasibility of optical imaging of oral squamous cell carcinoma based on targeting of alphavbeta3 integrins and the EPR effect. Once these NIR fluorescence agents become available for clinical testing, optical image-guided surgery could reduce residual disease after oral cancer surgery.