Yanfeng Meng

Intrabiliary RF Heat-enhanced Local Chemotherapy of a Cholangiocarcinoma Cell Line: Monitoring with Dual-Modality Imaging—Preclinical Study

PURPOSE To determine whether magnetic resonance (MR) imaging heating guidewire-mediated radiofrequency (RF) hyperthermia could enhance the therapeutic effect of gemcitabine and 5-fluorouracil (5-FU) in a cholangiocarcinoma cell line and local deposit doses of chemotherapeutic drugs in swine common bile duct (CBD) walls. MATERIALS AND METHODS The animal protocol was approved by the institutional animal care and use committee. Green fluorescent protein-labeled human cholangiocarcinoma cells and cholangiocarcinomas in 24 mice were treated with (a) combination therapy with chemotherapy (gemcitabine and 5-FU) plus RF hyperthermia, (b) chemotherapy only, (c) RF hyperthermia only, or (d) phosphate-buffered saline. Cell proliferation was quantified, and tumor changes over time were monitored with 14.0-T MR imaging and optical imaging. To enable further validation of technical feasibility, intrabiliary local delivery of gemcitabine and 5-FU was performed by using a microporous balloon with (eight pigs) or without (eight pigs) RF hyperthermia. Chemotherapy deposit doses in the bile duct walls were quantified by means of high-pressure liquid chromatography. The nonparametric Mann-Whitney U test and the paired-sample Wilcoxon signed rank test were used for data analysis. RESULTS Combination therapy induced lower mean levels of cell proliferation than chemotherapy only and RF hyperthermia only (0.39 ± 0.13 [standard deviation] vs 0.87 ± 0.10 and 1.03 ± 0.13, P < .001). Combination therapy resulted in smaller relative tumor volume than chemotherapy only and RF hyperthermia only (0.65 ± 0.03 vs 1.30 ± 0.021 and 1.37 ± 0.05, P = .001). Only in the combination therapy group did both MR imaging and optical imaging show substantial decreases in apparent diffusion coefficients and fluorescent signals in tumor masses immediately after the treatments. Chemotherapy quantification showed a higher average drug deposit dose in swine CBD walls with intrabiliary RF hyperthermia than without it (gemcitabine: 0.32 mg/g of tissue ± 0.033 vs 0.260 mg/g ± 0.030 and 5-FU: 0.660 mg/g ± 0.060 vs 0.52 mg/g ± 0.050, P < .05). CONCLUSION The use of intrabiliary MR imaging heating guidewire-mediated RF hyperthermia can enhance the chemotherapeutic effect on a human cholangiocarcinoma cell line and local drug deposition in swine CBD tissues.

Diffusion-weighted MRI monitoring of pancreatic cancer response to radiofrequency heat-enhanced intratumor chemotherapy

The aim of this study was to evaluate the feasibility of using diffusion‐weighted MRI to monitor the early response of pancreatic cancers to radiofrequency heat (RFH)‐enhanced chemotherapy. Human pancreatic carcinoma cells (PANC‐1) in different groups and 24 mice with pancreatic cancer xenografts in four groups were treated with phosphate‐buffered saline (PBS) as a control, RFH at 42 °C, gemcitabine and gemcitabine plus RFH at 42 °C. One day before and 1, 7 and 14 days after treatment, diffusion‐weighted MRI and T2‐weighted imaging were applied to monitor the apparent diffusion coefficients (ADCs) of tumors and tumor growth. MRI findings were correlated with the results of tumor apoptosis analysis. In the in vitro experiments, the quantitative viability assay showed lower relative cell viabilities for treatment with gemcitabine plus RFH at 42 °C relative to treatment with RFH only and gemcitabine only (37 ± 5% versus 65 ± 4% and 58 ± 8%, respectively, p < 0.05). In the in vivo experiments, the combination therapy resulted in smaller relative tumor volumes than RFH only and chemotherapy only (0.82 ± 0.17 versus 2.23 ± 0.90 and 1.64 ± 0.44, respectively, p = 0.003). In vivo, 14‐T MRI demonstrated a remarkable decrease in ADCs at day 1 and increased ADCs at days 7 and 14 in the combination therapy group. The apoptosis index in the combination therapy group was significantly higher than those in the chemotherapy‐only, RFH‐only and PBS treatment groups (37 ± 6% versus 20 ± 5%, 8 ± 2% and 3 ± 1%, respectively, p < 0.05). This study confirms that it is feasible to use MRI to monitor RFH‐enhanced chemotherapy in pancreatic cancers, which may present new options for the efficient treatment of pancreatic malignancies using MRI/RFH‐integrated local chemotherapy. Copyright

Magnetic resonance imaging of bone marrow cell-mediated interleukin-10 gene therapy of atherosclerosis.

