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Quantification of fluorescence in vivo is complicated by the influence of tissue optical properties on the collected fluorescence signal. When tissue optical properties in the measurement volume are quantified, one can obtain the intrinsic fluorescence, which equals the product of fluorophore absorption coefficient and quantum yield. We applied this method to in vivo single-fiber fluorescence spectroscopy measurements on mouse tongue, skin, liver, and oral squamous cell carcinoma, where we detected intrinsic fluorescence spectra of the photosensitizers chlorin e6 and Bremachlorin at t = [3, 4.5, 6, 24, 48] h incubation time. We observed a tissue-dependent maximum of 35% variation in the total correction factor over the visible wavelength range. Significant differences in spectral shape over time between sensitizers were observed. Although the wavelength position of the fluorescence intensity maximum for ce6 shifted to the red, Bremachlorin showed a blue shift. Furthermore, the Bremachlorin peak appeared to be broader than the ce6 fluorescence peak. Intrinsic fluorescence intensity, which can be related to photosensitizer concentration, was decreasing for all time points but showed significantly more Bremachlorin present compared to ce6 at long incubation times. Results from this study can be used to define an optimal treatment protocol for Bremachlorin-based photodynamic therapy. [ABSTRACT FROM AUTHOR]

Bioluminescence imaging (BLI) has shown its appeal as a sensitive technique for in vivo whole body optical imaging. However, the development of injectable tumor-specific near-infrared fluorescent (NIRF) probes makes fluorescence imaging (FLI) a promising alternative to BLI in situations where BLI cannot be used or is unwanted (e.g., spontaneous transgenic tumor models, or syngeneic mice to study immune effects). In this study, we addressed the questions whether it is possible to detect tumor progression using FLI with appropriate sensitivity and how FLI correlates with BLI measurements. In addition, we explored the possibility to simultaneously detect multiple tumor characteristics by dual-wavelength FLI (∼700 and ∼800 nm) in combination with spectral unmixing. Using a luciferase-expressing 4T1-luc2 mouse breast cancer model and combinations of activatable and targeting NIRF probes, we showed that the activatable NIRF probes (ProSense680 and MMPSense680) and the targeting NIRF probes (IRDye 800CW 2-DG and IRDye 800CW EGF) were either activated by or bound to 4T1-luc2 cells. In vivo, we implanted 4T1-luc2 cells orthotopically in nude mice and were able to follow tumor progression longitudinally both by BLI and dual-wavelength FLI. We were able to reveal different probe signals within the tumor, which co-localized with immuno-staining. Moreover, we observed a linear correlation between the internal BLI signals and the FLI signals obtained from the NIRF probes. Finally, we could detect pulmonary metastases both by BLI and FLI and confirmed their presence histologically. Taken together, these data suggest that dual-wavelength FLI is a feasible approach to simultaneously detect different features of one tumor and to follow tumor progression with appropriate specificity and sensitivity. This study may open up new perspectives for the detection of tumors and metastases in various experimental models and could also have clinical applications, such as image-guided surgery. [ABSTRACT FROM AUTHOR]

Myelodysplastic syndrome (MDS) are clonal stem cell diseases characterized mainly by ineffective hematopoiesis. Here, we present an approach that enables robust long-term engraftment of primary MDS stem cells (MDS-SCs) in mice by implantation of human mesenchymal cell-seeded scaffolds. Critically for modelling MDS, where patient sample material is limiting, mononuclear bone marrow cells containing as few as 10 4 CD34 + cells can be engrafted and expanded by this approach with the maintenance of the genetic make-up seen in the patients. Non-invasive high-resolution ultrasound imaging shows that these scaffolds are fully perfused. Our data shows that human microenvironment but not mouse is essential to MDS-SCs homing and engraftment. Notably, the alternative niche provided by healthy donor MSCs enhanced engraftment of MDS-SCs. This study characterizes a new tool to model MDS human disease with the level of engraftment previously unattainable in mice, and offers insights into human-specific determinants of MDS-SC microenvironment., Competing Interests: Conflict of interest statement The authors have declared that no conflict of interest exists.

Enforced activation of NF-κB signaling can be achieved by constitutive NF-κB-inducing kinases, IKK2 and NIK, or via lymphoma-associated mutants of MYD88, CARD11, and CD79B. In order to model Diffuse Large B Cell Lymphoma (DLBCL) in mice, conditional alleles for these proteins are combined with alleles targeting Cre recombinase expression in mature B cells. However, unopposed NF-κB signaling promotes plasmablast differentiation, and as a consequence the model system must be complemented with further mutations that block differentiation, such as Prdm1/BLIMP1 inactivation or overexpression of BCL6. Here, we describe the currently available tools for DLBCL models in mice and their relative advantages and drawbacks. Furthermore, we describe methods to monitor lymphomagenesis, using ultrasound tomography of the spleen, and the technique of partial splenectomy surgery with recovery. These powerful techniques allow paired comparison of individual lymphoma cases before and after interventions, including therapies, and to study the evolution of lymphoma over time. NF-κB activation also promotes widespread nodal involvement with lymphoma and we describe the post-mortem dissection of major nodal groups.

Optical imaging is a valuable technique for visualizing and quantifying biological processes in living -organisms. Optical imaging can be divided into two main imaging modalities: bioluminescence imaging and fluorescence imaging. This chapter describes the use of these imaging techniques to image tumour cells in mouse models of cancer and to detect early bone metastasis.

Objective: To assess the feasibility of optical imaging using activatable near-infrared fluorescence (NIRF) agents to detect oral cancer and cervical lymph node metastasis in vivo., Design: In vivo study., Setting: University medical center., Subjects: Female nude mice aged 4 to 6 weeks., Intervention: Luciferase-expressing OSC-19-luc cells were injected into the tongues of nude mice. A control group of nude mice was injected in the tongue with a physiologic saline solution. Tumor growth was followed by bioluminescence imaging. After 3 weeks, animals were randomly allocated to intravenous administration of 1 of 2 activatable NIRF agents: ProSense680 or MMPSense680. Fluorescence imaging of the mice was performed, and the tumor to background ratio (TBR) was determined on histologic sections of the tongue and cervical lymph nodes after resection at necropsy., Main Outcome Measure: Fluorescence signals., Results: The fluorescence signals in tongue tumor and cervical lymph node metastases were significantly higher than those in control animals. The mean (SD) TBR of ProSense680 in the tongue was 15.8 (8.1) and in the lymph nodes was 11.8 (3.6). For MMPSense680, the mean (SD) TBR in the tongue was 18.6 (9.4) and in the lymph nodes was 10.5 (4.0)., Conclusions: Oral cancer and cervical lymph node metastases can be detected by targeting increased proteolytic activity at the tumor borders using NIRF optical imaging. These NIRF agents could be used for real-time image-guided surgery, which has the potential to improve the complete surgical resection of oral cancer.