Nanomagnetic Actuation of Hybrid Stents for Hyperthermia Treatment of Hollow Organ Tumors

Preparation of stable colloidal dispersion of surface modified Fe3O4 nanoparticles for magnetic heating applications

The effect of surface modification on enhancing the magnetic heating behavior of magnetic nano fluids were investigated, for this purpose Fe3O4 nanoparticles were synthesized using co-precipitation method and surface modification was done using citric acid, ascorbic acid, tetraethyl orthosilicate (TEOS), polyvinyl alcohol (PVA) and polyethylene glycol (PEG). Experimental heating tests using AC magnetic field were done in the frequency of 100 kHz and different magnetic field (H) intensities. Theoretically the specific absorption rate (SAR) in magnetic nano fluids is independent of nanoparticles concentration but the experimental results showed different behavior. The theoretical SAR value @ H = 12kA.m-1 for Nano fluids containing bare Fe3O4 nanoparticles was 11.5 W/g but in experimental tests the obtained value was 9.72 W/g for nano fluid containing 20,000 ppm of dispersed nanoparticles. The experimental SAR calculation was repeated for sample containing 10,000 ppm of nanoparticles and the results showed increase in experimental SAR that is an evidence of nanoparticles agglomeration in higher concentrations. The surface modification has improved the dispersion ability of the nanoparticles. The Ratio of SAR, experimental, 20000ppm to SAR, experimental, 10000ppm was 0.85 for bare Fe3O4 nanoparticles dispersion but in case of surface modified nanoparticles this ratio has increased up to 0.98 that shows lower agglomeration of nanoparticles as a result of surface modification, although on the other hand the surface modification agents were magnetically passive and so it is expected that in constant concentration the SAR for bare Fe3O4 nanoparticles to be higher than this variable for surface modified nanoparticles. At lower concentrations the dispersions containing bare Fe3O4 nanoparticles showed higher SAR values but at higher concentrations the surface modified Fe3O4 nanoparticles showed better results although the active agent amount was lower at them. Finally, it should be noted that the nanoparticles that were surface modified using polymeric agents showed the highest decrease in experimental SAR amounts comparing theoretical results that was because of the large molecules of polymers comparing other implemented surface modification agents.

Paracrine Factors Released from Tonsil-Derived Mesenchymal Stem Cells Inhibit Proliferation of Hematological Cancer Cells Under Hyperthermia in Co-culture Model

Mesenchymal stem cells (MSCs) are promising biological therapeutic candidates in cancer treatment. As a source of MSCs, palatine tonsil tissue is one of the secondary lymphoid organs that form an essential part of the immune system, and the relation between the secondary lymphoid organs and cancer progression leads us to investigate the effect of tonsil-derived MSCs (T-MSC) on cancer treatment. We aimed to determine the anti-tumoral effects of T-MSCs cultured at the febrile temperature (40 °C) on hematological cancer cell lines. The co-culture of cancer cells with T-MSCs was carried out under fever and normal culture conditions, and then the cell viability was determined by cell counting. In addition, apoptosis rate and cell cycle arrest were determined by flow cytometry. We confirmed the apoptotic effect of T-MSC co-culture at the transcriptional level by using real-time polymerase chain reaction (RT-PCR). We found that co-culture of cancer cells with T-MSCs significantly decreased the viable cell number under the febrile and normal culture conditions. Besides, the T-MSC co-culture induced apoptosis on K562 and MOLT-4 cells and induced the cell cycle arrest at the G2/M phase on MOLT-4 cells. The apoptotic effect of T-MSC co-culture under febrile stimulation was confirmed at the transcriptional level. Our study has highlighted the anti-tumoral effect of the cellular interaction between the T-MSCs and human hematological cancer cells during in vitro co-culture under hyperthermia.

