PEGylated nanoliposomes encapsulating angiogenic peptides improve perfusion defects: Radionuclide imaging-based study.

INTRODUCTION: Although liposomes hold promise for cancer therapy, the effectiveness of treating myocardial ischemia by promoting angiogenesis has yet to be proved. Nanoliposomes loaded with therapeutic agents can effectively target ischemic myocardium via enhanced permeability and retention. Surface polyethylene glycol (PEG) modification can further facilitate effective targeting by prolonging liposomal circulation. This study aimed to determine whether PEGylated nanoliposomes are effective in facilitating targeted drug delivery and treating myocardial ischemia. METHODS: Rats subjected to 30min of myocardial ischemia were given (99m)Tc-hexamethylpropyleneamine oxime- or (99m)Tc-diethylenetriamine pentaacetate-labeled liposomes with mean diameters of ~100nm or ~600nm with or without PEG modifications to determine the extent of myocardial uptake in the different conditions. Therapeutic effectiveness was assessed by studying changes in myocardial perfusion defects with (99m)Tc-tetrofosmin autoradiography and vascular density with immunohistochemistry at 7days post-treatment. RESULTS: The liver and spleen showed the largest capacity for liposome uptake. Uptake by the liver and spleen was more pronounced when the liposomes were larger. Conversely, myocardial liposome uptake was significantly greater when the liposomes were ~100nm rather than ~600nm in diameter. Surface modification with PEG significantly augmented myocardial uptake of ~100nm liposomes. PEG modification did not affect the size dependence. To investigate therapeutic efficacy, hearts subjected to ischemia received PEGylated nanoliposomes encapsulated with angiogenic peptides. Our data demonstrated that PEGylated nanoliposomes loaded with angiogenic peptides improved myocardial perfusion defects and increased vascular density. A 10-fold increase in liposomal concentration did not further benefit myocardial ischemia. CONCLUSIONS: Liposomal angiogenic formulation with size control and PEG modification may be effective treatment strategy for myocardial ischemia. Increasing the concentration of liposomes does not necessarily benefit myocardial ischemia.

Effect of High-Intensity Focused Ultrasound on Drug Release from Doxorubicin-Loaded PEGylated Liposomes and Therapeutic Effect in Colorectal Cancer Murine Models.

The goal of the study described here was to evaluate the use of high-intensity focused ultrasound (HIFU) in drug release and its application in cancer therapy. HIFU was set to minimize hyperthermia, particularly non-specific hyperthermia, of exposed areas. An in vitro temperature-sensitive hydrogel phantom model determined the parameters of HIFU under mild condition settings (spatial average temporal average intensity [ISATA] = 83.35 W/cm(2)). PEGylated liposomal indocyanine green (LCLP-ICG) and PEGylated liposomal doxorubicin (LCLP-Dox) were prepared with the same mole ratio to allow direct comparison of drug release in vitro and in vivo. We induced drug release with HIFU treatment using LCLP-ICG coupled with optical imaging in vitro and in vivo. The size distribution changes in LCLP-ICG in vitro and fluorescence intensity changes in ICG after intra-tumoral injection of LCLP-ICG into CT26 solid tumors in vivo followed by HIFU confirmed the feasibility of the system. We validated the therapeutic effect of HIFU treatment of the CT26 mouse tumor model. The tumor growth rate was significantly reduced (p < 0.05) only in the group administered LCLP-Dox followed by cycles of HIFU treatment, and the chemotherapy of the CT26 solid tumors was found to be highly efficient.

Evaluation of Selective Arterial Embolization Effect by Chitosan Micro-Hydrogels in Hindlimb Sarcoma Rodent Models Using Various Imaging Modalities.

PURPOSE: Embolization is mainly used to reduce the size of locally advanced tumors. In this study, selective arterial catheterization with chitosan micro-hydrogels (CMH) into the femoral artery was performed and the therapeutic effect was validated using different imaging methods. METHODS: Male SD rats (n = 18, 6 weeks old) were randomly assigned into three groups: Group 1 as control, Group 2 without any ligation of distal femoral artery, and Group 3 with temporary ligation of the distal femoral artery. RR1022 sarcoma cell lines were inoculated into thigh muscle. After 1 week, CMH was injected into the proximal femoral artery. Different imaging modalities were performed during a 3-week follow-up. RESULTS: The tumor size was significantly (P < 0.001) decreased in both Group 2 and Group 3 (P < 0.001) after selective arterial embolization therapy. (18)F-FDG-PET/CT revealed decreased intensity of (18)F-FDG uptake in tumors. The accumulation status of (125)I-CMH near the tumor was verified by gamma camera. CONCLUSIONS: Appropriate selective arterial embolization therapy with CMH was.