Background A characteristic feature of atherosclerosis is its diffuse involvement of arteries across the entire human body. Bone marrow cells (BMC) can be simultaneously transferred with therapeutic genes and magnetic resonance (MR) contrast agents prior to their transplantation. Via systemic transplantation, these dual-transferred BMCs can circulate through the entire body and thus function as vehicles to carry genes/contrast agents to multiple atherosclerosis. This study was to evaluate the feasibility of using in vivo MR imaging (MRI) to monitor BMC-mediated interleukin-10 (IL-10) gene therapy of atherosclerosis. Methodology For in vitro confirmation, donor mouse BMCs were transduced by IL-10/lentivirus, and then labeled with a T2-MR contrast agent (Feridex). For in vivo validation, atherosclerotic apoE−/− mice were intravenously transplanted with IL-10/Feridex-BMCs (Group I, n = 5) and Feridex-BMCs (Group II, n = 5), compared to controls without BMC transplantation (Group III, n = 5). The cell migration to aortic atherosclerotic lesions was monitored in vivo using 3.0T MRI with subsequent histology correlation. To evaluate the therapeutic effect of BMC-mediated IL-10 gene therapy, we statistically compared the normalized wall indexes (NWI) of ascending aortas amongst different mouse groups with various treatments. Principal Findings Of in vitro experiments, simultaneous IL-10 transduction and Feridex labeling of BMCs were successfully achieved, with high cell viability and cell labeling efficiency, as well as IL-10 expression efficiency (≥90%). Of in vivo experiments, MRI of animal groups I and II showed signal voids within the aortic walls due to Feridex-created artifacts from the migrated BMCs in the atherosclerotic plaques, which were confirmed by histology. Histological quantification showed that the mean NWI of group I was significantly lower than those of group II and group III (P<0.05). Conclusion This study has confirmed the possibility of using MRI to track, in vivo, IL-10/Feridex-BMCs recruited to atherosclerotic lesions, where IL-10 genes function to prevent the progression of atherosclerosis.

Development of an Intrabiliary MR Imaging-monitored Local Agent Delivery Technique: A Feasibility Study in Pigs

PURPOSE To investigate the feasibility of using magnetic resonance (MR) imaging to monitor intrabiliary delivery of motexafin gadolinium (MGd) into pig common bile duct (CBD) walls. MATERIALS AND METHODS Animal studies were approved by the Institutional Animal Care and Use Committee. Initially, human cholangiocarcinoma cells were treated with various concentrations of MGd, a compound serving as a T1-weighted MR imaging contrast agent, chemotherapy drug, and cell marker. These cells were then examined by means of confocal microscopy to confirm the intracellular uptake of MGd. In addition, an MGd/trypan blue mixture was locally infused into CBD walls of six cadaveric pigs using a microporous balloon catheter. CBDs of six pigs were infused with saline to serve as controls. Ex vivo T1-weighted MR imaging of these CBDs was performed. For in vivo technical validation, the microporous balloon catheter was placed in the CBD by means of a transcholecytic access to deliver MGd/trypan blue into CBD walls of six living pigs. T1-weighted images were obtained with both a surface coil and an intrabiliary MR imaging guidewire, and contrast-to-noise ratios of CBD walls before and after MGd/trypan blue infusions were compared in the two groups by means of paired t test, with subsequent histologic analysis to confirm the penetration and distribution of the MGd/trypan blue agent into CBD walls. RESULTS In vitro experiments confirmed uptake of MGd by human cholangiocarcinoma cells. The ex vivo experiments demonstrated the penetration of MGd/trypan blue into the CBD walls. The in vivo experiment confirmed the uptake of MGd/trypan blue, showing an increased contrast-to-noise ratio for the CBD after administration of the mixture, compared with images obtained prior to MGd/trypan blue administration (11.6 ± 4.2 [standard deviation] vs 5.7 ± 2.8; P = .04). Histologic results depicted the blue dye stains and red fluorescence of MGd in CBD walls, confirming the imaging findings. CONCLUSION It is feasible to use MR imaging to monitor the penetration of locally delivered MGd into pig CBD walls.