On the Evaluation of the Hyperthermic Efficiency of Magnetic Scaffolds

Goal: Deep-seated tumors (DST) can be treated using thermoseeds exposed to a radiofrequency magnetic field for performing local interstitial hyperthermia treatment (HT). Several research efforts were oriented to the manufacturing of novel biocompatible magnetic nanostructured thermo-seeds, called magnetic scaffolds (MagS). Several iron-doped bioceramics or magnetic polymers in various formulations are available. However, the crucial evaluation of their heating potential has been carried out with significantly different, lab specific, variable experimental conditions and protocols often ignoring the several error sources and inaccuracies estimation. Methods: This work comments and provides a perspective analysis of an experimental protocol for the estimation methodology of the specific absorption rate (SAR) of MagS for DST HT. Numerical multiphysics simultions have been performed to outline the theoretical framework. After the in silico analysis, an experimental case is considered and tested. Results: From the simulations, we found that large overestimation in the SAR values can be found, due to the axial misplacement in the radiofrequency coil, while the radial misplacement has a lower impact on the estimated SAR value. Conclusions: The averaging of multiple temperature records is needed to reliably and effectively estimate the SAR of MagS for DST HT.

Lifelike Transformative Materials for Biohybrid Implants: Inspired by Nature, Driven by Technology

Today's living world is enriched with a myriad of natural biological designs, shaped by billions of years of evolution. Unraveling the construction rules of living organisms offers the potential to create new materials and systems for biomedicine. From the close examination of living organisms, several concepts emerge: hierarchy, pattern repetition, adaptation, and irreducible complexity. All these aspects must be tackled to develop transformative materials with lifelike behavior. This perspective article highlights recent progress in the development of transformative biohybrid systems for applications in the fields of tissue regeneration and biomedicine. Advances in computational simulations and data-driven predictions are also discussed. These tools enable the virtual high-throughput screening of implant design and performance before committing to fabrication, thus reducing the development time and cost of biomimetic and biohybrid constructs. The ongoing progress of imaging methods also constitutes an essential part of this matter in order to validate the computation models and enable longitudinal monitoring. Finally, the current challenges of lifelike biohybrid materials, including reproducibility, ethical considerations, and translation, are discussed. Advances in the development of lifelike materials will open new biomedical horizons, where perhaps what is currently envisioned as science fiction will become a science-driven reality in the future.

Heating of Large Endovascular Stents and Stent Grafts in Magnetic Particle Imaging-Influence of Measurement Parameters and Isocenter Distance

PURPOSE

Magnetic particle imaging (MPI) is a tomographic imaging modality with the potential for cardiovascular applications. In this context, the extent to which stents are heated should be estimated from safety perspective. Furthermore, the influence of the measurement parameters and stent distance to the isocenter of the MPI scanner on stent heating were evaluated.

MATERIALS AND METHODS

Nine different endovascular stents and stent grafts were tested in polyvinyl-chloride tubes. The stents had diameters from 10 to 31 mm, lengths between 25 and 100 mm and were made from stainless steel, nitinol or cobalt-chromium. The temperature differences were recorded with fiber-optic thermometers. All measurements were performed in a preclinical commercial MPI scanner. The measurement parameters were varied (drive field strengths: 3, 6, 9, 12 mT and selection field gradients: 0, 1.25 and 2.5 T/m). Furthermore, measurements with different distances to the scanner's isocenter were performed (100 to 0 mm).

RESULTS

All stents showed heating (maximum 53.1 K, minimum 4.6 K). The stent diameter directly correlated with the temperature increase. The drive field strength influenced the heating of the stents, whereas the selection field gradient had no detectable impact. The heating of the stents decreased with increasing distance from the scanner's isocenter and thus correlated with the loss of the scanner's magnetic field.

CONCLUSION

Stents can cause potentially harmful heating in MPI. In addition to the stent diameter and design, the drive field strength and the distance to the MPI scanner's isocenter must be kept in mind as influencing parameters.