Establishment of animal models with orthotopic hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is one of the most serious health problems worldwide. Many researchers have investigated HCC at the level of genes, ribonucleic acid, proteins, cells, and animals. The resultant development of animal models and monitoring methods has improved the effectiveness of guidelines provided to researchers working with preclinical HCC models. HCC in animal models and clinical patients is monitored by various current imaging modalities such as ultrasound (US) imaging, computed tomography (CT), magnetic resonance imaging (MRI), single photon emission computed tomography (SPECT), positron emission tomography (PET) and bioluminescence imaging (BLI). These techniques are currently used for both preclinical and clinical assessment, and provide valuable diagnostic information. In this article, we have mainly reviewed the established animal models and the assessment of orthotopic HCC using imaging modalities. Additionally, we have introduced a method of orthotopic HCC rat model developed in our laboratory. We have furthermore evaluated the occurrence of tumor mass using molecular imaging techniques.

Effect of angiogenesis induced by consecutive intramuscular injections of vascular endothelial growth factor in a hindlimb ischemic mouse model.

PURPOSE: Angiogenesis plays a major role in various physiological and pathological situations. Thus, an angiogenic therapy with vascular endothelial growth factor (VEGF) has been commonly recommended as a representative therapeutic solution to recover the insufficient blood supply of collateral vessels in an ischemic lesion. In this study, the injection method and injection time point of VEGF proteins were focused to discover how to enhance the angiogenic effect with VEGF. METHODS: Mouse models (n = 15) were divided into control, VEGF treatment by intra-venous injection (VEGF-IV) and VEGF treatment by intra-muscular injection (VEGF-IM). Right proximal femoral arteries of mice were firmly sutured to obstruct arterial blood-flow. In the VEGF-IV treatment group, VEGF proteins were injected into the tail vein and, in the VEGF-IM treatment group, VEGF proteins were directly injected into the ischemic site of the right thigh after postoperative day 5, 10, 15, 20 and 25 follow-ups. Blood-flow images were acquired by (99m)Tc Gamma Image Acquisition System to compare the ischemic-to-non-ischemic bloodstream ratio at postoperative days 5, 15, and 30. RESULTS: VEGF-IM treatment significantly induced higher an angiogenic effect rather than both the control group (P = 0.008) and VEGF-IV treatment group (P = 0.039) at the 30th day. CONCLUSION: During all experiments, angiogenesis of VEGF-IM treatment represented the most evident effect compared with control and VEGF-IV group in a mouse model of hindlimb ischemia.

Peptide-loaded nanoparticles and radionuclide imaging for individualized treatment of myocardial ischemia.

