Radioembolization of Hepatocellular Carcinoma with Built-In Dosimetry: First in vivo Results with Uniformly-Sized, Biodegradable Microspheres Labeled with 188Re.

A common form of treatment for patients with hepatocellular carcinoma (HCC) is transarterial radioembolization (TARE) with non-degradable glass or resin microspheres (MS) labeled with 90Y (90Y-MS). To further simplify the dosimetry calculations in the clinical setting, to have more control over the particle size and to change the permanent embolization to a temporary one, we developed uniformly-sized, biodegradable 188Re-labeled MS (188Re-MS) as a new and easily imageable TARE agent. Methods: MS made of poly(L-lactic acid) were produced in a flow focusing microchip. The MS were labeled with 188Re using a customized kit. An orthotopic HCC animal model was developed in male Sprague Dawley rats by injecting N1-S1 cells directly into the liver using ultrasound guidance. A suspension of 188Re-MS was administered via hepatic intra-arterial catheterization 2 weeks post-inoculation of the N1-S1 cells. The rats were imaged by SPECT 1, 24, 48, and 72 h post-radioembolization. Results: The spherical 188Re-MS had a diameter of 41.8 ± 6.0 µm (CV = 14.5%). The site and the depth of the injection of N1-S1 cells were controlled by visualization of the liver in sonograms. Single 0.5 g tumors were grown in all rats. 188Re-MS accumulated in the liver with no deposition in the lungs. 188Re decays to stable 188Os by emission of ߯ particles with similar energy to those emitted by 90Y while simultaneously emitting γ photons, which were imaged directly by single photon computed tomography (SPECT). Using Monte Carlo methods, the dose to the tumors was calculated to be 3-6 times larger than to the healthy liver tissue. Conclusions:188Re-MS have the potential to become the next generation of ߯-emitting MS for TARE. Future work revolves around the investigation of the therapeutic potential of 188Re-MS in a large-scale, long-term preclinical study as well as the evaluation of the clinical outcomes of using 188Re-MS with different sizes, from 20 to 50 µm.

Current update of a thermosensitive liposomes composed of DPPC and Brij78.

Thermosensitive liposomes (TSLs) have been a prominent area of study in the discipline of tumour-targeted chemotherapeutics. The representative product of TSLs is ThermoDox® (DPPC/lyso-PC/PEG-lipid), which has advanced to Phase III clinical trials. Various groups have sought to develop a new TSL to improve upon the LTSL (lyso-lipid temperature-sensitive liposomes) formulation that is used to prepare ThermoDOX®. This review focuses on the development and recent update of an innovative TSL formulation, HaT-liposomes composed of DPPC and Brij78. Various parameters of LTSL and HaT-liposomes are compared, including size, loading efficiency, transition temperature, temperature-dependent release kinetics, stability, pharmacokinetics, biodistribution and antitumour activity. Theranostic techniques involving HaT-liposomes are reported with regard to magnetic resonance imaging of drug delivery to tumours and identification of an early therapeutic biomarker in the treated tumour. The development of a further improved TSL formulation upon HaT-liposomes with improved stability and prolonged blood circulation is reported. Delivery of membrane impermeable drugs using HaT-liposomes is explored. Finally, the challenges and future perspectives of this technology are discussed.

A single microfluidic chip with dual surface properties for protein drug delivery.

Principles of double emulsion generation were incorporated in a glass microfluidic chip fabricated with two different surface properties in order to produce protein loaded polymer microspheres. The microspheres were produced by integrating two microfluidic flow focusing systems and a multi-step droplet splitting and mixing system into one chip. The chip consists of a hydrophobic and a hydrophilic section with two different heights, 12µm and 45µm, respectively. As a result, the protein is homogenously distributed throughout the polymer microsphere matrix, not just in its center (which has been studied before). In our work, the inner phase was bovine serum albumin (BSA) in phosphate buffered saline, the disperse phase was poly (lactic acid) in chloroform and the continuous phase was an aqueous solution of poly(vinyl alcohol). After solvent removal, BSA loaded microspheres with an encapsulation efficiency of up to 96% were obtained. Our results show the feasibility of producing microspheres loaded with a hydrophilic drug in a microfluidic system that integrates different microfluidic units into one chip.

188Re image performance assessment using small animal multi-pinhole SPECT/PET/CT system.

