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A recent paper, by author Dr. P. M. Darbyshire, demonstrates how the numerical simulation of a system of complex nonlinear partial differential equations (PDEs) implemented using parallel algorithms, can be used to realistically describe the dynamics of magnetic nanoparticles (MNPs) in newly formed microvasculature surrounding solid tumours.
In the past few decades, nanomedicine, the exploitation of the unique properties of nanoscale and nanostructured materials in medical applications, has been explored extensively as a promising strategy in the advancement of anticancer therapies with the ability to overcome many of the limitations common to chemotherapeutic agents. Nanoparticles (NPs) have the potential to improve the biological distribution of chemotherapy drugs by protecting them from degradation, delivering them directly to the tumour site and preventing them from affecting healthy tissues. These systems are designed such that chemotherapeutics are either physically encapsulated within or chemically conjugated to the NP.
“Despite the ample evidence and extensive research effort supporting the benefits of nanotechnology in the treatment of cancer, clinically, both strategies have met with only moderate success. This is likely due to the fact that the complexity of the tumour microenvironment is commonly overlooked and has a major effect on NP extravasation, accumulation, and penetration into the tumour”, said Darbyshire.
One strategy that has been employed which can overcome many of the problems encountered by NPs upon extravasation from the tumour vessels is to target NPs to the tumour vasculature. Since the luminal surface of tumour vessels is completely accessible to circulating compounds, NPs targeting the tumour endothelium can bind to their target molecules without the need to penetrate into the tumour to deliver their contents. Recently, magnetic fields have been explored for enhancing NP delivery and efficacy in tumours. For example, in magnetic drug targeting (MDT), MNPs with surface-bound drug molecules are injected into the vascular system upstream from the malignant tissue, and are captured at the tumour via a localised magnetic field.
“It is also possible to know exactly where the MNPs are located within the microvasculature with great precision by making use of the wavelength of their fluorescent emissions from biologically reactive substances they can be decorated with”, said Darbyshire.
Upon achieving a sufficient concentration inside the tumour, the drug molecules are released from the carriers by changing physiological conditions, such as pH, osmolality, temperature, or by enzymatic activity. The released drug is taken up by the tumour cells, and the magnetic carriers are ultimately processed by the body. Since the therapeutic agents are localised to regions of diseased tissue, higher dosages can be applied which enables more effective treatment. This is in contrast to conventional chemotherapy in which a drug is distributed in a systemic fashion throughout the body, which can have a detrimental effect on healthy tissue.
Dr P. M. Darbyshire is Technical Director, Computational Biophysics Group, Algenet Cancer Research, Nottingham. UK.
Dynamics of Magnetic Nanoparticles in Newly Formed Microvascular Networks Surrounding Solid Tumours: A Parallel Programming Approach