Manganese-enhanced MRI (MEMRI) in breast and prostate cancers: Preliminary results exploring the potential role of calcium receptors.

PROCEDURES: To preliminary assess the relationship between Manganese Enhanced Magnetic Resonance Imaging (MEMRI) and the expression of calcium receptors in human prostate and breast cancer animal models. METHODS: NOD/SCID mice were inoculated with MDA-MB-231 breast cancer cells and prostate PC3 cancer cells to develop orthotopic or pseudometastatic cancer animal models. Mice were studied on a clinical 3T scanner by using a prototype birdcage coil before and after intravenous injection of MnCl2. Assessment of receptor's status was carried out after the MR images acquisition by immunohistochemistry on excised tumours. RESULTS: Manganese contrast enhancement in breast or prostate cancer animal models well correlated with CaSR expression (p<0.01), whereas TRPV6 expression levels appeared not relevant to the Mn uptake. CONCLUSION: Our preliminary results suggest that MEMRI appears an efficient tool to characterize human breast and prostate cancer animal models in the presence of different expression level of calcium receptors.

Author Correction: Faithful animal modelling of human glioma by using primary initiating cells and its implications for radiosensitization therapy.

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Faithful animal modelling of human glioma by using primary initiating cells and its implications for radiosensitization therapy [ARRIVE 1].

It has been reported that the ATM kinase inhibitor KU60019 preferentially radiosensitizes orthotopic high grade gliomas (HGG) driven by established U87 and U1242 cell lines bearing specific TP53 mutations. We wished to determine whether those results could be extended to tumors driven by primary glioma initiating cells (GIC) that closely mimic clinical tumors. Orthotopic HGG were developed in immunodeficient non-obese diabetic-severe combined immunodeficient (NOD-SCID) mice by intracranial injection of primary GIC isolated from the adult glioblastoma COMI (acronym of patient's name) and the pediatric anaplastic astrocytoma 239/12. Similar to the clinical tumors of origin, the orthotopic tumors COMI and 239/12 displayed different growth properties with a voluminous expansive lesion that exerted considerable mass effect on the adjacent structures and an infiltrating, gliomatosis-like growth pattern with limited compressive attitude, respectively. Significant elongations of median animal survival bearing the adult COMI tumor was observed after one KU60019 convection enhanced delivery followed by total 7.5 Gy of ionizing radiation delivered in fifteen 0.5 Gy fractions, as compared to animals treated with vehicle + ionizing radiation (105 vs 89 days; ratio: 0.847; 95% CI of ratio 0.4969 to 1.198; P:0.0417) [ARRIVE 16]. Similarly, a trend to increased median survival was observed with the radiosensitized pediatric tumor 239/12 (186 vs 167 days; ratio: 0.8978; 95% CI of ratio: 0.5352 to 1.260; P: 0.0891) [ARRIVE 16]. Our results indicate that radiosensitization by KU60019 is effective towards different orthotopic gliomas that faithfully mimic the clinical tumors and that multiple GIC-based animal models may be essential to develop novel therapeutic protocols for HGG transferable to the clinics.

Functional Activation of Osteoclast Commitment in Chronic Lymphocytic Leukaemia: a Possible Role for RANK/RANKL Pathway.

Skeletal erosion has been found to represent an independent prognostic indicator in patients with advanced stages of chronic lymphocytic leukaemia (CLL). Whether this phenomenon also occurs in early CLL phases and its underlying mechanisms have yet to be fully elucidated. In this study, we prospectively enrolled 36 consecutive treatment-naïve patients to analyse skeletal structure and bone marrow distribution using a computational approach to PET/CT images. This evaluation was combined with the analysis of RANK/RANKL loop activation in the leukemic clone, given recent reports on its role in CLL progression. Bone erosion was particularly evident in long bone shafts, progressively increased from Binet stage A to Binet stage C, and was correlated with both local expansion of metabolically active bone marrow documented by FDG uptake and with the number of RANKL + cells present in the circulating blood. In immune-deficient NOD/Shi-scid, γcnull (NSG) mice, administration of CLL cells caused an appreciable compact bone erosion that was prevented by Denosumab. CLL cell proliferation in vitro correlated with RANK expression and was impaired by Denosumab-mediated disruption of the RANK/RANKL loop. This study suggests an interaction between CLL cells and stromal elements able to simultaneously impair bone structure and increase proliferating potential of leukemic clone.

A non-invasive approach to monitor chronic lymphocytic leukemia engraftment in a xenograft mouse model using ultra-small superparamagnetic iron oxide-magnetic resonance imaging (USPIO-MRI).

