Estimation of the optimum number and location of nanoparticle injections and the specific loss power for ideal hyperthermia

Design of the distribution of iron oxide (Fe3O4) nano-particle drug in realistic cholangiocarcinoma model and the simulation of temperature increase during magnetic induction hyperthermia

The prognosis for Cholangiocarcinoma (CCA) is unfavorable, necessitating the development of new therapeutic approach such as magnetic hyperthermia therapy (MHT) which is induced by magnetic nano-particle (MNPs) drug to bridge the treatment gap. Given the deep location of CCA within the abdominal cavity and proximity to vital organs, accurately predict the individualized treatment effects and safety brought by the distribution of MNPs in tumor will be crucial for the advancement of MHT in CCA. The Mimics software was used in this study to conduct three-dimensional reconstruction of abdominal computed tomography (CT) and magnetic reso-nance imaging images from clinical patients, resulting in the generation of a realistic digital geometric model representing the human biliary tract and its adjacent structures. Subsequently, The COMSOL Multiphysics software was utilized for modeling CCA and calculating the heat transfer law resulting from the multi-regional distribution of MNPs in CCA. The temperature within the central region of irregular CCA measured approximately 46°C, and most areas within the tumor displayed temperatures surpassing 41°C. The temperature of the inner edge of CCA is only 39 ∼ 41℃, however, it can be ameliorated by adjusting the local drug concentration through simulation system. For CCA with diverse morphologies and anatomical locations, the multi-regional distribution patterns of intratumoral MNPs and a slight overlap of drug distribution areas synergistically enhance intratumoral temperature while ensuring treatment safety. The present study highlights the practicality and imperative of incorporating personalized intratumoral MNPs distribution strategy into clinical practice for MHT, which can be achieved through the development of an integrated simulation system which incorporates medical image data and numerical calculations.

Focused magnetic stimulation for motor recovery after stroke

BACKGROUND AND OBJECTIVES

The effects of noninvasive focused magnetothermal brain stimulation using magnetic nanoparticles (MNPs) on post-stroke motor deficits and metabolic dormancy in subacute ischemic injury are not well-established. This study examined if magnetothermal brain stimulation using magnetic nanoparticles (Nano-MS) enhances motor recovery after stroke.

METHODS

We randomly distributed rats into Sham, Control, MNP injection only, and Nano-MS groups. We administered focused magnetic stimulation for 30 minutes daily following an MNP injection (15 mg/mL) into the targeted motor cortex via the carotid artery three weeks after the transient (90 minutes) middle cerebral artery occlusion. We assessed motor functionality via behavioral tests and conducted positron emission tomography (PET) imaging to verify cerebral metabolic activity. We assessed neuronal excitability, neuroinflammation, blood-brain barrier (BBB) integrity, and neurogenesis four weeks post-stroke.

RESULTS

The Nano-MS group exhibited significantly improved motor deficits and cerebral metabolic activity compared to the Control and MNP groups (p < 0.05). Focused Nano-MS modulated neuronal excitability, evident by a depolarized action potential threshold for spike initiation and reduced firing frequency post-stroke. The Nano-MS group demonstrated markedly decreased inflammatory markers, such as IL-1β, IL-6, TNF-α, MCP-1, and ICAM-1, compared to the Control and MNP groups. BBB integrity and immunofluorescence for neurogenesis markers were substantially improved in the Nano-MS group.

CONCLUSIONS

Focused Nano-MS facilitates the recovery of motor deficits and metabolic inactivity in the brain by effectively modulating excitability, reducing neuroinflammation, enhancing BBB stability, and promoting neurogenesis. Nano-MS is a potential novel, noninvasive therapy for stroke rehabilitation. Further investigation is warranted.

Estimation of the injection criteria for magnetic hyperthermia therapy based on tumor morphology

Intratumoral multi-injection strategy enhances the efficacy of magnetic nanoparticle hyperthermia therapy (MNPH). In this study, criteria for the selection of injections and their location depending on the tumor shape/geometry are developed. The developed strategy is based on the thermal dosimetry results of different invasive 3D tumor models during MNPH simulation. MNPH simulations are conducted on physical tumor tissue models encased within healthy tissue. The tumor shapes are geometrically divided into a central tumor region containing maximum tumor volume and a peripheral tumor portion protruding in any random direction. The concepts of core and invasive radius are used to geometrically divide the tumor volume. Primary & secondary injections are used to inject MNP fluid into these respective tumor regions based on the invasiveness of the tumor. The optimization strategy is devised based on the zone of influence of primary & secondary injection. Results indicate that the zone of influence of secondary injection lies between 0.7 and 0.8 times the radial distance between the center of the tumor core and branch node point (extreme far endpoint on the invasive tumor surface). Additionally, the multi-injection strategy is more effective when the protrusion volume exceeds10%of the total volume. The proposed algorithm is used to devise multi-injection strategies for arbitrarily shaped tumors and will assist in pre-planning magnetic nanoparticle hyperthermia therapy.

FEM thermal assessment of a 3-D irregular tumor with capillaries in magnetic nanoparticle hyperthermia via dissimilar injection points

In this study, simulation of magnetic nanoparticle hyperthermia is performed on a 3D tumor model constructed based on a CT image of a tumor. In the first step, magnetic nanoparticles are injected into two points of the tumor tissue with the same parameters. Results show that temperature profiles in the vicinity of the injection points are not similar due to the presence of blood capillaries. Therefore, the effects of using dissimilar injection parameters for the two injection points on the heating pattern and damage fraction of the tumor are investigated. The results demonstrate that using dissimilar values for injection parameters such as injection rate, injection time, and nanofluid volume fraction is a way to achieve a higher damage fraction of the tumor cells, but, the asynchronous injections strategy does not lead to more significant damage to the tumor. None of the cases showed significant improvement in the uniformity of the temperature distribution, suggesting that conducting injections under the same conditions is the best way to create an almost uniform temperature profile. The numerical simulation validation results also advocate the accuracy of the model used in this study. This research can serve as a guide for designing parameters for future studies.