Iron nanoparticles - biodistribution in the chicken embryo model

Magnetic nanoparticles (MNPs) show promise in many biomedical applications, including magnetic resonance imaging (MRI). Iron carbide compounds are good theragnostic contrast agents. Being nanosized might enable passage through a placenta, posing risks to embryonic development. This study investigates the biodistribution of intravenously injected carbon coated iron nanoparticles (ICNP) in chicken embryos.

Carbon coated iron nanoparticles (300 μg or 600 μg) were injected into a blood vessel on the chorioallantoic membrane (CAM) of chicken embryos (stages 23 to 26) according to Hamburger-Hamilton (H&H). 24 h after ICNP injection, embryos were formalin-fixed and imaged with T2-weighted MRI. Eighteen embryos (three per H&H stage 24-26 and dosage) were further analysed for ICNP deposits via MRI, histology, scanning electron microscopy (SEM) and X-ray spectroscopy (EDX).

Strong signal void artefacts were observed when treated with 600 μg and more pronounced with advancing stages. Deposits were prominent around the vascular system, however all developing organs showed ICNP deposits. Histological and SEM microscopy confirmed inter- and intracellular ICNP uptake in the developing brain. Iron was quantitatively verified in spots of histological sections by EDX. The overall tissue architecture remained intact.

The ICNPs are distributed into most embryo organs and cells without causing damage to the tissue and cells. Their potential to affect embryogenesis warrants further long-term investigation. If proven safe, ICNPs may be used as effective theragnostic agents in MRI as well as for personalized medicine because they can be functionalized with specific proteins or antibodies tailored at patient-specific targets.