Abstract Vitamin H (biotin) is delivered to the fetus transplacentally by an active biotin-transport mechanism and is critical for fetal development. Our objective was to develop a comprehensive MRI technique for mapping biotin transporter activity in the murine placenta. Visualization of transporter activity can employ MRI’s unique T 2 *-dependent signal ‘off-switch’, which is triggered by transporter mediated aggregation of biotinylated contrast agent (b-BSA-Gd-DTPA). MRI data were collected from pregnant mice after administration of b-BSA-Gd-DTPA and analyzed using a new sub-voxel biophysical signal model. Validation experiments included competition with native biotin, comparative tests using PET, histology, and ICPMS. MRI signal was governed by binding, aggregation, and clearance of biotin (confirmed by histology). Signal dynamics reflected the placenta’s perfusion pattern modulated by biotin transporter activity and trophoblast mediated retention, and were in congruence with a three-compartment sub-voxel model. Pre-saturation of the transporters with free biotin suppressed b-BSA-Gd-DTPA uptake. The results were confirmed by PET, histology and ICPMS. The presented MRI-based platform allows to track activity of essential molecular transporters in the placenta, reflecting a transporter-mediated uptake, followed by retention and aggregation, and recycling associated with the large b-BSA-Gd-DTPA conjugate. The presented DCE-MRI technique can furthermore be used to map and characterize microstructural compartmentation and transporter activity without exposing the fetus to contrast media.
Metastatic ovarian cancer, the most lethal of gynecologic malignancies, is typically managed by debulking surgery, followed by chemotherapy. However, despite significant efforts, survival rate remains low. We have previously demonstrated, in mouse models, a specific systemic homing of labeled fibroblasts to solid ovarian tumors. Here, we demonstrate the feasibility of utilizing this specific homing of genetically modified fibroblasts for detection and targeted therapy of orthotopic metastatic ovarian carcinoma model in immune-deficient mice. Using an in vivo metastatic mouse model for ovarian cancer, we demonstrated that fibroblasts expressing fluorescent reporters injected intra-peritoneally, were specifically recruited to peritoneal tumor nodules (resulting in 93-100% co-localization). We further used fibroblasts over expressing the soluble receptor variant of VEGFR1 (s-Flt1). Mice bearing tumors were injected weekly with either control or s-Flt1 expressing fibroblasts. Injection of s-Flt1 expressing fibroblasts resulted in a significant reduction in the ascites volume, reduced vascularization of adherent metastases, and improved overall survival. Using fluorescently labeled fibroblasts for tumor detection with readily available intra-operative fluorescence imaging tools may be useful for tumor staging and directing biopsies or surgical efforts during exploratory or debulking surgery. Fibroblasts may serve as a beacon pointing to the otherwise invisible metastases in the peritoneal cavity of ovarian cancer patients. Utilizing the recruited fibroblasts also for targeted delivery of anti angiogenic or antitumor molecules may aid in controlling tumor progression. Thus, these results suggest a novel approach for targeting ovarian tumor metastases for both tumor detection and therapy.
Abstract The preovulatory rat follicle reaches a diameter of 1 mm with no internal blood vessels. Nutrient supply to the enclosed oocyte depends solely on passive diffusion across the follicular wall and the follicular fluid. Spin‐echo and stimulatedecho NMR microscopy experiments were applied here for studying modulations in water diffusion during gonadotropin‐induced maturation of perfused rat ovarian follicles (32°C). Two diffusion compartments were observed for the follicular wall. The intracellular water diffusion coefficient, measured at a short diffusion time (9 ms) was 0.28 x 10 −5 cm 2 /s. Diffusion at long diffusion times was restricted to 16 μm, the size of cells in the follicular wall, and did not change during maturation. In the follicular fluid a transient 26% decrease in the diffusion coefficient was observed 4–7 h after gonadotropin stimulation, a change that is bound to affect the metabolic balance of the oocyte before ovulation.
Ovarian cancer is the most lethal gynecologic malignancy, often diagnosed at advanced stage leading to poor prognosis. In the study reported here, magnetic resonance imaging and near-infrared reflectance imaging were applied for in vivo analysis of two competing endocytic pathways affecting retention of bifunctional daidzein-bovine serum albumin (BSA)-based contrast media by human epithelial ovarian carcinoma cells. Suppression of caveolae-mediated uptake using nystatin or by BSA competition significantly enhanced daidzein-BSA-GdDTPA/CyTE777 uptake by tumor cells in vitro. In vivo, perivascular myofibroblasts generated an effective perivascular barrier excluding delivery of BSA-GdDTPA/CyTE777 to tumor cells. The ability to manipulate caveolae-mediated sequestration of albumin by perivascular tumor myofibroblasts allowed us to effectively overcome this tumor-stroma barrier, increasing delivery of daidzein-BSA-GdDTPA/CyTE777 to the tumor cells in tumor xenografts. Thus, both in vitro and in vivo, endocytosis of daidzein-BSA-GdDTPA/CyTE777 by ovarian carcinoma cells was augmented by albumin or by nystatin. In view of the cardinal role of albumin in affecting the availability and pharmacokinetics of drugs, this approach could potentially also facilitate the delivery of therapeutics and contrast media to tumor cells.
Dehydrative aromatization of 4-bromo-10β-hydroxyoestr-4-ene-3,17-dione (3a), obtained regiospecifically from 4β,5β-epoxy-10β-hydroxyoestrane-3,17-dione (1) by α-mode oxiran opening to 4-bromo-oestrone (5), was accomplished by treatment with trifluoroacetic anhydride in dioxan at ambient temperature. The stability of the 17β-hydroxy-group to trifluoroacetic anhydride was established, and the synthesis of 4-bromo-17β-oestradiol (6) by the analogous 19-norsteroid route was accomplished.
The goal of this study was to examine the use of diffusion-weighted magnetic resonance imaging (DW-MRI) for the assessment of early progression of photodamage induced by Pd-bacteriopheophorbide (TOOKAD)-based photodynamic therapy (PDT). TOOKAD is a novel second-generation photosensitizer for PDT of solid tumors developed in our laboratory and presently under clinical trials for prostate cancer (PC) therapy. Using the subcutaneous human prostate adenocarcinoma WISH-PC14 xenografts in nude mice as a model, a unique biphasic change in the apparent diffusion coefficient (ADC) was observed within the first 24 hours post-PDT, with initial decrease followed by an increase in ADC. Using DW-MRI, this phenomenon enables the detection of successful tumor response to PDT within 7 hours posttreatment. This process was validated by direct, histological, immunohistochemical examinations and also by evaluation of serum prostate-specific antigen (PSA) levels that decreased significantly already 7 hours posttreatment. In vitro studies of multicellular cell spheroids confirmed a PDT-induced decrease in ADC, suggesting that lipid peroxidation (LPO) significantly contributes to ADC decline observed after PDT. These results demonstrate that TOOKAD-based PDT successfully eradicates prostate adenocarcinoma xenografts and suggests DW-MRI to be useful for the detection of early tumor response and treatment outcome in the clinical setting.