PURPOSE: The goal of this study was to investigate the performance of a pre-clinical SPECT/PET/CT system for 188Re imaging. METHODS: Phantom experiments were performed aiming to assess the characteristics of two multi-pinhole collimators: ultra-high resolution collimator (UHRC) and high-energy ultra high resolution collimator (HE-URHC) for imaging 188Re. The spatial resolution, image contrast and contrast-to-noise ratio (CNR) were investigated using micro-Jaszczak phantoms. Additionally, the quantification accuracy of 188Re images was evaluated using two custom-designed phantoms. The 188Re images were compared to those obtained with 99mTc (gold standard); the acquired energy spectra were analyzed and Monte-Carlo simulations of the UHRC were performed. To verify our findings, a C57BL/6-mouse was injected with 188Re-microspheres and scanned with both collimators. RESULTS: The spatial resolution achieved in 188Re images was comparable to that of 99mTc. Acquisitions using HE-UHRC yielded 188Re images with higher contrast and CNR than UHRC. Studies of quantitative accuracy of 188Re images resulted in <10% errors for both collimators when the activity was calculated within a small VOI around the object of interest. Similar quantification accuracy was achieved for 99mTc. However, 188Re images showed much higher levels of noise in the background. Monte-Carlo simulations showed that 188Re imaging with UHRC is severely affected by down-scattered photons from high-energy emissions. The mouse images showed similar biodistribution of 188Re-microspheres for both collimators. CONCLUSIONS: VECTor/CT provided 188Re images quantitatively accurate and with quality comparable to 99mTc. However, due to large penetration of UHRC by high-energy photons, the use of the HE-UHRC for imaging 188Re in VECTor/CT is recommended.

Magnetic nanoparticle and magnetic field assisted siRNA delivery in vitro.

This chapter describes how to design and conduct experiments to deliver siRNA to adherent cell cultures in vitro by magnetic force-assisted transfection using self-assembled complexes of small interfering RNA (siRNA) and cationic lipids or polymers that are associated with magnetic nanoparticles (MNPs). These magnetic complexes are targeted to the cell surface by the application of a gradient magnetic field. A further development of the magnetic drug-targeting concept is combining it with an ultrasound-triggered delivery using magnetic microbubbles as a carrier for gene or drug delivery. For this purpose, selected MNPs, phospholipids, and siRNAs are assembled in the presence of perfluorocarbon gas into flexible formulations of magnetic lipospheres (microbubbles). Methods are described how to accomplish the synthesis of magnetic nanoparticles for magnetofection and how to test the association of siRNA with the magnetic components of the transfection vector. A simple method is described to evaluate magnetic responsiveness of the magnetic siRNA transfection complexes and estimate the complex loading with magnetic nanoparticles. Procedures are provided for the preparation of magnetic lipoplexes and polyplexes of siRNA as well as magnetic microbubbles for magnetofection and downregulation of the target gene expression analysis with account for the toxicity determined using an MTT-based respiration activity test. A modification of the magnetic transfection triplexes with INF-7, fusogenic peptide, is described resulting in reporter gene silencing improvement in HeLa, Caco-2, and ARPE-19 cells. The methods described can also be useful for screening vector compositions and novel magnetic nanoparticle preparations for optimized siRNA transfection by magnetofection in any cell type.

Lung perfusion imaging with monosized biodegradable microspheres.

After intravenous injection, particles larger than red blood cells will be trapped in the first capillary bed that they encounter. This is the principle of lung perfusion imaging in nuclear medicine, where macroaggregated albumin (MAA) is radiolabeled with (99m)Tc, infused into a patient's arm vein, and then imaged with gamma scintigraphy. Our aim was to evaluate if monosized microspheres could replace (99m)Tc-MAA. Biodegradable poly(L-lactide) microspheres containing chelating bis(picolylamine) end groups were prepared by a flow focusing method on a microfluidic glass chip and were of highly homogeneous size (9.0 +/- 0.4 microm). The microspheres were radiolabeled with [(99m)Tc(H(2)O)(3)(CO)(3)](+) and then evaluated in mice for lung perfusion imaging. Fifteen minutes after injection, 79.6 +/- 3.8% of the injected activity was trapped in the lungs of mice. Monosized biodegradable radioactive microspheres are, thus, appropriate lung perfusion imaging agents. Other sizes of these highly uniform microspheres have the potential to improve diagnostic and therapeutic approaches in diverse areas of medicine.