A new study suggests that larger magnetic nanoparticles, which are used to carry a drug to the site in the human body and release it there, can be excreted by the kidneys. It was previously understood that the larger nanocarriers had to be dissolved in the liver in a process that could imply stronger side effects for the patient.
Scientists at the National University of Science and Technology in Moscow (NUST MISiS) have uncovered a new mechanism of removing nanoparticles from the body through the kidneys — a discovery that will help develop more effective and safer drugs.
The development of nanocarriers — extremely small materials used to deliver drugs to targeted sites in the human body — is an area of major scientific concern.
How they are transported through the organism depends on many properties, including their size, composition and coating.
Kidneys, for example, deal with particles of up to 6 nanometres in size, due to the small size of renal pores.
The liver — the main organ responsible for accumulation and elimination of nanoparticles — handles materials larger than 200 nanometers.
But the evidence is growing that larger nanoparticles can also be exerted into the urine by the kidneys.
In their findings, published in the Journal of Controlled Release in August, MISiS researchers and their peers from Pirogov Russian National Research Medical University described how they explored the possibility of eliminating iron oxide nanoparticles, coming in the shape of clusters and cubes measuring as much as 140 nanometres, through the kidneys.
Using a combination of methods such as atomic emission spectroscopy, fluorescence microscopy and magnetic resonance imaging, they discovered the rapid accumulation of magnetic nanoparticles in the kidneys of lab animals.
The scientists also tracked the transportation of nanoparticles in real time — and said they passed from the blood into the lumen of renal tubules just one hour after injection.
“Within two hours, magnetic nanoparticles were identified in the animals’ urine via transmission electron microscopy,” said study co-author Maxim Abakumov.
The findings lead the research team to suggest that nanoparticles can be transported directly into the renal tubules rather than into the glomeruli, the filtering units of the kidneys.
The study indicates the possibility of creating magnetic nanoparticles with a lower dose and fewer side effects, which will be excreted without waiting for dissolution in the liver for several weeks.
The scientists now plan to look into the best possible surface design and structure of magnetic nanoparticles to increase the efficiency of renal excretion.
