Radiolabeling of Herceptin with 99mTc as a Her2 tracer

Introduction: Trastuzumab is a monoclonal antibody that is used in treating breast cancer. We labeled this monoclonal antibody with Technetium-99m and performed in vitro and in vivo quality control tests as a first step in the production of a new radiopharmaceutical. Methods: Trastuzumab was labeled with Technetium-99m using Succinimidyl Hydrazinonicotinamide (HYNIC) as chelator. Radiochemical Purity and stability in buffer and serum were determined. Immunoreactivity and toxicity of the complex were tested on SKBR3, MCF7 and A431 breast cancer cell lines. Biodistribution study was performed in normal mice at 4 and 24 h post injection.Results: The radiochemical purity of the complex was 95±1.4%. The stabilities in phosphate buffer and in human blood serum at 24 h post preparation were 85±3.5% and 74±1.2%, respectively. The immunoreactivity of the complex was 86±1.4%. The binding of labeled antibody to the surface of SKBR3, MCF7 and A431 cells were increased by increasing Her2 concentration on the cells surface.Conclusions: The findings showed that the new radiopharmaceutical can be a promising candidate as Her2 antigen scanning for human breast cancer

Preparation and biological studies of 68Ga-DOTA-alendronate

Objective(s): In line with previous research on the development of conjugated bisphosphonate ligands as new bone-avid agents, in this study, DOTA conjugated alendronate (DOTA-ALN) was synthesized and evaluated after labeling with gallium-68 (68Ga).Methods: DOTA-ALN was synthesized and characterized, followed by 68Ga-DOTA-ALN preparation, using DOTA-ALN and 68GaCl3 (pH: 4-5) at 92-95°C for 10 min. Stability tests, hydroxyapatite assay, partition coefficient calculation,biodistribution studies, and imaging were performed on the developed agent in normal rats.Results: The complex was prepared with high radiochemical purity (>99% as depicted by radio thin-layer chromatography; specific activity: 310-320GBq/mmol) after solid phase purification and was stabilized for up to 90 min with a logP value of -2.91. Maximum ligand binding (65%) was observed in the presence of 50 mg of hydroxyapatite; a major portion of the activity was excreted through the kidneys. With the exception of excretory organs, gastrointestinal tract organs, including the liver, intestine, and colon, showed significant uptake; however, the bone uptake was low

Effect of coating thickness of iron oxide nanoparticles on their relaxivity in the MRI

Objective(s):Iron oxide nanoparticles have found prevalent applications in various fields including drug delivery, cell separation and as contrast agents. Super paramagnetic iron oxide (SPIO) nanoparticles allow researchers and clinicians to enhance the tissue contrast of an area of interest by increasing the relaxation rate of water. In this study, we evaluate the dependency of hydrodynamic size of iron oxide nanoparticles coated with Polyethylene  glycol (PEG) on their relativities with 3 Tesla clinical MRI. Materials and Methods: We used three groups of nanoparticles with nominal sizes 20, 50 and 100 nm with a core size of 8.86 nm, 8.69 nm and 10.4 nm that they were covered with PEG 300 and 600 Da. A clinical magnetic resonance scanner determines the T1 and T2 relaxation times for various concentrations of PEG-coated nanoparticles. Results: The size measurement by photon correlation spectroscopy showed the hydrodynamic sizes of MNPs with nominal 20, 50 and 100 nm with 70, 82 and 116 nm for particles with PEG 600 coating and 74, 93 and 100 nm for  particles with PEG 300 coating, respectively. We foud that the relaxivity decreased with increasing overall particle size (via coating thickness). Magnetic resonance imaging showed that by increasing the size of the nanoparticles, r2/r1 increases linearly. Conclusion: According to the data obtained from this study it can be concluded that increments in coating thickness have more influence on relaxivities compared to the changes in core size of magnetic nanoparticles

99m Technetium-HMPAO-labeled platelet scan in practice: Preparation, quality control, and biodistribution studies

There is no biodistribution or imaging data on 99mtechnetium (Tc)-hexamethyl propylamine oxime (HMPAO)-labeled platelets in the literature. The current study aimed to present updated information about the clinical procedures for preparation and use of labeled platelets. Following two-step centrifugation at 1500 and 2500 rpm, the platelets were extracted from whole blood into platelet-rich plasma (PRP) above the buffy coat and then from PRP into a platelet pellet at the bottom of the tube. The 99mTc-HMPAO-labeled platelets were inspected for purity, viability, release of 99mTc from platelets, and sterility. Also, microscopic examination and thin layer chromatography (TLC) were performed. Biodistribution was assessed following necropsy in BALB/c mice and through imaging of New Zealand rabbits. The separation ratio was estimated at 98%, and radiochemical purity was measured to be 80%. The labeling efficiency was above 30% in more than half of the assays (range: 17-43%). The release of 99mTc from platelets was 9% per hour at 37ºC. After 24 hours, stability was estimated at 54% in the human serum. The target organs of mice included the spleen and liver. In rabbits, the imaging results indicated liver as the target organ. Thyroid uptake was negligible up to 90 minutes. Based on the findings, extraction of platelets and labeling them with 99mTc-HMPAO is a feasible and safe approach in routine practice