Bone Tumor Suppression in Rabbits by Hyperthermia below the Clinical Safety Limit Using Aligned Magnetic Bone Cement

Demonstrating highly efficient alternating current (AC) magnetic field heating of nanoparticles in physiological environments under clinically safe field parameters has remained a great challenge, hindering clinical applications of magnetic hyperthermia. In this work, exceptionally high loss power of magnetic bone cement under the clinical safety limit of AC field parameters, incorporating direct current field-aligned soft magnetic Zn_0.3 Fe_2.7 O₄ nanoparticles with low concentration, is reported. Under an AC field of 4 kA m^-1 at 430 kHz, the aligned bone cement with 0.2 wt% nanoparticles achieves a temperature increase of 30 °C in 180 s. This amounts to a specific loss power value of 327 W gmetal-1 and an intrinsic loss power of 47 nHm² kg^-1 , which is enhanced by 50-fold compared to randomly oriented samples. The high-performance magnetic bone cement allows for the demonstration of effective hyperthermia suppression of tumor growth in the bone marrow cavity of New Zealand White Rabbits subjected to rapid cooling due to blood circulation, and significant enhancement of survival rate.

Iron Oxide Nanoparticle-Based Hyperthermia as a Treatment Option in Various Gastrointestinal Malignancies

Iron oxide nanoparticle-based hyperthermia is an emerging field in cancer treatment. The hyperthermia is primarily achieved by two differing methods: magnetic fluid hyperthermia and photothermal therapy. In magnetic fluid hyperthermia, the iron oxide nanoparticles are heated by an alternating magnetic field through Brownian and Néel relaxation. In photothermal therapy, the hyperthermia is mainly generated by absorption of light, thereby converting electromagnetic waves into thermal energy. By use of iron oxide nanoparticles, this effect can be enhanced. Both methods are promising tools in cancer treatment and are, therefore, also explored for gastrointestinal malignancies. Here, we provide an extensive literature research on both therapy options for the most common gastrointestinal malignancies (esophageal, gastric and colorectal cancer, colorectal liver metastases, hepatocellular carcinoma, cholangiocellular carcinoma and pancreatic cancer). As many of these rank in the top ten of cancer-related deaths, novel treatment strategies are urgently needed. This review describes the efforts undertaken in vitro and in vivo.

Characterization of Ferromagnetic Composite Implants for Tumor Bed Hyperthermia

Hyperthermia therapy (HT) is becoming a well-recognized method for the treatment of cancer when combined with radiation or chemotherapy. There are many ways to heat a tumor and the optimum approach depends on the treatment site. This study investigates a composite ferromagnetic surgical implant inserted in a tumor bed for the delivery of local HT. Heating of the implant is achieved by inductively coupling energy from an external magnetic field of sub-megahertz frequency. Implants are formed by mechanically filling a resected tumor bed with self-polymerizing plastic mass mixed with small ferromagnetic thermoseeds. Model implants were manufactured and then heated in a 35 cm diameter induction coil of our own design. Experimental results showed that implants were easily heated to temperatures that allow either traditional HT (39-45°C) or thermal ablation therapy (>50°C) in an external magnetic field with a frequency of 90 kHz and amplitude not exceeding 4 kA/m. These results agreed well with a numerical solution of combined electromagnetic and heat transfer equations solved using the finite element method.

Magnetic Particle Imaging: Current and Future Applications, Magnetic Nanoparticle Synthesis Methods and Safety Measures

Magnetic nanoparticles (MNPs) have a wide range of applications; an area of particular interest is magnetic particle imaging (MPI). MPI is an imaging modality that utilizes superparamagnetic iron oxide particles (SPIONs) as tracer particles to produce highly sensitive and specific images in a broad range of applications, including cardiovascular, neuroimaging, tumor imaging, magnetic hyperthermia and cellular tracking. While there are hurdles to overcome, including accessibility of products, and an understanding of safety and toxicity profiles, MPI has the potential to revolutionize research and clinical biomedical imaging. This review will explore a brief history of MPI, MNP synthesis methods, current and future applications, and safety concerns associated with this newly emerging imaging modality.