MRI of Auto-Transplantation of Bone Marrow-Derived Stem-Progenitor Cells for Potential Repair of Injured Arteries

Background This study was to validate the feasibility of using clinical 3.0T MRI to monitor the migration of autotransplanted bone marrow (BM)-derived stem-progenitor cells (SPC) to the injured arteries of near-human sized swine for potential cell-based arterial repair. Methodology The study was divided into two phases. For in vitro evaluation, BM cells were extracted from the iliac crests of 13 domestic pigs and then labeled with a T2 contrast agent, Feridex, and/or a fluorescent tissue marker, PKH26. The viability, the proliferation efficiency and the efficacies of Feridex and/or PKH26 labeling were determined. For in vivo validation, the 13 pigs underwent endovascular balloon-mediated intimal damages of the iliofemoral arteries. The labeled or un-labeled BM cells were autotransplanted back to the same pig from which the BM cells were extracted. Approximately three weeks post-cell transplantation, 3.0T T2-weighted MRI was performed to detect Feridex-created signal voids of the transplanted BM cells in the injured iliofemoral arteries, which was confirmed by subsequent histologic correlation. Principal Findings Of the in vitro study, the viability of dual-labeled BM cells was 95–98%. The proliferation efficiencies of dual-labeled BM cells were not significantly different compared to those of non-labeled cells. The efficacies of Feridex- and PKH26 labeling were 90% and 100%, respectively. Of the in vivo study, 3.0T MRI detected the auto-transplanted BM cells migrated to the injured arteries, which was confirmed by histologic examinations. Conclusion This study demonstrates the capability of using clinical 3.0T MRI to monitor the auto-transplantation of BM cells that migrate to the injured arteries of large animals, which may provide a useful MRI technique to monitor cell-based arterial repair.

Cardiovascular magnetic resonance of quinticuspid aortic valve with aortic regurgitation and dilated ascending aorta

We report a rare case of a quinticuspid aortic valve associated with regurgitation and dilation of the ascending aorta, which was diagnosed and post-surgically followed up by cardiovascular magnetic resonance and dual source computed tomography.

MRI-Monitored Intra-Shunt Local Agent Delivery of Motexafin Gadolinium: Towards Improving Long-Term Patency of TIPS

Background Transjugular intrahepatic portosystemic shunt (TIPS) has become an important and effective interventional procedure in treatment of the complications related to portal hypertension. Although the primary patency of TIPS has been greatly improved due to the clinical application of cover stent-grafts, the long-term patency is still suboptimal. This study was to investigate the feasibility of using magnetic resonance imaging (MRI)-monitored intra-shunt local agent delivery of motexafin gadolinium (MGd) into shunt-vein walls of TIPS. This new technique aimed to ultimately inhibit shuntstenosis of TIPS. Methodology Human umbilical vein smooth muscle cells (SMCs) were incubated with various concentrations of MGd, and then examed by confocal microscopy and T1-map MRI. In addition, the proliferation of MGd-treated cells was evaluated. For in vivo validation, seventeen pigs underwent TIPS. Before placement of the stent, an MGd/trypan-blue mixture was locally delivered, via a microporous balloon, into eleven shunt-hepatic vein walls under dynamic MRI monitoring, while trypan-blue only was locally delivered into six shunt-hepatic vein walls as serve as controls. T1-weighted MRI of the shunt-vein walls was achieved before- and at different time points after agent injections. Contrast-to-noise ratio (CNR) of the shunt-vein wall at each time-point was measured. Shunts were harvested for subsequent histology confirmation. Principal Findings In vitro studies confirmed the capability of SMCs in uptaking MGds in a concentration-dependent fashion, and demonstrated the suppression of cell proliferation by MGds as well. Dynamic MRI displayed MGd/blue penetration into the shunt-vein walls, showing significantly higher CNR of shunt-vein walls on post-delivery images than on pre-delivery images (49.5±9.4 vs 11.2±1.6, P<0.01), which was confirmed by histology. Conclusion Results of this study indicate that MRI-monitored intra-shunt local MGd delivery is feasible and MGd functions as a potential therapeutic agent to inhibit the proliferation of SMCs, which may open alternative avenues to improve the long-term patency of TIPS.

