What happens to magnetic nanoparticles in cells?

February 13, 2019, CNRS
What happens to magnetic nanoparticles in cells?
Synthesis of magnetic nanoparticles within stem cells, starting from the degradation product from previously internalized nanoparticles. These biosynthesized nanoparticles are produced in situ within endosomes (white arrows) and measure 8 nm on average. Credit: Laboratory MSC (CNRS/University of Paris Diderot)

Although magnetic nanoparticles are being used more and more in cell imaging and tissue bioengineering, what happens to them within stem cells in the long term remained undocumented. Researchers from CNRS, the Sorbonne Université, and universities Paris Diderot and Paris 13, have shown substantial degradation of these nanoparticles, followed in certain cases by the cells "re-magnetizing." This phenomenon is the sign of biosynthesis of new magnetic nanoparticles from iron released in the intracellular medium by the degradation of the first nanoparticles. Published in PNAS on February 11, 2019, this work may explain the presence of "natural" magnetism in human cells, and help to envisage new tools for nanomedicine, thanks to this magnetism produced by the cells themselves.

Magnetic nanoparticles are at the core of today's nanomedicine: they serve as imaging diagnosis agents, thermal anti-cancer agents, drug targeting agents, and tissue engineering agents. The question of their fate in cells, after they have accomplished their therapeutic mission, was not well understood.

To follow the journey of these nanoparticles in cells, researchers at the Laboratoire Matière et Systèmes Complexes (CNRS/Université Paris Diderot) and the Laboratoire de Recherche Vasculaire Translationnelle (INSERM/Université Paris Diderot/Université Paris 13), in collaboration with scientists from Sorbonne Université1 have developed an original approach to nanomagnetism in living systems: first they incorporated in vitro in human . They then left them to differentiate and develop for one month, to observe them long term in the intracellular environ ment and to monitor their transformations.

By following the "magnetic fingerprint" of these nanoparticles in the cells, the researchers have shown that they were first being destroyed (cell magnetization falls) and releasing iron into the intracellular environment. Next, this "free" iron was stored in non-magnetic form in ferritin, the protein responsible for storing iron, or served as a base for the biosynthesis of new magnetic nanoparticles within the cell.

This phenomenon is known to occur in some bacteria, but a biosynthesis like this had never been shown in mammalian cells. This could explain the presence of magnetic crystals in humans, observed in the cells of diverse organs, particularly the brain. What is more, this iron storage in magnetic form could also be a way for the cell to "detoxify" over the to counter excess . From the point of view of nanomedicine, this biosynthesis open up a new path to the possibility of purely biological magnetic marking in cells.

Explore further: Magnetic cellular Legos for the regenerative medicine of the future

More information: Biosynthesis of magnetic nanoparticles from nano-degradation products revealed in human stem cells. PNAS, February 11, 2019, doi.org/10.1073/pnas.1816792116

Related Stories

Combining magnetism and light to fight cancer

April 1, 2015

By combining, in a liposome, magnetic nanoparticles and photosensitizers that are simultaneously and remotely activated by external physical stimuli (a magnetic field and light), scientists at the Laboratoire Matière et ...

Rare earth orthoferrite LnFeO3 nanoparticles for bioimaging

September 4, 2018

Magnetic resonance imaging (MRI) has emerged as one of the most powerful clinical imaging tools because of its superb spatial resolution and soft tissue contrast, especially when using contrast agents. In the European Journal ...

Recommended for you

When a defect might be beneficial

February 19, 2019

In the quest to design more efficient solar cells and light-emitting diodes (LEDs), a team of engineers has analyzed different types of defects in the semiconductor material that enables such devices to determine if and how ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.