MRI and US imaging reveal evolution of spatial heterogeneity of murine tumor vasculature.

The tumor microenvironment, especially the vasculature, undergoes dynamic remodeling during tumor growth and progression. The aim of this study was to investigate changes in the structure and function of tumor microenvironment (TME), with a special focus on vasculature, during the growth of the Lewis Lung Carcinoma tumor (LLC). We have used several MRI techniques and ultrasound imaging of live animals to assess how heterogenous TME features change in time. Lewis lung carcinoma bearing C57BL/6 mice were examined for three weeks. During this time, assessment of tumor vasculature was performed with Time of Flight (TOF) angiography, Dynamic Contrast Enhanced (DCE) MRI and Power Doppler Ultrasound. Additionally, diffusion and perfusion were analyzed using Diffusion Weighted MRI (DWI). Consecutive measurements of the same animals revealed an approximately twofold decrease in the density of LLC vessels in time. Heterogeneity of vasculature was best uncovered by changes in histogram based DCE analysis and revealed deterioration of tumor vessels during its progression. The tumor vasculature became less dense and with slower blood flow, with larger and more permeable vessels. As a rule, tumor tissue perfusion and diffusion parameters decreased in time, but locally increase was observed. Time- and spatial heterogeneity of tumor microenvironment, including vasculature, was revealed by 3D imaging, demonstrating that local changes are often contradictory to parameters averaged over the whole tumor volume.

Low-cost, programmable infusion pump with bolus mode for in-vivo imaging.

Syringe pumps are routinely used in biomedical imaging laboratories for delivering contrast agents and either infusing or injecting a precise amount of liquids. Commercial syringe pumps that are developed by specialized companies are expensive and only have standard functions, which often do not meet the requirements of individual experiments. In this paper, we demonstrate an open-source single syringe pump with the possibility of adapting to the needs of a researcher. The device that was designed, is controlled by an Arduino Leonardo, along with the stepper motor driver. For sending commands and receiving the current plunger position, a C# software was developed with serial communication via USB. Additionally, the 3D models were made in a universal way, which allows for the use of any syringe size. An example of the application of the syringe pump for biomedical applications was demonstrated using electron resonance imaging (ERI). The single syringe pump tests were demonstrated by simulating the filling of a particular volume inside the resonator. This example reflects the clearance process after an intravascular (I.V) drug administration in the murine model. The experiments were performed on an ERI TM 600 tomograph. The results confirmed that the designed syringe pump allowed for controlling the infusion speed and injected volume. Moreover, we present a user-friendly and open-source graphical interface that is a low-cost alternative for commercial devices.

Multiharmonic electron paramagnetic resonance imaging as an innovative approach for in vivo studies.

This work is the first report when multiharmonic analysis (MHA) was applied for electron paramagnetic resonance imaging (EPRI) for in vivo applications. Phantom studies were performed for established methodology, and in vivo imaging was conduct as a proof-of-concept. Phantom studies showed at least six times improvement of the signal - to - noise (S/N) ratio. Application MHA for 3D EPR in vivo imaging provides images of spin probe distribution in mouse head. The EPRI, in combination with nitroxide and trityl spin probe, was performed to obtained 3D EPR in vivo images using MHA. For both used spin probes, MHA provided images with better S/N ratio, especially in the case of nitroxide, where projections obtained using conventional CW did not allow for reconstructing reliable data. Trityl radical exhibited high resolution and quality of obtained images after MHA. The MHA methodology allows the selection of a second modulation amplitude even 40 times higher than the natural EPR linewidth of the spin probe without line shape distortion, which highly improves the sensitivity of the acquired signal and allowing for imaging mice regardless of their size in a routine animal experiment.

Effects of Photodynamic Therapy with Redaporfin on Tumor Oxygenation and Blood Flow in a Lung Cancer Mouse Model.