3.0-T MR Imaging of Intracoronary Local Delivery of Motexafin Gadolinium into Coronary Artery Walls

PURPOSE To develop a technique with clinical 3.0-T magnetic resonance (MR) imaging to delineate local contrast agent distribution in coronary artery walls for potential molecular MR imaging-guided local gene or drug therapy of atherosclerotic coronary artery disease. MATERIALS AND METHODS This animal protocol was approved by the institutional animal care and use committee and was in compliance with the Guide for the Care and Use of Laboratory Animals. For in vitro confirmation, human arterial smooth muscle cells (SMCs) were used to determine capability of SMCs in uptake of motexafin gadolinium (MGd) and its optimal dose. For ex vivo evaluation, a 2-mL mixture of MGd and trypan blue was locally infused into coronary artery walls of six cadaveric pig hearts with MR monitoring and an MR imaging guidewire, surface coils, or both. For in vivo validation, the balloon catheter was placed into coronary arteries of seven living pigs, and the MGd and trypan blue mixture was infused into arterial walls with MR guidance. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of coronary artery walls were recorded by using different coils between pre- and postcontrast infusion, with subsequent histologic confirmation. Paired Student t tests were used to compare average SNRs and CNRs of arterial walls before and after contrast agent infusion with different coils. RESULTS SMCs could take up MGd with the optimal concentration at 150 µmol/L. Average SNR with the MR imaging guidewire and surface coil combination was significantly higher than that with the MR imaging guidewire only or with surface coils only (P < .05), and average SNR and CNR of postinfusion MR imaging was significantly higher than that of preinfusion MR imaging (P < .05). Histologic analysis was used to confirm successful intracoronary infiltration of MGd and trypan blue within coronary artery walls. CONCLUSION MR imaging can be used to delineate locally infused contrast agent distribution in coronary artery walls. This establishes groundwork for development of molecular MR imaging-guided intracoronary therapy.

Orthotopic Esophageal Cancers: Intraesophageal Hyperthermia-enhanced Direct Chemotherapy in Rats

Purpose To determine the feasibility of using intraesophageal radiofrequency (RF) hyperthermia to enhance local chemotherapy in a rat model with orthotopic esophageal squamous cancers. Materials and Methods The animal protocol was approved by the institutional animal care and use committee and the institutional review board. Human esophageal squamous cancer cells were transduced with luciferase lentiviral particles. Cancer cells, mice with subcutaneous cancer esophageal xenografts, and nude rats with orthotopic esophageal cancers in four study groups of six animals per group were treated with (a) combination therapy of magnetic resonance imaging heating guidewire-mediated RF hyperthermia (42°C) plus local chemotherapy (cisplatin and 5-fluorouracil), (b) chemotherapy alone, (c) RF hyperthermia alone, and (d) phosphate-buffered saline. Bioluminescent optical imaging and transcutaneous ultrasonographic imaging were used to observe bioluminescence signal and changes in tumor size among the groups over 2 weeks, which were correlated with subsequent histologic results. The nonparametric Mann-Whitney U test was used for comparisons of variables. Results Compared with chemotherapy alone, RF hyperthermia alone, and phosphate-buffered saline, combination therapy with RF hyperthermia and chemotherapy induced the lowest cell proliferation (relative absorbance of formazan: 23.4% ± 7, 44.6% ± 7.5, 95.8% ± 2, 100%, respectively; P < .0001), rendered the smallest relative tumor volume (0.65 mm3 ± 0.15, P < .0001) and relative bioluminescence optical imaging photon signal (0.57 × 107 photons per second per square millimeter ± 0.15, P < .001) of mice with esophageal cancer xenografts, as well as the smallest relative tumor volume (0.68 mm3 ± 0.13, P < .05) and relative photon signal (0.56 × 107 photons per second per square millimeter ± 0.11. P < .001) of rat orthotopic esophageal cancers. Conclusion Intraesophageal RF hyperthermia can enhance the effect of chemotherapy on esophageal squamous cell cancers.