Chronic lymphocytic leukemia (CLL) is the most prevalent leukemia among adults. Despite its indolent nature, CLL remains an incurable disease. Herein we aimed to monitor CLL disease engraftment and, progression/regression in a xenograft CLL mouse model using ultra-small superparamagnetic iron oxide-magnetic resonance imaging (USPIO-MRI). Spleen contrast enhancement, quantified as percentage change in signal intensity upon USPIO administration, demonstrated a difference due to a reduced USPIO uptake, in the spleens of mice injected with CLL cells (NSG-CLL, n=71) compared to controls (NSG-CTR, n=17). These differences were statistically significant both after 2 and 4weeks from CLL cells injection. In addition comparison of mice treated with rituximab with untreated controls for changes in spleen iron uptake confirmed that it is possible to monitor treatment efficacy in this mouse model of CLL using USPIO-enhanced MRI. Further applications could include the preclinical in vivo monitoring of new therapies and the clinical evaluation of CLL patients.

Correlation between Choline Peak at MR Spectroscopy and Calcium-Sensing Receptor Expression Level in Breast Cancer: A Preliminary Clinical Study.

PURPOSE: The calcium-sensing receptor (CaSR) is overexpressed in many pathological states including breast cancer. Since choline kinase may be activated in breast cancer cells by CaSR resulting in increased phosphocholine production, we sought to correlate the total choline peak in breast lesions as measured by in vivo proton magnetic resonance spectroscopy ((1)H-MRS) with the CaSR expression levels in surgical specimens. PROCEDURES: Thirty-six patients with breast lesions were MR scanned at 3T scanner. Tumour morphology and DCE-MR kinetics were evaluated. (1)H-MRS was applied for Cho detection and compared with the CaSR immunohistochemistry analysis (score 0-5) on surgical breast specimens. RESULTS: Thirty-four lesions demonstrated a DCE malignant kinetics curve (types 2 and 3), while two lesions showed a benign (type 1). Twenty of the 23 breast cancer lesions (87%) with a consistent Cho peak expressed a CaSR score of 3-5, and ten of the 11 breast lesions negative for Cho (91%) had a CaSR score of 1-2. The two benign lesions showed a non-uniform/weak intense expression of the CaSR (score 3) with a consistent Cho peak. CONCLUSIONS: The presence or absence of choline peak evaluated by (1)H-MRS, well correlated with the expression of CaSR in patients with breast lesions (p < 0.01), supports the hypothesis that CaSR may play an important role in the production of choline in breast cancer.

In vivo imaging of human breast cancer mouse model with high level expression of calcium sensing receptor at 3T.

OBJECTIVES: To demonstrate that manganese can visualise calcium sensing receptor (CaSR)-expressing cells in a human breast cancer murine model, as assessed by clinical 3T magnetic resonance (MR). METHODS: Human MDA-MB-231-Luc or MCF7-Luc breast cancer cells were orthotopically grown in NOD/SCID mice to a minimum mass of 5 mm. Mice were evaluated on T1-weighted sequences before and after intravenous injection of MnCl(2). To block the CaSR-activated Ca(2+) channels, verapamil was injected at the tumour site 5 min before Mn(2+) administration. CaSR expression in vivo was studied by immunohistochemistry. RESULTS: Contrast enhancement was observed at the tumour periphery 10 min after Mn(2+) administration, and further increased up to 40 min. In verapamil-treated mice, no contrast enhancement was observed. CaSR was strongly expressed at the tumour periphery. CONCLUSION: Manganese enhanced magnetic resonance imaging can visualise CaSR-expressing breast cancer cells in vivo, opening up possibilities for a new MR contrast agent. KEY POINTS: • Manganese contrast agents helped demonstrate breast cancer cells in an animal model. • Enhancement was most marked in cells with high calcium sensing receptor expression. • Manganese uptake was related to the distribution of CaSR within the tumour. • Manganese MRI may become useful to investigate human breast cancer.

Brachial plexus MR imaging: accuracy and reproducibility of DTI-derived measurements and fibre tractography at 3.0-T.

OBJECTIVE: To estimate intrastudy, intraobserver and interobserver reproducibility of DTI-derived measurements and fibre tractography (FT) at 3.0 T MR imaging in subjects without known brachial plexus pathology. METHODS: IRB approval and written informed consent were obtained. Forty healthy volunteers underwent bilateral 3.0-T DTI of the brachial plexus. Postprocessing included FT and analysis of fractional anisotropy (FA) and apparent diffusion coefficient (ADC). Four authors performed postprocessing and analysis independently and in different sessions at baseline and after 4 weeks. Non-parametric tests and Bland-Altman statistics were used. RESULTS: Minimum and maximum percent variability were 6% and 20% for FA (85%-93% reproducibility). For ADC minimum and maximum percent variability were 6% and 18% (86%-97% reproducibility). Quality of fibre tract was rated equal in 80% and slightly different in 20% of subjects. Minimum detectable differences between limb were 37% for FA and 32% for ADC. Intra- and inter-observer agreement were good. Evaluating the combined influence of the observer and of the repeated measurements the reproducibility was 81-92%. CONCLUSION: DTI of brachial plexus nerves is reliable. The healthy contralateral side can be used as an internal control considering that changes in FA and ADC values of less that 37% and 32% will not be clinically detectable with confidence.