PURPOSE: To determine whether chitosan hydrogel nanoparticles loaded with vascular endothelial growth factor (VEGF) peptides (81-91 fragments) capable of targeting the ischemic myocardium enhance angiogenesis and promote therapeutic effects and whether radionuclide image-guided dosage control is feasible. MATERIALS AND METHODS: Experimental procedures and protocols were approved by the Institutional Animal Care and Use Committee. Rats (n = 32, eight per group) were subjected to myocardial ischemia (control group) and received chitosan hydrogel nanoparticles with VEGF165 proteins (chitosan VEGF) or VEGF81-91 peptides (chitosan peptides) via apical puncture. Ischemic hearts receiving chitosan without angiogenic factors served as the chitosan control. Myocardial perfusion was examined 7 days after surgery by using technetium 99m ((99m)Tc) tetrofosmin (37 MBq) autoradiography, and changes in vascular density with immunohistochemical staining were reviewed. Kruskal-Wallis test and Bonferroni corrected Mann-Whitney U test were used for multiple comparisons. Wilcoxon signed rank test was used to compare myocardial retention of (99m)Tc chitosan. RESULTS: Thirty minutes of myocardial ischemia resulted in perfusion defects (median, 54%; interquartile range [IQR], 41%-62%). Chitosan VEGF decreased perfusion defect extent (median, 68%; IQR, 63%-73%; P = .006 vs control) and increased vascular density (median, 81 vessels per high-power field; IQR, 72-100; P = .009 vs control). Administration of chitosan peptides reduced the degree of perfusion defects (median, 66%; IQR, 62%-73%; P = .006 vs control) and increased vascular density (median, 82 vessels; IQR, 78-92; P = .006 vs control). The effects of chitosan peptides on perfusion and vascular density were comparable to those seen with chitosan VEGF proteins (P = .713 and P = .833, respectively). Chitosan radiolabeled with (99m)Tc was administered twice at reperfusion with a 1-hour interval to determine whether image-guided dosage control is feasible. The hearts initially retained 4.6% (IQR, 4.1%-5.0%) of (99m)Tc chitosan administered and 9.2% (IQR, 6.6%-12.7%; P = .068) with subsequent injection. CONCLUSION: VEGF peptides have angiogenic potential and resulted in therapeutic effectiveness. Adjunct use of single photon emission computed tomography was also demonstrated for individualized treatment of myocardial ischemia by further tailoring the therapeutic dosing. Online supplemental material is available for this article.

Optical imaging of absorption and distribution of RITC-SiO2 nanoparticles after oral administration.

PURPOSE: In this study, we investigated the absorption and distribution of rhodamine B isothiocyanate (RITC)-incorporated silica oxide nanoparticles(SiNPs) (RITC-SiNPs) after oral exposure, by conducting optical imaging, with a focus on tracking the movement of RITC-SiNPs of different particle size and surface charge. METHODS: RITC-SiNPs (20 or 100 nm; positively or negatively charged) were used to avoid the dissociation of a fluorescent dye from nanoparticles via spontaneous or enzyme-catalyzed reactions in vivo. The changes in the nanoparticle sizes and shapes were investigated in an HCl solution for 6 hours. RITC-SiNPs were orally administered to healthy nude mice at a dose of 100 mg/kg. Optical imaging studies were performed at 2, 4, and 6 hours after oral administration. The mice were sacrificed at 2, 4, 6, and 10 hours post-administration, and ex vivo imaging studies were performed. RESULTS: The RITC-SiNPs were stable in the HCl solution for 6 hours, without dissociation of RITC from the nanoparticles and without changes in size and shape. RITC-SiNPs flowed into the small intestine from the stomach and gradually moved along the gut during the experiment. In the ex vivo imaging studies, optical signals were observed mostly in the lungs, liver, pancreas, and kidneys. The orally administered RITC-SiNPs, which were absorbed in the systemic circulation, were eliminated from the body into the urine. The 20 nm RITC-SiNPs showed higher uptake in the lungs than the 100 nm RITC-SiNPs. The distribution of the 100 nm RITC-SiNPs in the liver was higher than that of the 20 nm RITC-SiNPs, but the differences in the surface charge behavior were imperceptible. CONCLUSION: We demonstrated that the movement of RITC-SiNPs after oral exposure could be traced by optical imaging. Optical imaging has the potential to provide valuable information that will help in understanding the behavior of SiNPs in the body following exposure.

Local Retention and Combination Effects of Biocompatible Doxorubicin-Loaded and Radioiodine-Labeled Microhydrogels in Cancer Therapy.

I-131-labeled chitosan microhydrogels (I-131-CMH) that are retained at an injection site without leaking free I-131 into normal tissue can provide opportunities to improve cancer therapy. This study focuses on the development of doxorubicin-loaded I-131-CMH (Dox-I-131-CMH) for use in radiochemotherapy against cancer. The radiolabeling of I-131-CMH was found to be stable over a period of 2 weeks with no disassociation of free I-131, and Dox showed a sustained release from the CMH. When I-131-CMH were injected into the thigh muscle or tumor tissue, in vivo gamma imaging showed a retention at the injection site with no significant leakage of I-131 into other areas of normal tissue, and after an intrahepatic arterial injection, I-131-CMH were selectively retained in the liver. Dox-I-131-CMH had significant synergistic therapeutic effects of radiation and chemotherapy on mouse breast cancer models. In this regard, Dox-I-131-CMH may be a new alternative agent for cancer therapy.