Three photodynamic therapy (PDT) protocols with 15 min, 3 h and 72 h drug-to-light time intervals (DLIs) were performed using a bacteriochlorin named redaporfin, as a photosensitizer. Blood flow and pO2 changes after applying these protocols were investigated in a Lewis lung carcinoma (LLC) mouse model and correlated with long-term tumor responses. In addition, cellular uptake, cytotoxicity and photocytotoxicity of redaporfin in LLC cells were evaluated. Our in vitro tests revealed negligible cytotoxicity, significant cellular uptake, generation of singlet oxygen, superoxide ion and hydroxyl radicals in the cells and changes in the mechanism of cell death as a function of the light dose. Results of in vivo studies showed that treatment focused on vascular destruction (V-PDT) leads to a highly effective long-term antineoplastic response mediated by a strong deprivation of blood supply. Tumors in 67% of the LLC bearing mice treated with V-PDT regressed completely and did not reappear for over 1 year. This significant efficacy can be attributed to photosensitizer (PS) properties as well as distribution and accurate control of oxygen level and density of vessels before and after PDT. V-PDT has a greater potential for success than treatment based on longer DLIs as usually applied in clinical practice.

Merging Preclinical EPR Tomography with other Imaging Techniques.

This paper presents a survey of electron paramagnetic resonance (EPR) image registration. Image registration is the process of overlaying images (two or more) of the same scene taken at different times, from different viewpoints and/or different techniques. EPR-imaging (EPRI) techniques belong to the functional-imaging modalities and therefore suffer from a lack of anatomical reference which is mandatory in preclinical imaging. For this reason, it is necessary to merging EPR images with other modalities which allow for obtaining anatomy images. Methodological analysis and review of the literature were done, providing a summary for developing a good foundation for research study in this field which is crucial in understanding the existing levels of knowledge. Out of these considerations, the aim of this paper is to enhance the scientific community's understanding of the current status of research in EPR preclinical image registration and also communicate to them the contribution of this research in the field of image processing.

Activation pattern of ACE2/Ang-(1-7) and ACE/Ang II pathway in course of heart failure assessed by multiparametric MRI in vivo in Tgαq*44 mice.

Here, we analyzed systemic (plasma) and local (heart/aorta) changes in ACE/ACE-2 balance in Tgαq*44 mice in course of heart failure (HF). Tgαq*44 mice with cardiomyocyte-specific Gαq overexpression and late onset of HF were analyzed at different age for angiotensin pattern in plasma, heart, and aorta using liquid chromatography/mass spectrometry, for progression of HF by in vivo magnetic resonance imaging under isoflurane anesthesia, and for physical activity by voluntary wheel running. Six-month-old Tgαq*44 mice displayed decreased ventricle radial strains and impaired left atrial function. At 8-10 mo, Tgαq*44 mice showed impaired systolic performance and reduced voluntary wheel running but exhibited preserved inotropic reserve. At 12 mo, Tgαq*44 mice demonstrated a severe impairment of basal cardiac performance and modestly compromised inotropic reserve with reduced voluntary wheel running. Angiotensin analysis in plasma revealed an increase in concentration of angiotensin-(1-7) in 6- to 10-mo-old Tgαq*44 mice. However, in 12- to 14-mo-old Tgαq*44 mice, increased angiotensin II was noted with a concomitant increase in Ang III, Ang IV, angiotensin A, and angiotensin-(1-10). The pattern of changes in the heart and aorta was also compatible with activation of ACE2, followed by activation of the ACE pathway. In conclusion, mice with cardiomyocyte Gαq protein overexpression develop HF that is associated with activation of the systemic and the local ACE/Ang II pathway. However, it is counterbalanced by a prominent ACE2/Ang-(1-7) activation, possibly allowing to delay decompensation. NEW & NOTEWORTHY Changes in ACE/ACE-2 balance were analyzed based on measurements of a panel of nine angiotensins in plasma, heart, and aorta of Tgαq*44 mice in relation to progression of heart failure (HF) characterized by multiparametric MRI and exercise performance. The early stage of HF was associated with upregulation of the ACE2/angiotensin-(1-7) pathway, whereas the end-stage HF was associated with downregulation of ACE2/angiotensin-(1-7) and upregulation of the ACE/Ang II pathway. ACE/ACE-2 balance seems to determine the decompensation of HF in this model.