Two-step in vivo tumor targeting by biotin-conjugated antibodies and superparamagnetic nanoparticles assessed by magnetic resonance imaging at 1.5 T.

PURPOSE: The purpose of this study was to assess two-step in vivo tumor targeting by specific biotin-conjugated antibodies and ultrasmall superparamagnetic iron oxide (USPIO)-anti-biotin nanoparticles as contrast agents for magnetic resonance imaging (MRI) at 1.5 T. PROCEDURES: D430B human lymphoma cells, expressing the CD70 surface antigen, were injected either s.c. or i.v. to induce pseudo-metastases in NOD/SCID mice. Thirty micrograms of biotin-conjugated monoclonal anti-CD70 was injected i.v., followed 4 h later by 8 micromol Fe/Kg USPIO-anti-biotin. After 24 h, MRI was performed on T2* and b-FFE sequences. Signal intensity (SI) was calculated before and after USPIO-anti-biotin administration. RESULTS: Subcutaneous xenografts showed a dishomogeneous 30% decrease in SI on T2* with anti-CD70 + USPIO-anti-biotin treatment. Pseudo-metastatic xenografts showed a slight reduction in SI on T2*, but a 60% decrease in SI on b-FFE-weighted sequences. Prussian blue staining confirmed the presence of iron nanoparticles in the excised tumors. CONCLUSION: MRI at 1.5 T can detect tumors by a two-step in vivo biotin-based protocol, which may allow the targeting of any cell surface antigen.

MR and iron magnetic nanoparticles. Imaging opportunities in preclinical and translational research.

Ultrasmall superparamagnetic iron oxide nanoparticles and magnetic resonance imaging provide a non-invasive method to detect and label tumor cells. These nanoparticles exhibit unique properties of superparamagnetism and can be utilized as excellent probes for magnetic resonance imaging. Most work has been performed using a magnetic resonance scanner with high field strength up to 7 T. Ultrasmall superparamagnetic iron oxide nanoparticles may represent a suitable tool for labeling molecular probes that target specific tumor-associated markers for in vitro and in vivo detection by magnetic resonance imaging. In our study, we demonstrated that magnetic resonance imaging at 1.5 T allows the detection of ultrasmall superparamagnetic iron oxide nanoparticle conjugated antibody specifically bound to human tumor cells in vitro and in vivo, and that the magnetic resonance signal intensity correlates with the concentration of ultrasmall superparamagnetic iron oxide nanoparticle antibody used and with the antigen density at the cell surface. The experiments were performed using two different means of targeting: direct and indirect magnetic tumor targeting. The imaging of tumor antigens using immunospecific contrast agents is a rapidly evolving field, which can potentially aid in early disease detection, monitoring of treatment efficacy, and drug development. Cell labeling by iron oxide nanoparticles has emerged as a potentially powerful tool to monitor trafficking of a large number of cells in the cell therapy field. We also studied the labeling of natural killer cells with iron nanoparticles to a level that would allow the detection of their signal intensity with a clinical magnetic resonance scanner at 1.5 T. Magnetic resonance imaging and iron magnetic nanoparticles are able to increase the accuracy and the specificity of imaging and represent new imaging opportunities in preclinical and translational research.

Color Doppler appearance of penile cavernosal-spongiosal communications in patients with normal and impaired erection.

Our objective was to investigate prevalence and Doppler characteristics of penile cavernosal-spongiosal communications (CSC). These vessels are either anastomoses connecting the cavernosal arteries with the urethral arterial network or afferent vessels to the corpus spongiosum. Sixty-one consecutive patients underwent penile color Doppler US. Waveform changes in CSC were evaluated in comparison with changes in the cavernosal artery. Eighteen of 61 patients had normal erection, 17 of 61 had arterial insufficiency, and 26 of 61 had veno-occlusive dysfunction. Resistance index (RI) in CSC was significantly lower than in cavernosal arteries in all patients and increased during phases 1-2 (positive diastolic flow). Peak systolic velocity (PSV) in CSC was significantly higher in the patients with veno-occlusive dysfunction. During cavernosal phase 4 (diastolic flow reversal) CSC of patients with normal erection or with arterial insufficiency disappeared, underwent markedly reduced diastolic flow, or had systolic flow inversion. Conversely, low resistance flow was appreciable in CSC of patients with veno-occlusive dysfunction who reached phase 4. During phase 5 (systolic peak reduction) all CSC disappeared. Color Doppler US allows evaluation of CSC both in patients with normal and impaired erection.